GABA and GABA receptors in the gastrointestinal tract: from motility to inflammation

Although an extensive body of literature confirmed γ-aminobutyric acid (GABA) as mediator within the enteric nervous system (ENS) controlling gastrointestinal (GI) function, the true significance of GABAergic signalling in the gut is still a matter of debate. GABAergic cells in the bowel include neuronal and endocrine-like cells, suggesting GABA as modulator of both motor and secretory GI activity. GABA effects in the GI tract depend on the activation of ionotropic GABAA and GABAC receptors and metabotropic GABAB receptors, resulting in a potential noteworthy regulation of both the excitatory and inhibitory signalling in the ENS. However, the preservation of GABAergic signalling in the gut …

“Intracellular events following P2Y receptor activation in murine colonic circular muscle”.

Essential oil of Sicilian Prangos ferulacea (L.) Lindl. and its major component, β−ocimen, affect contractility in rat small and large intestine

Ethnopharmacological relevance: Prangos ferulacea (L.) Lindl is an Apiaceae plant, widely used in traditional medicine. Recently, chemical composition and biological activities of its essential oil (Prangroil) have been reported, but there are no studies on possible effects on intestinal contractility. Aims of the study: We investigated the effects of essential oil Sicilian Prangoil on the contractility of rat small (duodenum) and large (colon) intestine and the related action mechanism. Materials and methods: Responses to Prangoil and to its major component β-ocimen in intestinal segments were assessed in vitro as changes in isometric tension. Results: Prangoil, induced in duodenum, depend…

Nonsense codons suppression. An acute toxicity study of three optimized TRIDs in murine model, safety and tolerability evaluation.

Stop mutations cause 11% of the genetic diseases, due to the introduction of a premature termination codon (PTC) in the mRNA, followed by the production of a truncated protein. A promising therapeutic approach is the suppression therapy by Translational Readthrough Inducing Drugs (TRIDs), restoring the expression of the protein. Recently, three new TRIDs (NV848, NV914, NV930) have been proposed, and validated by several in vitro assays, for the rescue of the CFTR protein, involved in Cystic Fibrosis disease. In this work, an acute toxicological study for the three TRIDs was conducted in vivo on mice, according to the OECD No.420 guidelines. Animals were divided into groups and treated with …

Correlation of Metabolic Syndrome with Redox Homeostasis Biomarkers: Evidence from High-Fat Diet Model in Wistar Rats

Metabolic Syndrome (MetS) is an extremely complex disease. A non-balanced diet such as high-fat diet (HFD) induces metabolic dysfunction that could modify redox homeostasis. We here aimed at exploring redox homeostasis in male Wistar rats, following 8 weeks of HFD, correlating the eventual modification of selected biomarkers that could be associated with the clinical manifestations of MetS. Therefore, we selected parameters relative to both the glucose tolerance and lipid altered metabolism, but also oxidative pattern. We assessed some biomarkers of oxidative stress i.e., thiols balance, lipid peroxidation and antioxidant barriers, via the use of specific biochemical assays, individuating e…

Novel evidences for a role of dopamine as modulator of intestinal motility: a study on mouse distal colon

Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimer’s disease. It has been classically considered that the pathological hallmarks of PD affect primarily the substantia nigra. Nevertheless, it has become increasingly evident that PD is a multicentric neurodegenerative process that affects several neuronal structures outside the substantia nigra, among which is the enteric nervous system (ENS). Pathological alterations within the ENS could be involved in the gastrointestinal (GI) dysfunction frequently encountered by PD patients. Dopamine (DA) seems to be a major candidate for the impairment of GI function in PD since its levels were found to be decrea…

Involvement of inducible nitric oxide synthase in gastric relaxation of dystrophyc (mdx) mice.”

Mechanisms involved in adenosine-induced relaxation of mouse colon

Tachykinergic neurotransmission is enhanced in duodenum from dystrophic (mdx) mice

1 Duodenal longitudinal muscle of mdx mice, an animal model for Duchenne muscular dystrophy, showed a decrease in the electrically evoked nonadrenergic, noncholinergic (NANC) inhibitory responses associated with a reduction of the participation of nitric oxide (NO). In this study, we investigated whether the impairment of NO could also lead to alterations in the NANC excitatory transmission. 2 Nerve-evoked responses consisted of an inhibitory phase followed, at the end of stimulation, by an excitatory response characterised by an increase in amplitude of the spontaneous contractions. In mdx mice, the amplitude of the nerve-evoked contractions was significantly higher than in normals. 3 N(om…

Functional evidence for GABA as modulator of the contractility of the longitudinal muscle in mouse duodenum: Role of GABAA and GABAC receptors

We investigated, in vitro, the effects of gamma-aminobutyric acid (GABA) on the spontaneous mechanical activity of the longitudinal smooth muscle in mouse duodenum. GABA induced an excitatory effect, consisting in an increase in the basal tone, which was antagonized by the GABA(A)-receptor antagonist, bicuculline, potentiated by (1,2,5,6-Tetrahydropyridin-4-yl)methylphosphinic acid hydrate (TPMPA), a GABA(C)-receptor antagonist and it was not affected by phaclofen, a GABA(B)-receptor antagonist. Muscimol, GABA(A) receptor agonist, induced a contractile effect markedly reduced by bicuculline, tetrodotoxin (TTX), hexamethonium and atropine. Cis-4-aminocrotonic acid (CACA), a specific GABA(C) …

D1 receptors play a major role in the dopamine modulation of mouse ileum contractility

Since the role of dopamine in the bowel motility is far from being clear, our aim was to analyse pharmacologically the effects of dopamine on mouse ileum contractility. Contractile activity of mouse ileum was examined in vitro as changes in isometric tension. Dopamine caused a concentration-dependent reduction of the spontaneous contraction amplitude of ileal muscle up to their complete disappearance. SCH-23390, D1 receptor antagonist, which per se increased basal tone and amplitude of spontaneous contractions, antagonized the responses to dopamine, whilst sulpiride or domperidone, D2 receptor antagonists, were without effects. The application of both D1 and D2 antagonists had additive effe…

Cyclooxygenase inhibitors counteract pro-fibrotic signalling in experimental colitis through modulation of TGF-beta/SMAD network

Aims. Cyclooxygenase isoforms (COX-1, COX-2) have been implicated in the development of fibrosis at gastrointestinal sites. Under bowel inflammation, transforming growth factor beta (TGF-beta) has been identified as the main regulator of fibrotic remodelling. The present study investigated the effects of cyclooxygenase inhibitors on pro-fibrotic signalling mediated by the TGF-beta/SMAD pathway in experimental colitis. Methods. Colitis was induced in rats by intrarectal 2,4-dinitrobenzenesulfonic acid (DNBS, 30 mg/rat in 0.25 ml ethanol 50%). After 6 days, systemic [body and spleen weight] and tissue inflammatory parameters [macroscopic and microscopic damage] were assessed. Three days befor…

Anti-Inflammatory Potential of Brassicaceae-Derived Phytochemicals: In Vitro and In Vivo Evidence for a Putative Role in the Prevention and Treatment of IBD.

AbstractAbstract Inflammatory bowel disease (IBD) is a group of intestinal disorders, of unknown etiology, characterized by chronic inflammation within the gut. They are gradually becoming critical because of the increasing incidence worldwide and improved diagnosis. Due to the important side effects observed during conventional therapy, natural bioactive components are now under intense investigation for the prevention and treatment of chronic illnesses. The Brassicaceae family comprises vegetables widely consumed all over the world. In recent decades, a growing body of literature has reported that extracts from the Brassicaceae family and their purified constituents have anti-inflammatory…

Interplay between PACAP and NO in mouse ileum

Abstract We investigated the possibility that pituitary adenylate cyclase activating peptide (PACAP) has a role in the control of contractility in the mouse ileum. PACAP-(1-27) produced tetrodotoxin (TTX)-insensitive, concentration-dependent reduction of the amplitude of the spontaneous contractions of longitudinal muscle up to their complete disappearance. This effect was inhibited by PACAP-(6-38), PACAP receptor antagonist, and by apamin, blocker of small-conductance Ca2+-activated K+-channels. Nω-nitro- l -arginine methyl ester (L-NAME), nitric oxide (NO) synthase inhibitor, reduced the PACAP-inhibitory response, and the joint application of apamin plus L-NAME produced additive effects. …

Cellular transduction mechanisms underlying P2Y receptor activation in mouse colonic muscle

Adenosine negatively regulates duodenal motility in mice: role of A1 and A2A receptors

BACKGROUND AND PURPOSE Adenosine is considered to be an important modulator of intestinal motility. This study was undertaken to investigate the role of adenosine in the modulation of contractility in the mouse duodenum and to characterize the adenosine receptor subtypes involved. EXPERIMENTAL APPROACH RT-PCR was used to investigate the expression of mRNA encoding for A1, A2A, A2B and A3 receptors. Contractile activity was examined in vitro as changes in isometric tension. KEY RESULTS In mouse duodenum, all four classes of adenosine receptors were expressed, with the A2B receptor subtype being confined to the mucosal layer. Adenosine caused relaxation of mouse longitudinal duodenal muscle; …

Arginine vasopressin, via activation of post-junctional V1 receptors, induces contractile effects in mouse distal colon

The aim of this study was to analyze whether arginine vasopressin (AVP) may be considered a modulator of intestinal motility. In this view, we evaluated, in vitro, the effects induced by exogenous administration of AVP on the contractility of mouse distal colon, the subtype(s) of receptor(s) activated and the action mechanism. Isometric recordings were performed on longitudinal and circular muscle strips of mouse distal colon. AVP (0.001 nM-100 nM) caused concentration-dependent contractile effects only on the longitudinal muscle, antagonized by the V1 receptor antagonist, V-1880. AVP-induced effect was not modified by tetrodotoxin, atropine and indomethacin. Contractile response to AVP was…

Postnatal development of the dopaminergic signaling involved in the modulation of intestinal motility in mice

Background:Since antidopaminergic drugs are pharmacological agents employed in the management of gastrointestinal motor disorders at all ages, we investigated whether the enteric dopaminergic system may undergo developmental changes after birth.Methods:Intestinal mechanical activity was examined in vitro as changes in isometric tension.Results:In 2-d-old (P2) mice, dopamine induced a contractile effect, decreasing in intensity with age, replaced, at the weaning (day 20), by a relaxant response. Both responses were tetrodotoxin (TTX)-insensitive. In P2, dopaminergic contraction was inhibited by D1-like receptor antagonist and mimicked by D1-like receptor agonist. In 90-d-old (P90) mice, the …

"In medio stat virtus": Concentration-dependent effects of GABA on colonic motor patterns in mice

BACKGROUND AND AIMS: In the enteric nervous system, GABA (gamma amino butyric acid) has been shown to modulate neuronal activity via activation of different GABAergic receptors. The consequences of this modulation remain poorly understood and depend on the region of the gastrointestinal (GI) tract or on the animal species examined. Although several studies have been addressed the role of GABA as neuromodulator in the upper part of GI tract, accumulating data suggest that it may play a key role also in GI distal tract function in health and disease. Therefore, the aim of this study was to investigate the role of GABA in both spontaneous and electrically-evoked contractions and in the perista…

Investigating the inhibition of FTSJ1 a tryptophan tRNA-specific 2’-O-methyltransferase by NV TRIDs, as a mechanism of readthrough in nonsense mutated CFTR

Abstract: Cystic Fibrosis (CF) is an autosomal recessive genetic disease caused by mutations in the CFTR gene, coding for the CFTR chloride channel. About 10% of the CFTR gene mutations are "stop" mutations, which generate a Premature Termination Codon (PTC), thus synthesizing a truncated CFTR protein. A way to bypass PTC relies on ribosome readthrough, which is the ri-bosome’s capacity to skip a PTC, thus generating a full-length protein. “TRIDs” are molecules exerting ribosome readthrough; for some, the mechanism of action is still under debate. We in-vestigate a possible mechanism of action (MOA) by which our recently synthesized TRIDs, namely NV848, NV914, and NV930, could exert their r…

AphaMax®, an Aphanizomenon Flos-Aquae Aqueous Extract, Exerts Intestinal Protective Effects in Experimental Colitis in Rats

Background: Aphanizomenon flos-aquae (AFA) is a unicellular cyanobacterium considered to be a &ldquo

INVOLVEMENT OF GUANINE-BASED PURINES IN THE MODULATION OF CHOLINERGIC TRANSMISSION IN MOUSE COLONIC PREPARATIONS

ADENOSINE IS A MODULATOR OF THE CONTRACTILITY OF THE DUODENAL LONGITUDINAL MUSCLE IN MICE

Duodenal contractile activity in dystrophic (mdx) mice: reduction of nitric oxide influence.

The present study was undertaken to analyse duodenal contractility in adult dystrophic (mdx) mice. The spontaneous changes of the isometric tension and the responses of longitudinal duodenal muscle to nonadrenergic, noncholinergic (NANC) nerve stimulation and to exogenous drugs were compared between normal and mdx mice. Duodenal segments from mdx mice displayed spontaneous contractions with higher frequency than normals. N omega-nitro-L-arginine methyl ester (L-NAME) increased the frequency of contractions in normals without affecting that in mdx mice. In normals, NANC nerve stimulation elicited a transient relaxation abolished by L-NAME. In mdx mice a frank relaxation was not observed, the…

Non cholinergic excitatory transmission is enhanced in duodenum from dystrophic (mdx) mice

PD123319, angiotensin II type II receptor antagonist, inhibits oxidative stress and inflammation in 2, 4-dinitrobenzene sulfonic acid-induced colitis in rat and ameliorates colonic contractility

Angiotensin II, the main effector of renin angiotensin system, plays an important role in the inflammatory process and most of its effects are mediated through the AT1 receptor activation. However, the knowledge about the AT2 receptor involvement in this process is still evolving. We previously found that in an experimental model of colitis, AT2 receptor activation can contribute to the impairment of the muscle contractility in vitro in the course of inflammation. Here, we investigated the potential alleviating effects of the in vivo treatment of PD123319 (1-[[4-(Dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7- tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid ditriflu…

Excitatory neurotransmission in duodemun from dystrophic (mdx) mice

AT1 receptors mediate contractile effects of Angiotensin II on mouse colon

Angiotensin II (Ang II) is a potent smooth muscle contractile neurohumoral agonist via interaction with AT1 and AT2 receptors. Although these receptors are well expressed in the gut, very little research has been devoted to analysed the physiological role played by Ang II (and its receptors) in the regulation of gastrointestinal motility. The effects of Ang II on mouse proximal and distal colon contractility, the receptor subtypes involved were investigated in vitro, using the organ bath technique. Longitudinally-oriented segments from mouse proximal and distal colon displayed ongoing contractile activity, characterized by phasic contractions. Ang II induced a concentration-dependent muscul…

THE ENTERIC NERVOUS SYSTEM: NEW DEVELOPMENTS AND EMERGING CONCEPTS

The enteric nervous system (ENS) is an integrative neuronal network, organized in two ganglionated plexuses, myenteric and submucosal, composed of neurons and enteric glial cells, controlling the activity of the smooth muscle of the gut, mucosal secretion and blood flow. The ENS contains as many neurons as the spinal cord, and the functional and chemical diversity of enteric neurons closely resembles that of the central nervous system. This highly integrated neural system is also referred to as the ‘brain-in-the-gut’, because of its capability to function in the absence of nerve inputs from the central nervous system.

Opposite role played by GABAA and GABAB receptors in the modulation of peristaltic activity in mouse distal colon.

We investigated the role of GABA on intestinal motility using as model the murine distal colon. Effects induced by GABA receptors recruitment were examined in whole colonic segments and isolated circular muscle preparations to analyze their influence on peristaltic reflex and on spontaneous and neurally-evoked contractions. Using a modified Trendelenburg set-up, rhythmic peristaltic contractions were evoked by gradual distension of the colonic segments. Spontaneous and neurally-evoked mechanical activity of circular muscle strips were recorded in vitro as changes in isometric tension. GABA, at low concentrations (10-50 µM), potentiated peristaltic activity and the neural cholinergic contrac…

Pharmacological characterization of Uracil nucleotide-sensitive P2Y receptors in mouse ileum

Since uracil nucleotide-preferring receptors, belonging to the P2Y receptor family and responding to either uridine triphosphate (UTP) or uridine diphosphate (UDP), have been proposed to be present at different cellular level in the gut, regulating various functions, we aimed to investigate whether their activation by uracil nucleotides may modulate the contractility of the intestinal muscle. Experiments were carried out in vitro, and the contractility of the longitudinal muscle from mouse ileum was recorded as changes of the isometric tension. UDP or UTP evoked a concentrationdependent, tetrodotoxin insensitive, contractile response. UDP effect was antagonized by suramin and by PPADS, P2 r…

Defective dopaminergic control of contractility in colon from hypoxanthine‐guanine phosphoribosyltransferase deficient (HPRT‐) knockout mice

Ruolo del GABA come modulatore della attività contrattile nel duodeno di topo :coinvolgimento dei recettori GABAA E GABAC.”

Mechanisms underlying nitric oxide inhibitory effects in mouse ileal longitudinal muscle

Tachykinergic neurotransmission is enhanced in duodenum from dystrophic (mdx ) mice

1 Duodenal longitudinal muscle of mdx mice, an animal model for Duchenne muscular dystrophy, showed a decrease in the electrically evoked nonadrenergic, noncholinergic (NANC) inhibitory responses associated with a reduction of the participation of nitric oxide (NO). In this study, we investigated whether the impairment of NO could also lead to alterations in the NANC excitatory transmission. 2 Nerve-evoked responses consisted of an inhibitory phase followed, at the end of stimulation, by an excitatory response characterised by an increase in amplitude of the spontaneous contractions. In mdx mice, the amplitude of the nerve-evoked contractions was significantly higher than in normals. 3 N(om…

Inhibitory control of duodenal contractility by adenosine in mice

Chemical Characterization and Cytotoxic and Antioxidant Activity Evaluation of the Ethanol Extract from the Bulbs of Pancratium maritimun Collected in Sicily

P. maritimum L., belonging to the Amaryllidaceae family, is a species that grows on beaches and coastal sand dunes mainly on both sides of the Mediterranean Sea and Black Sea, the Middle East, and up to the Caucasus region. It has been largely investigated due to its several interesting biological properties. With the aim of providing new insights into the phytochemistry and pharmacology of this species, the ethanolic extract of the bulbs from a local accession, not previously studied, growing in Sicily (Italy), was investigated. This chemical analysis, performed by mono- and bi-dimensional NMR spectroscopy, as well as LC-DAD-MSn, allowed to identify several alkaloids, three of which were n…

Mechanisms underlying hyperpolarization evoked by P2Y receptor activation in mouse distal colon

In murine colonic circular muscle, ATP mediates fast component of the nerve-evoked inhibitory junction potentials, via activation of P2Y receptors and opening of apamin-sensitive Ca2+-dependent K+ channels. We investigated, using microelectrode recordings, the intracellular events following P2Y-receptor activation by electrical field stimulation or by adenosine 5'-O-2-thiodiphosphate (ADPbetaS), ATP stable analogue. The fast-inhibitory junction potential amplitude was reduced by thapsigargin or ciclopiazonic acid (CPA), sarcoplasmic reticulum Ca2+-ATPase inhibitors, by ryanodine, which inhibits Ca2+ release from ryanodine-sensitive stores, and by 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (S…

Prejunctional Modulation of Purinergic Neurotransmission by P2Y1 Receptors in Mouse Caecum

Inhibitory purinergic transmission in mouse caecum: Role for P2Y1 receptors as prejunctional modulators of ATP release

Using conventional microelectrode recording techniques, we investigated, in the circular muscle of the mouse caecum, the neurotransmitter(s) involved in the neurally-evoked inhibitory junction potentials (IJPs) and the existence of possible prejunctional mechanisms controlling neurotransmitter release. Electrical field stimulation with single pulses elicited IJPs, consisting only of a "fast" hyperpolarization, while using train stimuli (30-50 Hz) the initial fast hyperpolarization was followed by a slower hyperpolarization. The fast and the slow component were selectively antagonized by apamin, a blocker of calcium-activated potassium channels, and N(omega)-nitro-l-arginine methyl ester (l-…

Translational readthrough inducing drugs: a study of toxicity in mice models and in vitro safety validation of the specific readthrough process.

Objective Nonsense mutations are responsible for 15% of Cystic Fibrosis (CF) patients due to the introduction of a premature stop codon (PTC) in the mRNA and the production of a truncated CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein1. A promising therapeutic approach for stop mutations is the suppression therapy by Translational Readthrough Inducing Drugs (TRIDs) to restore the expression of the protein2,3. Recently three new TRIDS (NV848, NV914, NV930) have been proposed and validated by several assays. Our work was focused on TRIDs NV848, NV914, NV930. Important aspects of TRIDs to be evaluated are their specificity towards PTC, to demonstrate that TRIDs do not inter…

A1 receptor-mediated modulatory effects of adenosine on the contractility in mouse ileum: characterization of signal transduction pathway

Functional analysis of the digestive tract in mdx mice

Angiotensin II contractile effects in mouse colon: role for pre- and post-junctional AT1A receptors

Aim This study investigates whether a local renin–angiotensin system (RAS) exists in mouse colon and whether angiotensin II (Ang II) may play a role in the regulation of the contractile activity. Methods Isometric recordings were performed in vitro on the longitudinal muscle of mouse proximal and distal colon. Transcripts encoding for RAS components were investigated by RT-PCR. Results Ang II caused, in both preparations, a concentration-dependent contractile effect, antagonized by losartan, AT1 receptor antagonist, but not by PD123319, AT2 receptor antagonist. The combination of losartan plus PD123319 caused no change on the Ang II-induced contraction than losartan alone. Tetrodotoxin, neu…

Age-related differences of γ-aminobutyric acid (GABA)ergic transmission in human colonic smooth muscle.

Background: Enteric neurons undergo to functional changes during aging. We investigated the possible age-associated differences in enteric γ-aminobutyric acid (GABA)ergic transmission evaluating function and distribution of GABAergic receptors in human colon. Methods: Mechanical responses to GABA and GABA receptor agonists on slow phasic contractions were examined in vitro as changes in isometric tension in colonic muscle strips from young (<65 years old) and aged patients (>65 years old). GABAergic receptor expression was assessed by quantitative RT-PCR. Key Results: In both preparations GABA induced an excitatory effect, consisting in an increase in the basal tone, antagonized by th…

Angiotensin II type II receptors and colonic dysmotility in 2,4-dinitrofluorobenzenesulfonic acid-induced colitis in rats

Background: Angiotensin II (Ang II), the main peptide of the renin-angiotensin system (RAS), has been suggested to be involved in inflammatory bowel diseases. Since RAS has emerged as gut motility regulator, and dysmotility is associated with intestinal inflammation, our objective was to investigate in rat 2,4-dinitrobenzenesulfonic acid (DNBS)-induced colitis the functionality of RAS and its contribution to colonic motor alterations. Methods: The effects of Ang II on the longitudinal colonic muscular contractility of control and DNBS-treated rats were characterized in vitro. Transcripts encoding for Ang II receptors were investigated by RT-PCR. Key Results: Inflamed preparations showed a l…

Pharmacological characterization of uracil nucleotide-preferring P2Y receptors modulating intestinal motility: a study on mouse ileum.

We investigated the possible modulation of the intestinal contractility by uracil nucleotides (UTP and UDP), using as model the murine small intestine. Contractile activity of a mouse ileum longitudinal muscle was examined in vitro as changes in isometric tension. Transcripts encoding for uracil-sensitive receptors was investigated by RT-PCR. UDP induced muscular contractions, sensitive to PPADS, suramin, or MRS 2578, P2Y(6) receptor antagonist, and mimicked by PSB 0474, P2Y(6)-receptor agonist. UTP induced biphasic effects characterized by an early inhibition of the spontaneous contractile activity followed by muscular contraction. UTP excitatory effects were antagonized by PPADS, suramin,…

Control of enteric neuromuscular functions by purinergic P2X7 receptors in normal rat distal colon and experimental bowel inflammation

Introduction: Purinergic signalling plays a pivotal role in the physiological regulation of several enteric functions, as well as in the modulation of immune/inflammatory cell activity. Recent evidence has shown an active involvement of the purinergic P2X7 receptor (P2X7R) in the fine tuning of immune functions, as well as its critical role in driving enteric neuron apoptosis under intestinal inflammation. However, the participation of this receptor pathway in the regulation of enteric neuromuscular functions remains undetermined. Aims: This study investigated the role of P2X7Rs in the control of colonic motility, both under normal conditions and in the presence of experimental colitis. Met…

Preventive effects of guanosine on intestinal inflammation in 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rats

Background: Guanosine, a guanine-based purine, is an extracellular signaling molecule exerting anti-inflammatory and antioxidative effects in several in vivo and in vitro injury models. We aimed to investigate its protective effects on 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rat. Methods: Rats were divided into five groups and colitis was induced by intracolonic instillation of DNBS (15 mg/rat). Guanosine (4 or 8 mg/kg) was administered for 6 days i.p. starting the day of the colitis induction. Body weight loss, stool consistency, colon weight/length, histological analysis, myeloperoxidase activity (MPO) and pro-inflammatory cytokine levels were assessed. Immunoblotting …

Altered gastrointestinal motility in an animal model of Lesch-Nyhan disease.

Mutations in the HGPRT1 gene, which encodes hypoxanthine-guanine phosphoribosyltransferase (HGprt), housekeeping enzyme responsible for recycling purines, lead to Lesch-Nyhan disease (LND). Clinical expression of LND indicates that HGprt deficiency has adverse effects on gastrointestinal motility. Therefore, we aimed to evaluate intestinal motility in HGprt knockout mice (HGprt(−)). Spontaneous and neurally evoked mechanical activity was recorded in vitro as changes in isometric tension in circular muscle strips of distal colon. HGprt(−) tissues showed a lower in amplitude spontaneous activity and atropine-sensitivity neural contraction compared to control mice. The responses to carbachol a…

Evidence for a role of inducible nitric oxide synthase in gastric relaxation of mdx mice

Alterations of gastric mechanical activity have been reported in mdx mouse, animal model for Duchenne muscular dystrophy. This study examined if alterations in the vasoactive intestinal polypeptide (VIP) system are present in mdx stomach. Gastric mechanical activity was recorded in vitro as changes of endoluminal pressure and neurally or pharmacologically evoked relaxations were analysed in mdxvs normal stomach. Reverse-transcription polymerase chain reaction was used to detect inducible nitric oxide synthase (iNOS) expression. Relaxations to sodium nitroprusside in mdx stomach showed no difference in comparison with normal preparations. In normal stomach, VIP produced relaxation, which was…

Adenosine negatively regulates duodenal motility in mice: role of A1 and A2a receptors .

Evidence that ATP or a related purine is an excitatory neurotransmitter in the longitudinal muscle of mouse distal colon

Background and purpose: This study analysed the contribution of the purinergic system to enteric neurotransmission in the longitudinal muscle of mouse distal colon. Experimental approach: Motor responses to exogenous ATP and to nerve stimulation in vitro were assessed as changes in isometric tension. Key results: ATP induced a concentration-dependent contraction, reduced by 4-[[4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzene disulphonic acid (PPADS), suramin, P2Y purinoreceptor desensitisation with adenosine 5’-O-2-thiodiphosphate (ADPβS), and atropine, but unaffected by P2X purinoceptor desensitisation with α,β-methylene ATP (α,β-meATP) and by 2,2-dimethyl…

DEFECTS IN DOPAMINERGIC PATHWAY AFFECT CONTRACTILITY OF COLON FROM HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE (HPRT) KNOCKOUT MICE.

Lesch-Nyhan disease is an X-linked neurobehavioral and metabolic disorder caused by lack of hypoxanthine phosphoribosyltransferase (HPRT), a housekeeping enzyme responsible for recycling purines. The mechanisms underlying the neuropathology are not well understood, but the main neurochemical defect, in central nervous system, is linked to a dysfunction of dopaminergic pathway. In the enteric nervous system the dopaminergic nerves are a subset neurons of regulating gut motility, thus we investigated possible changes in colonic motility of HPRT ¯mice related to the dopaminergic control. We evaluated, in vitro, the mechanical activity of circular muscle strips from wild type and HPRT – mouse c…

Tracking the invasion of the red swamp crayfish Procambarus clarkii (Girard, 1852) (Decapoda Cambaridae) in Sicily: a “citizen science” approach

Author(s): Faraone, Francesco Paolo; Giacalone, Gabriele; Canale, Domenica Emanuela; D'Angelo, Stefania; Favaccio, Giorgio; Garozzo, Vincenzo; Giancontieri, Giacoma Lidia; Isgro, Carmelo; Melfi, Raffaella; Morello, Bruno; Navarria, Federica; Russo, Giuseppe; Tinnirello, Viviana; Torre, Antonio; Torre, Daniele; Torre, Giancarlo; Urso, Giuseppe; Vinci, Pierluigi; Zizzo, Maria Grazia; Marrone, Federico | Abstract: The first record of the red swamp crayfish in Sicily dates back to 2003 and, since then, the species seemed to be confined to a few localities in western Sicily. A small “citizen science” project carried out from November 2016 onwards led to the creation of the “Sicilian Procambarus …

Activation of angiotensin II type 1 receptors and contractile activity in human sigmoid colon in vitro.

We propose and validate a non-invasive method that enables accurate detection of the discharge times of a relatively large number of motor units during excitatory and inhibitory reflex stimulations. HDsEMG and intramuscular EMG (iEMG) were recorded from the tibialis anterior muscle during ankle dorsiflexions performed at 5%, 10%, and 20% of the maximum voluntary contraction (MVC) force, in 9 healthy subjects. The tibial nerve (inhibitory reflex) and the peroneal nerve (excitatory reflex) were stimulated with constant current stimuli. In total, 416 motor units were identified from the automatic decomposition of the HDsEMG. The iEMG was decomposed using a state-of-the-art decomposition tool a…

GUANOSINE EFFECTS ON THE MOTOR ACTIVITY OF THE MOUSE STOMACH

Guanine-based purines are part of the purinergic system and recently have been shown to act as neuromodulators, interfering with acetylcholine release by enteric neurons in mouse colon. Due to the pivotal role played by enteric neurons in the control of gastrointestinal motility, the aim of the present study was to verify whether guanosine may affect gastric emptying and the mechanical tone, detected in vitro as changes in intraluminal pressure, of the isolated mouse stomach. Guanosine induced a TTX-insensitive concentration-dependent relaxation of isolated stomach, which at the maximal concentration tested (1 mM), reached about 60% of the relaxation induced by 1 mM isoproterenol. The inhib…

Guanine-based purines affects the enteric cholinergic neurotransmission via a mechanism not involving membrane receptors

Increasing evidence indicate that guanine-based purines, known as modulators of intracellular processes, can exert extracellular effects, raising the possibility of the existence of specific receptors for these compounds. We investigated if guaninebased purine receptors may be present in the rodent gastrointestinal tract modulating intestinal contractility, as the well known adenine-based purine receptors. Experiments were performed in vitro recording spontaneous and neurally-evoked contractile activity, as changes in isometric tension, in mouse distal colon circular muscle. Guanosine up to 3 mM or guanine up to 1 mM, did not affect the spontaneous mechanical activity, but they significantl…

GABA & “LITTLE BRAIN”: RUOLO EMERGENTE NEL CONTROLLO DELLA MOTILITÀ INTESTINALE

L’acido gamma-ammino butirrico (GABA) è ampiamente riconosciuto come principale neurotrasmettitore inibitore nel sistema nervoso centrale dei mammiferi. Tuttavia numerose evidenze sperimentali suggeriscono una sua azione anche a livello del sistema nervoso enterico (o “little brain”), sezione del sistema nervoso periferico deputata al controllo della funzionalità del tratto gastrointestinale (GI). Dal momento che, ad oggi, gli effetti del GABA rimangono ancora non chiari e sembrerebbero dipendere dalla porzione del tratto GI considerata o dal modello animale esaminato, lo scopo di questo lavoro è stato quello di studiare l’effetto del GABA sulla contrattilità della muscolatura circolare del…

Interaction between cannabinoid CB1 receptors and endogenous ATP in the control of spontaneous mechanical activity in mouse ileum

Background and purpose Although it is well accepted that cannabinoids modulate intestinal motility by reducing cholinergic neurotransmission mediated by CB(1) receptors, it is not known whether the endocannabinoids are involved in more complex circuits and if they interact with other systems. The aim of the present study was to examine possible interactions between cannabinoid CB(1) receptors and purines in the control of spontaneous contractility of longitudinal muscle in mouse ileum. Experimental approach The mechanical activity of longitudinally oriented ileal segments from mice was recorded as isometric contractions. Key results The selective CB(1) receptor agonist, N-(2-chloroethyl)5,8…

Angiotensin II type-2 receptors and colonic dysmotility associated to experimental colitis in rats

Angiotensin II (Ang II) is a newly discovered modulator of intestinal motility, mainly via activation of excitatory AT1 receptors (AT1R). We demonstrated that during gut inflammation there is a recruitment of inhibitory AT2 receptors (AT2R) which would counteract the AT1R-induced effects. Our objective was to explore the consequence of AT2R activation in the pathogenesis of experimental colitis. Colitis was induced in rats by intrarectal administration of 2,4-Dinitrobenzene sulfonic acid (DNBS). Colonic damage was assessed by macro- and microscopic scores, myeloperoxidase activity and inflammatory cytokine expression on day 6 after colitis induction. Colonic contractility was recorded in vi…

Un’alterata funzionalita’ del sistema nitrergico determina modificazioni della motilita’ del duodeno di topi distrofici (mdx)”

ANTIPROLIFERATIVE EFFECTS OF GUANINE-BASED PURINES AND IDENTIFICATION OF A CANDIDATE RECEPTOR

Residual out-of-plane capacity of infills damaged by in-plane cyclic loads

Abstract During earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the case of strong earthquakes, infills may progressively change their mechanical behavior resulting in a reduction of IP and OOP stiffness and strength. Recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also for buildings designed to resist seismic events in agreement to the most modern codes. This is potentially a very dangerous event with risk for human health. The strong interaction between IP and OOP behavior of infills traduces in a progressive reduction of the OOP strength. The IP damaging loads may cause a loss of the OOP capacity not predicted…

Activation of P2Y receptors by ATP and by its analogue, ADPbetaS, triggers two calcium signal pathways in the longitudinal muscle of mouse distal colon.

Our previous research showed that ATP and adenosine 5'-O-2-thiodiphosphate (ADPbetaS) induce contractile effects in the longitudinal muscle of mouse distal colon via activation of P2Y receptors which are not P2Y(1) or P2Y(12) subtypes. This study investigated the nature of the P2Y receptor subtype(s) and the mechanisms leading to the intracellular calcium concentration increase necessary to trigger muscular contraction. Motor responses of mouse colonic longitudinal muscle to P2Y receptor agonists were examined in vitro as changes in isometric tension. ATP or ADPbetaS induced muscular contraction, which was not affected by P2Y(11) or P2Y(13) selective antagonists. Calcium-free solution or th…

Role for D1-like and D2-like dopamine receptors in the modulation of intestinal motility in mice

Objective: In the last years a plethora of studies addressed dopamine (DA) as a modulator within the enteric nervous system (ENS), controlling gastrointestinal (GI) functions via activation of D1- and D2-like receptors. However, the effective role and functional significance of DA in the ENS, and the contribution of its receptors, are still a matter of debate. Pathological alterations of dopaminergic system in the gut may be likely implicated in different motor GI disorders, including dyspepsia and gastroparesis. Thus, a detailed characterization of the enteric dopaminergic signalling is necessary. The aim of this study was to explore the role of DA in the GI tract, using as model the mouse…

Guanosine negatively modulates the gastric motor function in mouse

The aim of the present study was to evaluate if guanine-based purines may affect the gastric motor function in mouse. Thus, the influence of guanosine on the gastric emptying rate in vivo was determined and its effects on spontaneous gastric mechanical activity, detected as changes of the intraluminal pressure, were analyzed in vitro before and after different treatments. Gastric gavage of guanosine (1.75-10 mg/kg) delayed the gastric emptying. Guanosine (30 μM-1 mM) induced a concentration-dependent relaxation of isolated stomach, which was not affected by the inhibition of the purine nucleoside phosphorylase enzyme by 4'-deaza-1'-aza-2'-deoxy-1'-(9-methylene)-immucillin-H. The inhibitory …

Aging modifies receptor expression but not muscular contractile response to angiotensin II in rat jejunum

AbstractThe involvement of renin-angiotensin system in the modulation of gut motility and age-related changes in mRNA expression of angiotensin (Ang II) receptors (ATR) are well accepted. We aimed to characterize, in vitro, the contractile responses induced by Ang II, in jejunum from young (3–6 weeks old) and old rats (≥ 1 year old), to evaluate possible functional differences associated to changes in receptor expression. Mechanical responses to Ang II were examined in vitro as changes in isometric tension. ATR expression was assessed by qRT-PCR. Ang II induced a contractile effect, antagonized by losartan, AT1R antagonist, and increased by PD123319, AT2R antagonist, as well by neural block…

Opposite effects of dopamine on the mechanical activity of longitudinal and circular muscles in human colon

Objective: Dopamine (DA) has been proposed to act as a modulator of GI motility, via activation of specific receptors D1- and D2-like receptors widely expressed throughout the length of the gastrointestinal tract, in different animal species. However, little and not clear information are available about DA effect in the human gut. The aims of this study were to elucidate whether dopamine may affect contractility in human colon, the receptor subtypes involved and the possible differences in the function and distribution of dopaminergic receptors between longitudinal and circular muscle. Methods: Mechanical responses to dopamine were examined in vitro as changes in isometric tension in strips…

Ultrastructural changes in the Interstitials Cells of Cajal and gastric dysrhythmias in mice lacking full-length dystrophin (mdx mice)

At least two populations of c-kit positive interstitial cells of Cajal (ICC) lie in the gastric wall, one located at the myenteric plexus level has a pace-making function and the other located intramuscularly is intermediary in the neurotransmission and regenerates the slow waves. Both of these ICC sub-types express full-length dystrophin. Mdx mice, an animal model lacking in full-length dystrophin and used to study Duchenne muscular dystrophy (DMD), show gastric dismotilities. The aim of the present study was to verify in mdx mice whether: (i) gastric ICC undergo morphological changes, through immunohistochemical and ultrastructural analyses; and (ii) there are alterations in the electrica…

A1 receptors mediate adenosine inhibitory effects in mouse ileum via activation of potassium channels.

Abstract Aims We investigated the effects induced by exogenous adenosine on the spontaneous contractile activity of the longitudinal muscle of a mouse ileum, the receptor subtypes activated, the involvement of enteric nerves and whether opening of K + channels was a downstream event leading to the observed effects. Main methods Mechanical responses of the mouse ileal longitudinal muscle to adenosine were examined in vitro as changes in isometric tension. Key findings Adenosine caused a concentration-dependent reduction of the spontaneous contraction amplitude of the ileal longitudinal muscle up to its complete disappearance. This effect induced was markedly reduced by an A 1 receptor antago…

Inducible nitric oxide synthase participates to the evoked relaxation in dystrophic (mdx) gastric preparations

Step-by-Step Regeneration of Tentacles after Injury in Anemonia viridis—Morphological and Structural Cell Analyses

Benthic marine invertebrates, such as corals, are often subjected to injury caused by several sources. Here, the differences and characteristics in injured and health tissues in terms of cellular components are shown through a histological investigation of the soft coral Anemonia viridis at 0 h, 6 h, 24 h, and 7 days after injury caused by tentacle amputation. In addition, a new tool was used for the first time in invertebrates, positron emission tomography, in order to investigate the events that occur during regeneration within a longer time period (0 h, 24 h, and 14 days after the tentacles were cut). Higher integrated density values were measured through a densitometric analysis in sect…

Nitric oxide induces muscular relaxation via cyclic GMP-dependent and -independent mechanisms in the longitudinal muscle of the mouse duodenum

The aim of this study was to investigate, in mouse duodenum, the role of nitric oxide (NO) in the relaxation of longitudinal muscle evoked by nerve activation and the coupled action mechanism. Electrical field stimulation (EFS; 0.5ms, 10-s train duration, supramaximal voltage, at various frequencies) under nonadrenergic noncholinergic conditions evoked muscular relaxation occasionally followed, at the higher stimulus frequencies, by rebound contractions. Inhibition of the synthesis of NO by Nω-nitro-L-arginine methyl ester (L-NAME; 100μM) virtually abolished the evoked relaxation. The relaxation was reduced also by apamin (0.1μM) and by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 1μM)…

Inhibition of FTSJ1, a tryptophan tRNA-specific 2’-O-methyltransferase as possible mechanism to readthrough premature termination codons (UGAs) of the CFTR mRNA

Cystic Fibrosis (CF) is an autosomal recessive genetic disease caused by mutations in the CFTR gene, coding for the CFTR chloride channel. About 10 % of the mutations affecting the CFTR gene are "stop" mutations, which generate a Premature Termination Codon (PTC), thus resulting in the synthesis of a truncated CFTR protein. A way to bypass PTC relies on ribosome readthrough, that is the capacity of the ribosome to skip a PTC, thus generating a full-length protein. “TRIDs” are molecules exerting ribosome readthrough and for some of them the mechanism of action is still under debate. By in silico analysis as well as in vitro studies, we investigate a possible mechanism of action (MOA) by whic…

Opposite effects of dopamine on the mechanical activity of circular and longitudinal muscle of human colon.

Background Because dopamine (DA) has gained increasing evidence as modulator of gut motility, we aimed to characterize dopaminergic response in human colon, evaluating function and distribution of dopamine receptors in circular vs longitudinal muscle strips. Methods Mechanical responses to DA and dopaminergic agonists on slow phasic contractions and on basal tone were examined in vitro as changes in isometric tension. RT-PCR was used to reveal the distribution of dopaminergic receptors. Key results In spontaneous active circular muscle, DA induced an increase in the amplitude of slow phasic contractions and of the basal tone, via activation of D1-like receptors. DA contractile responses wer…

Activation of P2Y receptors by ATP and by its analogue, ADPbetaS, triggers two calcium signal pathways in the longitudinal muscle of mouse distal colon.

Our previous research showed that ATP and adenosine 5'-O-2-thiodiphosphate (ADPbetaS) induce contractile effects in the longitudinal muscle of mouse distal colon via activation of P2Y receptors which are not P2Y(1) or P2Y(12) subtypes. This study investigated the nature of the P2Y receptor subtype(s) and the mechanisms leading to the intracellular calcium concentration increase necessary to trigger muscular contraction. Motor responses of mouse colonic longitudinal muscle to P2Y receptor agonists were examined in vitro as changes in isometric tension. ATP or ADPbetaS induced muscular contraction, which was not affected by P2Y(11) or P2Y(13) selective antagonists. Calcium-free solution or th…

The GABAergic System and the Gastrointestinal Physiopathology.

Since the first report about the presence of γ-aminobutyric acid (GABA) within the gastrointestinal (GI) tract, accumulating evidence strongly supports the widespread representation of the GABAergic system in the enteric milieu, underlining its potential multifunctional role in the regulation of GI functions in health and disease. GABA and GABA receptors are widely distributed throughout the GI tract, constituting a complex network likely regulating the diverse GI behaviour patterns, cooperating with other major neurotransmitters and mediators for maintaining GI homeostasis in physiologic and pathologic conditions. GABA is involved in the circuitry of the enteric nervous system, controlling…

GABA and its receptors in the enteric nervous system of the gastrointestinal tract.

Altered electrical activity in duodenal muscle cells from mdx (dystrophic) mice.

Postnatal developmental changes in the dopaminergic signaling in mouse gut

The presence of dopamine-containing neurons in the enteric nervous system has been described, but it is far to be clear their role in the modulation of gut motility. Moreover, ontogenetic studies shows that dopaminergic neurons are late-developing neurons, arising perinatally, but there are no informations if dopaminergic signaling may undergo to developmental changes after birth, as demonstrated for other signaling. Thus, using a pharmacological approach, we examined, in vitro, the role of dopaminergic neurons in the regulation of duodenal contractility in neonatal mice (≤48 h postnatal) compared to the adults. Transcripts for all dopaminergic receptors were detected in mouse duodenum at e…

Intracellular mechanisms involved in NO-induced relaxation of mouse ileum

ATP contributes to excitatory enteric neurotransmission in the longitudinal muscle of mouse distal colon.

A1 ADENOSINE RECEPTOR MODULATION OF CONTRACTILITY IN MOUSE DUODENUM LONGITUDINAL MUSCLE.

Experimental evidence suggests that adenosine is involved in the regulation of gastrointestinal functions. In the present study we examined the influence of adenosine on the contractile activity of mouse duodenum longitudinal muscle. Reverse transcription-polymerase chain reaction revealed the expression of all the adenosine receptors in whole thickness duodenum, being the A2B receptors expressed only in the neuromuscular layer. Mechanical activity of longitudinally oriented duodenal segments was recorded in vitro as changes in isometric tension. Adenosine produced concentration-dependent relaxation, markedly reduced by DPCPX, A1 receptor antagonist, but unaffected by DMPX or MRS 1220, A2 a…

Relaxation Induced By Guanosine in Mouse Stomach

Guanine-based purines are part of the purinergic system and recently have been shown to act as neuromodulators, interfering with acetylcholine release by enteric neurons in mouse colon. Due to the pivotal role played by enteric neurons in the control of gastrointestinal motility, the aim of the present study was to verify whether guanosine may affect gastric emptying and the mechanical tone, detected in vitro as changes in intraluminal pressure, of the isolated mouse stomach. Guanosine induced a TTX-insensitive concentration-dependent relaxation of isolated stomach, which at the maximal concentration tested (1 mM), reached about 60% of the relaxation induced by 1 µM isoproterenol. The inhib…

P100 Guanosine prevents nuclear factor-κB nuclear translocation ameliorating experimental colitis in rats

Comparison of pacing activity in duodenal muscle cells from and mdx (dystrophic) mice.

POSTNATAL MATURATION OF SEROTONIN SIGNALING SYSTEM IN MOUSE DUODENUM

BACKGROUND AND AIMS: A plethora of study in animal neurodevelopmental models demonstrate that in central nervous system (CNS) temporal differences occur in the maturation of different neurotransmitter systems (Goldman-Rakic & Brown, 1982, Ehrlich et al., 2013). Although significant advances have been made in understanding the modifications in CNS, only primarily descriptive studies about the changes taking place in enteric nervous system (ENS), main regulator of gastrointestinal (GI) functions, have been underway. As the other organ systems, digestive system is still developing and maturing after birth and thus it is possible to speculate that the changes in the chemical coding of ENS may o…

P2Y-mediated contractile responses in the longitudinal muscle of mouse distal colon: distinct signaling pathways

The renin–angiotensin system in gastrointestinal functions

In this chapter, we describe the role played by classical and alternative renin–angiotensin system (RAS) in the physiological regulation of gastrointestinal functions. RAS modulates gut motility and mucosal functions, including secretion, fluid, and nutrient absorption. We focus mainly on the activation of angiotensin II type 1 and 2 receptors located on the smooth muscle and epithelial cells or on the enteric neurons. Few studies indicate that alternative RAS may counteract classical RAS functions. Although data on the enteric RAS system are still scarce, they encourage further investigations in consideration also of a potential involvement in gastrointestinal disorders.

Is guanine a regulator of contractility in rat colon?

"A1 receptors mediate the inhibitory effects of adenosine on the contractility in mouse ileum.”

Agonist-specific Ca2+ signaling at P2Y receptors

POSTNATAL DEVELOPMENT OF THE 5-HYDROXYTRYPTAMINE (5-HT) SIGNALING SYSTEM IN THE MOUSE

Enhanced anticancer effect of quercetin microparticles formulation obtained by spray drying

This study unravels a formulation made of food-based microparticles (MPs) able to control the release of quercetin, a natural anticancer compound, which activity is only limited by its poor aqueous solubility and consequent low bioavailability. To solve this issue, a spray-dried micro delivery system was developed using a bench mini spray dryer B290 Buchi. The resulting MPs were only manufactured with foodderived ingredients such as whey proteins and milk, avoiding the use of any other synthetic material. These microparticles were characterised with a testing campaign encompassing either the physical–chemical characterisation with SEM, DSC and DLS, or the technological and biological featur…

Inhibitory responses to exogenous adenosine in murine proximal and distal colon”

The aims of the present study were firstly, to characterize pharmacologically the subtypes of P(1) purinoreceptors involved in the inhibitory effects induced by exogenous adenosine in longitudinal smooth muscle of mouse colon, and secondly, to examine differences in the function and distribution of these receptors between proximal and distal colon. Adenosine (100 microM-3 mM) caused a concentration-dependent reduction of the amplitude of spontaneous contractions in the proximal colon, and muscular relaxation in the distal colon. In the proximal colon, adenosine effects were antagonized by a selective A(1) receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10 nM), but were not m…

Out-of-plane behaviour of unreinforced masonry infill walls: Review of the experimental studies and analysis of the influencing parameters

Abstract Over the last 50 years, research has mainly focused on characterizing the In-Plane behaviour of unreinforced masonry infill walls. Recently, the focus of research has been addressed to understanding Out-of-Plane behaviour, also from the experimental point of view. However, in the experimental campaigns, there is high variability in the geometrical and mechanical properties of URM infill walls and also in the application of Out-of-Plane loads. Therefore, it is important to outline and critically evaluate the major findings obtained by experimental studies and identify research gaps to better understand the differences and the affinity of apparently equivalent tests. In this paper, t…

Changes in the contractility of colon from hypoxanthine-guanine phosphoribosyltransferase (HPRT) knockout mice (Lesch-Nyhan disease)

New actors in the gut :emerging players in motility and in inflammatory bowel diseae

Gastrointestinal motility is an integrated process generated and modulated by local and circulating hormones and neurotransmitters which act and interact directly and indirectly on muscle cells. A plethora of regulators have been identified, but this field is continuously in expansion. Among the new actors in gut accumulating evidence strongly supports a role of renin-angiotensin system (RAS) in the digestive tract cooperating with other major mediators for maintaining gastrointestinal homeostasis. Transcripts encoding RAS components were detected in gastrointestinal tract and the involvement of RAS in gut motility modulation is increasingly emerging. The available literature demonstrated t…

Differential recruitment of Angiotensin II receptors in the modulation of rat colonic contractile activity in experimental inflammation

Objective: Inflammatory Bowel Diseases (IBD), are severe gastrointestinal (GI) disorders, with unknown aetiology, characterized by a chronic intestinal inflammatory reaction, progressively affecting GI functions, as gut motility. During inflammatory events, modifications in the functionality of some enteric modulators could contribute to the pathological changes of GI motor patterns. Angiotensin II (Ang II), the main effector of the renin-angiotensin system (RAS), has been recently reported as novel regulator of GI motility, acting on the specific receptors (AT1R and AT2R) located on the gut wall. Since recent studies have pointed out an involvement of RAS system in GI inflammation, we expl…

IMPAIRMENT OF NEURAL CONTROL IN DUODENAL SEGMENTS OF DYSTROPHIC (MDX ) MICE.”

Actions of vasostatins on gastrointestinal function in rodents

FUNCTIONAL STUDY ON THE ROLE OF TACHYKININS IN COLONIC PERISTALTIC ACTIVITY IN MICE

Because the role of tachykinin receptors in colonic peristalsis remains incompletely understood, we studied the effect of tachykinin receptor antagonists on mouse colonic peristaltic activity. Peristaltic activity was assessed by quantifying the amplitude and interval of distension-induced pressure waves in proximal and distal colon segments of mice using a modified Trendelenburg set-up. We studied the effect of the NK1, NK2 and NK3 tachykinin receptor antagonists RP67580 (2 mM), nepadutant (1 mM) and SR142801 (0.3 mM) respectively. Gradual distension of proximal and distal colon segments induced repetitive rhythmic pressure waves which were blocked by tetrodotoxin (1 mM) and virtually abol…

POSTNATAL DEVELOPMENTAL CHANGES IN ENTERIC DOPAMINERGIC SYSTEM

The postnatal period is a key period of life, characterized by the maturation of various organs and in particular of the gut. Currently, we have a poor understanding of the development of neurological and endocrine factors that control intestinal motility. Such knowledge can provide indications about the potency, efficacy, or therapeutic range of a drug in premature infants. Dopaminegic antagonists are often used as prokinetic drugs to treat impaired GI propulsion, although the role of the enteric dopaminergic system in the control of intestinal motility in neonatal vs adult has not been adequately addressed. In this view the aim of this study, was to examine, the functionality of the dopam…

Adenosine receptor subtypes in mouse colon

In rat fibrotic colon TGF-beta/SMAD signalling is modulated by cyclooxygenases inihibitors

ROLE OF RENIN-ANGIOTENSIN SYSTEM IN COLONIC DYSMOTILITY ASSOCIATED WITH BOWEL INFLAMMATION IN RATS

Dysregulation of different mediator systems could contribute to the gut dismotility in inflammatory bowel diseases (IBDs), chronic disorders characterized by an exasperated immune response disturbing gut functions. Among these, Angiotensin II (Ang II), the main peptide of renin-angiotensin system (RAS), can participate in inflammatory responses and RAS components are increased in IBD patients. Since RAS has emerged as gut motility regulator, our objectives was to investigate, in an IBD rat model, the RAS functionality and its eventual contribution to colonic dismotility. Experimental colitis was induced in rats by intracolonic administration of 2,4-dinitrobenzenesulfonic acid (DNBS). Drug e…

Dopaminergic signaling in mouse duodenum and postanatal developmental changes

APHAMAX® ATTENUATES INFLAMMATORY AND OXIDATIVE STRESS IN 2, 4-DINITROBENZENE SULFONIC ACID-INDUCED COLITIS IN RAT AMELIORATING INTESTINAL FUNCTIONALITY

Accumulating evidences indicate that inflammatory and oxidative stress play an essential role in the pathogenesis and progression of inflammatory bowel disease (IBD). In IBD the excessive production of reactive oxygen species (ROS) and nitrogen metabolites contribute to tissue injury and could have also a profound impact on gut functions, including motility. We characterised the inflammatory and oxidative condition and the impact on colon motility in an experimental rat model of colitis, the 2, 4-dinitrobenzene sulfonic acid (DNBS)- induced colitis, and we evaluated if oral treatment with a nat- ural extract of Aphanizomenon flos-aquae (AFA) AphaMax®, containing concentrated quantity of AFA…

MATERNAL HIGH FAT DIET CONSUMPTION DURING PREGNANCY AND LACTATION: IMPACT ON INTESTINAL MORPHOLOGY AND FUNCTION IN PREWEANING OFFSPRING

Different evidence supports an important role for maternal obesity in the development of childhood obesity and subsequent adult disease. This study is addressed to investigate if and to which extend maternal high fat feeding would induce compensatory and adaptative responses in gut predisposing to the eventual development of paediatric obesity. Adult female mice were divided into two groups fed with i) high fat (HF) diet and ii) standard chow (SC)diet, during pregnancy and lactation. HF mothers showed a significant weight gain, higher levels of blood glucose and an abnormal glucose tolerance compared to SC mother, indicating the establishment of metabolic syndrome. Then, offspring subdivide…

Properties of slow wave activity in duodenal smooth muscle from mice lacking full-length dystrophin

Mechanism by which Prostaglandin E2 reduces the response to motilin in CHO-hMTLR cells.” .