Search results for "RATS"
showing 10 items of 3537 documents
Neuronal nicotinic receptors in synaptic functions in humans and rats: physiological and clinical relevance.
2000
The present report describes the participation of nicotinic receptors (nAChRs) in controlling the excitability of local neuronal circuitries in the rat hippocampus and in the human cerebral cortex. The patch-clamp technique was used to record responses triggered by the non-selective agonist ACh and the alpha7-nAChR-selective agonist choline in interneurons of human cerebral cortical and rat hippocampal slices. Evidence is provided that functional alpha7- and alpha4beta2-like nAChRs are present on somatodendritic and/or preterminal/terminal regions of interneurons in the CA1 field of the rat hippocampus and in the human cerebral cortex and that activation of the different nAChR subtypes pres…
Na+ ions binding to the bradykinin B2 receptor suppress agonist-independent receptor activation.
1996
Control of the balance between receptor activation and inactivation is a prerequisite for seven transmembrane domain (7TM) receptor function. We asked for a mechanism to stabilize the inactive receptor conformation which prevents agonist-independent receptor activation. Na+ ions have reciprocal effects on agonist versus antagonist interaction with various 7TM receptors. To investigate the Na+ dependence of receptor activation we chose the bradykinin B2 receptor as a prototypic 7TM receptor. Decrease of the intracellular Na+ content from 40 mM to 10 mM of COS-1 cells transiently expressing rat B2 receptors activated the B2 receptor in the absence of agonist as shown by a 3-fold increase in t…
Systemic administration of D-penicillamine prevents the locomotor activation after intra-VTA ethanol administration in rats.
2010
Although recently published studies seem to confirm the important role displayed by acetaldehyde (ACH), the main metabolite of ethanol, in the behavioral effects of ethanol, the origin of ACH is still a matter of debate. While some authors confer more importance to the central (brain metabolism) origin of ACH, others indicate that the hepatic origin could be more relevant. In this study we have addressed this topic using an experimental approach that combines local microinjections of ethanol into the ventral tegmental area (VTA) (which guarantees the brain origin of the ACH) to induce motor activation in rats together with systemic administration (i.p.) of several doses (0, 12.5, 25 and 50 …
Role of CB2 receptors and cGMP pathway on the cannabinoid-dependent antiepileptic effects in an in vivo model of partial epilepsy.
2014
This study aimed at providing an insight on the possible role of cannabi-noid (CB) type 2 receptors (CB2R) and cGMP pathway in the antiepileptic activity ofWIN 55,212-2, (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo[1,2,3-de]-1,4-benzoxazin-6-Yl]-1-naphthalenylmethanone, a non-selective CB agonist, in the maximal dentate activation (MDA) model of partial epilepsy in adult male rats. We evaluated the activity of a CB2 antagonist/inverse agonist AM630, [6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)methanone or 6-iodopravadoline, alone or in co-administration with WIN 55,212-2. Also, in the MDA model it was investigated the co-treatment of WIN55,212…
Histaprodifens: synthesis, pharmacological in vitro evaluation, and molecular modeling of a new class of highly active and selective histamine H(1)-r…
2000
A new class of histamine analogues characterized by a 3, 3-diphenylpropyl substituent at the 2-position of the imidazole nucleus has been prepared outgoing from 4,4-diphenylbutyronitrile (4b) via cyclization of the corresponding methyl imidate 5b with 2-oxo-4-phthalimido-1-butyl acetate or 2-oxo-1,4-butandiol in liquid ammonia, followed by standard reactions. The title compounds displayed partial agonism on contractile H(1) receptors of the guinea-pig ileum and endothelium-denuded aorta, respectively, except 10 (histaprodifen; 2-[2-(3, 3-diphenylpropyl)-1H-imidazol-4-yl]ethanamine) which was a full agonist in the ileum assay. While 10 was equipotent with histamine (1), methylhistaprodifen (…
Intraventricular insulin decreases kappa opioid-mediated sucrose intake in rats.
2002
The hormone insulin acts in the central nervous system (CNS) as a regulator of body adiposity and food intake. Recent work from our laboratory has provided evidence that one way by which insulin may decrease food intake is by decreasing the rewarding properties of food. Evidence from others suggests that endogenous opioids may mediate the palatable properties of foods, and insulin may decrease nonfood-related reward via interaction with some CNS kappa opioid systems. In the present study we examined the ability of insulin to interact with exogenous or endogenous kappa opioids to modulate feeding of palatable sucrose pellets by nondeprived rats. Insulin (5 mU intracerebroventricular (i.c.v.)…
Locomotor and antidepressant-like effects of 5-HT(1A) agonist LY 228729 in prenatally benzodiazepine-exposed rats.
1998
Locomotor activity and antidepressant-like effect in the forced swim test (FST) of 5-HT(1A) agonist LY 228729 were investigated in adult rats prenatally exposed at doses of diazepam (DZ) and alprazolam (ALP) which induce persistent downregulation of GABA/ benzodiazepine (BZ) receptors. Prenatal exposure to ALP and DZ did not modify the efficacy of subchronic LY 228729 to decrease immobility time in the FST. Prenatal DZ and ALP potentiated the facilitatory effect of subchronic LY 228729 on locomotor activity; prenatal DZ was more effective than prenatal ALP. Moreover, prenatal DZ increased stereotypic movements induced by LY 228729. These data suggest that the persistent downregulation of GA…
Purinoceptor-mediated modulation by endogenous and exogenous agonists of stimulation-evoked [3H]noradrenaline release on rat iris.
1992
To investigate whether endogenous purinoceptor agonists affect the sympathetic neurotransmission in the rat isolated iris, and to classify the purinoceptors modulating exocytotic [3H]-noradrenaline release, we have determined the effect of adenosine receptor antagonists on, and the relative potency of selected agonists in modulating, the field stimulation-evoked (3 Hz, 2 min) [3H]-noradrenaline overflow. In addition, the apparent affinity constants of 8-phenyltheophylline (8-PT) and 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) in antagonizing the prejunctional effects of purinoceptor agonists were estimated. The relatively A1-selective DPCPX 10 and 100 nmol/l increased the evoked [3H]-noradre…
Coupling between agonist and chloride ionophore sites of the GABA(A) receptor: agonist/antagonist efficacy of 4-PIOL.
2000
Eight gamma-aminobutyric acid (GABA) mimetics were tested on their ability to differentiate native GABA(A) receptor subtypes present in various rat brain regions. In rat brain cryostat sections, little regional variations by the agonistic actions of muscimol, thiomuscimol, 4,5,6,7-tetrahydroisoazolo(5,4-c)pyridin-3-ol, piperidine-4-sulphonic acid, taurine and beta-alanine on [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to GABA(A) receptor channels were found. They were very similar to those found for GABA itself and indicated no direct correlation with single subunit distributions for any of these compounds. Only the low-efficacy GABA mimetic 5-(4-piperidyl)isoxazol-3-ol (4-PIOL…
New dopamine D2 receptor polymorphisms in rats and association with apomorphine-induced stereotypies.
2002
Adult Wistar rats injected with the dopamine receptor agonist apomorphine display different types of motility patterns with respect to oral stereotypes and locomotor activities. It was tested whether phenotypes exhibiting either ‘sniffing’ or ‘non-sniffing’ behaviour differed in gene structures of dopamine receptors D1 or D2. Forty-five Wistar rats of both genders were tested after a single dose of apomorphine (2 mg/kg s.c.) for stereotyped behaviour. Sequence analysis of the 5′ flanking region, the 5′ untranslated region and the coding region of the two genes revealed a new sequence for the 5′ flanking region of the D1 receptor gene and two polymorphisms in the promoter region of the D2 re…