Search results for "cyclic"

Regulation of fructose 2,6-bisphosphate in perfused flight muscle of the locust, Locusta migratoria: The effect of octopamine

1991

Impact of the Prone Position in an Animal Model of Unilateral Bacterial Pneumonia Undergoing Mechanical Ventilation

2013

Abstract Background: The prone position (PP) has proven beneficial in patients with severe lung injury subjected to mechanical ventilation (MV), especially in those with lobar involvement. We assessed the impact of PP on unilateral pneumonia in rabbits subjected to MV. Methods: After endobronchial challenge with Enterobacter aerogenes, adult rabbits were subjected to either “adverse” (peak inspiratory pressure = 30 cm H2O, zero end-expiratory pressure; n = 10) or “protective” (tidal volume = 8 ml/kg, 5 cm H2O positive end-expiratory pressure; n = 10) MV and then randomly kept supine or turned to the PP. Pneumonia was assessed 8 h later. Data are presented as median (interquartile range). Re…

Regulation of noradrenergic coerulean neuronal firing mediated by 5-HT2 receptors: involvement of the prepositus hypoglossal nucleus.

1991

Abstract Previous studies have indicated a 5-HT2-mediated inhibitory influence on unit activity in the locus coeruleus. In the present work, attempts were made to determine which area(s) of the brain is (are) involved in this effect: (1) Microiontophoretic application of serotoninergic compounds (quipazine, ketanserin, RU 24969 (Roussel Uclaf), 8-hydroxy-2(di-n-propylamino) tetralin (8-OH-DPAT), metergoline, serotonin) in the locus coeruleus, did not alter the coerulean discharge. Local microinjection of quipazine or ketanserin in the area of the locus coeruleus, as well as in one of its major afferents, the prepositus hypoglossi, had no effect on the unit activity in the locus coeruleus. 1…

A possible role for cyclic guanosine monophosphate in the rat pineal gland.

1990

Abstract Adrenergic stimulation of pinealocytes induces an increase of both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). However, for cGMP no biological effects have been demonstrated so far. Therefore we tested the effects of the analog 8-bromo-cGMP on synaptic ribbon numbers and on melatonin synthesis as reflected by N -acetyltransferase (NAT) activity in the rat pineal gland in vitro. Incubation for 6 h with 8-bromo-cGMP did not change the activity of serotonin NAT but in increased the number of synaptic ribbons. These results indicate that cGMP is involved as a second messenger in the regulation of synaptic ribbon numbers in the rat pineal gland.

Rat pineal arylalkylamine-N-acetyltransferase: cyclic AMP inducibility of its gene depends on prior entrained photoperiod.

2003

The nocturnal biosynthesis of melatonin in the rat pineal depends on strongly enhanced expression of the enzyme N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87]. AA-NAT transcription is stimulated during darkness by adrenergic inputs to the pineal from the suprachiasmatic nucleus (SCN). Nocturnal activation of the AA-NAT promotor following stimulation of pinealocyte adrenoceptors involves cAMP-dependent stimulation of protein kinase A (PKA). The nocturnal rise in AA-NAT depends on the lighting conditions. As compared with light/dark (LD) 12:12, the delay between dark onset and the nocturnal rise in AA-NAT is shortened under long photoperiods and prolonged under…

Receptor identification and physiological characterisation of glucagon-like peptide-2 in the rat heart.

2010

Abstract Background and aims The anorexigenic glucagon-like peptide (GLP)-2 is produced by intestinal L cells and released in response to food intake. It affects intestinal function involving G-protein-coupled receptors. To verify whether GLP-2 acts as a cardiac modulator in mammals, we analysed, in the rat heart, the expression of GLP-2 receptors and the myocardial and coronary responses to GLP-2. Methods and results GLP-2 receptors were detected on ventricular extracts by quantitative real-time polymerase chain reaction (Q-RT-PCR) and Western blotting. Cardiac GLP-2 effects were analysed on Langendorff perfused hearts. Intracellular GLP-2 signalling was investigated on Langendorff perfuse…

Lack of effect of oxytocin on the numbers of ?synaptic? ribbons, cyclic guanosine monophosphate and serotonin N-acetyltransferase activity in organ-c…

1993

In addition to the stimulating influence of the sympathetic system on the function of the mammalian pineal gland, neuropeptides such as neuropeptide Y, vasoactive intestinal polypeptide and arginine-vasopressin (AVP) are thought to function as modulators. Since AVP has been shown to influence pineal melatonin synthesis, the aim of the present study was to investigate the possible effects of the second hypothalamic nonapeptide oxytocin (OT), which likewise has been detected in the pineal gland. We therefore studied "synaptic" ribbon (SR) numbers, N-acetyltransferase (NAT) activity and the intracellular concentration of cyclic guanosine monophosphate (cGMP) following in vitro incubation of ra…

Cyclic AMP-inducible genes respond uniformly to seasonal lighting conditions in the rat pineal gland

2006

The encoding of photoperiodic information ensues in terms of the daily profile in the expression of cyclic AMP (cAMP)-inducible genes such as the arylalkylamine N-acetyltransferase (AA-NAT) gene that encodes the rate-limiting enzyme in melatonin formation. In the present study, we compared the influence of the photoperiodic history on the cAMP-inducible genes AA-NAT, inducible cyclic AMP early repressor (ICER), fos-related antigen-2 (FRA-2), mitogen-activated protein kinase phosphatase-1 (MKP-1), nerve growth factor inducible gene-A (NGFI-A) and nerve growth factor inducible gene-B (NGFI-B) in the pineal gland of rats. For this purpose, we monitored the daily profiles of each gene in the sa…

The differential influences of melanocortins on nociception in the formalin and tail flick tests

2006

Melanocortins exert multiple physiological effects that include the modulation of immune responses, inflammation processes, and pain transmission. In the present study we investigated the peripheral activity of natural melanocortins - alpha-, beta-, gamma1- and gamma2-melanocyte stimulating hormone (MSH) - and melanocortin receptor subtypes 3 and 4 (MC3/4 receptor) antagonist HS014 in pain (formalin and tail flick) tests after peptide subcutaneous administration in mice. In the formalin test, among all substances tested only alpha-MSH (1 micromol/kg) statistically significantly inhibited the formalin-induced first phase pain response, however, all tested peptides (except gamma1-MSH) at the …

Fos-related antigen 2 (Fra-2) memorizes photoperiod in the rat pineal gland

2004

As the physiological role of fos-related antigen-2 (Fra-2) is largely unknown and since the pineal plays an important role in the photoperiodic control of the body, we have tested the hypothesis that Fra-2 expression is photoperiod-dependent and may be involved in imprinting photoperiod on the pineal gland and the body as a whole. To this end, we have investigated Fra-2 mRNA expression and Fra-2 protein expression under various light/dark (LD) cycles. A clear nocturnal increase occurs for both monitored parameters under all photoperiodic conditions studied. The level of Fra-2 protein expression clearly depends on photoperiod, because the amount of protein at dark onset and during the night …