Search results for "acetyltransferase"
showing 10 items of 170 documents
Role of cholinergic neurons in the motor effects of glucagon-like peptide-2 in mouse colon
2010
Glucagon-like peptide-2 (GLP-2) reduces mouse gastric tone and small intestine transit, but its action on large intestine motility is still unknown. The purposes of the present study were 1) to examine the influence of GLP-2 on spontaneous mechanical activity and on neurally evoked responses, by recording intraluminal pressure from mouse isolated colonic segments; 2) to characterize GLP-2 mechanism of action; and 3) to determine the distribution of GLP-2 receptor (GLP-2R) in the mouse colonic muscle coat by immunohistochemistry. Exogenous GLP-2 (0.1–300 nM) induced a concentration-dependent reduction of the spontaneous mechanical activity, which was abolished by the desensitization of GLP-…
The effects of a number of short-term exogenous stimuli on pineal serotonin-N-acetyltransferase activity in rats
1984
The present study deals with the question as to what extent the sympathetically innervated rat pineal gland is affected by a number of short-term exogenous stimuli given during day-time, as assessed by measuring pineal serotonin-N-acetyltransferase activity (NAT) which is directly proportional to melatonin formation. In male Sprague-Dawley rats kept under LD 12:12 pineal NAT was statistically significantly depressed by physical immobilization for 2 hours, swimming for 15 min in water of 10 and 30 degrees C, exposure for 2 hours to cold (5 degrees C) or heat (40 degrees C), noise (90 db) for 2 hours and hunger for 17 hours. An increase in NAT was noted after swimming for 15 min in water of 2…
Daily oscillation of gene expression in the retina is phase-advanced with respect to the pineal gland
2007
Abstract The photoreceptive retina and the non-photoreceptive pineal gland are components of the circadian and the melatonin forming system in mammals. To contribute to our understanding of the functional integrity of the circadian system and the melatonin forming system we have compared the daily oscillation of the two tissues under various seasonal lighting conditions. For this purpose, the 24-h profiles of the expression of the genes coding for arylalkylamine N-acetyltransferase (AA-NAT), nerve growth factor inducible gene-A (NGFI-A), nerve growth factor inducible gene-B (NGFI-B), retinoic acid related orphan receptor β (RORβ), dopamine D4 receptor, and period2 (Per2) have been simultane…
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…
The effects of short pulses of light at night on numbers of pineal "synaptic" ribbons and serotonin N-acetyltransferase activity in male Sprague-Dawl…
1986
To characterize further the functionally enigmatic "synaptic" ribbons (SR) of the mammalian pineal gland and to study possible relationships to melatonin synthesis, in the present investigation rats were exposed to short pulses of light at night when both SR numbers and serotonin N-acetyltransferase (NAT) activity are high in comparison to day-time values. Male Sprague-Dawley rats were killed at 13:00 and 01:00 h, respectively, and at 01:10 and 02:00 h after exposure to light for 10 and 60 min, respectively. The pineals were rapidly taken out and cut sagittally in half. One half was processed for electron-microscopic quantitation of SR numbers and the other half for NAT determinations. It w…
Atypical 24-hour rhythms of serotonin N-acetyltransferase activity in the rat pineal gland.
1988
Previous long-term studies have shown that in the pineal gland of rats melatonin synthesis is subject to infradian rhythms with periods between 4 and 7 days. Since in these studies melatonin-related parameters were measured at one timepoint of a 24-hr cycle only, the aim of the present investigation was to extend these experiments by more frequent sampling, to characterize the infradian rhythmicity in more detail. Male Sprague-Dawley rats kept under a light schedule of LD 12:12 (lights on at 0700) were killed at 6-hr intervals on 8 consecutive days. After decapitation the pineal gland was rapidly dissected out, followed by measurements of one of the melatonin-forming enzymes, serotonin N-ac…
Synaptic ribbons of the rat pineal gland: responses to in-vivo and in-vitro treatment with inhibitors of protein synthesis.
1990
To elucidate the role of protein synthesis in the nocturnal increase of synaptic ribbons in the rat pineal gland, actinomycin-D, which inhibits transcription, and cycloheximide, an inhibitor of translation, were used. To assure that the drugs were effective and to relate morphological changes to pineal biosynthetic phenomena, the activity of N-acetyltransferase and levels of pineal indoleamine were measured. Results of in-vivo, short-term and long-term treatment with either drug suggest that transcription of proteins related to synaptic ribbon formation occurs during the first half of the light phase, whereas translation takes place during the first few hours of the dark phase. In contrast,…
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 …
The role of arginine-vasopressin for pineal melatonin synthesis in the rat: involvement of vasopressinergic receptors.
1991
Abstract The endogenously synthesized nonapeptide arginine vasopressin (AVP) is thought to be involved in transduction of photic information to the pineal gland. The enhancement of circulating AVP leads to a suppression of the nocturnal melatonin surge the mechanisms of which are unknown so far. We therefore studied the effect of dDAVP, an AVP analog with antidiuretic but without vasopressor activity, on pineal melatonin synthesis in Sprague-Dawley and AVP-deficient Brattleboro rats. The nocturnal intra-arterial application of dDAVP mimicked the inhibitory effect of AVP on the activity of the rate-limiting enzyme for pineal melatonin synthesis, N-acetyltransferase (NAT), in both rat strains…
Phosphodiesterase 10A in the Rat Pineal Gland: Localization, Daily and Seasonal Regulation of Expression and Influence on Signal Transduction
2010
The cyclic nucleotide phosphodiesterase 10A (PDE10A) is highly expressed in striatal spiny projection neurons and represents a therapeutic target for the treatment of psychotic symptoms. As reported previously [J Biol Chem 2009; 284:7606–7622], in this study PDE10A was seen to be additionally expressed in the pineal gland where the levels of PDE10A transcript display daily changes. As with the transcript, the amount of PDE10A protein was found to be under daily and seasonal regulation. The observed cyclicity in the amount of PDE10A mRNA persists under constant darkness, is blocked by constant light and is modulated by the lighting regime. It therefore appears to be driven by the master cloc…