Search results for "NEUROSCIENCE"
showing 10 items of 8040 documents
Daidzein has neuroprotective effects through ligand-binding-independent PPARγ activation.
2011
Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-γ (PPARγ), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARγ. Our results show that daidzein (0.05-5 μM) decreases cell death induced b…
Expression and regulation of mPer1 in immortalized GnRH neurons.
2003
Hypothalamic GnRH (gonadotropin-releasing hormone) neurons play a critical role in the initiation and maintenance of reproduction competence. Using the mouse GnRH neuronal cell line, GT1-7, we have characterized the expression of the gene mPer1, a recognized key element of the mammalian circadian clockwork. Both mPer1 transcripts and the 136 kDa mPER1 gene product could be detected in these cells. Immunocytochemical analysis also confirmed expression of mPER1 both in vitro and in vivo in GnRH neurons. Activation of cyclic AMP signalling pathways in vitro elevated GnRH secretion as well as mPer1 expression and nuclear mPER1 immunoreactivity. As mPER1 is known to feedback on transcriptional a…
In vitro synthesis of dopamine and noradrenaline in the isolated rat pineal gland: day-night variations and effects of electrical stimulation.
1989
: Isolated rat pineal glands were incubated in vitro in a medium containing [I4C]dopamine or [14C]tyrosine, and the tissue contents of l4C-labelled and total dopamine and noradrenaline were determined by HPLC followed by electrochemical detection and scintillation spectrometry. During incubation with [l4C]dopamine, the labelled amine accumulated in pineal glands and was partially converted into [l4C]noradrenaline. Nomifensine, a neuronal amine uptake blocker, largely inhibited the accumulation of [l4C]dopamine and the formation of [14C]noradrenaline. These experiments demonstrated dopamine β-hydroxylase activity in the sympathetic nerves of the pineal gland. During incubation with [14C]tyro…
'TRPing' synaptic ribbon function in the rat pineal gland: neuroendocrine regulation involves the capsaicin receptor TRPV1.
2009
Synaptic ribbons (SRs) are presynaptic structures thought to regulate and facilitate multivesicular release. In the pineal gland, they display a circadian rhythm with higher levels at night paralleling melatonin synthesis. To gain more insight into the processes involved and the possible functions of these structures, a series of experiments were conducted in rodents. We studied the regional distribution of a molecular marker of pineal SRs, the kinesin motor KIF3A in the gland. Respective immunoreactivity was abundant in central regions of the gland where sympathetic fibers were less dense, and vice versa, revealing that intercellular communication between adjacent pinealocytes is enhanced …
Neuropeptide Y (NPY)-like immunoreactivity in the guinea pig pineal organ.
1986
Relatively little is known about mammalian pineal neuropeptides. In the present study neuropeptide Y-like immunoreactivity (NPY-LI) was examined in the guinea pig pineal gland. NPY-LI was restricted to few intrapineal nerve fibers of faint fluorescence intensity. They showed no preferential localization with regard to the different pineal portions. As catecholaminergic fibers are abundant in the guinea pig pineal gland, the scarcity of NPY-LI fibers indicates that in the pineal colocalization of noradrenaline and NPY-LI is not a regular feature, in contrast to other organs. The possibility exists that in the pineal NPY-LI fibers are not of peripheral sympathetic but of central origin.
Transgenic overexpression of corticotropin releasing hormone provides partial protection against neurodegeneration in an in vivo model of acute excit…
2008
Abstract Corticotropin releasing hormone (CRH) is the central modulator of the mammalian hypothalamic–pituitary–adrenal (HPA) axis. In addition, CRH affects other processes in the brain including learning, memory, and synaptic plasticity. Moreover, CRH has been shown to play a role in nerve cell survival under apoptotic conditions and to serve as an endogenous neuroprotectant in vitro . Employing mice overexpressing murine CRH in the CNS, we observed a differential response of CRH-overexpressing mice (CRH-COE hom -Nes) to acute excitotoxic stress induced by kainate compared with controls (CRH-COE con -Nes). Interestingly, CRH-overexpression reduced the duration of epileptic seizures and pre…
Memory for time intervals is impaired in left hemi-Parkinson patients.
2004
The basal ganglia have been proposed as one of the neural correlates of timekeeping functions. Both encoding and memory retrieval components for time perception are impaired in Parkinson's disease (PD). The aim of our study was to investigate in hemi-Parkinsonian patients the existence of a specific alteration in memory for time depending on the affected side, to better understand the contribution of the left or right basal ganglia circuits in different components of time perception. Right and left hemi-PD patients performed a time reproduction task in which they were required to reproduce in the same session short (5 s) and long (15 s) time intervals, in off- and on-therapy condition. Whil…
Circadian rhythm and effects of light on cAMP content of the dwarf hamster suprachiasmatic nucleus
1998
The present study was conducted in the dwarf hamster (Phodopus sungorus) to investigate whether a circadian rhythm is present in the content of the second messenger cyclic adenosine 3',5'-monophosphate (cAMP) in the suprachiasmatic nucleus (SCN), the endogenous clock in mammals. In animals held under light/dark conditions (LD), we observed high levels at the end of the light phase and low levels during the night in frozen SCN punches. In animals held in continuous dark, a similar rhythm was seen although a second peak was present in the subjective day. In senile hamsters under LD, the decrease of cAMP levels at the light transition was not seen. These data, obtained for the first time from …
Glucagon-like peptide-1 relaxes gastric antrum through nitric oxide in mice.
2010
Abstract Glucagon-like-peptide-1 (GLP-1) is a proglucagon-derived peptide expressed in the intestinal enteroendocrine-L cells and released after meal ingestion. GLP-1 reduces postprandial glycemia not only by its hormonal effects, but also by its inhibitory effects on gastrointestinal motility. Recently, we showed that GLP-1 acts in the enteric nervous system of mouse intestine. Therefore our working hypothesis was that GLP-1 may have also a direct influence on the gastric mechanical activity since the major part of experimental studies about its involvement in the regulation of gastric motility have been conducted in in vivo conditions. The purposes of this study were (i) to examine exogen…
Relaxation induced by N-terminal fragments of chromogranin A in mouse gastric preparations.
2007
Abstract A definitive role for chromogranin A (CGA)-derived fragments in the control of the gastrointestinal smooth muscle contractility has not been yet established. The purpose of the present study was to evaluate, in vitro , the effects of the recombinant vasostatin 1–78 (VS-1), CGA 7–57 and CGA 47–66 on the mouse gastric mechanical activity, recording the changes of intraluminal pressure. VS-1, CGA 7–57 and CGA 47–66 produced concentration-dependent relaxations. Mouse anti-vasostatin-1 monoclonal antibody 5A8, recognising the region 53–57, abolished the relaxation induced by VS-1, indicating the specificity of the effect. The relaxation was significantly reduced by tetrodotoxin (TTX), b…