Neuroendocrine Control (neuroendocrine + control)

Distribution by Scientific Domains

Selected Abstracts

Orexins/hypocretins control bistability of hippocampal long-term synaptic plasticity through co-activation of multiple kinases

O. Selbach
Abstract Aim:, Orexins/hypocretins (OX/Hcrt) are hypothalamic neuropeptides linking sleep,wakefulness, appetite and neuroendocrine control. Their role and mechanisms of action on higher brain functions, such as learning and memory, are not clear. Methods:, We used field recordings of excitatory post-synaptic potentials (fEPSP) in acute mouse brain slice preparations to study the effects of orexins and pharmacological inhibitors of multiple kinases on long-term synaptic plasticity in the hippocampus. Results:, Orexin-A (OX-A) but not orexin-B (OX-B) induces a state-dependent long-term potentiation of synaptic transmission (LTPOX) at Schaffer collateral-CA1 synapses in hippocampal slices from adult (8- to 12-week-old) mice. In contrast, OX-A applied to slices from juvenile (3- to 4-week-old) animals causes a long-term depression (LTDOX) in the same pathway. LTPOX is blocked by pharmacological inhibition of orexin receptor-1 (OX1R) and plasticity-related kinases, including serine/threonine- (CaMKII, PKC, PKA, MAPK), lipid- (PI3K), and receptor tyrosine kinases (Trk). Inhibition of OX1R, CaMKII, PKC, PKA and Trk unmasks LTDOX in adult animals. Conclusion:, Orexins control not only the bistability of arousal states and threshold for appetitive behaviours but, in an age- and kinase-dependent manner, also bidirectional long-term synaptic plasticity in the hippocampus, providing a possible link between behavioural state and memory functions. [source]

Quo vadis neurohypophysial hormone research?

Alison J. Douglas
Here we highlight just a few of the outstanding questions in the field of neurohypophysial hormones that we envisage will be addressed successfully in the new millennium. To begin, we focus on the regulation of receptors. Despite intensive investigation with new drugs, molecular modelling and transgenic models, the determinants of receptor selectivity remain elusive; there may even be more vasopressin or oxytocin receptor subtypes to be discovered. We discuss the controversy over the interesting studies that indicate modulation of oxytocin receptor-binding by steroids. Oxytocin and vasopressin release and action in the brain are discussed from several aspects. Dendritically released oxytocin acting locally is important for the milk ejection reflex, and similarly released vasopressin is important in regulating patterning of vasopressin neurone activity. Such dendritically released oxytocin and vasopressin is likely to be important in paracrine modulation of neural circuitry involved in neuroendocrine control, and for a range of behaviours. Is it possible that the whole range of behaviours that comprise ,social' (or ,anti-social') or ,maternal' behaviour can be engineered by modifying the expression of just these one or two peptides and their receptors? However, whether gene expression and knockout approaches will answer all the open questions about the real functions of oxytocin and vasopressin remains to be shown. [source]

KiSS-1 and GPR54 Genes are Co-Expressed in Rat Gonadotrophs and Differentially Regulated In Vivo by Oestradiol and Gonadotrophin-Releasing Hormone

N. Richard
Kisspeptin, the product derived from KiSS-1, and its cognate receptor, GPR54, both exert a role in the neuroendocrine control of reproduction by regulating gonadotrophin-releasing hormone (GnRH) secretion. In the present study, we demonstrate, using dual immunofluorescence with specific antibodies, that the KiSS-1 and GPR54 genes are both expressed in rat gonadotrophs. All luteinising hormone ,-immunoreactive (LH,-ir) cells were stained by the KiSS-1 antibody but some kisspeptin-ir cells were not LH, positive; thus, we cannot exclude the possibility that kisspeptins are expressed in other pituitary cells. All GPR54-ir are co-localised with LH, cells, but only a subset of LH, cells are stained with the GPR54 antibody. Using the real-time reverse transcription-polymerase chain reaction (RT-PCR), we found that the expression of KiSS-1 and GPR54 is differentially regulated by steroids. In the female, KiSS-1 mRNA levels dramatically decreased following ovariectomy (OVX), and this decrease was prevented by administration of 17,-oestradiol (E2), but not by administration of GnRH antagonist or agonist. Administration of E2 in OVX rats receiving either GnRH antagonist or agonist clearly shows that E2 acts directly on the pituitary to positively control KiSS-1 expression. In OVX rats, administration of the selective oestrogen receptor (ER), ligand propylpyrazoletriol, but not the selective ER, ligand diarylpropionitrile, mimics this effect. By contrast, our study shows that GPR54 expression is positively regulated by GnRH and negatively controlled by chronic exposure to E2. In summary, our data document for the first time that, in the female rat pituitary, KiSS-1 expression is up-regulated by oestradiol, similarly to that seen in the anteroventral periventricular nucleus of the hypothalamus. Conversely, GPR54 is up-regulated by GnRH, which exclusively targets gonadotrophs. [source]

Female sex pheromone suppression and the fate of sex-peptide-like peptides in mated moths of Helicoverpa armigera

V.K. Nagalakshmi
Abstract Insect males produce accessory gland (MAG) factors that are transferred in the seminal fluid to females during copulation, and elicit changes in the mated female's behavior and physiology. Our previous studies showed that the injection of synthetic Drosophila melanogaster sex-peptide (DrmSP) into virgin females of the moth Helicoverpa armigera causes a significant inhibition of pheromone production. In this and other moth species, pheromone production, correlated with female receptivity, is under neuroendocrine control due to the circadian release of the neuropeptide PBAN. In this study, we show that PBAN, present in the hemolymph during the scotophase in females, is drastically reduced after mating. We also identify 4 DrmSP-like HPLC peaks (Peaks A, S1, S2, and B) in MAGs, with increasing levels of DrmSP immunoreactivity during the scotophase, when compared to their levels observed during the photophase. In H. armigera MAGs, a significant reduction in the pheromonostatic peak (Peak B) was already evident after 15 min of copulation, and depletion of an additional peak (Peak S2) was evident after complete mating. Peak A is also detected in female brains, increasing significantly 1 h after mating, at which time inhibition of pheromone biosynthesis also occurs. However, changes corresponding to the other MAG peaks were not detected in mated female tissues. Arch. Insect Biochem. Physiol. 64:142,155, 2007. 2007 Wiley-Liss, Inc. [source]