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Hypothalamus
About: Hypothalamus is a research topic. Over the lifetime, 22301 publications have been published within this topic receiving 1085925 citations.
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TL;DR: A new polypeptide from bovine hypothalamus is purified and sequenced, a potent and selective agonist at the PTH2-R, which was highly expressed in hypothalamic areas that regulate pituitary hormone secretion and spinal cord regions involved in pain perception.
Abstract: Activation by parathyroid hormone (PTH)1 and peripheral distribution2,3 the of PTH2 receptor (PTH2-R) are well described. Highest expression of PTH2-R is found in the brain1, where PTH synthesis is undetectable. We have now purified and sequenced a new polypeptide from bovine hypothalamus (referred to here as tuberoinfundibular peptide of 39 residues; TIP39), a potent and selective agonist at the PTH2-R. The PTH2-R was highly expressed in hypothalamic areas that regulate pituitary hormone secretion and spinal cord regions involved in pain perception.
204 citations
TL;DR: The studies indicate that this dose of dexamethasone exerts its inhibitory effects on the HPA axis primarily by acting at GR in the pituitary, and support and extend other studies which suggest that the DST provides a direct test of the effects of increased GR activation in thepituitary on ACTH and cortisol secretion.
204 citations
TL;DR: Investigation of the ultrastructure of GnRH neurons in the preoptic area and medial basal hypothalamus of rhesus monkeys provided strong evidence that alterations in the gonadal steroid milieu can produce morphological changes in the GnRH neuron and its immediate environment in the primate.
Abstract: The secretion of the gonadotropins is modulated by the gonadal steroids, but the means by which these effects are mediated are not well understood. The present anatomical study was undertaken to investigate the possibility that the GnRH system responds to alterations in the gonadal steroid environment with reversible changes in synaptic input and glial wrapping such as have been observed in other neuroendocrine systems. The ultrastructure of GnRH neurons was studied in the preoptic area and medial basal hypothalamus of rhesus monkeys in various steroid conditions including five intact cycling, four long-term ovariectomized animals, two long-term ovariectomized animals with steriod replacement (LtOVX+), and two animals replaced with steroid at the time of ovariectomy (StOVX+). Electron micrographic montages of GnRH neuronal profiles were analyzed using computerized morphometrics, and the percentages of the length of perikaryal membrane immediately apposed by glial processes and that with postsynaptic modif...
204 citations
TL;DR: The experiments are consistent with the notion that brain progestin receptors mediate at least some of the behavioral effects of progesterone.
203 citations
TL;DR: Evidence is provided for an endogenous release of oxytocin within the magnocellular nuclei in lactating rats and it is suggested that the increase in such a release induced by suckling is likely to be a pre-requisite for the onset and the maintenance of the characteristic intermittent bursting electrical activity of Oxytocin cells leading to milk ejections.
Abstract: To investigate the hypothesis that oxytocin may be released within the magnocellular nuclei in vivo, push-pull cannula perfusions were performed in anaesthetized lactating rats in one supraoptic nucleus of the hypothalamus while recording the intramammary pressure and/or the electrical activity of oxytocin cells in the contralateral supraoptic nucleus. Oxytocin content was measured in samples collected over 15 min, under various conditions: 1) with no stimulation; 2) during suckling and suckling-induced reflex milk ejections; 3) during electrical stimulation of the neurohypophysis by trains of pulses that mimicked oxytocin cell bursts; 4) under osmotic stimulation by i.p. injection of 2 ml of 1.5 M NaCl to evoke a tonic and sustained oxytocin release from the neurohypophysis. Oxytocin release within the supraoptic nucleus increased significantly during the milk ejection reflex and, to a lesser extent, during burst-like electrical stimulation of the neurohypophysis. In suckled rats, the increase started before the first reflex milk ejection occurred. There was no apparent correlation between the amount of oxytocin in the perfusates and the number of milk ejections and oxytocin cell bursts occurring during each perfusion period. The amount of oxytocin in the perfusates further increased during facilitation of the milk ejection reflex by intraventricular injections of oxytocin or its analogue, isotocin. When suckling failed to evoke the milk ejection reflex, there was no change in intra-supraoptic oxytocin release. There was also no change after osmotic stimulation. When the push-pull cannula was positioned outside the supraoptic nucleus, there was no increase in the amount of oxytocin during the three types of stimulation tested. These results provide evidence for an endogenous release of oxytocin within the magnocellular nuclei in lactating rats. It is suggested that the increase in such a release induced by suckling is likely to be a pre-requisite for the onset and the maintenance of the characteristic intermittent bursting electrical activity of oxytocin cells leading to milk ejections.
203 citations