Hypothalamus

About: Hypothalamus is a research topic. Over the lifetime, 22301 publications have been published within this topic receiving 1085925 citations.

Corticotropin-releasing hormone deficiency reveals major fetal but not adult glucocorticoid need

Abstract: The body responds to stress by activation of the hypothalamic-pituitary-adrenal (HPA) axis and release of glucocorticoids. Glucocorticoid production in the adult regulates carbohydrate and amino-acid metabolism, maintains blood pressure, and restrains the inflammatory response. In the fetus, exogenous glucocorticoids accelerate maturation of lung and gastrointestinal enzyme systems and promote hepatic glycogen deposition. Corticotropin-releasing hormone (CRH), a 41-amino-acid neuropeptide produced in the paraventricular nucleus of the hypothalamus and many regions of the cerebral cortex, has been implicated in both the HPA axis and behavioural responses to stress. To define the importance of CRH in the response of the HPA axis to stress and fetal development, we have constructed a mammalian model of CRH deficiency by targeted mutation in embryonic stem (ES) cells. We report here that corticotropin-releasing hormone-deficient mice reveal a fetal glucocorticoid requirement for lung maturation. Postnatally, despite marked glucocorticoid deficiency, these mice exhibit normal growth, fertility and longevity, suggesting that the major role of glucocorticoid is during fetal rather than postnatal life.

Somatostatin: Hypothalamic Inhibitor of the Endocrine Pancreas

Abstract: Somatostatin, a hypothalamic peptide that inhibits the secretion of pituitary growth hormone, inhibits basal insulin secretion in fasted cats and rats. In fasted baboons both basal and arginine-stimulated secretion of insulin and glucagon are inhibited. Somatostatin appears to act directly on the endocrine pancreas. The action is dose-related, rapid in onset, and readily reversed.

Studies on the mechanism of the dopamine-mediated inhibition of prolactin secretion.

Abstract: A study of the in vitro effect of dopamine on the release of newly synthesized prolactin is reported. Pituitary glands of female rats were incubated with 4,5-3H-leucine and the radioactive prolactin present in the pituitary gland and that released into the incubation medium were measured. Incubation with 5 × l 10–7M dopamine caused an 85% decrease in prolactin release. Prior injection of the rats with perphenazine or haloperidol rendered the pituitary gland refractory to the in vitro inhibitory effect of dopamine. Although in vitro perphenazine and haloperidol had little or no effect on release of prolactin, 5 × 10–9M of these drugs directly blocked the in vitro action of dopamine on prolactin release. Phentolamine, an α-blocking agent, was partially able to block the inhibitory effect, of dopamine. Propranolol, however, was not effective. Apomorphine, an agent known to mimic the effects of dopamine, caused a significant decrease in the amount of radioactive and radioimmunoassayable prolactin released int...

Efferent projections of the suprachiasmatic nucleus: II. Studies using retrograde transport of fluorescent dyes and simultaneous peptide immunohistochemistry in the rat

Abstract: In a previous study (Watts et al., '87) we reexamined the projections of the suprachiasmatic nucleus (SCh) with the PHA-L method and found that they could be divided conveniently into six groups of fibers. By far the densest projection ends just dorsal to the SCh in a comma-shaped region designated the "subparaventricular zone," although some fibers continue on through the paraventricular nucleus of the hypothalamus to end in the overlying midline thalamus, and others continue on to end in the dorsomedial nucleus, the region around the ventromedial nucleus, and the posterior hypothalamic area. Other relatively sparse projections from the SCh were also described to the preoptic region, lateral septal nucleus, parataenial and paraventricular nuclei of the thalamus, and ventral lateral geniculate nucleus. In addition, the same method was used to show that the subparaventricular zone projects in turn massively to these same regions, as well as back to the SCh itself and to the periaqueductal gray. The present series of experiments was designed to confirm these observations with retrograde tracer injections and to investigate the cellular and possible neurotransmitter organization of the major projections from the SCh and subparaventricular zone with a combined retrograde tracer-immunohistochemical method. For this, the distribution of neuronal cell bodies within the SCh that stain with antisera to vasopressin, vasoactive intestinal polypeptide (VIP), corticotropin-releasing factor, bombesin, substance P, neurotensin, somatostatin, thyrotropin-releasing hormone, and angiotensin II was described in detail first. Then the distribution of retrogradely labeled neurons that were also stained for one or another of these peptides was described after injections of true blue, or in some cases SITS, into the regions of the subparaventricular zone, the paraventricular and parataenial nuclei of the thalamus, the ventromedial nucleus, the dorsomedial nucleus, and the periaqueductal gray. The results confirm previous immunohistochemical and anterograde tracing studies and in addition indicate that cells in dorsal as well as ventral parts of the SCh project to each of the terminal fields examined, as do many cells in surrounding areas, including the subparaventricular zone. Our results also suggest that, at the very least, vasopressin-, VIP-, and neurotensin-stained cells in the SCh project to the subparaventricular zone, midline thalamus, and dorsomedial nucleus, and that the vasopressin and VIP-stained fiber systems are partially segregated at the level of the subparaventricular zone.(ABSTRACT TRUNCATED AT 400 WORDS)