Crh

Control of secretion of anterior pituitary hormones also includes inhibition by hormones produced by target organs. For example, CRH stimulates the anterior pituitary to secrete ACTH, which in turn stimulates the adrenal cortex to secrete corticosteroids. Corticosteroids then feed back to inhibit the secretion of ACTH. Feedback mechanisms are important for the control of most hormones. For example, insulin (qv) secretion from the pancreas increases in response to increased blood glucose resulting from ingestion of a meal. Insulin increases tissue uptake and metaboHsm of glucose, which lowers blood glucose and in turn reduces insulin secretion. 

SRIF acts as an excitatory neuromodulator in the CNS inhibiting the release of TRH, corticotropin-releasing hormone (CRH), growth hormone releasing factor (GHRH), and NE. It produces general arousal and hypotension. It inhibits the release of a number of peptides and modulators in the GI tract. 

Figure 1 A schematic diagram of the endocrine system of fish. TRH = thyrotrophin releasing hormone GnRH = gonadotrophin releasing hormone CRH = corticotrophin releasing hormone TSH = thyroid stimulating hormone GtH = gonadotrophins I and II ...

Other hydrides with interstitial or metallic properties are formed by V, Nb and Ta they are, however, very much less stable than the compounds we have been considering and have extensive ranges of composition. Chromium also forms a hydride, CrH, though this must be prepared electrolytically rather than by direct reaction of the metal with hydrogen. It has the anti-NiAs structure (p.. 555). Most other elements... 

The binary borides (p. 145), carbides (p. 299), and nitrides (p. 418) have already been discussed. Suffice it to note here that the chromium atom is too small to allow the ready insertion of carbon into its lattice, and its carbide is consequently more reactive than those of its predecessors. As for the hydrides, only CrH is known which is consistent with the general trend in this part of the periodic table that hydrides become less stable across the d block and down each group. 

Lesions of the lateral hypothalamic area (LHA) cause anorexia, whereas ablation of the paraventricular nucleus (PVN) cause a hyperphagic obesity syndrome. Consistent with these results, LHA neurons express the orexigenic neuropeptides MCH and orexin. PVN neurons produce several neuropeptides that are anorex-igenic when administered directly into the brain (CRH, TRH, oxytocin), in addition to their better known roles as endocrine regulators. LHA and PVN receive rich inputs from axons of NPY/AgRP and aMSH/CART-producing neurons in the arcuate nucleus. 

CRH (Corticotropin releasing hormone) is expressed in the nucleus paraventricularis of the hypothalamus and drives the stress hormone system by activating synthesis and release of corticotropin at the pituitary and in turn corticosteroid from the adrenal cortex. CRH is also expressed at many other brain locations not involved in neuroendocrine regulation, e.g. the prefrontal cortex and the amygdala. Preclinical studies have shown that CRH also coordinates the behavioral adaptation to stress (e.g. anxiety, loss of appetite, decreased sleepiness, autonomic changes, loss of libido). 

The paraventricular nucleus in the hypothalamus is located adjacent to the third ventricle and has been identified as a satiety center. Neurons in the paraventricular nucleus produce neuropeptides which inhibit feeding when injected into the brain (thyrotropinreleasing hormone (TRH), corticotropin-releasing hormone (CRH), oxytocin). 

Neurotransmitter Transporters Brain Derived Neurotrophic Factor Neurotrophic Factors Corticotropin Releasing Hormone CRH... 

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