Ghrelin Ghrelin Ghrelin (pronounced ), the "hunger hormone", also known as lenomorelin (INN), is a peptide hormone produced by ghrelinergic cells in the gastrointestinal tract that functions as a neuropeptide in the central nervous system. Besides regulating appetite, ghrelin also plays a significant role in regulating the distribution and rate of use of energy. When the stomach is empty, ghrelin is secreted. When the stomach is stretched, secretion stops. It acts on hypothalamic brain cells both to increase hunger, and to increase gastric acid secretion and gastrointestinal motility to prepare the body for food intake. The receptor for ghrelin, the ghrelin/growth
Growth hormone–releasing hormone in vesicle fusion and release of secretory vesicles containing premade growth hormone. Some Ca influx is also a direct action of cAMP, which is distinct from the usual "cAMP-dependent pathway" of activating "protein kinase A". Activation of GHRHRs by GHRH also conveys opening of Na+ channels by phosphatidylinositol 4,5-bisphosphate, causing cell depolarization. The resultant change in the intracellular voltage opens a voltage-dependent calcium channel, resulting in vesicle fusion and release of GH. The actions of GHRH are opposed by somatostatin (growth-hormone-inhibiting hormone). Somatostatin is released from neurosecretory nerve terminals of periventricular somatostatin neurons, and is carried by the hypothalamo-hypophysial portal