Ghrelin growth hormone secretagogue receptor, with the "GHS-R1b" splice being inactive) is involved in mediating a wide variety of biological effects of ghrelin, including: stimulation of growth hormone release, increase in hunger, modulation of glucose and lipid metabolism, regulation of gastrointestinal motility and secretion, protection of neuronal and cardiovascular cells, and regulation of immune function. They are present in high density in the hypothalamus and pituitary, on the vagus nerve (on both afferent cell bodies and afferent nerve endings) and throughout the gastrointestinal tract. Ghrelin promotes intestinal cell proliferation and inhibits apoptosis during inflammatory states and oxidative stress. It also suppresses
Counterregulatory hormone Counterregulatory hormone A counterregulatory hormone is a hormone that opposes the action of another. The action of insulin is counterregulated by glucagon, epinephrine (adrenaline), norepinephrine (noradrenaline), cortisol, and growth hormone. These counterregulatory hormones—the term is usually used in the plural—raise the level of glucose in the blood by promoting glycogenolysis, gluconeogenesis, ketogenesis, and other catabolic processes. In healthy people, counterregulatory hormones constitute a principal defense against hypoglycemia, and levels are expected to rise as the glucose falls. As an example, the exercise-induced reduction in blood glucose is counterregulated by increases in levels of epinephrine, norepinephrine, cortisol, and growth hormone. The