Growth hormone secretagogue receptor secretagogue receptor is activated, a variety of different intracellular signaling cascades can result, depending on the cell type in which the receptor is expressed. These intracellular signaling cascades include mitogen-activated protein kinase (MAPK)), protein kinase A (PKA), protein kinase B (PKB), also known as AKT), and AMP Activated Protein Kinase (AMPK) cascades. It is well-characterized that activating the growth hormone secretagogue receptor with ghrelin induces an orexigenic state, or general feeling of hunger. However, ghrelin may also play a role in behavioral reinforcement. Studies in animal models, found that food intake increased when ghrelin was specifically administered to just the
Counterregulatory hormone rise in blood concentrations of these counterregulatory hormones is dependent upon both exercise intensity and duration, and is proportional to the rate of glucose uptake by the contracting skeletal muscle. Similarly, the natriuretic peptides counterregulate against renin, angiotensin, and aldosterone which elevate blood pressure. In the reproductive system, inhibins and follistatin counterregulate activins, to control follicle-stimulating hormone and so the release of gonads. Inhibins and activins also regulate bone mass. 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.