Neuropeptides: central nervous system effects on nutrient metabolism.

Several neural peptides have been demonstrated to influence central nervous system control of nutrient metabolism. The principal mechanism by which these peptides influence peripheral nutrient metabolism is by altering the secretion of adrenal epinephrine. Bombesin or its mammalian counterpart, gastrin releasing peptide, and TRF act within the brain to stimulate the secretion of epinephrine from the adrenal gland. Associated with these changes in epinephrine secretion is a reduction of plasma insulin and elevation of plasma glucagon and glucose. Somatostatin and various somatostatin analogs act in the brain to inhibit adrenal epinephrine secretion stimulation by a variety of stimuli.