The Effects of Neurally Active Amino Acids on Prolactin Secretion

Abstract

Several neurally active amino acids were injected into the 3rd ventricle of anesthetized male rats. Two or 8 .mu.mol of GABA produced significant increases in plasma concentrations of prolactin (PRL), indicating increased PRL release from the pituitary. Two .mu.mol of glycine was effective in elevating PRL levels. The intraventricular injection of the lowest dose of GABA (1.0 .mu.mol), glutamate (0.4 or 2.0 .mu.mol), lysine (0.2 or 2.0 .mu.mol), or 0.9% NaCl did not alter PRL levels significantly. Plasma PRL concentrations did not increase following the injection of GABA or glycine directly into the anterior pituitary gland. GABA and glycine may play a role in the neural regulation of PRL secretion.