EFFECT OF GLUCOPRIVATION ON GLUTAMATE-DECARBOXYLASE ACTIVITY IN THE VENTROMEDIAL NUCLEUS

Activity of the GABA-synthesizing enzyme, glutamate decarboxylase (GAD), was measured in brain areas involved in glucoregulation 60 min after a glucoprivic challenge. The rate of GAD activity in the ventromedial nucleus of the hypothalamus (VMN) increased in a dose-dependent manner in response to intraperitoneal injection of 2-deoxy-D-glucose (2-DG). The increase in VMN GAD activity was significantly correlated with an increase in food intake (r2 = .77, p < 0.01). The increase in VMN GAD activity was not due to the higher food intake since rats receiving 2-DG and denied access to food also had elevated rates of VMN GAD activity. VMN GAD activity was increased 28% and 32% after intracerebroventricular injection of 2-DG or 5-thioglucose, respectively. The rates of GAD activity in the lateral hypothalamus and area postrema were not affected by either peripherally or centrally administered 2-DG. The increase in VMN GAD activity after glucoprivation may be involved in the regulation of blood glucose by influencing food intake.