Regulation of [3H]mazindol binding to subhypothalamic areas: involvement in glucoprivic feeding.

The distribution of low-affinity sodium-sensitive binding sites of [3H]mazindol were studied in rat hypothalamic nuclei. Using microdissection methods, it was demonstrated that the highest level of [3H]mazindol binding is localized to the paraventricular nucleus (PVN) and the lowest binding is observed in the lateral hypothalamus. Following food deprivation, a significant decrease in [3H]mazindol binding in the PVN and ventromedial hypothalamus (VHM) were observed. Refeeding food-deprived rats resulted in restoration of the level of binding in the PVN, and this was correlated with changes in blood glucose levels. Thus, changes in the binding of [3H]mazindol in the PVN may reflect local changes in glucose levels. In related studies, the involvement of the PVN in the regulation of food deprivation or 2-deoxyglucose (2-DG)-induced food intake was studied. Application of amphetamine (20 micrograms) into the PVN had no effect on food deprivation induced feeding, but significantly inhibited 2-DG induced (glucoprivic) feeding. The PVN may play an important role in the glucostatic regulation of feeding and in mediating the anorectic action of amphetamine and related anorectic drugs on glucoprivic feeding.