STRIATAL REGULATION OF MORPHINE-INDUCED HYPERPHAGIA - AN ANATOMICAL MAPPING STUDY

Both systemic and intracranial administration of morphine can result i n spontaneous feeding in non-deprived rats. The present investigation was conducted to examine the involvement of the striatum in this pheno menon. Morphine sulfate (0, 0.5, 1.0, 5.0, 10.0, and 20.0 mug/0.5 mul) was microinjected into five discrete striatal subregions in non-depri ved rats: the nucleus accumbens, the ventromedial striatum, the ventro lateral striatum, the anterior dorsal striatum, and the posterior dors al striatum. Feeding, drinking, locomotion, rearing, and food intake w ere measured over 4 h after infusion. Results indicate that the striat um is a heterogeneous structure with regard to the regulation of opiat e-induced feeding behavior and locomotor activity. Morphine infusion i nto anteroventromedial regions including the nucleus accumbens resulte d in a marked hyperphagia that was generally delayed in onset; much sm aller increases or no change in feeding occurred after administration into more dorsal, lateral and posterior areas. It is hypothesized that there may exist within the striatum an anatomical gradient that is mo st sensitive to opiate-induced feeding within the anteroventromedial s ector. Since this area has extensive connections with other brain site s sensitive to opiate-induced feeding, it may be a critical part of an opiatergic feeding system within the brain. In addition, a possible r ole for the anteroventromedial striatum in compulsive feeding and buli mia is discussed.