BROMOCRIPTINE ENHANCES FEEDING-BEHAVIOR WITHOUT CHANGING DOPAMINE METABOLISM

Bromocriptine is an ergot derivative and has been thought to act as a selective D-2 receptor agonist, but its effects on dopamine release in vivo have not been confirmed. We administered bromocriptine into the striatum of rats and studied the effects on feeding behavior and dopam ine release. Bromocriptine was perfused via a microdialysis probe into the ventrolateral striatum of rats fasted for 22 h, and the rats were then allowed to feed freely for 6 h. Bromocriptine perfusion increase d food intake in a dose-dependent manner, whereas the extracellular co ncentrations of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) did not change. Perfusion of (-)sulpiride, a s elective D-2 receptor antagonist, decreased food intake, but increased dopamine release and the levels of DOPAC and HVA. Pretreatment with ( -)sulpiride perfusion for 1 h prior to bromocriptine perfusion inhibit ed the increase of food intake induced by bromocriptine, and it increa sed dopamine release and the levels of DOPAC and HVA. These findings s uggest that bromocriptine directly perfused into the ventrolateral str iatum acts selectively on postsynaptic D-2 receptors and enhances feed ing behavior. (C) 1997 Elsevier Science Inc.