Cocaine- and amphetamine-regulated transcript peptide-(55-102) and thyrotropin releasing hormone inhibit hypothalamic dopamine release

Cocaine- and amphetamine-regulated transcript (CART) peptide-(55-102) and t hyrotropin releasing hormone (TRH) play an anorectic role in the hypothalam us. Catecholamines are also involved in appetite control and we have previo usly found that leptin, an adipocyte-derived anorectic hormone, inhibits hy pothalamic norepinephrine and dopamine release. We have studied the effect of CART peptide-(55-102) and TRH on basal and depolarization (K+ 15 mM)-ind uced norepinephrine and dopamine release from rat hypothalamic neuronal end ings (synaptosomes) in vitro. We have found that basal catecholamine releas e was not modified; both CART peptide-(55-102) and TRH, the former with a h igher sensitivity, dose-dependently inhibited depolarization-induced dopami ne release, and did not affect the stimulated norepinephrine release. Consi dering the role played by dopamine in the central mechanisms of reward, the se findings suggest that the inhibition of dopamine release could underlie the decreased appetitive behaviour induced by CART peptide-(55-102) and TRH . (C) 2000 Elsevier Science B.V. All rights reserved.