The MC4 receptor mediates alpha-MSH induced release of nucleus accumbens dopamine

Strong evidence suggests a functional link between the melanocortin and dop amine systems. alpha -Melanocyte stimulating hormone (alpha -MSH) induced g rooming behaviour, which can be blocked by dopamine receptor antagonists, i s associated with increased dopaminergic transmission in the striatal regio ns. Whether this effect is mediated specifically by melanocortin (MC) recep tors has not previously been established. Using in vivo microdialysis on an esthesized rats we have shown that alpha -MSH administered into the ventral tegmental area induced a significant increase in dopamine and DOPAC levels in the nucleus accumbens. This increase was completely blocked by pre-trea tment with the MC4 receptor selective antagonist HS131, indicating that the effects of alpha -MSH on dopamine transmission may be mediated by the MC4 receptor. Neuro-Report 12:2155-2158 (C) 2001 Lippincott Williams & Wilkins.