MELANOCORTINS AND OPIATE ADDICTION

Adrenocorticotropic hormone (ACTH) and alpha-melanocyte stimulating ho rmone (alpha-MSH) are centrally acting melanocortin peptides with nume rous reported functions, including induction of excessive grooming and antipyresis, among others. Also reported is a role for melanocortins in aspects of opiate action. Although early work examined the effects of ACTH and MSH on opiate-induced behaviors, further progress has been limited. Recently, however, advances in the identification and charac terization of melanocortin receptor (MC-R) subtypes have provided nove l tools with which to study interactions between melanocortins and add iction. The present review discusses the effects of ACTH and MSH on op iate-induced behaviors and relates these findings to more recent repor ts on the regulation of melanocortin systems by exogenous opiates. Eme rging from these data is the possibility that melanocortin receptor ac tivation, specifically at the MC4-R subtype, may act to antagonize cer tain properties of exogenous opiates, including perhaps addiction.