Regulation of the mesocorticolimbic and mesostriatal dopamine systems by α-melanocyte stimulating hormone and agouti-related protein

The melanocortin system of the hypothalamus, including the neuropeptides alpha-melanocyte stimulating hormone (alpha MSH) and agouti-related protein (AgRP), and their receptors, the melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R), have been well-studied for their roles in the central control of feeding and body weight. In this review, we discuss the evidence demonstrating that alpha MSH and AgRP also act on the mesocorticolimbic and mesostriatal dopamine systems to regulate a wide variety of behaviors. In addition to the well described ability of alpha MSH to increase dopamine transmission and to increase grooming and rearing when injected directly into the ventral tegmental area, a growing body of evidence indicates that alpha MSH and AgRP can also act on dopamine pathways to regulate feeding and drug abuse, including reward-related behaviors toward food and drugs. Increasing our understanding of how aMSH and AgRP act on dopamine pathways to affect behavior may allow for identification of new strategies to combat disorders involving dysfunction of dopamine pathways, such as obesity and drug abuse. (C) 2015 Elsevier Ltd. All rights reserved.