Melanin-Concentrating Hormone

MCH was originally discovered as a cyclic neuropeptide in the chum salmon pituitary. MCH is secreted from the pituitary into the circulation, and is responsible for aggregating melanin granules in teleost fishes. Mammalian MCH was subsequently identified in the rat hypothalamus. MCH is highly expressed in the lateral hypothalamus and zona incerta in rodents, both of which have extensive projections throughout the brain. Acute intracerebroventricular injections of MCH transiently stimulate food intake in rats, while chronic infusion of MCH significantly increases food intake, body weight, and white adipose tissue mass in mice fed a moderately high-fat diet ad libitum. Further lines of evidence for the importance of MCH in feeding come from studies wherein the expression levels of MCH were manipulated by knockout and overexpression techniques. Current evidence also shows that MCH receptor antagonists are efficacious in animal models of depression, anxiety, sleep disturbance, and reward.