CARTPT and major depressive disorder: Besides its abundant expression in the hypothalamus, CART is also widely expressed in the central nervous system (CNS)[8–10], peripheral nervous system (PNS), and other peripheral tissues of mammals, including the pituitary, adrenal gland, pancreas, ovary, and adipose tissue [4,11–19], and thus CART peptide has recently been suggested to control many other physiological processes, such as stress response, drug reward and reinforcement, anxiety, depression, reproduction, pancreatic islet β-cell development and function, and bone remodeling [20–31].