CART (Cocaine- and Amphetamine-Regulated Transcript) is a recently discovered peptide, which was initially identified as mRNA produced primarily in the rat hypothalamus after administration of psychomotor stimulants. It is a satiety factor and closely associated with the actions of two important regulators of food intake, leptin and neuropeptide Y. When systemic leptin or receptors for leptin are inhibited, expression of CART mRNA is suppressed. CART (55-102) has been isolated from the hypothalamus of ovine suggesting in vivo processing at the Lys⁵³-Arg⁵⁴ region. When injected intracerebroventricularly into rats, recombinant CART peptides inhibited both normal and starvation-induced feeding, and completely blocked the feeding response induced by neuropeptide Y. Thus far, CART (55-102) appears to be the most potent fragment with a conserved secondary structure consisting of three disulfide bridges. Disruption of this secondary structure by reduction leads to a loss of the appetite induction.