Cocaine and amphetamine-related transcript

Even if an over-simplification, this first order-second order model is useful in understanding how leptin signalling in the brain is translated into whole animal responses. The ARC contains two major neuronal populations (Gao and Horvath, 2007, Schwartz et al, 2000). The first population produces the peptides pro-opiomelanocortin (POMC) and cocaine and amphetamine related transcript (CART). Leptin increases POMC synthesis and processing into anorexic neuropeptides such as the melanocortin a-melanocyte stimulating hormone (oMSH). The second population of neurons is the diametrical opposite to POMC neurons They produce the orexigenic agouti related protein (AGRP) and neuropeptide Y (NPY) and leptin inhibits their production (Schwartz et al, 2000). 

Other peptides which affect feeding behaviour are found in the hypothalamus. They include the orexigenic peptides neuropeptide Y (NPY) and agouti-related protein (AgRp), and the anorexic peptides melanocyte-stimulating hormone (MSH) and cocaine- and amphetamine-regulated transcript (CART) (see below). 

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