Present in both classic neuroendocrine neurons and hypothalamic projection neurons, Arc CART displays an almost 100% colocalization with POMC and complete segregation from the more medially located orexigenic NPY in rodents (Elias et al., 1998; Vrang et al., 1999a; Fekete et al., 2000, 2004). The co-existence of CART with POMC and derivatives such as α-MSH were found to persist throughout the rostrocaudal extent of the Arc (Vrang et al., 1999a), wherein CART immunoreactivity (IR) was depicted in a separate study to pervade all α-MSH-IR perikarya and axons (Menyhért et al., 2007), which accords with the anorectic role widely adopted for POMC/CART neurons. In accordance with established neuronal projections from Arc (Schwartz et al., 2000), all α-MSH-IR axons in the PVN have also been shown to contain CART immunoreactivity (Menyhért et al., 2007).