Cocaine- and amphetamine-regulated transcript (CART) encodes several putative peptide fragments, some of which decrease feeding upon central administration.36,37 (see ref 38). CART is expressed in numerous brain nuclei, and the actual site of its anorexigenic actions has not yet been fully determined. In the rat LHA, CART is detected in the lion's share of MCH neurons of the zona incerta and medial LHA, whereas most peripeduncular MCH cells do not contain CART.39-40 In contrast, no Hcrt neurons stain for CART.39-40 Notably, according to a preliminary report, some degree of Hcrt/CART coexistence can be seen in the human brain.41 This would not be the first example of differential distribution of CART in primate and rodent brain; the transcript displays prominent discrepancies in expression e.g. between the human and rat thalamus.42 Coexpression of orexigenic and anorexigenic neuromodulators within the same cell presents an intriguing paradox, which remains to be explained. Further elucidation of the pre- and postsynaptic actions of CART peptides may shed light on this issue; see ref 38.
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