Pre- and postprandial changes in orexigenic and anorexigenic factors in channel catfish (Ictalurus punctatus).

Ghrelin (GRLN), cocaine and amphetamine regulated transcript (CART), neuropeptide Y (NPY), and cholecystokinin (CCK) are neuropeptides involved in the regulation of appetite and feeding in vertebrates. We examined pre- and postprandial changes in the expression of plasma GHRL and mRNAs encoding GRLN, CART, NPY, and CCK in channel catfish. Fish were entrained to eat at 0900 h for 2 weeks. Fish were then sampled at 0700, 0800, and 0900 h. Remaining fish were either offered feed at 0900 h (Fed) or fasted (Unfed). Fish sampling continued at 0.5, 1, 2, and 4 h post feeding. Feeding increased abundance of whole brain CART mRNA out to 4 h with no effect observed in unfed fish. Whole brain NPY expression peaked at 0.5 h in both treatments. NPY expression then declined in fed fish but remained elevated in unfed fish. No differences in plasma or stomach GRLN expression were observed. Two separate cDNAs for CCK were identified. Brain CCKa and CCKb expression increased after feeding. These results suggest CART, NPY, and CCK play roles in the regulation of channel catfish feeding. Taken together, these results provide new insights into the neural and gastroenteric mechanisms regulating appetite in channel catfish.