Effects Of Neuropeptide Y On Food Intake And Gene Expression In Grass Carp (Ctenopharyngodon Idellus)

Neuropeptide Y (NPY), which promoted positive food intake by its receptors, was a kind ofshort, single stranded polypeptide. But very little is known about NPY actions in fish.In this study, a partial length cDNA of grass carp NPY was cloned and the sequence ofmature peptide was obtained. The effects of NPY on food intake and energy metabolism wereassessed by intracerebroventricular (I.C.V.) injection of NPY. A significantly increase effect onfood intake was observed in NPY injection group (the middle dose group and high dose group)between2-8h after I.C.V. injection of NPY (compared to teleost saline injection group), but notduring the following8-72h. A significantly increase effect on Cumulative food intake wasobserved in the middle dose group, but not in the high dose group.In order to further expose the molecular regulative mechanism of NPY on food intake andenergy metabolism, partial cDNA sequences of eighteen genes correlating to food intake (suchas NPY, Y8a, Y8b, LEP, LEPR, LEPROT, CCK, CART, PACAP), growing development (IGF1,IGF2, IGF1R), degestion (such as BSAL, TRY, AMY) and lipid metabolism (such as HL, FAD,ELO) were also isolated form grass carp.The acute effects of NPY on the expression of the above18genes were further characterizedby real-time PCR. The mRNA levels of LEP, LEPR, LEPROT, CCK, CART and PACAP weresignificantly reduced whereas the mRNA levels of NPY, Y8a, Y8b, IGF1, IGF2, IGF1R, AMY,TRY, BSAL, HL, FAD and ELO were significantly elevated between2-4h after injection. Ourresults suggest that NPY has an acute effect on the regulation of food intake, energy expenditureand lipid metabolism in grass carp.