Expression of Orexigenic and Anorexigenic Neuropeptides Before and During Hibernation in the Daurian Ground Squirrel (Spermophilus dauricus)

Abstract

Hibernation is one of the most important energy-saving strategies used by some mammals during periods of relative food shortage. Fat-storing hibernators need to store enough body fat to survive the winter. To understand the roles leptin played before and during hibernation, we measured changes in body weight, food intake, serum leptin level, and the expression of genes related to food intake regulation in the neurons of the hypothalamic arcuate nucleus (ARC), in Daurian ground squirrels (Spermophilus dauricus). During the fattening period, the expression of neuropeptide Y (NPY) significantly decreased (P < 0.01, df = 8.348, t = −4.649), and the expression of cocaine- and amphetamine-regulated transcript (CART) peptide (P < 0.01, df = 12, t = 3.324) and serum leptin level (P < 0.05, df = 10, t = 3.070) significantly increased compared to the levels before fattening started. However, changes in neuropeptide expression did not inhibit food intake during the fattening period. The expression of pro-opiomelanocortin reached the peak value before hibernation that might be involved in reducing food intake in ground squirrels. There was no significant change in the expression of peptides during hibernation compared with the euthermic stage before fattening had started. These results suggest that leptin can regulate the expressions of Ob-Rb, CART, and NPY during the fattening period but food intake and body weight continued to rise despite the changes of serum leptin level and expressions of neuropeptides.