This article compared the effects of spontaneous obesity on the daily profile in the relative amount of the leptin receptor (LepRb), and its output. That is the precursor Pro-opiomelanocortin (POMC) over a 24-hour period and compared with differences in locomotion and food intake in periods of artificial light. Differences between lean and obese mice were examined, as were sex differences. Body weight, food intake and locomotor activity were monitored in freely moving lean and obese mice. Hypothalamic tissue was collected at 5 h, 10 h, 15 h, 19 h and 24 h. Samples were analyzed by western blotting to determine the relative presence of protein for LepRb, STAT3 phosphorylation (by pSTAT3/STAT3 ratio) and POMC. Obese mice were 60% less active in locomotion than lean mice during the night. While both locomotor activity and food intake were noticeably greater during the day in obese mice than in lean mice, the hypothalamus in obese mice showed a lower relative abundance of POMC and reduced pSTAT3/STAT3 ratio and leptin receptors. Behavioral and biochemical differences were more evident in obese females than in obese males. These results indicate that obesity in N. alstoni affects hypothalamic leptin signaling according to sex.
Keywords: Neotomodon; daily changes; hypothalamus; leptin; obesity; sex differences.