EFFECTS OF FASTING AND INSULIN TREATMENT ON BLOOD GLUCOSE AND LEPTIN-A GENE EXPRESSION IN CHINESE PERCH

Leptin has been reported to play important roles in regulation of glucose homeostasis in mammals. However, the relationship between blood glucose and leptin gene expression in teleosts is largely unknown. In the present study, blood glucose and leptin-A gene expression in liver, intestine and visceral adipose tissue were characterized in Chinese perch (Siniperca chuatsi) after fasting or insulin treatment. In the fasting experiment, Chinese perch were fasted for 10 days, sampling at 0, 4h, 2d, 6d and 10d after fasting. Blood glucose was significantly decreased at 10d after fasting; leptin-A mRNA expression was significantly increased in liver at 6d after fasting, and significantly increased in intestine and visceral adipose tissue at 4h after fasting. In the insulin treatment experiment, Chinese perch were intraperitoneally injected with bovine insulin (80 IU/kg body weight) or 0.7% saline as control, sampling at 12h and 36h post treatment. Blood glucose decreased significantly at 12h after insulin treatment, and leptin-A mRNA expression in intestine increased significantly at 36h after insulin treatment, which suggesting that prolonged fasting and insulin treatment decreased blood glucose, and increased leptin-A gene expression in fat depot organ and digestive organ of fish.