Regulation Of AMP-activated Protein Kinase On Lipid Metabolism Of Piglet Hepatocytes Under Stress

Two experiments were conducted to study the effects of AMP-activated protein kinase(AMPK) on lipid metabolism in incubating hepatocytes of piglets under heat stress and nutritional stress.Exp.1 Effects of AMPK activity on lipid metabolism in hepatocytes of piglets under heat stressThe study was performed to evaluate the effect of AMPK on lipid metabolism in hepatocytes of piglets under heat stress. The experiment included three treatments: control, heat stress and heat stress adding AMPK inhibitor ⁸Br-AMP(0.5mmol/L). Each treatment had two incubating time points : 60min,120min.The results showed that:1. Heat stress activated AMPK activity and inhibited ACC activity of hepatocytes. At the incubating time of 60min and 120min, the AMPK activity of the group adding inhibitor was decreased by 14.35%, 7.76%(p > 0.05 )compared to the group of heat stress.2. Heat stress enhanced fatty acid oxidation of hepatocytes. On the other side, the inhibitor depressed fatty acid oxidation of hepatocytes . After incubating for 60min and 120min, the production of [¹⁴C]-CO₂ of inhibitor group was decreased by 26.89% (p< 0.05) , 50.40%(p<0.05) compared to that of heat stress group respectively. The production of [¹⁴C]-ASM was decreased by 31.24% (p<0.05)compared to heat stress group after incubating for 120min.3. Heat stress depressed lipid synthesis metabolism obviously. The group of adding inhibitor tended to accelerate lipid synthesis metabolism. After incubating for 60min, the productions of phospholipids, monoglycerides, triglycerides, cholesterol in the group of adding inhibitor were increased by 54.87%, 82.47%, 25.60%, 58.60% respectively except that cholesterol ester was decreased by 0.21%.The data indicated that AMPK influenced lipid metabolism of piglets' hepatocytes under the heat stress in effect.Exp.2 Effects of AMPK activity on lipid metabolism in hepatocytes of piglets under nutritional stressThe study was performed to evaluate the effect of AMPK on lipid metabolism in hepatocytes of piglets under nutritional stress. The experiment included three treatments: control, nutritional stress and nutritional stress adding AMPK inhibitor 8Br-AMP(0.5mmol/L). Each treatment had two incubating time points: 60min,120min.The results showed that:1. Nutritional stress activated AMPK activity and inhibited ACC activaty of hepatocytes.The AMPK activity of the group adding inhibitor was decreased by 20.77% > 41.15% (p<0.01 = compared to the group of nutritional stress when the time of incubation was 60min and 120 min.2. Nutritional stress enhanced fatty acid oxidation of hepatocytes. On the other side, the inhibitor depressed fatty acid oxidation of hepatocytes. After incubating for 60min and 120 min, the production of [14C]-CO2 of inhibitor group was decreased by 48.78%(p=0.18) and 21.73% (p=0.42) compared to heat nutritional group respectively. The production of[14C]-ASM was decreased by 31.33% (p=0.248) and 25.56% (p=0.315) compared to nutritional stress group respectively.3. Nutritional stress depressed lipid synthesis metabolism obviously. The group of adding inhibitor tended to accelerate lipid synthesis metabolism. The productions of phospholipids, monoglycerides, triglycerides, cholesterol and cholesterol ester in the group of adding inhibitor tended to increase when incubating for 60min and 120min.The data indicated that AMPK influenced lipid metabolism of piglet's hepatocytes under the nutritional stress in effect.IMPLICATIONSIn conclusion, AMP-activated protein kinase changes lipid metabolism under nutritional stress and heat stress.