Diet-induced Changes In Adipose Tissue Expression Of AMPK In Rats

Objective: To explore the possible mechanisms of dietary induced obesity by studying the effect of high-fat diet on expression of AMPK in adipose tissue of rats.Methods: Thirty-six male SD rats were randomly divided into high-fat diet group (HF, n=27) and chow food group (CF, n=9), and given either HF or CF diet for 15-week. The HF group was designated as dietary induced obesity (DIO, n=14) and dietary induced obesity resistant (DIO-R, n=7) rats according to their final body weights. Then half of the DIO rats (DIO-HF/CF, n=7) were switched to CF diet, the other DIO (DIO-HF, n=7), CF and DIO-R rats continued their primary diet for another 8-week. Body weight and caloric intake were measured and compared. Plasma was collected for testing the concentrations of blood glucose, blood lipids and insulin. At the end of the experiment by the 23rd week, the rats were sacrificed after overnight fasting and adipose tissue around kidney were collected to measure the expression of AMPK by reverse transcription polymerase chain reaction (RT-PCR) and western blotting. The Waist and Epididymis adipose tissue were separated and weighed. Results: Body weight, adipose tissue depots, calorie intake, TC, TG, LDL-C, FINS, FBG and I/G were greater in DIO than in CF or DIO-HF rats(P<0.05), the HDL-C in DIO was lower than in CF rats(P<0.05). 8 weeks after transferred from HF diet to chow diet, body weight, adipose tissue depots, calorie intake, TC, LDL-C, FINS, FBG and I/G were significant lower in DIO-HF/LF than in DIO-HF rat(sP<0.05), and HDL-C was significant higher in DIO-HF/LF than DIO-HF rats(P<0.05). No significant difference in AMPKα1 mRNA expression was found among the four groups, but AMPKα2 mRNA and AMPKαprotein levels in DIO-HF group were the lowest among the four groups(P<0.05), and no significant difference was found among the other three groups(P>0.05).Conclusions: SD rat fed a high-fat diet showed different susceptibility to obesity. After 15-week HF feeding in DIO and DIO-R rats, DIO rats differed from DIO-R rats not only in body weight, fat body percent but also in blood biochemical such glucose, insulin and lipids. High-fat feeding result in down-regulated AMPKα2 mRNA expression and AMPKαprotein level along with increased calorie intake and body weight in individuals predisposed to obesity, but so such change was found in DIO-R rats. Taken together, AMPK may play an important role in avoiding overeating and obesity after high-fat feeding, AMPKα2 may be even important.