Effects of high-fat diet and treadmill exercise on glucose transporter 4 and cAMP response element binding protein in rat gastrocnemius muscle / 中国组织工程研究

ABSTRACT

BACKGROUND:Some studies indicate that PI3K/Akt signaling pathway is associated with the expression of glucose transporter 4 (GLUT4) and the function of cAMP response element binding protein (CREB) in skeletal muscle. However, it is stil unclear whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in skeletal muscle of the rats with high-fat diet and treadmil exercise. OBJECTIVE:To investigate whether PI3K/Akt signaling pathway has the effects on CREB and GLUT4 in gastrocnemius muscle of the rats with high-fat diet and treadmil exercise. METHODS:A total of 70 rats were fed with normal diet for 2 weeks, and randomly divided into common feed group (n=20) and high-fat feed group (n=50). Rats in both groups were respectively fed with common feed and high-fat feed for 8 weeks. The rats in the common feed group were equaly assigned to common feed quiet group and common feed exercise group. 20 rats from the high-fat feed group whose body weight was 1.4 times of common rats were randomly and equaly assigned to obese quiet group and obese exercise group. Rats in the quiet groups did not do exercises. Rats in the exercise groups received adaptive sports for 1 week and medium-intensity treadmil exercise for 8 weeks. RESULTS AND CONCLUSION:(1) Impairments of PI3K/Akt signaling pathway appeared in obese rats, however, the quantity of GLUT4 expression did not change obviously in gastrocnemius muscles of obese rats. The reasons for the decrease of the nuclear protein CREB level of gastrocnemius muscles of obese rats might be related to the decrease of pAkt-Ser473 level. (2) The increase of the quantity of GLUT4 expression was accompanied by significantly up-regulated pAkt-Ser473 level by exercise intervention in gastrocnemius muscles of obese rats. Exercise intervention significantly increased the expression of nuclear protein CREB in gastrocnemius muscles of chow-fed rats and obese rats, which was consistent with the changes of pAkt-Ser473. These findings suggest that pAkt-Ser473 can play an important role in the effects of high-fat diet and exercise intervention on GLUT4 and CREB protein expression in gastrocnemius muscles of obese rats.