Effects Of Long-term Exercise With Medium Intensity On The Expression Of Hypoxia Inducible Factor-1α (HIF-1α) MRNA And Glucose Transport In Skeletal Muscle Of Mice

OBJECTIVES:To investigate the effect of long-term exercise with medium intensity on the expression of vascular endothelial growth factor (VEGF-A),glucose transporter-1(GLUT-1 ),glucose transporter (GLUT-4)and hypoxia inducible factor- 1α(HIF- 1α) in skeletal muscle of mouse and to explore the possible mechanisms of the effects in glucose transport induced by exercise.METHODS:Kunming male mice(n = 24) were randomly divided into:the control group(n=12) and the exercise group(n=12).The mice in exercise group were forced to run with medium intensity on a treadmill (speed:15m/min,Gradient:6°) for 1 hour per day,5 days per week.All the treatments in control group are the same as in the exercise group except no running exercise involved.After 12 weeks of exercise,all mice were sacrificed immediately and both sides of gastrocnemiuses were harvest. The middle parts of the tissue samples were prepared for H & E Staining and the transmission electron microscope analysis.In addition,the expression of VEGF-A mRNA,GLUT-1 mRNA,GLUT-4 mRNA and HIF- la mRNA were detected by Real-time PCR.RESULTS:①Compared to control group,the body weight of exercise group significantly increased(P＜0.05 ) as well as the number of muscle cells and the size of muscle fibers.②Ultra-structural analysis by the transmission electron microscope showed that the diameter of myofibril and the number of mitochondria were significantly increased.③The expression of VEGF-A mRNA,GLUT-1 mRNA,GLUT-4 mRNA,and HIF-1αmRNA in exercise group were significantly higher (increased by 2.68,2.14,3.31 and 2.92-fold separately,P＜0.05 separately) than those of control group.CONCLUSION:①Long-term exercise with medium intensity cause weight gain,thickened skeletal muscle fibers,increase of mitochondria number and expression of VEGF-A mRNA;②Long-term exercise with medium intensity can increase the expression of GLUT-1 mRNA,GLUT-4 mRNA in skeletal muscle.Induction of HIF-1αmRNA expression in skeletal muscle by exercise might be one of the possible mechanisms.