活化AMPK促进骨骼肌蛋白质降解过程中FoxO3 mRNA的表达

Purpose: By injecting AICAR, an AMPK excitant, into SD rats to boost the activity of AMPK in the skeletal muscles of the rats, the authors probed into the effects of FoxO3 mRNA changes on the degradation of proteins in skeletal muscles. Methods: Rats was divided into a bout AICAR injection, with a subcutaneous injection (AICAR; 0.5 mg/g body wt; 75 mg AICAR/ml saline), or an equivalent volume of normal saline as control. Gastrocnemius samples were collected at 1hour, 2 hours and 7 hours after AICAR injection. MAFbx mRNA, MURF-1 mRNA, FoxO3 mRNA was determined by Realtime PCR. AMPK activity was determined by [γ-32P] ATP as P donor and SAMS peptide as substrate. Results: AMPK activity were significantly increased（P<0.05）at post-inject 1 hour, 2 hours and 7 hours, then decreased at post-inject 7 hours. AICAR injection increased mRNA Expression of MuRF1(2.67-fold,2.30-fold)and MAFbx(2.45-fold, 2.23-fold) at post-inject 1 hour and 2 hours, respectively. MuRF1 mRNA were significantly elevated（P<0.05）, whereas MAFbx mRNA has increased, but no significant differences at post-inject 7 hours; FoxO3 mRNA has not changed at post-inject 1 hour, 2 hours and 7 hours. Conclusion: Rat with AICAR injection may increase AMPK activity and promote the protein degradation，whereas the increase of the AMPK activity may not change FoxO3 mRNA expression. Therefore foxO3 mRNA content may be dissociated from changes in skeletal muscle protein degradation.