Effects Of Ala-Gln On Protein Synthesis In Skeletal Muscle Of Plateau Training Rats And Its Relationship With MTOR

Objective:This paper aims to explore the effect of supplement Gln or Ala-Gln on skeletal muscle protein synthesis in the rats and its possible mechanisms under simulation altitude training, with Comparisons of the effect of supplement Gln or Ala-Gln as the experiental basis.Method:40,6-week-old male SD rats were randomly divided into normal oxygen control group (NC group, n=10), hypoxic exercise group (HE group, n=10), hypoxic exercise+glutamine+ alanine group (HEG group, n=10), hypoxic exercise+alanyl glutamine group (HEAG group, n =10). After 6 weeks of 13.6% hypoxic exposure and weight loading swimming training in 80% lactate threshold intensity (2.1%* 80% of the weight load), the serum IGF-1;Pro, Myo, IGF-1, mTOR, PI3K content and the expression of mTOR, AKT, eEF2,4EBP-1 mRNA in skeletal muscle are measured.Result:(1) Compared with group NC, in group HE, the amount of Pro and Myo in skeletal muscle significantly decreases (P< 0.05, P< 0.01); the amount of serum and skeletal muscle IGF-1 significantly decreases (P< 0.05, P< 0.01); PI3K significantly decreases (P< 0.01); mTOR and the expression of AKT mRNA slightly decrease, but there is no significant difference (P> 0.05); the expression of mTOR mRNA significantly decreases (P< 0.01); the expression of eEF2 mRNA slightly decreases, but there is no significant difference (P> 0.05); the expression of 4EBP-1 mRNA significantly increases (P< 0.05).(2) Compared with group HE, in group HEG, the amount of Pro and Myo in skeletal muscle increases, but there is no significant difference (P> 0.05); IGF-1 in serum and skeletal muscle significantly increases (P< 0.01, P< 0.05); PI3K in the skeletal muscle significantly increases (P< 0.05), while the expression of AKT mRNA slightly decreases (P> 0.05); the expression of mTOR mRNA had no significant increase (P> 0.05), while the amount of mTOR in skeletal muscle significantly increases (P< 0.05); the expression of eEF2 mRNA slightly decreases (P> 0.05), the expression of 4EBP-1 mRNA significantly decreases (P< 0.05).(3) Compared with group HE, in group HEAG, the amount of Pro and Myo in skeletal muscle significantly increases (P< 0.05); IGF-1 serum and skeletal muscle significantly increases (P< 0.01, P< 0.05); the amount of PI3K and the expression of AKT mRNA in skeletal muscle significantly increases (P< 0.05); the expression of mTOR mRNA and mTOR significantly increases (P< 0.05); the expression of eEF2mRNA significantly increases (P< 0.05); the expression of 4EBP-1 mRNA significantly decreases (P< 0.05).(4) Compared with group HEG, in group HEAG, the amount of Pro and Myo in skeletal muscle slightly increases, but there is no significant difference (P> 0.05); the amount of serum IGF-1 significant increases (P< 0.05), and the amount of IGF-1 and PI3K in skeletal muscle slightly decreases, but there is no significant difference (P> 0.05); The expression of AKT mRNA and mTOR mRNA significantly increases (P< 0.01, P< 0.05), and the amount of mTOR has no significant increase (P> 0.05); The expression of eEF2 mRNA significantly increases (P< 0.05), while the expression of 4EBP-1 mRNA has no significant increase (P> 0.05).Conclusion:(1) Reduced secretion of IGF-1 caused by long-term altitude trainning, inhibits PI3K/Akt/mToR pathway which results in the reduced expression of eEF2 mRNA and the increased expression of 4EBP-1 mRNA, and skeletal muscle protein synthesis which results in decreased amount of Pro, Myo in rats’s skeletal muscle.(2) Under altitude training, the supplement of Gin or Ala-Gin, to a certain extent, can promote the secretion of IGF-1 which can activate the PI3K/Akt/mToR pathway, causing the increased expression of eEF2 mRNA and decreased expression of 4EBP-1 mRNA. And the increased synthesis of skeletal muscle protein plays an important role in preventing the loss of skeletal muscle protein under altitude training.(3) The supplement of Ala-Gln is better than the supplement of Gln in promoting the synthesis of skeletal muscle protein.