Ｅｆｆｅｃｔｓ ｏｆ Ｈｉｇｈ Ｐｒｏｔｅｉｎ Ｎｕｔｒｉｔｉｏｎ Ｉｎｔｅｒｖｅｎｔｉｏｎ ｏｎ Ｂｏｄｙ Ｃｏｍｐｏｓｉｔｉｏｎ ａｎｄ Ｓｋｅｌｅｔａｌ Ｍｕｓｃｌｅ ｍＴＯＲ Ａｃｔｉｖｉｔｙ ｏｆ ＩＵＧＲ Ｒａｔｓ ｄｕｒｉｎｇ Ｄｉｆｆｅｒｅｎｔ Ｐｅｒｉｏｄｓ

【Objective】 To investigate the effects of high protein nutrition intervention on body composition and skeletal muscle mTOR(mammalian target of rapamycin) activity of IUGR(intrauterine growth restriction) rats during different periods.【Methods】 There were 64 male IUGR rats: 40 IUGR rats in the IUGR control group(CR group),24 IUGR rats in the early high protein intervention IUGR group(EPR group).There were 24 normal birth weight male rats in normal control group(CN group).At 4 weeks of age,8 rats of these groups were executed and 16 rats in CR group were randomly assigned to the delay high protein intervention IUGR group(DPR group).All rats were lactated for 3 weeks and the mother rats of CN and CR group were provided free access to basic diet while the mother rats of EPR group were provided free access to high protein diet.After weaning rats in CN and CR group were provided free access to basic diet until 12 weeks of age.After weaning rats in EPR group were provided free access to high protein diet until 4 weeks of age.At 4 weeks of age they were provided free access to basic diet until 12 weeks of age.Rats in DPR group were provided free access to high protein diet from 4 weeks of age to 8 weeks of age,and then they were provided free access to basic diet until 12 weeks of age.At 8,12 weeks of age,8 rats of these groups were executed.The body composition,serum adiponectin,blood glucose and insulin level,cross sectional area of skeletal muscle fibers,skeletal muscle mTOR activity were measured at 4,8,12 weeks of age.The homeostasis model assessment model for insulin resistance index(HOMA-IR) was calculated.【Results】 The percentage of fat mass was significantly higher in the CR group than in the CN group at 4,8,and 12 weeks of age and the DPR group at 12 weeks of age(P 0.05 or P 0.01).The percentage of lean mass,cross sectional area of skeletal muscle fibers,skeletal muscle mTOR activity,serum adiponectin level were significantly lower in the CR group than in the CN group at 4,8,and 12 weeks of age and the DPR group at 12 weeks of age(P 0.05 or P 0.01).HOMA-IR was significantly higher in the CR group than in the CN group at 8,12 weeks of age and the DPR group at 12 weeks of age(P 0.05 or P 0.01).The percentage of fat mass was significantly lower in the EPR group at 4,8,and 12 weeks of age and in DPR group at 8 weeks of age than in the CR group(P 0.05 or P 0.01).The percentage of lean mass,cross sectional area of skeletal muscle fibers,skeletal muscle mTOR activity,serum adiponectin level were significantly higher in the EPR group at 4,8,and 12 weeks of age and in DPR group at 8 weeks of age than in the CR group(P 0.05 or P 0.01).HOMA-IR was significantly lower in the EPR group at 8,12 weeks of age and in DPR group at 8 weeks of age than in the CR group(P 0.01).【Conclusions】 Birth to 4 weeks of age is the appropriate window period of high protein nutrition intervention of IUGR rats.High protein nutrition intervention from birth to 4 weeks of age improves the short and long term body composition and insulin sensitivity of IUGR rats.High protein nutrition intervention increases lean mass and decreases fat mass of IUGR rats possibly by activating mTOR of skeletal muscle.