高脂饮食对幼鼠生长及胰岛素样生长因子表达的影响

Effects of high-fat feeding on growth and expression of IGF-I in young rats

目的研究高脂饮食对幼鼠生长及胰岛素样生长因子(IGF-I)表达的影响,闸明血清和肝脏组织IGF-I代谢紊乱与非酒精性脂肪性肝病(NAFLD)幼鼠生长迟缓的关系。方法 21日龄SD雄性大鼠40只,随机分成正常(N)组、高脂(HF)组。高脂饮食成功诱导NAFLD幼鼠造模成功后,测定血清IGF-I及胰岛素样生长因子结合蛋白-3(IGFBP-3)水平,采用RT-PCR与Western-blot检测肝脏IGF-I和IGFBP3的mRNA和蛋白表达。结果5周高脂饲料喂养后,高脂组幼鼠肝脏符合典型的NAFLD病理特征;与正常组相比,高脂组血清总胆固醇(TC)、血清高敏C反应蛋白、血清ALT及肝组织三酰甘油(TG)含量均显著升高(P均<0.01)。高脂组幼鼠体质量、鼻-尾长度较正常组增长缓慢(P<0.01)。胫骨长度和股骨长度两组差异无统计学意义;高脂组股骨的骨密度和骨矿含量均低于正常组(P均<0.05)。高脂组幼鼠血清IGF-I和IGFBP-3均较正常组表达显著下降(P均<0.01);血清生长激素(GH)两组差异无统计学意义(P>0.05);高脂组肝脏组织IGF-I和IGFBP3 mRNA和蛋白表达水平与血清学结果一致。结论血清IGF-I浓度与大鼠鼻-尾长度、体质量呈正相关,长期高脂饮食幼鼠生长迟缓,可能与肝脏组织和血清IGF-I浓度减低有关。

Objective To investigate the effects of high-fat feeding on growth and expression of insulin-like growth factor-Ⅰ（IGF-Ⅰ） level in young rats,and to illustrate the relationship between growth failure in young rats with non-alcoholic fatty liver disease（NAFLD）and IGF-I turbulence.Methods Forty SD young rats of 3 weeks old were randomly divided into two groups,normal group（N）and high-fat feeding group（HF）.The levels of serum IGF-I and insulin-like growth factor binding protein 3（IGFBP3）were determined in NAFLD rats induced by high fat feeding.The mRNA and protein level of IGF-I and IGFBP3 in liver tissue were measured by RT-PCR and Western-blot methods.Results The typical pathological change of NAFLD was observed in young rats induced by high-fat feeding for 5 weeks.The levels of total cholesterol（TC）,C-reactive protein（CRP）and alanine aminotransferase（ALT）were significantly higher in HF group than in N group（P 0.01）.The level of liver triglyceride（TG）was significantly higher in HF group than in N group（P 0.01）.The body weight and the nose-tail length were significantly decreased.The femoral and the tibial lengths were shorter in HF group than in N group,but this reduction was not significant.The femoral bone mineral density（BMD）and bone mineral content（BMC）were lower in HF group than in N group（P 0.05）.The levels of serum IGF-I and IGFBP3 were significantly lower in HF group than in N group.The liver tissue mRNA and protein level of IGF-I and IGFBP3 were significantly decreased in HF group than in N group（P 0.01）.The serum growth hormone（GH）level was lower in HF group than in N group,but this reduction was not significant.Conclusions Serum IGF-I is correlated with the nose-tail length and the weight.The growth restriction of young rats,induced by high-fat feeding,may be related to the decreased expression of IGF-I.