Overtraining induces renal tubular cells apoptosis through activating caspase-related signal pathway by impairing the balance of Bax and Bcl-2 in exhaustive swimming rats / 中华肾脏病杂志

ABSTRACT

Objective To observe the expression changes of renal tissue Bax,Bcl-2 and caspase-3,to wxamine the correlation between the ratio of Bax to Bcl-2,caspase-3 and renal tubular cells apoptosis,and to investigate the role of caspase-related signal pathway.Methods Forty-eight male Wistar rats were randomly divided into three groups control (CN,n=8),exhaustive swimming (ES,n=24) and inula britannica (IB,n=16) group.The rats of CN were quiet without swimming.The rats of ES swam to exhaustive state and were sacrificed at immediately(ESI),6 hour (ES 6 h) and 24 hour (ES 24 h) after exhaustive swimming respectively.The rats of IB took orally inala britannica at the dose of 25 ml/kg body weight at 24 h before swimming and then swam to exhaustive state.The rats of IB group were sacrificed at 6 hour (IB 6 h) and 24 hour (IB 24 h)after exhaustive swimming.The animal model of overtraining-induced acute kidney injury was developed by exhaustive swimming.The renal cell apoptosis was measured by the method of TUNEL.The expressions of Bax,Bcl-2,caspase-3 in renal tissue were observed by immunohistochemistry.The expression of caspase-3 protein was examined by Western blotting.The correlation between the ratio of Bax to Bcl-2 and caspase-3 was analysed by Pearson method,and the correlation between the ratio of Bax to Bcl-2,caspase-3 and renal tubular cell apoptosis was analysed by Spearman method.Results The number of renal tubular apeptotic cells was increased progressively in ESI to ES 24 h rats by TUNEL (P＜0.05).Immunohistochemistry staining showed that the ratio of Bax to Bcl-2 and caspase-3 in renal tubular cells were increased progressively at 0 h,6 h and 24 h after exhaustive swimming compared with control group (P＜0.05).The change of renal tissue caspase-3 was also revealved by Western blotting analysis.The ratio of Bax to Bcl-2 and caspase-3 in renal tubular cell was correlated positively (r=0.865,P＜0.05),The ratio of Bax to Bcl-2,and caspase-3 was also correlated positively to renal tubular cell apoptosis (r=0.674,r=0.837,P＜0.05) in ES rats.Pretreatment with inula britannica inhibited the up-regulation of the ratio of Bax to Bcl-2,caspase-3 and cell apoptosis in renal tubular cell induced by exhaustive swimming.Conclusion Overtraining can induce renal tubular cells apoptosis through activating caspase-related signal pathway by impairing the balance of Bax and Bcl-2,which may be one of the important molecular mechanisms of overtraining-induceed renal tubular cells apoptosis.