Effects Of 5-week Sub-ultimate Intensity Exercise On StAR Protein And Its Regulatory Factors

Objective: To investigate the effects of continuous intermittent high-intensity exercise on testosterone levels and StAR in rats by studying the time sequence change in expression of PKA,pCREB and SF-1,the cholesterol transporter regulation pathway corresponding factors,in order to reveal the mechanism of exercise-induced low serum testosterone,and provide the basis for finding an intervention for prevention and treatment.Methods: Modeling Experiment: 30 Eight-week-old SD rats were divided into three groups: A,B and C.The rats in the exercise group were subjected to 4 min × 5 swimming training(5% and 6%BW,respectively).Interval is 90 seconds,2 times per day,6 days per week and the entire experiment is lasted for 5 weeks.48 hours after late training,rats from each groups were anesthetized,blood and testicles were sampled for further analysis.The changes of CK,BU,T and StAR mRNA were detected in rats.Formal Experiment: 90 Eight-week-old male rats were divided into five exercise groups(T1,T2,T3,T4,T5)and two control groups(C0,C5)according to the training time.Exercise groups,weighed 6%BW,were trained based on the basis of above training program and 48 h after final training rats from each groups were anesthetized,sampled for further analysis.Western Blot,RT-PCR and other techniques are applied to detect the relevant protein and gene mRNA changes.Results: Modeling Experiment: 1)The serum lactate of group A and group B measured 3 minutes after training finish increase significantly compared with that of group C(p<0.01),and there was significant difference between group A and group B(p <0.01).2)Compared with the control group,the serum CK and BU of the exercise group increased significantly(p <0.01),however there was no significant difference between the exercise groups.3)The expression of StAR mRNA in group B was significantly lower than that in group C(p <0.05).Formal Experiment:1)The testosterone level in intervention group decreased slowly in the first three weeks,then decreased significantly,and the testosterone level in T5 group decreased by 70% compared with C0 group.(P <0.01).The LH level is descend irregularly,the fifth week LH level decreased by 41% compared with C0 group(P <0.01).2)The serum lactate measured 3 minutes after training finish increase significantly(P <0.01),and maintained at a high level and slightly increased in the next two weeks(p> 0.05).The trend was as follows: in first three weeks the level of lactate increased dramatically,however in next two weeks it maintained in high level with slight increase.SOD activity is declining.SOD activity of T5 group decreased to 77% compared with C0 group(p <0.01).MDA level was slightly fluctuated in the first three weeks,and increased remarkably in the fourth and fifth weeks,which was significantly higher than that in C0 group(p <0.01).3)The expression of PKA,pCREB and SF-1 protein expression in testis were stable in the first three weeks,then decreased significantly(p <0.05).4)The expression of StAR mRNA in the exercise intervention group was steady in the first three weeks,but the expression of mRNA in T5group was significantly decreased compared with which in C0 group.(p<0.05)SF-1 mRNA increased slightly in the first week compared with the C0 group.Followed by SF-1 mRNA expression gradually decreased to the fifth week,which was significant.(p<0.01)Conclusion: 1.Medium and long term sub-ultimate intensity exercise resulted in peroxidation in testicular tissue,serum testosterone,StAR and its associated regulators PKA pCREB SF-1 in testicular leydig cells.2.StAR mRNAexpression decrease due to StAR regulatorsinhibition,leading to mitochondrial cholesterol transfer limitation might be the mechanism of accelerated decline in serum testosterone.