Comparative study of effects of heavy load swimming training and simulated microgravity on monoamine neurotransmitters of hypothalamus in rats

Purpose:This study was to investigate the centre mechanism of the effects of heavy load exercise training and simulated microgravity on HPG axis and HPA axis in rats.Effects of the two stressors on monoamine neurotransmitters of hypothalamus in rats were compared.Method:Fifty male Sprague-Dawley rats were divided into gorups randomly as control group(CON),swimming training group(EXE),hindlimb suspension group(model of simulated microgarvity)(HLS),swimming training group with supplementation of testosterone(ETR) and hindlimb suspension group with supplementation of testosterone(HTR).The EXE and ETR rats took a siex-week swimming protocol with training load increased progressively.The HLS and HTR rats endured a six-week suspension by tail one week after an operation of annulus abdominals shortened.Testosterone propinate was supplemented to the ETR and HTR rats by the way of intraperitoneal injection,with a dose of 2.5mg/kg body weight/day.The supplementation lasted for six weeks.The EXE and ETR rats were sacrificed by decapitation immediately after the last swimming training.The CON,HLS and HTR rats were decapitated at resting state at the same time.Hypothalamus was taken out as soon as the skulls of rats were opened after being decapitated.Monoamine neurotransmitters of hypothalamus were measured by electrochemical method with HPLC.It could be seen that the hypothalamus monoamine neurotransmitters DA,NE and 5-HT of EXE and ETR rats immediate post-exercise tended to decrease when compared with those of CON rats,but the ratio of(DA+NE)/ 5-HT tended to increase.The monoamine neurotransmitters DA,NE and 5-HT increased significantly.Conclusion:It could be concluded that monoamine neruotransmitters and the ratio of(DA+NE) /5-HT changes of hypothalamus might be the centre mechanism for the changes of HPG axis and HPA axis induced by the two stressors in rats.