甲状腺功能对调节雄性马鹿体重和繁殖活动季节性变化的研究

本研究探讨了甲状腺功能对雄性马鹿体重和繁殖活动季节性变化的调节作用，试验１从１９８８年１月（夏季）开始到１９８９年６月（冬季）结束，对照组５头正常鹿体中，血浆Ｔ３水平具有明显的季节性变化（Ｐ＜０．０１），在秋季和冬季较低，春季至秋季早期较高，而３头甲状腺摘除（ＴＨＸ）鹿血浆Ｔ３水平在１９８８年６月后（冬季）降低到不可测水平。在１９８８年９月以前，二组鹿的体重，睾丸直径和血浆睾酮水平的季节性变化趋势

INVOL VEMENT OF THYROID FUNCTION IN REGULATION OF SEASONAL CHANGES OF LIVE WEIGHT AND REPRODUCTION IN RED DEER STAGS

This study investigated the role of thyroid function in the regulaion of seasonalchanges of live weight and reproductive activities in red deer stags. Experiment 1observed the effects of thyroidectomy(THX)in 3 THX stags from January 1988 to June1989,with 5 intact stags as controls. Mean plasma concentration of T_3 in control stagsexhibited a seasonal pattern with high levels during spring to early autumn and lowlevels in atitumn and winter. From October 1988 (spring),control stags exhibited amarked reduction in testicular diameter, accompanied by a decrease of plasmatestosterone to undetectable levels,whereas none of the THX stags expressed thesechanges. After reaching the nadir in November 1988, testicular diameter of controlstags increased abrtiptly and reached the peak in March 1989(autumn),which wassignificantly higher than the peak of THX stags occurring in January 1989.Thesubstantial gain of live weight during December 1988 to March 1989(summer toautumn)in control stags did not occur in THX stags and these animals had lower(p<0.05)live weight than controls from February 1989. Experiment 2 observed the effectsof supplementing T_4 to 4 THX stags from September 1990 on changes in live weight andtesticular activities,with another 4 THX stags as controls.T_4 treated THX stagsinitially lost weight,but gained more weight during the growing period of spring andsummer than control THX stags(p<0.05).T_4 treated stags reduced testicular diameterin October and November 1990(spring and summer)with plasma testosteroneconcentrations undetectable, but increased thereafter and reached the peak in February1991 accompanied by a sharp rise of plasina testosterone concentrations. Testiculardiameter of control THX stags had little change in the course of experiment,and theseanimals maintained high levels of plasma testosterone in spring and summer.Results ofthis study demonstrate that THX prevented the seasonal changes in live weight andreproductive activities which occur in spring and early summer,and these effects areovercome by treatment with T_4.This indicates that thyroid function is involved inregulation of seasonal changes of live weight and reproduction in red deer stags.