甲状腺功能对雄性马鹿春季繁殖活动退化的影响

Thyroid Hormones Permit Seasonal Testicular Regression in Red Deer (Cervus elaphus) Stags

试验一，在秋季和冬季对正常雄性马鹿处理T3以升高血浆T3水平，但处理鹿和对照鹿的睾丸直径、血浆睾酮水平在试验过程中变化趋势无显著差异．试验二，从冬季开始至春季，对正常雄性马鹿处理T4，使其血浆甲状腺激素从冬季开始就升高，处理鹿与对照鹿的睾丸直径和血浆酮水平都是在春季急剧下降．两试验的结果表明，正常雄性马鹿在春季发生的季节性繁殖退化，不是由于春季甲状腺激素水平上升的结果．

In experiment 1, 4 15 - month old red deer stags were injected with exogenous T3 during autumn and winter seasonas, whereas another 4 stags of the same age served as controls. Plasma T3 levels of treated stags were elevated compared wigh the values of controls. However both groups of animals had similar changes in testicular diameter and plasma testosterone levels during the course of experiment. In experiment 2, 4 19 - month old stags were treated with T4 from winter to spring, with 4 non - treated control stags of the same age. Although treated stags experienced an earlier rise in plasma concentrations of thyroid hormones from winter, their testicular diameter and plasma testosterone decreased abruptly in spring, at the same rate as in control animals. Results of these experiemts indicated that the seasonal testicualr regression in red deer stags in spring is not caused by a precedant rise of plasma concentrations of thyroid hormones. Therefore thyroid hormones play a permissive role in seasonal testicular regcession in red deer stags.