雄性布氏田鼠光周期不应现象初探

A preliminary study on the photorefractoriness in male Brandt’s voles Lasiopodomys brandtii

日照时长是调控季节性繁殖动物性腺功能的重要因子。长期处于繁殖抑制光周期相位中的动物,往往出现性腺功能恢复的现象,被称为“光周期不应性”。布氏田鼠是严格的季节性繁殖鼠类,但是其光周期不应现象是否存在仍不明确。本研究对比了室内秋季出生的雄鼠在长光照(16 h)、短光照(8 h)和自然光照条件下的体重、睾丸、储精囊的重量,及粪便睾酮含量变化。结果表明,与长光照组相比,自然光照组和短光照组雄鼠性腺重量和睾酮含量在6周龄时被显著抑制,而在6~24周龄增长迅速,至24周龄(春分左右)达到长光照组水平。这些结果说明,短光照可以显著抑制雄性布氏田鼠性腺发育,但布氏田鼠存在光周期不应机制,在春季繁殖期到来前恢复性腺活性。

Photorefractoriness is characterized as the state of gonadal development that is insensitive to inhibitory photoperiods and triggers gonadal recrudescence in mammals.To study the photorefractoriness in Brandt’s voles(Lasiopodomys brandtii),we analyzed the variations in the body weight,gonadal weight and testosterone level in feces along with the postnatal development of new-born males under long-day light(LD,16 h light),short-day light(SD,8 h light)and natural photoperiod conditions from autumn to the following spring.Our results showed that the gonadal development of SD males was inhibited at the 6th postnatal week compared with that of LD males.The gonadal developmental rate of SD males was the highest during 6-24 postnatal weeks compared with the two other groups.SD males displayed a similar status as males under LD and natural photoperiod conditions around the vernal equinox(24 weeks).These results indicate the existence of photorefractoriness in Brandt’s voles,which is an important mechanism for regulating individual reproductive states before the onset of LD condition in early spring.