高原鼠兔的季节性繁殖(英文)

SEASONAL REPRODUCTIVE CYCLES IN MALE PLATEAU PIKA(OCHOTONA CURZONIAE)

作者对成年雄性高原鼠兔（Ｏｃｈｏｔｏｎａｃｕｒｚｏｎｉａｅ）野外繁殖进行了全周年的调查。同时，对松果腺在其季节性繁殖周期调控中所起的作用进行了探讨。２月至４月上旬为其季节性繁殖的恢复期，睾丸、附睾、输精管和精囊腺的重量增加，血浆睾硐水平升高；但松果腺重量和褪黑素（Ｍｅｌａｔｏｎｉｎ，ＭＬＴ）含量降低。４月中旬至５月下旬为性活跃期，性腺器官显著增重，睾硐水平升至最高；而松果腺重量和ＭＬＴ含量呈现最低水平。６月至８月，鼠兔的性腺功能明显减弱；而松果腺重量和ＭＬＴ含量开始升高，此时为抑制期。９月至１月为性休止期，性腺器官的重量及血浆睾硐水平维持在最低水平；而松果腺重量和ＭＬＴ含量在较高的水平波动。结果表明，高原鼠兔的繁殖呈现明显的季节性。其松果腺活动的年周期反映了自然光周期的变化，并与鼠兔的季节性繁殖密切相关。

? Annual changes of the reproductive activity in adult male plateau pika (Ochotona curzoniae), a small endemic mammal in QinghaiTibet Plateau, were investigated from January to December, 1991. All of the animals were killed and decapitated during the night (23∶00～24∶00) and the plasma, pineal glands, testes epididymis, seminal vesicles, deferent ducts were collected and used for biochemical, and histological studies. Significant changes associated with seasonal cycles were found. (1) In February～early April, the restoration phase, the weights of testes, epididymides and deferent ducts were increased; the process of spermatogenesis was strengthened and testosterone level in plasma was increased, but the pineal weight and its melatonin content were decreased. (2) During the middle of April～late May, the sexually active phase, a significant elevation of gonadal activity was observed. In this period, gonadal weights were increased, spermatogenesis was completed, pineal weights were decreased and melatonin contents were fluctuated at a low level. These results suggested the increasing in sexual activity as well as in the ability of testosterone secretion. (3) A striking reduction of testicular activity appears in June～August. In this inhibition phase, gonadal weight, process of spermatogenesis, plasma testosterone level were decreased while the pineal weight and pineal melatonin content were increased. (4) During September～January, the sexually quiescent phase, declining in weights of testes and epididymides, arrest of spermatogenesis, decreasing of plasma testosterone concentration, fluctuating in pineal weights and increasing in pineal melatonin level were observed. Our findings indicated that the male pikas under natural conditions exhibited an annual reproductive cycle. A possible relationship between pineal activity and reproductive function was also suggested.