Wada M, Hatanaka F, Tsuyoshi H, Sonoda Y
Department of General Education, Tokyo Medical and Dental University, Chiba, Japan.
Gen Comp Endocrinol. 1990 Dec;80(3):465-72. doi: 10.1016/0016-6480(90)90195-r.
Long days induced LH release in photosensitive Japanese quail and ambient temperature did not affect this process. Temperature also did not affect the levels of circulating LH concentrations at the steady state of LH release on long days. On the other hand, low ambient temperature was required to reduce circulating LH to a nonbreeding level together with the change of the photoperiod from long to short days; the changes of the photoperiod without low ambient temperature induced a decrease of circulating LH only to a certain level (1-2 ng/ml) which could maintain reproductive activity. The results also indicated that there were three levels of circulating LH in quail which were tentatively designated as a nonbreeding level (less than 0.5 ng/ml), a basal breeding level (1-2 ng/ml), and a steady breeding level (ca. 4 ng/ml). By photostimulation, levels of circulating LH increased to the steady breeding level directly and gradually, or leveled off after overshooting it. Photoperiodic changes from long to short days under moderate temperature resulted in a decrease in circulating LH to the basal breeding level which, however, could keep the gonad and the accessory sex organs active. Photoperiodic changes under cold ambient temperature reduce circulating LH to the nonbreeding level at which the gonad and the accessory sex organs regressed completely. These results suggest that ambient temperature is involved in the mechanism controlling an annual reproductive cycle, especially at the termination of the reproductive activity, in Japanese quail.
长日照可诱导光敏日本鹌鹑释放促黄体生成素（LH），环境温度对此过程无影响。在长日照下LH释放达到稳态时，温度对循环中LH的浓度水平也无影响。另一方面，需要低温环境，才能在光周期从长日照转变为短日照时，使循环中的LH降至非繁殖水平；在没有低温环境的情况下，光周期的变化仅能使循环中的LH降至一定水平（1 - 2纳克/毫升），该水平可维持生殖活动。结果还表明，鹌鹑体内循环中的LH存在三个水平，暂定为非繁殖水平（低于0.5纳克/毫升）、基础繁殖水平（1 - 2纳克/毫升）和稳定繁殖水平（约4纳克/毫升）。通过光刺激，循环中的LH水平可直接逐渐升至稳定繁殖水平，或在超过该水平后趋于平稳。在适度温度下，光周期从长日照转变为短日照会使循环中的LH降至基础繁殖水平，然而，此时性腺和附属生殖器官仍保持活跃。在寒冷环境温度下，光周期变化会使循环中的LH降至非繁殖水平，此时性腺和附属生殖器官会完全退化。这些结果表明，环境温度参与了日本鹌鹑年度繁殖周期的调控机制，尤其是在生殖活动终止时。
