Stetson M H, Hamilton B
J Exp Zool. 1981 Feb;215(2):173-8. doi: 10.1002/jez.1402150206.
Cyclic female hamsters were rendered anovulatory by daily subcutaneous melatonin injections (25 microgram/0.1 ml oil) in 29 days or by transfer to a short light cycle, LD 6:18 (lights 1000-1600 hrs) in 33 days. Estrous cyclicity was reinitiated in these animals in 44 or 45 days following cessation of melatonin injections or transfer to long light cycles (LD 14:10, lights 0600-2000 hrs), respectively. Exposure of both groups to LD 6:18 after reinitiation of estrous cyclicity caused a second cessation of ovulation in 75 (melatonin group) or 61 (short light cycle group) days. Thus, although both treatments disrupted estrous cyclicity for nearly 6 weeks, this was not sufficient to induce photorefractoriness (failure to respond to short light cycles with continued estrous cyclicity). Rather, every animal responded to LD 6:18 and ceased ovulating. Melatonin-induced anovulatory hamsters showed daily gonadotropin release patterns identical to those reported in hamsters in other anovulatory states (lactating, prepubertal, and photoinduced anovulatory hamsters); that is, peak LH and FSH release at 1700 hrs daily.
通过在29天内每日皮下注射褪黑素（25微克/0.1毫升油）或在33天内将雌性仓鼠转移到短光照周期LD 6:18（光照时间为1000 - 1600小时），使周期性发情的雌性仓鼠停止排卵。在停止注射褪黑素或分别转移到长光照周期（LD 14:10，光照时间为0600 - 2000小时）后的44或45天，这些动物重新开始发情周期。在发情周期重新开始后，两组仓鼠暴露于LD 6:18，分别在75天（褪黑素组）或61天（短光照周期组）导致第二次排卵停止。因此，尽管两种处理都使发情周期中断了近6周，但这不足以诱导光不应性（对短光照周期无反应，持续发情周期）。相反，每只动物对LD 6:18都有反应并停止排卵。褪黑素诱导的无排卵仓鼠每日促性腺激素释放模式与其他无排卵状态（哺乳期、青春期前及光诱导无排卵仓鼠）的仓鼠所报道的模式相同；即，LH和FSH每日在1700小时释放达到峰值。
