Donham R S, Di Pinto M N, Stetson M H
Biol Reprod. 1985 Mar;32(2):284-9. doi: 10.1095/biolreprod32.2.284.
Daily rhythms of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are measurable in the serum of prepubertal female golden hamsters by 17 days after birth. These rhythms, which are characterized by peak levels at 1700 h, persist until they are replaced by a 4-day rhythm as ovulatory cycles begin, approximately 3 wk later. We have tested the proposition that the ovaries are required for the onset and maintenance of clock-timed gonadotropin release by removing the ovaries and measuring the levels of LH and FSH in prepubertal hamsters. Ovariectomy was performed both before and after the onset of the rhythm and the effect of removal was determined by subsequent collection of blood samples during the mid- to late-prepubertal period. Ovariectomy on 7, 10 or 13 days after birth results in tonic levels of LH and FSH in blood samples collected at 1400, 1700 and 2000 h on Days 17 through 29. Sham-operated or intact controls had significantly elevated levels of these hormones at 1700 h. Ovariectomy on Day 21 and killing on Day 25 at the same times of day abolished the rhythm of serum LH measured in sham-ovariectomized controls. Ovariectomy on Day 21 and killing on Days 26, 28 or 30 at hourly intervals resulted in variable but nonrhythmic patterns of circulating LH. Thus, ovariectomy before the initiation of clock-timed gonadotropin release prevented its initiation; ovariectomy after its initiation abolished the rhythm. These results show that the ovary provides an essential "message" to the brain-pituitary axis for the initiation and maintenance of clock-timed gonadotropin release in prepubertal females.
出生后17天，就能在青春期前雌性金黄仓鼠的血清中检测到促黄体生成素（LH）和促卵泡激素（FSH）的每日节律。这些节律的特点是在1700时达到峰值，一直持续到大约3周后排卵周期开始时被4天的节律所取代。我们通过切除卵巢并测量青春期前仓鼠体内LH和FSH的水平，来验证卵巢对于定时释放促性腺激素的起始和维持是否是必需的这一假设。在节律开始之前和之后都进行了卵巢切除术，并通过在青春期前中后期随后采集血样来确定切除的效果。出生后第7、10或13天进行卵巢切除术，会导致在第17至29天的1400、1700和2000时采集的血样中LH和FSH处于持续水平。假手术或完整对照组在1700时这些激素的水平显著升高。在第21天进行卵巢切除术并在第25天同一时间处死，消除了假卵巢切除对照组中测得的血清LH节律。在第21天进行卵巢切除术并在第26、28或30天每隔一小时处死，导致循环LH出现可变但无节律的模式。因此，在定时释放促性腺激素开始之前进行卵巢切除术可阻止其开始；在其开始之后进行卵巢切除术则消除了节律。这些结果表明，卵巢为青春期前雌性动物的脑垂体轴提供了启动和维持定时释放促性腺激素所必需的“信号”。
