Pohl C R, deRidder C M, Plant T M
School of Health Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, USA.
J Clin Endocrinol Metab. 1995 Jul;80(7):2094-101. doi: 10.1210/jcem.80.7.7608261.
The present study reexamined the role of the ovary in determining the prepubertal hiatus of gonadotropin secretion in the rhesus monkey. Day- and nighttime blood samples were obtained weekly from neonatally (7-10 days of age) ovariectomized and intact monkeys from birth until 3 yr of age. In the intact monkeys, plasma FSH levels increased during the first month of life, remained elevated until approximately 3 months of age, and then decreased to become undetectable by 7 months of age. Thereafter, plasma FSH remained undetectable until approximately 19 months of age, at which time it again increased to detectable concentrations. In animals ovariectomized as neonates, the developmental pattern in FSH secretion was similar to that in intact animals, but, quantitatively, mean plasma FSH concentrations in the agonadal females were greater than those in the intact control group at all times. Circulating daytime LH concentrations in intact animals were generally below the sensitivity of the assay during the neonatal and prepubertal phases of development, but after 27 months of age, this plasma hormone was measurable on occasion. In neonatally ovariectomized monkeys, daytime LH was elevated during the first month of life, undetectable between 2-20 months of age, and then rose into the adult range by the end of the study. Nocturnal plasma FSH and LH concentrations in agonadal monkeys were generally greater than those during the day at all stages of development. Of particular note was the finding that during the prepubertal hiatus in gonadotropin secretion, when daytime LH levels were mostly immeasurable, nighttime levels of this gonadotropin were consistently elevated. The hypersecretion of gonadotropin during prepubertal development in agonadal animals also occurred when ovariectomy was performed at 61-62 weeks of age. These findings demonstrate that in the female monkey, the open loop activity of the GnRH pulse generator during juvenile development is only partially suppressed, and the ovary contributes significantly to the prepubertal restraint on gonadotropin secretion. We also report the serendipitous finding that a precipitous, albeit transient, decline in circulating gonadotropin concentrations occurred in juvenile monkeys after separation from their mothers and relocation to individual cages. This suppression, which was accompanied by elevated plasma cortisol levels, was apparently not related to any impairment in growth.
本研究重新审视了卵巢在决定恒河猴青春期前促性腺激素分泌间隙方面的作用。从出生到3岁，每周从新生期（7 - 10日龄）切除卵巢和未切除卵巢的猴子身上采集白天和夜间的血样。在未切除卵巢的猴子中，血浆促卵泡激素（FSH）水平在出生后的第一个月升高，一直维持在较高水平直到大约3个月龄，然后下降，到7个月龄时降至检测不到的水平。此后，血浆FSH一直检测不到，直到大约19个月龄时再次升高到可检测的浓度。在新生期切除卵巢的动物中，FSH分泌的发育模式与未切除卵巢的动物相似，但从数量上看，性腺切除的雌性动物的平均血浆FSH浓度在所有时间都高于未切除卵巢的对照组。在未切除卵巢的动物中，在发育的新生儿期和青春期前阶段，循环中的白天促黄体生成素（LH）浓度通常低于检测方法的灵敏度，但在27个月龄后，这种血浆激素偶尔可检测到。在新生期切除卵巢的猴子中，白天LH在出生后的第一个月升高，在2 - 20个月龄之间检测不到，然后在研究结束时升至成年范围。性腺切除的猴子夜间血浆FSH和LH浓度在发育的所有阶段通常都高于白天。特别值得注意的是，发现在青春期前促性腺激素分泌间隙期间，当白天LH水平大多无法检测到时，这种促性腺激素的夜间水平持续升高。当在61 - 62周龄时进行卵巢切除时，性腺切除动物在青春期前发育期间也会出现促性腺激素分泌过多的情况。这些发现表明，在雌性猴子中，GnRH脉冲发生器在幼年发育期间的开环活动仅部分受到抑制，卵巢对青春期前促性腺激素分泌的抑制作用显著。我们还报告了一个意外发现，即幼年猴子与母亲分离并转移到单独笼子后，循环促性腺激素浓度出现急剧（尽管是短暂的）下降。这种抑制伴随着血浆皮质醇水平升高，显然与生长方面的任何损害无关。
