Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093, USA.
Endocrinology. 2012 Sep;153(9):4522-32. doi: 10.1210/en.2012-1283. Epub 2012 Jul 9.
Sex steroid hormone production and feedback mechanisms are critical components of the hypothalamic-pituitary-gonadal (HPG) axis and regulate fetal development, puberty, fertility, and menopause. In female mammals, developmental exposure to excess androgens alters the development of the HPG axis and has pathophysiological effects on adult reproductive function. This study presents an in-depth reproductive analysis of a murine model of prenatal androgenization (PNA) in which females are exposed to a low dose of dihydrotestosterone during late prenatal development on embryonic d 16.5-18.5. We determined that PNA females had advanced pubertal onset and a delay in the time to first litter, compared with vehicle-treated controls. The PNA mice also had elevated testosterone, irregular estrous cyclicity, and advanced reproductive senescence. To assess the importance of the window of androgen exposure, dihydrotestosterone was administered to a separate cohort of female mice on postnatal d 21-23 [prepubertal androgenization (PPA)]. PPA significantly advanced the timing of pubertal onset, as observed by age of the vaginal opening, yet had no effects on testosterone or estrous cycling in adulthood. The absence of kisspeptin receptor in Kiss1r-null mice did not change the acceleration of puberty by the PNA and PPA paradigms, indicating that kisspeptin signaling is not required for androgens to advance puberty. Thus, prenatal, but not prepubertal, exposure to low levels of androgens disrupts normal reproductive function throughout life from puberty to reproductive senescence.
性类固醇激素的产生和反馈机制是下丘脑-垂体-性腺(HPG)轴的关键组成部分,调节胎儿发育、青春期、生育和绝经期。在雌性哺乳动物中,发育过程中暴露于过量雄激素会改变 HPG 轴的发育,并对成年生殖功能产生病理生理影响。本研究对一种产前雄激素化(PNA)的小鼠模型进行了深入的生殖分析,其中雌性在胚胎第 16.5-18.5 天接受低剂量二氢睾酮的暴露。我们发现 PNA 雌性的青春期起始提前,首次产仔时间延迟,与对照组相比。PNA 小鼠还表现出睾酮升高、发情周期不规则和生殖衰老提前。为了评估雄激素暴露窗口的重要性,在另一批雌性小鼠的产后第 21-23 天(青春期前雄激素化(PPA))给予二氢睾酮。PPA 显著提前了青春期起始的时间,表现为阴道开口的年龄,但对成年期的睾酮或发情周期没有影响。在 Kiss1r 基因敲除小鼠中缺乏 kisspeptin 受体并没有改变 PNA 和 PPA 范式对青春期的加速作用,这表明 kisspeptin 信号不是雄激素促进青春期所必需的。因此,产前而非青春期前暴露于低水平雄激素会破坏从青春期到生殖衰老的整个生命周期的正常生殖功能。