ANZAC Research Institute, Department of Andrology, Concord Hospital, University of Sydney, Sydney, New South Wales, Australia.
Biol Reprod. 2012 Dec 27;87(6):151. doi: 10.1095/biolreprod.112.102012. Print 2012 Jun.
Ovarian granulosa cells display strong androgen receptor (AR) expression, suggesting a functional role for direct AR-mediated actions within developing mammalian follicles. By crossing AR-floxed and anti-Müllerian hormone (AMH)-Cre recombinase mice, we generated granulosa cell-specific androgen receptor knockout mice (GCARKO). Cre expression, assessed by lacZ activity, localized to 70%-100% of granulosa cells in most preantral to antral follicles, allowing for selected evaluation of granulosa cell AR-dependent actions during follicle development. Relative to wild-type (WT) females, GCARKO females were subfertile, producing a 24% reduction in the number of litters (P < 0.05) over 6 mo and an age-dependent decrease in total number of pups born, evident from 6 mo of age (P < 0.05). Follicle dynamics were altered in GCARKO ovaries at 3 mo of age, with a significant reduction in large preantral and small antral follicle numbers compared to WT ovaries (P < 0.05). Global premature follicle depletion was not observed, but increased follicular atresia was evident in GCARKO ovaries at 6 mo of age, with an 81% increase in unhealthy follicles and zona pellucida remnants (P < 0.01). Cumulus cell expansion was decreased (P < 0.01) and oocyte viability was diminished in GCARKO females, with a significant reduction in the percentage of oocytes fertilized after natural mating and, thus, in the rate of progression to the two-cell embryo stage (P < 0.05). In addition, compared with age-matched WT females, 6-mo-old GCARKO females exhibited significantly prolonged estrous cycles (P ≤ 0.05), suggesting altered hypothalamic-pituitary-gonadal feedback signaling. In conclusion, our findings revealed that selective loss of granulosa cell AR actions during preantral and antral stages of development leads to a premature reduction in female fecundity through reduced follicle health and oocyte viability.
卵巢颗粒细胞显示出强烈的雄激素受体 (AR) 表达，表明 AR 介导的直接作用在哺乳动物卵泡发育中有功能作用。通过交叉 AR 基因敲除和抗 Müllerian 激素 (AMH)-Cre 重组酶小鼠，我们生成了颗粒细胞特异性雄激素受体敲除小鼠 (GCARKO)。通过β-半乳糖苷酶活性评估的 Cre 表达，定位于大多数原始卵泡到窦状卵泡的 70%-100%的颗粒细胞中，允许在卵泡发育过程中选择性评估颗粒细胞 AR 依赖性作用。与野生型 (WT) 雌性相比，GCARKO 雌性的生育力降低，在 6 个月内产仔数减少了 24%（P < 0.05），并且从 6 个月龄开始，出生的总幼仔数呈年龄依赖性下降（P < 0.05）。GCARKO 卵巢中的卵泡动力学在 3 个月龄时发生改变，与 WT 卵巢相比，大原始卵泡和小窦卵泡的数量显著减少（P < 0.05）。没有观察到卵泡的全局过早耗竭，但在 6 个月龄时 GCARKO 卵巢中明显增加了卵泡闭锁，不健康的卵泡和透明带残余物增加了 81%（P < 0.01）。GCARKO 雌性的卵丘细胞扩张减少（P < 0.01），卵母细胞活力降低，自然交配后受精的卵母细胞百分比显著减少，因此，向两细胞胚胎阶段的进展率降低（P < 0.05）。此外，与年龄匹配的 WT 雌性相比，6 个月龄的 GCARKO 雌性的发情周期明显延长（P ≤ 0.05），表明下丘脑-垂体-性腺反馈信号发生改变。总之，我们的研究结果表明，在原始卵泡和窦状卵泡发育阶段选择性地丧失颗粒细胞 AR 作用会导致卵泡健康和卵母细胞活力降低，从而导致雌性生育力过早降低。
