Director, Environmental Disease Medicine Program, Chief, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 Alexander Drive, Research Triangle Park, North Carolina 27709, USA.
Endocrinology. 2010 Jun;151(6):2826-34. doi: 10.1210/en.2009-1446. Epub 2010 Apr 8.
Gonadotropin-stimulated estrogen receptor-beta (ERbeta)-null preovulatory follicles exhibit submaximal estradiol production, insufficient acquisition of LH receptor, and attenuated expression of essential ovulatory genes. These observations lead to low ovulatory rates compared with wild-type (WT) follicles. We hypothesize that insufficient LH receptor results in reduced cAMP production after an ovulatory stimulus. Individual preantral follicles were cultured with FSH for 4 d and then induced to ovulate with a single dose of human chorionic gonadotropin (hCG). cAMP levels 1 h after hCG were 50% lower in ERbeta-null than WT follicles. To determine whether the lack of LH receptor, and resulting lack of cAMP, could be bypassed by direct activation of adenylyl cyclase, WT and ERbeta-null follicles were induced to ovulate with forskolin. Ten micromolar forskolin doubled the ovulatory rate of ERbeta-null follicles compared with treatment with hCG ( approximately 50 vs. 25%, respectively). In WT follicles, 10 microm forskolin reduced the ovulation rate compared with hCG (14 vs. 83%, respectively), indicating that high doses of forskolin inhibited WT ovulation. A 10 microm concentration of forskolin induced cAMP levels in ERbeta-null follicles that were comparable to levels produced in WT follicles after hCG and either partially or completely rescued the attenuated expression of LH-responsive genes. These data indicate that direct activation of adenylyl cyclase, resulting in increased production of cAMP, partially rescues the ovulatory response of ERbeta-null follicles, suggesting that insufficient LH receptor and low cAMP levels contribute to their poor ovulatory rates. We also determined that ERbeta-null ovaries exhibit an alteration in the activation of ERK1/2. Our evaluation of the ERbeta-null ovarian phenotype indicates that ERbeta plays a role in facilitating folliculogenesis. We show that expression of ERbeta in preovulatory follicles is required for adequate cAMP production and propose that an optimal level of cAMP is required for hCG-stimulated ovulation.
促性腺激素刺激的雌激素受体-β（ERβ）-null 预排卵卵泡表现出亚最大的雌二醇产生、LH 受体获取不足和必需排卵基因表达减弱。与野生型（WT）卵泡相比，这些观察结果导致排卵率较低。我们假设 LH 受体不足导致排卵刺激后 cAMP 产生减少。单个原始卵泡用 FSH 培养 4 天，然后用人绒毛膜促性腺激素（hCG）单次剂量诱导排卵。hCG 后 1 小时，ERβ-null 卵泡中的 cAMP 水平比 WT 卵泡低 50%。为了确定缺乏 LH 受体，以及由此导致的 cAMP 缺乏，是否可以通过直接激活腺苷酸环化酶来绕过，WT 和 ERβ-null 卵泡用 forskolin 诱导排卵。10μM 的 forskolin 将 ERβ-null 卵泡的排卵率提高了一倍，与 hCG 处理相比（分别约为 50%和 25%）。在 WT 卵泡中，10μM 的 forskolin 降低了与 hCG 相比的排卵率（分别为 14%和 83%），表明高剂量的 forskolin抑制了 WT 的排卵。10μM 的 forskolin 诱导 ERβ-null 卵泡中的 cAMP 水平与 hCG 后 WT 卵泡中的水平相当，并部分或完全挽救了 LH 反应基因的表达减弱。这些数据表明，直接激活腺苷酸环化酶，导致 cAMP 产量增加，部分挽救了 ERβ-null 卵泡的排卵反应，表明 LH 受体不足和 cAMP 水平低导致其排卵率低。我们还确定 ERβ-null 卵巢表现出 ERK1/2 的激活改变。我们对 ERβ-null 卵巢表型的评估表明，ERβ 在促进卵泡发生中发挥作用。我们表明，预排卵卵泡中 ERβ 的表达是充分产生 cAMP 的必要条件，并提出 cAMP 的最佳水平是 hCG 刺激排卵所必需的。
