Liang Bo, Wei De-Li, Cheng Ya-Nan, Yuan Hong-Jie, Lin Juan, Cui Xiang-Zhong, Luo Ming-Jiu, Tan Jing-He
College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City, People's Republic of China.
Biol Reprod. 2013 Sep 19;89(3):64. doi: 10.1095/biolreprod.113.110619. Print 2013 Sep.
This study examined the role of CRH-induced ovarian cell apoptosis in the restraint stress (RS)-induced impairment of oocyte competence. Oocyte percentages of apoptotic cumulus cells (CCs) did not differ between stressed and control mice before in vitro maturation (IVM) but became significantly higher in stressed mice after IVM without serum, growth factor, and hormone. The level of Bcl2 mRNA decreased significantly in mural granulosa cells (MGCs) and ovarian homogenates after RS. Whereas ovarian estradiol, testosterone, and IGF1 decreased, cortisol and progesterone increased significantly following RS. RS increased the level of CRH in serum, ovary, and oocyte while enhancing the expression of CRHR1 in CCs, MGCs, and thecal cells. RS down-regulated ovarian expression of glucocorticoid receptor and brain-derived neurotrophic factor. Furthermore, CRH supplementation to IVM medium impaired oocyte developmental potential while increasing apoptotic CCs, an effect that was completely overcome by addition of the CRHR1 antagonist antalarmin. Results suggest that RS impaired oocyte competence by increasing CRH but not glucocorticoids. Increased CRH initiated a latent apoptotic program in CCs and oocytes during their intraovarian development, which was executed later during IVM to impair oocyte competence. Thus, elevated CRH interacted with increased CRHR1 on thecal cells and MGCs, reducing the production of testosterone, estrogen, and IGF1 while increasing the level of progesterone. The imbalance between estrogen and progesterone and the decreased availability of growth factors triggered apoptosis of MGCs and facilitated CC expression of CRHR1, which interacted with the oocyte-derived CRH later during IVM to induce CC apoptosis and reduce oocyte competence.
本研究探讨了促肾上腺皮质激素释放激素（CRH）诱导的卵巢细胞凋亡在束缚应激（RS）诱导的卵母细胞发育能力受损中的作用。在体外成熟（IVM）前，应激小鼠和对照小鼠的凋亡卵丘细胞（CCs）中的卵母细胞百分比没有差异，但在无血清、生长因子和激素的IVM后，应激小鼠的该百分比显著升高。RS后，壁层颗粒细胞（MGCs）和卵巢匀浆中Bcl2 mRNA水平显著降低。RS后，卵巢中的雌二醇、睾酮和胰岛素样生长因子1（IGF1）水平降低，而皮质醇和孕酮水平显著升高。RS增加了血清、卵巢和卵母细胞中CRH的水平，同时增强了CCs、MGCs和卵泡膜细胞中CRHR1的表达。RS下调了卵巢中糖皮质激素受体和脑源性神经营养因子的表达。此外，在IVM培养基中添加CRH会损害卵母细胞的发育潜力，同时增加凋亡CCs，而添加CRHR1拮抗剂安他乐明可完全克服这一效应。结果表明，RS通过增加CRH而非糖皮质激素来损害卵母细胞发育能力。增加的CRH在CCs和卵母细胞的卵巢内发育过程中启动了一个潜在的凋亡程序，该程序在随后的IVM过程中执行，以损害卵母细胞发育能力。因此，升高的CRH与卵泡膜细胞和MGCs上增加的CRHR1相互作用，减少睾酮、雌激素和IGF1的产生，同时增加孕酮水平。雌激素和孕酮之间的失衡以及生长因子可用性的降低引发了MGCs的凋亡，并促进了CCs中CRHR1的表达，后者在IVM后期与卵母细胞来源的CRH相互作用，诱导CCs凋亡并降低卵母细胞发育能力。
