Departments of Obstetrics and Gynecology and Cellular and Molecular Medicine, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
Endocrinology. 2013 Aug;154(8):2912-23. doi: 10.1210/en.2013-1001. Epub 2013 May 21.
In the present study, we have investigated the cellular mechanisms of androgen-induced antral follicular growth arrest and the possible involvement of chemerin and its receptor chemokine-like receptor 1 (CMKLR1) in this process, using a chronically androgenized rat model. We hypothesize that hyperandrogenism induces antral follicle growth arrest via the action of chemerin and ovarian structural changes, resulting from granulosa cell and oocyte apoptosis and theca cell survival. Dihydrotestosterone (DHT) treatment resulted in increased expression of chemerin and CMKLR1 in antral follicles, absence of corpus luteum, and increased atypical follicles. Addition of chemerin to follicle cultures induced granulosa cell apoptosis and suppressed basal, FSH- and growth differentiation factor-9-stimulated follicular growth. DHT down-regulated aromatase expression and increased active caspase-3 content and DNA fragmentation in granulosa cells in vivo. These changes were accompanied by higher phosphatase and tensin homolog and lower phospho-Akt (Ser473) content in antral follicles and higher calpain expression and down-regulation of cytoskeletal proteins in atypical follicles, which were constituted predominantly of theca cells. DHT also activated granulosa cell caspase-3, decreased X-linked inhibitor of apoptosis protein, poly(ADP-ribose) polymerase, and phospho-Akt contents and induced apoptosis in vitro, responses readily attenuated by forced X-linked inhibitor of apoptosis protein expression. These findings are consistent with our hypothesis that antral follicular growth arrest in DHT-treated rats results from increased chemerin expression and action, as well as changes in follicular cell fate and structure, which are a consequence of dysregulated interactions of pro-survival and pro-apoptotic modulators in a cell-specific manner. Our observations suggest that this chronically androgenized rat model may be useful for studies on the long-term effects of androgens on folliculogenesis and may have implications for the female reproductive disorders associated with hyperandrogenism.
在本研究中，我们使用慢性雄激素化大鼠模型研究了雄激素诱导的窦卵泡生长阻滞的细胞机制，以及趋化素及其受体趋化因子样受体 1（CMKLR1）在这一过程中的可能参与。我们假设，高雄激素血症通过趋化素的作用和卵巢结构的变化诱导窦卵泡生长阻滞，这些变化是由颗粒细胞和卵母细胞凋亡以及卵泡膜细胞存活引起的。二氢睾酮（DHT）处理导致窦卵泡中趋化素和 CMKLR1 的表达增加，黄体缺失，并且出现非典型卵泡。趋化素添加到卵泡培养物中诱导颗粒细胞凋亡，并抑制基础、FSH 和生长分化因子 9 刺激的卵泡生长。DHT 下调了颗粒细胞中的芳香酶表达，增加了活性 caspase-3 含量和体内卵泡颗粒细胞的 DNA 片段化。这些变化伴随着窦卵泡中磷酸酶和张力蛋白同源物（phosphatase and tensin homolog，PTEN）升高和磷酸化 Akt（Ser473）降低，以及非典型卵泡中钙蛋白酶表达升高和细胞骨架蛋白下调，这些非典型卵泡主要由卵泡膜细胞组成。DHT 还激活了颗粒细胞 caspase-3，降低了 X 连锁凋亡抑制剂（X-linked inhibitor of apoptosis protein，XIAP）、多聚（ADP-核糖）聚合酶（poly（ADP-ribose）polymerase，PARP）和磷酸化 Akt 的含量，并在体外诱导凋亡，这些反应很容易被强制表达的 XIAP 所减弱。这些发现与我们的假设一致，即 DHT 处理大鼠的窦卵泡生长阻滞是由于趋化素表达和作用增加，以及卵泡细胞命运和结构发生变化所致，这是生存和凋亡调节因子以细胞特异性方式失调相互作用的结果。我们的观察结果表明，这种慢性雄激素化大鼠模型可能有助于研究雄激素对卵泡发生的长期影响，并可能对与高雄激素血症相关的女性生殖障碍具有重要意义。
