Graduate School of Peking Union Medical College, Beijing, China.
J Cell Physiol. 2012 Jan;227(1):194-203. doi: 10.1002/jcp.22717.
Arsenic contamination is a principal environmental health threat throughout the world. However, little is known about the effect of arsenic on steroidogenesis in granulosa cells (GCs). We found that the treatment of preovulatory GCs with arsenite stimulated progesterone production. A significant increase in serum level of progesterone was observed in female Sprague-Dawley rats following arsenite treatment at a dose of 10 mg/L/rat/day for 7 days. Further experiments demonstrated that arsenite treatment did not change the level of intracellular cyclic AMP (cAMP) or phosphorylated ERK1/2 in preovulatory GCs; however, progesterone production was significantly decreased when cAMP-dependent protein kinase (PKA) or ERK1/2 pathway was inhibited. This implied that the effect of arsenite on progesterone production may require cAMP/PKA and ERK1/2 signaling but not depend on them. Furthermore, we found that arsenite decreased intracellular reactive oxygen species (ROS) but increased the antioxidant glutathione (GSH) levels and mitochondrial membrane potential (ΔΨm) in parallel to the changes in progesterone production. Progesterone antagonist blocked the arsenic-stimulated increase of GSH levels. Arsenite treatment induced caspase-3 activation, although no apoptosis was observed. Inhibition of caspase-3 activity significantly decreased progesterone production stimulated by arsenite or follicle-stimulating hormone (FSH). GSH depletion with buthionine sulfoximine led to cell apoptosis in response to arsenite treatment. Collectively, this study demonstrated for the first time that arsenite stimulates progesterone production through cleaved/active caspase-3-dependent pathway, and the increase of GSH level promoted by progesterone production may protect GCs against apoptosis and maintain the steroidogenesis of GCs in response to arsenite treatment.
砷污染是全世界主要的环境健康威胁之一。然而，人们对砷对颗粒细胞（GCs）甾体生成的影响知之甚少。我们发现亚砷酸盐处理促排卵 GC 可刺激孕酮的产生。在雌性 Sprague-Dawley 大鼠中，用 10mg/L/大鼠/天的剂量连续处理 7 天，观察到血清孕酮水平显著升高。进一步的实验表明，亚砷酸盐处理不会改变促排卵 GC 中的细胞内环磷酸腺苷（cAMP）或磷酸化 ERK1/2 水平；然而，当抑制 cAMP 依赖性蛋白激酶（PKA）或 ERK1/2 通路时，孕酮的产生明显减少。这表明亚砷酸盐对孕酮产生的影响可能需要 cAMP/PKA 和 ERK1/2 信号，但不依赖于它们。此外，我们发现亚砷酸盐降低了细胞内活性氧（ROS）的水平，但同时平行地增加了谷胱甘肽（GSH）水平和线粒体膜电位（ΔΨm），与孕酮的产生变化一致。孕酮拮抗剂阻断了砷刺激的 GSH 水平增加。亚砷酸盐处理诱导 caspase-3 激活，但未观察到细胞凋亡。抑制 caspase-3 活性显著降低了亚砷酸盐或卵泡刺激素（FSH）刺激的孕酮产生。用丁硫氨酸亚砜亚胺耗竭 GSH 导致细胞凋亡对亚砷酸盐处理作出反应。总的来说，这项研究首次表明，亚砷酸盐通过切割/活性 caspase-3 依赖的途径刺激孕酮的产生，并且由孕酮产生促进的 GSH 水平的增加可能保护 GC 免受凋亡，并维持 GC 对亚砷酸盐处理的甾体生成。
