Nishimura Ryo, Sakumoto Ryosuke, Tatsukawa Yuko, Acosta Tomas J, Okuda Kiyoshi
Laboratory of Reproductive Endocrinology, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
Endocrinology. 2006 Sep;147(9):4273-80. doi: 10.1210/en.2005-1611. Epub 2006 Jun 1.
Oxygen deficiency caused by a decrease in the blood supply is known to induce various responses of cells. Because luteal blood flow has been shown to decrease during luteolysis, a low-oxygen condition seems to be an integral part of the environment during luteolysis. To determine whether a low-oxygen condition is associated with functional luteolysis, we examined the influence of reduced oxygen tension on the luteal progesterone (P4) generating system in cultured bovine midluteal cells. Luteal cells obtained from midcycle corpus luteum (d 8-12) were incubated under different O2 concentrations (20, 10, 5, 3% O2) with or without LH for 24 h. P4 production decreased with decreasing O2 concentration but was significantly stimulated by LH regardless of O2 concentration. After 8 h of culture, both basal and LH-stimulated P4 production was significantly lower under 3% O2 than under 20% O2. Low-oxygen condition also inhibited pregnenolone production. Cytochrome P450 side-chain cleavage enzyme (P450scc) mRNA expression, measured by quantitative PCR, decreased under low-oxygen condition in both non-LH-treated and LH-treated cells. Low-oxygen condition did not affect the expressions of steroidogenic acute regulatory protein mRNA or protein, whereas steroidogenic acute regulatory protein mRNA expression was stimulated by LH during 4 h of culture. Low-oxygen condition also did not affect 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4 isomerase mRNA expression or the activity of the enzyme in the cells, regardless of the incubation period. The overall results indicate that a low-oxygen condition decreases P4 synthesis by attenuating P450scc production and P450scc activity in bovine luteal cells and suggest that oxygen deficiency is an essential condition for the progression of luteolysis in cattle.
已知血液供应减少导致的缺氧会引发细胞的各种反应。由于黄体溶解过程中黄体血流量已被证明会减少，低氧状态似乎是黄体溶解期间环境的一个组成部分。为了确定低氧状态是否与功能性黄体溶解有关，我们研究了降低氧张力对培养的牛中期黄体细胞中黄体孕酮（P4）生成系统的影响。从周期中期黄体（第8 - 12天）获得的黄体细胞在不同氧浓度（20%、10%、5%、3% O2）下，在有或无促黄体生成素（LH）存在的情况下孵育24小时。P4的产生随着氧浓度的降低而减少，但无论氧浓度如何，LH都能显著刺激其产生。培养8小时后，3% O2条件下的基础和LH刺激的P4产生均显著低于20% O2条件下。低氧状态也抑制孕烯醇酮的产生。通过定量PCR测量，细胞色素P450侧链裂解酶（P450scc）mRNA表达在低氧条件下，无论是否用LH处理的细胞中均下降。低氧状态不影响类固醇生成急性调节蛋白mRNA或蛋白的表达，而在培养4小时期间，LH刺激类固醇生成急性调节蛋白mRNA表达。低氧状态也不影响3β - 羟类固醇脱氢酶/Δ5 - Δ4异构酶mRNA表达或细胞中该酶的活性，无论孵育时间长短。总体结果表明，低氧状态通过减弱牛黄体细胞中P450scc的产生和P450scc活性来降低P4合成，并表明缺氧是牛黄体溶解进展的必要条件。
