Endocrinology-Reproductive Physiology Program and Department of Dairy Science, University of Wisconsin, Madison, Wisconsin 53706, USA.
Biol Reprod. 2011 Jan;84(1):26-33. doi: 10.1095/biolreprod.110.084368. Epub 2010 Aug 25.
Prostaglandin F2alpha (PGF) causes luteolysis of the pig corpus luteum (CL) only after Day 12 of the estrous cycle. Recent evidence indicates that progesterone (P4) may protect the CL from cell death. The present study tested the hypothesis that acute inhibition of P4 by treatment with epostane (EPO; 3betaHSD inhibitor) in CL lacking luteolytic capacity (Day 9 CL) will allow PGF to induce responses associated with luteolysis. Multiple PGF-induced responses were evaluated, including genes involved in production of PGF and estradiol-17beta, apoptosis (caspase 3), and transcription (FOSB). These responses are associated with PGF-induced luteolysis and do not normally occur in CL lacking luteolytic capacity. Animals on Day 7 after estrus were divided into four groups: 1) control (C), 2) PGF, 3) EPO, and 4) PGF plus EPO (PGF+EPO). Treatment with EPO (10 mg/kg) or vehicle was given every 12 h for 36 h. Treatment with PGF (25 mg) or vehicle was given at 38 h, and CL were collected from all animals at 48 h. Some CL from each animal were frozen in liquid nitrogen for mRNA and protein analysis. Remaining CL were incubated in media for 2 h for determination of P4 and PGF production. EPO dramatically decreased production of P4 by luteal tissue (ng/mg tissue) by 90% and 95% in EPO and PGF+EPO groups, respectively, compared to C (P < 0.01). Low production of PGF by luteal tissue was found in C, PGF, and EPO groups; however, treatment with PGF+EPO dramatically increased (782%) luteal PGF production. Similar to intraluteal PGF production, increased mRNA for cyclooxygenase 2 (PTGS2) and phospholipase A2 (group IB; PLA2G1B) was found in the PGF+EPO, but not in the EPO or PGF, group. Aromatase (CYP19A1) mRNA was not induced by PGF or EPO; however, PGF+EPO caused a more than 40-fold increase in CYP19A1 mRNA (P < 0.01). CASP3 mRNA was increased (P < 0.01) by EPO (3.4-fold) and by PGF (2.7-fold) but was most dramatically increased by PGF+EPO (5.3-fold), whereas caspase activity was only increased by PGF (1.5-fold) or PGF+EPO (2.2-fold). Thus, these data support the hypothesis that elimination of the protective effect of intraluteal P4 does not directly cause luteolysis of the early CL but allows PGF to induce luteolytic responses in CL lacking luteolytic capacity.
前列腺素 F2alpha（PGF）仅在发情周期的第 12 天后才能导致猪黄体（CL）的黄体溶解。最近的证据表明，孕酮（P4）可能保护 CL 免受细胞死亡。本研究检验了这样一个假设，即在缺乏黄体溶解能力的 CL（第 9 天 CL）中，用 epostane（EPO；3βHSD 抑制剂）急性抑制 P4 将允许 PGF 诱导与黄体溶解相关的反应。评估了多种 PGF 诱导的反应，包括参与 PGF 和雌二醇-17β产生、细胞凋亡（半胱天冬酶 3）和转录（FOSB）的基因。这些反应与 PGF 诱导的黄体溶解有关，通常不会在缺乏黄体溶解能力的 CL 中发生。发情后第 7 天的动物分为四组：1）对照组（C），2）PGF，3）EPO，和 4）PGF+EPO（PGF+EPO）。每隔 12 小时用 EPO（10mg/kg）或载体处理 36 小时。在 38 小时用 PGF（25mg）或载体处理，并在 48 小时从所有动物中采集 CL。每个动物的一些 CL 用液氮冷冻用于 mRNA 和蛋白质分析。剩余的 CL 在培养基中孵育 2 小时，以确定 P4 和 PGF 的产生。EPO 分别使 EPO 和 PGF+EPO 组的黄体组织中 P4 的产生降低了 90%和 95%（P<0.01）。在 C、PGF 和 EPO 组中，黄体组织中 PGF 的产生较低；然而，PGF+EPO 的处理显著增加（782%）了黄体 PGF 的产生。与黄体内 PGF 产生相似，PGF+EPO 组中发现环氧化酶 2（PTGS2）和磷脂酶 A2（组 IB；PLA2G1B）的 mRNA 增加，但在 EPO 或 PGF 组中未发现。PGF 或 EPO 未诱导芳香酶（CYP19A1）mRNA；然而，PGF+EPO 导致 CYP19A1 mRNA 增加了 40 多倍（P<0.01）。CASP3 mRNA 被 EPO（3.4 倍）和 PGF（2.7 倍）增加（P<0.01），但被 PGF+EPO 增加最多（5.3 倍），而 caspase 活性仅被 PGF（1.5 倍）或 PGF+EPO（2.2 倍）增加。因此，这些数据支持这样的假设，即消除黄体内 P4 的保护作用不会直接导致早期 CL 的黄体溶解，但允许 PGF 诱导缺乏黄体溶解能力的 CL 中的黄体溶解反应。
