Petrino T R, Schuetz A W
J Exp Zool. 1986 Sep;239(3):411-21. doi: 10.1002/jez.1402390312.
Involvement of protein synthesis in frog pituitary homogenate (FPH)-induced progesterone production and/or accumulation in ovarian follicles was investigated. In amphibians, cycloheximide (C), an inhibitor of protein synthesis, inhibits progesterone and FPH-induced germinal vesicle breakdown (GVBD). However, the site and mechanisms of action of cycloheximide within ovarian follicles have not been elucidated. Intrafollicular progesterone produced by FPH is considered to mediate oocyte maturation; thus, cycloheximide may interfere with production and/or action of progesterone. Simultaneous treatment of FPH-stimulated follicles with cycloheximide inhibited FPH-induced progesterone accumulation (measured by RIA) and the accompanying-GVBD in a dose-dependent fashion. Inhibitory effects of cycloheximide on either FPH-induced progesterone production or GVBD were not reversed when follicles were washed and returned to fresh medium devoid of FPH and cycloheximide. However, subsequent restimulation of washed follicles with FPH resulted in increased progesterone levels and oocyte maturation. The extent of reversibility, in terms of GVBD and progesterone production, after FPH restimulation varied between animals. Pretreatment of follicles with cycloheximide for 6 hours, without FPH, had little or no effect on progesterone production when follicles were washed and treated with FPH. Delayed addition of cycloheximide to follicles following FPH stimulation blocked further progesterone accumulation as indicated by measurement of intrafollicular progesterone at the time of cycloheximide addition and at the end of the incubation period. The results indicate that cycloheximide rapidly inhibits progesterone production and that continuous protein synthesis is required for progesterone accumulation. Furthermore, protein synthesis does not appear to be required for progesterone metabolism since intrafollicular progesterone declined with prolonged culture even in the presence of cycloheximide. The nature of protein(s) involved in follicular progesterone production remains to be elucidated. FPH mediation of oocyte maturation within ovarian follicles appears to depend upon protein synthesis in somatic follicle cells, which is required for progesterone production, and in the oocyte, to mediate the response to the steroid trigger.
研究了蛋白质合成在青蛙垂体匀浆（FPH）诱导的卵巢卵泡孕酮产生和/或积累中的作用。在两栖动物中，蛋白质合成抑制剂环己酰亚胺（C）可抑制孕酮和FPH诱导的生发泡破裂（GVBD）。然而，环己酰亚胺在卵巢卵泡内的作用位点和机制尚未阐明。FPH产生的卵泡内孕酮被认为介导卵母细胞成熟；因此，环己酰亚胺可能会干扰孕酮的产生和/或作用。用环己酰亚胺同时处理FPH刺激的卵泡，以剂量依赖的方式抑制了FPH诱导的孕酮积累（通过放射免疫分析测量）以及伴随的GVBD。当卵泡被冲洗并放回不含FPH和环己酰亚胺的新鲜培养基中时，环己酰亚胺对FPH诱导的孕酮产生或GVBD的抑制作用并未逆转。然而，随后用FPH再次刺激冲洗后的卵泡会导致孕酮水平升高和卵母细胞成熟。在FPH再次刺激后，就GVBD和孕酮产生而言，可逆程度在不同动物之间有所不同。在没有FPH的情况下，用环己酰亚胺预处理卵泡6小时，当卵泡被冲洗并用FPH处理时，对孕酮产生几乎没有影响。FPH刺激后延迟向卵泡中添加环己酰亚胺，如在添加环己酰亚胺时和孵育期结束时测量卵泡内孕酮所示，阻止了进一步的孕酮积累。结果表明，环己酰亚胺迅速抑制孕酮产生，并且孕酮积累需要持续的蛋白质合成。此外，由于即使在存在环己酰亚胺的情况下，卵泡内孕酮随着培养时间的延长而下降，因此蛋白质合成似乎不是孕酮代谢所必需的。参与卵泡孕酮产生的蛋白质的性质仍有待阐明。FPH介导卵巢卵泡内卵母细胞成熟似乎取决于体细胞卵泡细胞中的蛋白质合成，这是孕酮产生所必需的，并且在卵母细胞中，介导对类固醇触发的反应。
