Racowsky C
J Exp Zool. 1985 May;234(2):251-60. doi: 10.1002/jez.1402340211.
The effects of estradiol (E2) and the anti-E2 tamoxifen (tam) on forskolin (F)-dependent meiotic arrest in hamster oocytes were investigated. The hypotheses tested were that 1) the arresting action of F is enhanced by E2 and suppressed by tam and 2) the extent of heterologous metabolic coupling and the concomitant transfer of cumulus cell cAMP into the oocyte is increased and decreased by E2 and tam, respectively. E2 was tested with the ID25 F (where ID25 is the dose of F previously shown to arrest the meiosis of 25% cultured oocytes; intact, 3 microM; denuded, 10 microM) and tam was tested with the ID75 F (intact, 10 microM; denuded, 100 microM). E2 induced reversible dose-dependent increases in the percent germinal vesicle (%GV; determined cytogenetically) of both intact and denuded oocytes in the presence of ID25 F (intact: ID50 E2 = 18.0 microM; denuded: ID50 E2 = 17.2 microM) but, in contrast to intact oocytes, E2 also exerted a dose-dependent action on denuded oocytes in the absence of F (ID50 = 26.1 microM). E2 induced dose-dependent increases in the cAMP content (determined by RIA) of intact oocytes (cAMP-oo) and of cumulus masses (cAMP-cm) and in the ratio of cAMPooo:cAMP-cm but failed to elevate F-stimulated cAMP in denuded oocytes. Heterologous metabolic coupling, as assessed by determination of the fraction of radiolabeled uridine marker that was transferred from the cumulus cells to the oocyte, was not significantly enhanced by E2. In contrast to denuded oocytes, tam induced dose-dependent decreases in the %GV and cAMP content of intact oocytes in the presence of ID75 F and significantly depressed heterologous metabolic coupling. While tam failed to antagonize the E2 action on denuded oocytes in the presence of ID25 F, in intact oocytes cultured with E2 and the ID25 F, the anti-E2 significantly decreased the %GV, the cAMP-oo and cAMP-cm, and the extent of heterologous metabolic coupling. These data show that while E2 can directly arrest the maturation of denuded hamster oocytes with no associated elevation of cAMP-oo, E2-enhancement of arrest in intact oocytes is correlated with both elevation of cAMP within the oocyte-cumulus complex and maintenance of heterologous metabolic coupling and is accompanied by an increase in cAMP-oo.
研究了雌二醇（E2）和抗E2他莫昔芬（tam）对仓鼠卵母细胞中福斯高林（F）依赖性减数分裂阻滞的影响。所检验的假说是：1）F的阻滞作用被E2增强而被tam抑制；2）E2和tam分别增加和降低了异源代谢偶联程度以及伴随的卵丘细胞cAMP向卵母细胞的转移。E2与ID25 F一起进行测试（其中ID25是先前显示能使25%培养卵母细胞减数分裂阻滞的F剂量；完整卵母细胞为3 microM，裸卵为10 microM），tam与ID75 F一起进行测试（完整卵母细胞为10 microM，裸卵为100 microM）。在存在ID25 F的情况下，E2诱导完整和裸卵母细胞的生发泡百分比（%GV；通过细胞遗传学测定）出现可逆的剂量依赖性增加（完整卵母细胞：ID50 E2 = 18.0 microM；裸卵：ID50 E2 = 17.2 microM），但与完整卵母细胞不同的是，在不存在F的情况下，E2对裸卵母细胞也有剂量依赖性作用（ID50 = 26.1 microM）。E2诱导完整卵母细胞（cAMP-oo）和卵丘团块（cAMP-cm）的cAMP含量（通过放射免疫分析测定）出现剂量依赖性增加，以及cAMP-oo:cAMP-cm比值增加，但未能提高裸卵母细胞中F刺激的cAMP水平。通过测定从卵丘细胞转移到卵母细胞的放射性标记尿苷标记物的比例来评估的异源代谢偶联，并未被E2显著增强。与裸卵母细胞不同，在存在ID75 F的情况下，tam诱导完整卵母细胞的%GV和cAMP含量出现剂量依赖性降低，并显著抑制异源代谢偶联。虽然在存在ID25 F的情况下，tam未能拮抗E2对裸卵母细胞的作用，但在用E2和ID25 F培养的完整卵母细胞中，抗E2显著降低了%GV、cAMP-oo和cAMP-cm以及异源代谢偶联程度。这些数据表明，虽然E2可以直接阻滞裸仓鼠卵母细胞的成熟，且不伴随cAMP-oo升高，但E2增强完整卵母细胞中的阻滞与卵母细胞 - 卵丘复合物内cAMP升高、异源代谢偶联的维持相关，并伴随着cAMP-oo增加。
