EFFECTS OF GONADOTROPIN ON OVARIAN INTRAFOLLICULAR PROCESSES DURING THE DEVELOPMENT OF OOCYTE MATURATIONAL COMPETENCE IN A TELEOST, THE ATLANTIC CROAKER - EVIDENCE FOR 2 DISTINCT STAGES OF GONADOTROPIC CONTROL OF FINAL OOCYTE MATURATION
EFFECTS OF GONADOTROPIN ON OVARIAN INTRAFOLLICULAR PROCESSES DURING THE DEVELOPMENT OF OOCYTE MATURATIONAL COMPETENCE IN A TELEOST, THE ATLANTIC CROAKER - EVIDENCE FOR 2 DISTINCT STAGES OF GONADOTROPIC CONTROL OF FINAL OOCYTE MATURATION
复制标题
DOI：
10.1095/biolreprod43.5.818
复制
发表时间：
1990-11-01
影响因子：
3.6
通讯作者：
THOMAS, P
中科院分区：
文献类型：
--
作者：
PATINO, R;THOMAS, P
大西洋黄花鱼的成熟卵母细胞对成熟诱导类固醇 (MIS) 不敏感，除非用促性腺激素 (GtH) 引发。本研究的目的是检查 GtH 诱导黄花鱼卵母细胞成熟能力的机制。具体来说，我们确定了未引发或 hCG 引发的鱼的完整卵泡的体外类固醇分泌情况、类固醇对成熟能力的直接影响，以及类固醇（氰酮）、蛋白质（环己酰胺）和 RNA（放线菌素 D）合成抑制剂对 hCG 诱导的成熟能力和体外类固醇生成的影响。通过RIA测量hCG处理后培养介质中的类固醇含量。通过在标准生物测定中记录 MIS 诱导的 GVBD 后生发囊泡破裂 (GVBD) 的发生率来确定 hCG 或外源类固醇治疗对成熟能力的影响。我们的主要发现是： 在体内或体外将卵泡暴露于 hCG 后，可诱导成熟能力；在 hCG 引发的鱼的卵泡中检测到 MIS 分泌，但未引发的鱼中未检测到 MIS 分泌，并且在体外 hCG 诱导成熟能力期间未观察到 MIS 分泌；氰酮治疗可阻断 hCG 依赖性睾酮和雌二醇的分泌，但不会阻断成熟能力的发展；在缺乏 hCG 的情况下使用 MIS 或各种其他外源类固醇治疗不会诱导成熟能力； hCG 诱导的成熟能力被放线菌酮和放线菌素 D 抑制。因此，GtH 诱导大西洋黄花鱼卵母细胞成熟的机制可以描述为两个不同的阶段：δ-4 类固醇（包括 MIS）和雌激素非依赖性启动阶段，随后是 MIS 介导的 GVBD 阶段。启动阶段可能涉及需要RNA以及蛋白质合成的机制。
Full-grown oocytes of Atlantic croaker are insensitive to maturation-inducing steroid (MIS) unless they are primed with gonadotropin (GtH). The objective of the study was to examine the mechanism of GtH-induced maturational competence in croaker oocytes. Specifically, we determined the in vitro secretion of steroids by intact ovarian follicles of umprimed or hCG-primed fish, the direct effects of steroids on maturational competence, and the effects of steroid (cyanoketone), protein (cyclohexamide), and RNA (actinomycin D) synthesis inhibitors on hCG-induced maturational competence and steroidogenesis in vitro. The steroid content of the incubation medium after hCG treatment was measured by RIA. The effects of hCG or exogenous steriod treatment on maturational competence were determined by recording the incidence of germinal vesicle breakdown (GVBD) after MIS-induced GVBD in a standard bioassay. Our major findings were: induction of maturational competence occurred after exposure of ovarian follicles to hCG either in vivo or in vitro; MIS secretion was detected in follicles of hCG-primed fish but not unprimed fish, and no MIS secretion was observed during hCG induction of maturational competence in vitro; treatment with cyanoketone blocked the hCG-dependent secretion of testosterone and estradiol but not the development of maturational competence; treatment with MIS or various other exogenous steroids in the absence of hCG did not induce maturational competence; and hCG-induced maturational competence was inhibited by cycloheximide and actinomcyin D. Therefore, the mechanisms of GtH induction of oocyte maturation in Atlantic croaker can be described in two distinct stages: a delta-4 steroid-(including MIS) and estrogen-independent priming stage following by a MIS-mediated GVBD stage. The priming stage may involve mechanisms requiring RNA as well as protein synthesis.