DISSOCIATION BETWEEN THE INHIBITORY AND THE STIMULATORY ACTION OF CAMP ON MATURATION OF RAT OOCYTES
DISSOCIATION BETWEEN THE INHIBITORY AND THE STIMULATORY ACTION OF CAMP ON MATURATION OF RAT OOCYTES
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DOI：
10.1016/0303-7207(88)90015-9
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发表时间：
1988-03-01
影响因子：
4.1
通讯作者：
SHERIZLY, I
中科院分区：
文献类型：
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作者：
DEKEL, N;GALIANI, D;SHERIZLY, I
cAMP在促黄体生成素（LH）诱导卵母细胞成熟中可能的介导作用尚不清楚，因为已经提供了核苷酸对卵母细胞的抑制和刺激作用的证据。为了阐明cAMP在卵母细胞减数分裂调控中的作用，我们在本研究中试图分离这种核苷酸对卵母细胞成熟的抑制和刺激作用。为了诱导成熟，卵母细胞包围他们的卵泡短暂暴露于二丁酰cAMP（dbcAMP）或磷酸二酯酶抑制剂甲基异丁基黄嘌呤（MIX）。通过向LH存在下孵育的卵泡封闭的卵母细胞或在体外自发成熟的分离的无卵丘的卵母细胞中加入上述试剂来抑制成熟。我们发现，卵母细胞成熟的抑制是通过相对低剂量的dbcAMP或MIX获得的，而诱导卵母细胞成熟需要较高浓度的这些试剂。还测定了卵母细胞与卵丘细胞的偶联，所述偶联通过将卵泡封闭的卵丘-卵母细胞复合物暴露于MIX后从卵丘细胞转移至卵母细胞的标记尿苷的分数表示。我们发现，从卵丘细胞的卵母细胞的解偶联对应于诱导，但不抑制卵母细胞的成熟，无论是通过其浓度依赖性和时间过程。我们认为cAMP在卵母细胞成熟的调节中具有双重作用。较低水平的核苷酸作用于维持减数分裂停滞，而升高水平的cAMP介导LH作用以诱导减数分裂恢复。
The possible mediatory role of cAMP in the induction of oocyte maturation by luteinizing hormone (LH) is not yet clear since evidence for both inhibitory and stimulatory actions of the nucleotide on the oocyte has been provided. To elucidate the role of cAMP in regulation of oocyte meiosis we tried in the present study to dissociate between the inhibitory and stimulatory action of this nucleotide on oocyte maturation. To induce maturation, oocytes enclosed by their follicles were transiently exposed to either dibutyryl cAMP (dbcAMP) or to the phosphodiesterase inhibitor methylisobutylxanthine (MIX). Inhibition of maturation was obtained by the addition of the above agents to either follicle-enclosed oocytes incubated in the presence of LH or isolated cumulus-free oocytes that mature spontaneously in vitro. We found that inhibition of oocyte maturation is obtained by a relatively low dose of either dbcAMP or MIX while higher concentrations of these agents are required to induce oocyte maturation. Coupling of the oocyte to the cumulus cells, as expressed by the fraction of labeled uridine transferred from the cumulus cells to the oocyte following exposure of the follicle-enclosed cumulus-oocyte complex to MIX, was also determined. We found that uncoupling of the oocyte from the cumulus cells corresponded with the induction, but not inhibition of oocyte maturation, both by its concentration dependence and time-course. We suggest that cAMP has a dual role in regulation of oocyte maturation. Lower levels of the nucleotide act to maintain meiotic arrest, while elevated levels of cAMP mediate LH action to induce meiosis resumption.