Characteristics of prolonged dominant versus control follicles: follicle cell numbers, steroidogenic capabilities, and messenger ribonucleic acid for steroidogenic enzymes.
Characteristics of prolonged dominant versus control follicles: follicle cell numbers, steroidogenic capabilities, and messenger ribonucleic acid for steroidogenic enzymes.
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长期优势卵泡与对照卵泡的特征：卵泡细胞数量、类固醇生成能力和类固醇生成酶的信使核糖核酸。
DOI：
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发表时间：
1998
影响因子：
3.6
通讯作者：
J. E. Fortune
中科院分区：
文献类型：
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作者：
K. Bigelow;J. E. Fortune
血浆黄体酮水平较低（黄体以下）的牛会形成持续的优势卵泡；血浆雌二醇和 LH 脉冲频率升高，优势卵泡排卵时间延长后的生育能力受到损害。假设是 1) 延长的优势卵泡产生更多的雌二醇，因为它们的卵泡膜和颗粒细胞分别具有增强的产生雄激素和雌二醇的能力，2) 类固醇生成能力的这些变化与相应类固醇生成酶的 mRNA 的伴随变化是平行的。在周期的第 14 天至第 28 天，通过阴道内控制内部药物释放装置 (CIDR) 用外源黄体酮治疗荷斯坦小母牛，诱导优势卵泡延长。在去除 CIDR 之前（CIDRb，第 28 天；n=4）或之后（CIDRa，第 29 天；n=4）24 小时（CIDRa，第 29 天；n=4）收集延长的优势卵泡，并将其类固醇生成能力与在黄体后期注射前列腺素 F2α 之前（CONTb，n=4）或之后 24 小时（CONTa，n=4）获得的正在生长的对照优势卵泡进行比较。自然黄体溶解后，CIDR 小母牛维持黄体酮亚浓度 (1-2 ng/ml)，并且与对照小母牛相比，雌二醇和 LH 脉冲频率更高，正如预期的那样。在 CIDR 小母牛中，与对照小母牛的优势卵泡相比，延长的优势卵泡在卵巢上存在的时间更长，直径更大，并且具有更多的颗粒细胞和更大的卵泡膜质量 (p < 0.05)。卵泡液中类固醇的浓度、体外颗粒细胞分泌的雌二醇以及卵泡膜和颗粒细胞中类固醇生成酶的 mRNA 水平没有提供 CIDR 卵泡的卵泡膜和颗粒细胞产生雄激素和雌二醇的更大能力的证据。事实上，对照动物中卵泡液雌二醇和 P450 芳香酶 mRNA 在黄体溶解后比之前更高 (p < 0.05)，但在治疗动物中去除 CIDR 后则没有。因此，数据不支持假设。相反，有人认为延长的优势卵泡会产生更多的雌二醇，因为它们比对照优势卵泡具有更多的颗粒细胞和更大的卵泡膜质量。相反，CIDRa 卵泡中卵泡液中的孕酮浓度相对于 CIDRb 卵泡增加 (p < 0.05)，这一变化在对照卵泡中没有发生；来自 CIDRa 卵泡的颗粒细胞比任何其他组的颗粒细胞分泌更多的黄体酮。 CIDRa 卵泡分泌黄体酮的能力增加表明过早黄体化，这可能导致排卵优势卵泡延长的牛的生育能力下降。
Cattle with low (subluteal) levels of plasma progesterone develop a persistent dominant follicle; plasma estradiol and LH pulse frequency are elevated, and fertility subsequent to the ovulation of a prolonged dominant follicle is compromised. The hypotheses were 1) that prolonged dominant follicles produce more estradiol because they have theca and granulosa cells with an enhanced capacity to produce androgen and estradiol, respectively, and 2) that these changes in steroidogenic capacity are paralleled by concomitant changes in mRNA for the appropriate steroidogenic enzymes. Prolonged dominant follicles were induced by treating Holstein heifers with exogenous progesterone via an intravaginal controlled internal drug-release device (CIDR) from Day 14 to 28 of the cycle. Prolonged dominant follicles were collected just before (CIDRb, Day 28; n=4) or 24 h after (CIDRa, Day 29; n=4) CIDR removal, and their steroidogenic capacity was compared to that of growing, control dominant follicles obtained just before (CONTb, n=4) or 24 h after (CONTa, n=4) a luteolytic injection of prostaglandin F2alpha during the late luteal phase. After natural luteolysis, CIDR heifers maintained subluteal concentrations of progesterone (1-2 ng/ml) and had higher estradiol and LH pulse frequency than control heifers, as expected. In CIDR heifers, prolonged dominant follicles were present on the ovary for a longer time, reached a larger diameter, and had more granulosa cells and a larger mass of theca than dominant follicles from control heifers (p < 0.05). Concentrations of steroids in follicular fluid, estradiol secretion by granulosa cells in vitro, and levels of mRNA for steroidogenic enzymes in theca and granulosa cells provided no evidence for greater capacity of theca and granulosa cells of CIDR follicles to produce androgen and estradiol. In fact, follicular fluid estradiol and mRNA for P450 aromatase were higher after luteolysis than before in control animals (p < 0.05) but not after CIDR removal in treated animals. Therefore, the data do not support the hypotheses. Rather it is suggested that prolonged dominant follicles produce more estradiol because they have more granulosa cells and a larger mass of theca than control dominant follicles. In contrast, progesterone concentrations in the follicular fluid increased in CIDRa relative to CIDRb follicles (p < 0.05), a change that did not occur in control follicles; and granulosa cells from CIDRa follicles secreted more progesterone than granulosa cells from any other group. The increased capacity of CIDRa follicles to secrete progesterone suggests premature luteinization, which could contribute to decreased fertility in cattle that ovulate a prolonged dominant follicle.
牛颗粒细胞中的催产素/神经素-I信使核糖核酸在黄体生成素（LH）激增后增加，并在体外受到LH的刺激。
影响因子：
4.8
作者：
Voss,AK;Fortune,JE
通讯作者：
Fortune,JE