Rhodes F M, Peterson A J, Jolly P D
Dexcel Limited, Private Bag 3123, Hamilton, New Zealand.
Reproduction. 2001 Oct;122(4):561-9.
The aim of this study was to examine the function of granulosa cells and hormone concentrations in follicular fluid in bovine ovarian follicles during selection of the first dominant follicle. Ovaries were obtained from beef heifers on days 1-5 after ovulation: follicles > 4 mm in diameter were dissected and follicular fluid and granulosa cells were collected from individual follicles. Oestradiol production by granulosa cells after culture with testosterone was used to determine aromatase activity and responsiveness to gonadotrophins was determined by cAMP production after culture with FSH or LH. Concentrations of oestradiol, progesterone and insulin-like growth factor binding proteins (IGFBPs)-4 and -5 were measured in follicular fluid. Follicles were classified as largest or smaller (days 1 and 2), or dominant or subordinate (days 3-5). Aromatase activity was greater in granulosa cells from the largest follicle than in granulosa cells from smaller follicles on days 1, 3, 4 and 5 (P < 0.05). Responsiveness to LH was not detected in granulosa cells on day 1, but from day 2 to day 5 cells from the largest follicle were significantly more responsive than cells from smaller follicles (P < 0.05). Responsiveness to FSH was detected in granulosa cells from all follicles from day 1 onwards and did not differ between cells from the largest follicle or smaller follicles on any day. Follicular fluid concentrations of oestradiol and the ratio of oestradiol:progesterone were greater and concentrations of IGFBP-4 and -5 were lower in the largest follicle than in smaller follicles from day 2 to day 5 (P < 0.05). In conclusion, selection of the dominant follicle is associated with increased granulosa cell aromatase activity followed by increased cAMP response to LH and follicular fluid oestradiol concentrations, and decreased follicular fluid concentrations of IGFBP-4 and -5 within 2 days after ovulation.
本研究的目的是检测牛卵巢卵泡在首个优势卵泡选择过程中颗粒细胞的功能以及卵泡液中的激素浓度。在排卵后第1 - 5天从肉用小母牛获取卵巢：解剖直径大于4 mm的卵泡，并从单个卵泡中收集卵泡液和颗粒细胞。用睾酮培养颗粒细胞后测定其雌二醇生成量以确定芳香化酶活性，用促卵泡素（FSH）或促黄体素（LH）培养颗粒细胞后通过环磷酸腺苷（cAMP）生成量来确定其对促性腺激素的反应性。测定卵泡液中雌二醇、孕酮以及胰岛素样生长因子结合蛋白（IGFBP）-4和-5的浓度。卵泡被分为最大卵泡或较小卵泡（第1天和第2天），或优势卵泡或从属卵泡（第3 - 5天）。在第1、3、4和5天，最大卵泡的颗粒细胞中的芳香化酶活性高于较小卵泡的颗粒细胞（P < 0.05）。第1天在颗粒细胞中未检测到对LH的反应性，但从第2天到第5天，最大卵泡的颗粒细胞对LH的反应性明显高于较小卵泡的颗粒细胞（P < 0.05）。从第1天起在所有卵泡的颗粒细胞中均检测到对FSH的反应性，且在任何一天最大卵泡的颗粒细胞与较小卵泡的颗粒细胞之间对FSH的反应性均无差异。从第2天到第5天，最大卵泡的卵泡液中雌二醇浓度以及雌二醇与孕酮的比值高于较小卵泡，而IGFBP - 4和-5的浓度低于较小卵泡（P < 0.05）。总之，优势卵泡的选择与颗粒细胞芳香化酶活性增加相关，随后对LH的cAMP反应性增加以及卵泡液雌二醇浓度升高，且在排卵后2天内卵泡液中IGFBP - 4和-5的浓度降低。
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