Gérard N, Monget P
Equipe Reproduction Equine, Station PRMD, INRA-Haras Nationaux, Nouzilly, France.
Biol Reprod. 1998 Jun;58(6):1508-14. doi: 10.1095/biolreprod58.6.1508.
The profiles of insulin-like growth factor-binding proteins (IGFBPs) in follicular fluid have been characterized in a number of mammals (rats, pigs, sheep, cattle, humans) and are good indicators of follicular status. We studied the IGFBP profiles of equine serum and ovarian follicular fluid recovered at various stages of the follicular phase. The levels of IGFBPs were related to the morphology and the steroidogenic activity of the follicles. Follicular fluids were recovered by ultrasound-guided follicular aspiration. In the first experiment, the dominant follicles of 10 mares were partly punctured (aspiration of 0.5-2.2 ml of fluid) once at the early dominant stage (22-25 mm in diameter) and a second time at the preovulatory stage (PO), 34 h after induction of ovulation. Among these 10 PO follicles, 5 were classified as healthy whereas the other 5 were classified as hemorrhagic, as assessed by ultrasonic morphology and subsequent ovulation or not. In another group of mares (n = 5), the largest follicle was punctured once at the late dominant stage (33-35 mm in diameter) and then at the PO stage, 34 h after induction of ovulation. Serum was prepared at each puncture session. In the second experiment, follicular fluid was recovered from the dominant and contemporary cohort subordinate follicles (n = 5 mares). Samples were individually assayed for estradiol-17beta and progesterone content by RIA, and IGFBPs were studied by using Western ligand blotting and densitometry. Equine serum and follicular fluid displayed IGFBP at 42-44 kDa (likely corresponding to IGFBP-3), 28-32 kDa (likely corresponding to IGFBP-5), 24 kDa (likely corresponding to IGFBP-4), and 35 kDa, identified as IGFBP-2 by immunoblotting, plus one band at 120 kDa. IGFBP were clearly more abundant in serum than in fluid from healthy follicles. In the follicular fluid, 42-44-kDa IGFBP was the major binding protein, and its level was almost constant at the various physiological statuses studied. Follicular development of the dominant follicle in each mare was characterized by a decrease in intrafollicular IGFBP-2 and 28-32-kDa IGFBP levels before LH stimulation and by an increase in IGFBP-2 after LH stimulation. Follicular regression of large follicles, as well as subordinate ones, was characterized by a low level of intrafollicular estradiol-17beta and was associated with an increase in IGFBP-2, 24-kDa IGFBP, and 28-32-kDa IGFBP intrafollicular levels. Taking these results together, we have demonstrated clear correlations between the intrafollicular levels of estradiol-17beta and IGFBP-2 and 28-32-kDa IGFBP. Therefore, follicular growth and regression in the mare are associated with specific changes in IGFBP levels. These changes could be of crucial importance for follicular development in ovulation or atresia.
胰岛素样生长因子结合蛋白（IGFBPs）在卵泡液中的情况已在多种哺乳动物（大鼠、猪、绵羊、牛、人类）中得到了描述，并且是卵泡状态的良好指标。我们研究了在卵泡期不同阶段采集的马血清和卵巢卵泡液中的IGFBP情况。IGFBPs的水平与卵泡的形态和类固醇生成活性有关。卵泡液通过超声引导下的卵泡穿刺采集。在第一个实验中，10匹母马的优势卵泡在早期优势阶段（直径22 - 25毫米）被部分穿刺一次（抽取0.5 - 2.2毫升液体），在排卵诱导后34小时的排卵前期（PO）再次穿刺。在这10个PO卵泡中，根据超声形态以及随后是否排卵评估，5个被归类为健康卵泡，另外5个被归类为出血性卵泡。在另一组母马（n = 5）中，最大的卵泡在晚期优势阶段（直径33 - 35毫米）被穿刺一次，然后在排卵诱导后34小时的PO阶段再次穿刺。每次穿刺时都采集血清。在第二个实验中，从优势卵泡和同期从属卵泡中采集卵泡液（n = 5匹母马）。通过放射免疫分析法（RIA）分别检测样本中的雌二醇 - 17β和孕酮含量，并使用Western配体印迹法和光密度测定法研究IGFBPs。马血清和卵泡液中显示出分子量为42 - 44 kDa（可能对应于IGFBP - 3）、28 - 32 kDa（可能对应于IGFBP - 5）、24 kDa（可能对应于IGFBP - 4）的IGFBP，以及通过免疫印迹法鉴定为IGFBP - 2的35 kDa的IGFBP，还有一条120 kDa的条带。IGFBP在血清中的含量明显高于健康卵泡液中的含量。在卵泡液中，42 - 44 kDa的IGFBP是主要的结合蛋白，并且在研究的各种生理状态下其水平几乎保持恒定。每匹母马优势卵泡的卵泡发育特征是在促黄体生成素（LH）刺激前卵泡内IGFBP - 2和28 - 32 kDa的IGFBP水平降低，而在LH刺激后IGFBP - 2水平升高。大卵泡以及从属卵泡的卵泡退化特征是卵泡内雌二醇 - 17β水平较低，并与卵泡内IGFBP - 2、24 kDa的IGFBP和28 - 32 kDa的IGFBP水平升高有关。综合这些结果，我们已经证明卵泡内雌二醇 - 17β水平与IGFBP - 2和28 - 32 kDa的IGFBP之间存在明显的相关性。因此，母马的卵泡生长和退化与IGFBP水平的特定变化有关。这些变化对于排卵或闭锁过程中的卵泡发育可能至关重要。
