Putowski L, Rohan R M, Choi D S, Scherzer W J, Ricciarelli E, Mordacq J, Mayo K E, Adashi E Y
Department of Obstetrics and Gynecology, University of Maryland School of Medicine, Baltimore, USA.
J Soc Gynecol Investig. 1997 May-Jun;4(3):144-51. doi: 10.1016/s1071-5576(97)00020-8.
To assess the in vivo regulation of ovarian insulin-like growth factor binding protein-4 (IGFBP-4) mRNA expression by gonadotropins and estrogen.
Whole ovarian RNA, obtained from two models of follicular development, was extracted and analyzed by Northern blotting. Immature rats were treated with pregnant more serum gonadotropin (PMSG) followed 48 hours later with hCG, or alternatively were hypophysectomized and treated with FSH and/or diethylstilbestrol (DES). Localization of IGFBP-4 expression was assessed in the former study by in situ hybridization. Finally, the ability of human IGFBP-4 to antagonize FSH-stimulated progesterone accumulation was assessed in vitro.
The ovarian content of IGFBP-4 transcripts increased threefold (P < .05) at 12 hours after PMSG but was near baseline at 24 and 48 hours. The abundance of IGFBP-4 mRNA increased (P < .05) again at 6 and 24 hours after hCG. The expression of IGFBP-4 was localized to granulosa cells of preantral (untreated) and small antral (12 hours after PMSG) follicles. No IGFBP-4 expression was noted in large (gonadotropin-primed) antral follicles. Hypophysectomy increased (P < .05) the ovarian content of IGFBP-4 mRNA by 1.5-fold, an effect further enhanced (1.8-fold; P < .05) by the provision of FSH and DES. In vitro studies revealed the ability of increasing concentrations (0.01-1 microgram/mL) of recombinant human IGFBP-4 to inhibit the FSH-supported accumulation of progesterone.
Increased expression after administration of PMSG, hCG, and FSH/DES suggests that IGFBP-4 is a dynamic and hormonally responsive component of the ovarian cycle. The lack of expression in preovulatory follicles and its antigonadotropic actions in vitro imply that the attenuated expression of IGFBP-4 may constitute a requirement for successful follicular maturation.
评估促性腺激素和雌激素对卵巢胰岛素样生长因子结合蛋白-4（IGFBP-4）mRNA表达的体内调节作用。
从两种卵泡发育模型中获取整个卵巢的RNA，通过Northern印迹法进行提取和分析。对未成熟大鼠先用孕马血清促性腺激素（PMSG）处理，48小时后再用hCG处理，或者先进行垂体切除，然后用促卵泡激素（FSH）和/或己烯雌酚（DES）处理。在前面的研究中，通过原位杂交评估IGFBP-4表达的定位。最后，在体外评估重组人IGFBP-4拮抗FSH刺激的孕酮积累的能力。
PMSG注射后12小时，卵巢中IGFBP-4转录本含量增加了两倍（P <.05），但在24和48小时时接近基线水平。hCG注射后6和24小时，IGFBP-4 mRNA丰度再次增加（P <.05）。IGFBP-4的表达定位于窦前（未处理）卵泡和小窦状（PMSG注射后12小时）卵泡的颗粒细胞。在大的（经促性腺激素预处理）窦状卵泡中未观察到IGFBP-4表达。垂体切除使卵巢中IGFBP-4 mRNA含量增加了1.5倍（P <.05），给予FSH和DES后这一效应进一步增强（1.8倍；P <.05）。体外研究显示，重组人IGFBP-4浓度增加（0.01 - 1微克/毫升）可抑制FSH支持的孕酮积累。
PMSG、hCG和FSH/DES给药后表达增加表明IGFBP-4是卵巢周期中一个动态且对激素有反应的成分。排卵前卵泡中缺乏表达以及其在体外的抗促性腺激素作用意味着IGFBP-4表达减弱可能是卵泡成功成熟的必要条件。
