Shimizu T, Berisha B, Schams D, Miyamoto A
Graduate school of animal and food hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
Reprod Domest Anim. 2007 Apr;42(2):221-4. doi: 10.1111/j.1439-0531.2006.00748.x.
Ovarian follicular vasculature is involved in follicular development and ovulation. Angiopoietin (ANPT)-Tie system is important for vascularization of the tissue surrounding the developing follicles and corpus luteum (CL). To determine how the expression of ANPT-1, ANPT-2 and their receptors in the follicles would be associated with the ovulatory process, the present study was conducted to examine mRNA expressions of ANPT-1, ANPT-2 and their receptors during the periovulatory phase in gonadotrophin-releasing hormone (GnRH)-treated cows. The ovaries were collected by transvaginal ovariectomy (n = 5, cows/group) and the follicles (n = 5, one follicle/cow) were classified into following groups: before GnRH administration [before luteinizing hormone (LH) surge]; 3-5 h after GnRH (during LH surge); 10 h after GnRH; 20 h after GnRH; 25 h after GnRH (peri-ovulation); and early CL (days 2-3). The mRNA expression was analysed by quantitative real-time PCR (rotor-gene 3000). Angiopoietin-1 expression rapidly decreased at 3-5 h and kept low level at 10 h after GnRH treatment compared with that before GnRH, and returned to the level before LH surge in the follicles >20 h after GnRH treatment. The levels of ANPT-2 mRNA decreased at 10 and 25 h after treatment compared with other periods. The ratio of ANPT-2/ANPT-1 (an index for destabilization of blood vessels) increased in the follicles at 3-5 h after GnRH treatment only. Both of Tie-1 and Tie-2 receptor expressions decreased in the follicles at 25 h after GnRH treatment. The results of the present study indicated that mRNA expressions of ANPT-1, ANPT-2 and their receptors changed in the bovine follicles during periovulatory period. These results suggest that angiopoietin-Tie system is associated with the initiation of vasculature of follicle that grows towards ovulation.
卵巢卵泡血管系统参与卵泡发育和排卵过程。血管生成素（ANPT）-Tie系统对于发育中的卵泡和黄体（CL）周围组织的血管形成很重要。为了确定卵泡中ANPT-1、ANPT-2及其受体的表达如何与排卵过程相关，本研究旨在检测促性腺激素释放激素（GnRH）处理的奶牛在围排卵期ANPT-1、ANPT-2及其受体的mRNA表达。通过经阴道卵巢切除术收集卵巢（每组n = 5头奶牛），并将卵泡（每组n = 5个，每头奶牛1个卵泡）分为以下几组：GnRH给药前[促黄体生成素（LH）峰前]；GnRH给药后3 - 5小时（LH峰期间）；GnRH给药后10小时；GnRH给药后20小时；GnRH给药后25小时（排卵前后）；以及早期黄体（第2 - 3天）。通过定量实时PCR（rotor-gene 3000）分析mRNA表达。与GnRH给药前相比，GnRH处理后3 - 5小时血管生成素-1表达迅速下降，在10小时时维持在低水平，在GnRH处理后>20小时的卵泡中恢复到LH峰前的水平。与其他时期相比，处理后10小时和25小时ANPT-2 mRNA水平下降。仅在GnRH处理后3 - 5小时，卵泡中ANPT-2/ANPT-1的比值（血管不稳定指数）升高。GnRH处理后25小时，卵泡中Tie-1和Tie-2受体表达均下降。本研究结果表明，围排卵期牛卵泡中ANPT-1、ANPT-2及其受体的mRNA表达发生了变化。这些结果表明血管生成素-Tie系统与向排卵方向生长的卵泡血管形成的起始有关。
