Berisha B, Schams D, Kosmann M, Amselgruber W, Einspanier R
Institute of Physiology, Technical University of Munich, Weihenstephaner Berg 3, D-85350 Freising-Weihenstephan, Germany.
J Endocrinol. 2000 Dec;167(3):371-82. doi: 10.1677/joe.0.1670371.
Locally produced growth factors may have important modulatory roles in final ovarian follicular growth. The aim of this study was to investigate the possible participation of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF2) in bovine follicles during final growth. Ovaries were collected from a slaughterhouse within 10-20 min after exsanguination. A classification of follicles into five groups (<0.5; >0.5-5; >5-20; >20-180; >180 ng/ml) was performed according to the follicular fluid (FF) oestradiol-17 beta content. For a better characterisation of classes the mRNA expressions of FSH receptor, LH receptor and aromatase cytochrome P450 in theca interna (TI) and granulosa cells (GC) were determined. Analysis of VEGF transcript by RT-PCR showed that GC and theca cells express predominantly the smallest isoforms (VEGF(121) and VEGF(165)). VEGF mRNA expression in both tissues (TI and GC) and VEGF protein concentration in total follicle tissue increased significantly (and correlated) with developmental stages of follicle growth. The expression of mRNA for VEGF receptor (VEGFR)-1 and VEGFR-2 was very weak in GC, without any regulatory change during final follicle growth. In contrast, TI showed strong expression of mRNA for both receptors in all follicle classes examined. VEGF protein concentrations in FF increased significantly and continuously to maximum levels in preovulatory follicles. As shown by immunohistochemistry, VEGF protein was clearly localised in TI and GC of preovulatory follicles. FGF2 and FGF receptor (FGFR) mRNA expression in TI increased significantly during final growth of follicles. In contrast, the FGF2 and FGFR mRNA expression in GC was very weak and without any regulatory change during follicle growth. Histological observation revealed that FGF2 protein was localised in theca tissue (cytoplasm of endothelial cells and pericytes) but not in GC. Our results suggest that VEGF and FGF families are involved in the proliferation of capillaries that accompanies the selection of the preovulatory follicle resulting in an increased supply of nutrients and precursors, and therefore supporting the growth of the dominant follicle.
局部产生的生长因子可能在卵巢卵泡最终生长过程中发挥重要的调节作用。本研究的目的是调查血管内皮生长因子（VEGF）和碱性成纤维细胞生长因子（FGF2）在牛卵泡最终生长过程中可能的参与情况。在放血后10 - 20分钟内从屠宰场收集卵巢。根据卵泡液（FF）中雌二醇-17β含量将卵泡分为五组（<0.5；>0.5 - 5；>5 - 20；>20 - 180；>180 ng/ml）。为了更好地表征这些类别，测定了卵泡膜内层（TI）和颗粒细胞（GC）中促卵泡激素受体、促黄体生成素受体和芳香化酶细胞色素P450的mRNA表达。通过RT-PCR分析VEGF转录本表明，颗粒细胞和卵泡膜细胞主要表达最小的异构体（VEGF(121)和VEGF(165)）。两种组织（TI和GC）中的VEGF mRNA表达以及整个卵泡组织中的VEGF蛋白浓度均随着卵泡生长的发育阶段显著增加（且具有相关性）。颗粒细胞中VEGF受体（VEGFR）-1和VEGFR-2的mRNA表达非常弱，在卵泡最终生长过程中没有任何调节变化。相反，在所检查的所有卵泡类别中，TI均显示出两种受体的mRNA强表达。卵泡液中的VEGF蛋白浓度显著且持续增加，在排卵前卵泡中达到最高水平。免疫组织化学显示，VEGF蛋白明显定位于排卵前卵泡的TI和GC中。在卵泡最终生长过程中，TI中FGF2和FGF受体（FGFR）的mRNA表达显著增加。相反，颗粒细胞中FGF2和FGFR的mRNA表达非常弱，在卵泡生长过程中没有任何调节变化。组织学观察显示，FGF2蛋白定位于卵泡膜组织（内皮细胞和周细胞的细胞质），而不在颗粒细胞中。我们的结果表明，VEGF和FGF家族参与了伴随排卵前卵泡选择的毛细血管增殖，从而导致营养物质和前体供应增加，因此支持优势卵泡的生长。
