The objective of the study was to characterize expression patterns of hypoxia‐inducible factor‐1alpha (HIF1A), inducible nitric oxide synthase (iNOS) and endothelial (eNOS) isoforms in time‐defined follicle classes before and after GnRH application in the cow. Ovaries containing pre‐ovulatory follicles or corpora lutea were collected by transvaginal ovariectomy (n = 5 cows/group) as follow: (I) before GnRH administration; (II) 4h after GnRH; (III) 10h after GnRH; (IV) 20h after GnRH; (V) 25h after GnRH; and (VI) 60h after GnRH (early corpus luteum). The mRNA abundance of HIF1A in the follicle group before GnRH was high, followed by a significant down regulation afterwards with a minimum level 25h after GnRH (close to ovulation) and significant increase only after ovulation. The mRNA abundance of iNOS before GnRH was high, decreased significantly during LH surge, with minimum levels afterwards. In contrast, the mRNA of eNOS decreased in the follicle group 20h after GnRH, followed by a rapid and significant upregulation just after ovulation. Immunohistochemically, the granulosa cells of antral follicles and the eosinophils of the theca tissue as well of the early corpus luteum showed a strong staining for HIF1A. The location of the eosinophils could be clearly demonstrated by immunostaining with an eosinophil‐specific antibody (EMBP) and transmission electron microscopy. In conclusion, the parallel and acute regulated expression patterns of HIF1A and NOS isoforms, specifically during the interval between the LH surge and ovulation, indicate that these paracrine factors are involved in the local mechanisms, regulating final follicle maturation, ovulation and early luteal angiogenesis.

中文翻译：

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低氧诱导因子-1α和一氧化氮合酶在牛卵泡接近排卵和早期黄体血管生成。

这项研究的目的是表征在牛中应用GnRH之前和之后的时间确定的卵泡类别中的低氧诱导因子-1α（HIF1A），诱导型一氧化氮合酶（iNOS）和内皮（eNOS）亚型的表达模式。经阴道卵巢切除术收集卵巢中含有排卵前卵泡或黄体的卵巢（n ＝ 5头母牛/组）如下：（I）在施用GnRH之前；（II）GnRH后4h；（III）GnRH后10h；（IV）GnRH后20小时；（V）GnRH后25小时；（VI）GnRH（黄体早期）后60h。GnRH前卵泡组中HIF1A的mRNA丰度很高，随后显着下调，GnRH后至少25h达到最低水平（接近排卵），仅在排卵后才显着增加。GnRH之前iNOS的mRNA丰度很高，在LH激增期间显着下降，此后最低。相比之下，GnRH后20h卵泡组eNOS的mRNA下降，排卵后即迅速而明显的上调。免疫组织化学 肛门卵泡的颗粒细胞和卵泡膜组织的嗜酸性粒细胞以及早期黄体显示出对HIF1A的强染色。嗜酸性粒细胞的位置可以通过用嗜酸性粒细胞特异性抗体（EMBP）进行免疫染色和透射电镜清楚地证明。总之，HIF1A和NOS亚型的平行和急性调节表达模式，特别是在LH潮气和排卵之间的间隔期间，表明这些旁分泌因子参与了局部机制，调节了最终的卵泡成熟，排卵和早期黄体血管生成。