Impact of Intrafollicular Sulfated Steroids on Follicular Cells and the Oocyte's Developmental Capacity in Cattle

类固醇激素在协调卵母细胞成熟中是必不可少的，即卵泡来源的雌激素支持雌性配子的发育和受精。在本项目中，将分析卵泡发育过程中游离和结合雌激素的浓度，并与发育中卵泡的局部浓度进行比较。牛是合适的动物模型，因为其可获得性和适合于频繁检查和采样。此外，它已被用于了解人类生殖的几个特征，包括卵泡动力学，新兴的卵泡的命运主要是由促性腺激素和类固醇激素以类似的方式编排。卵巢SULT 1 E1局部参与卵泡雌激素活性的调节。EST催化的雌激素活性下调使正常排卵。相反，磺基共轭雌激素也可能是产生游离雌激素的前体，这取决于雌激素硫酸酯酶（StS）的活性。在哺乳动物中，卵泡黄体化/排卵是由LH激增触发的，其特征是许多物理和生化变化，包括雌二醇（E2）的产生减少。这种E2生物合成能力的丧失可以通过参与卵泡活性雌激素产生的关键类固醇生成酶的表达显著减少来解释。然而，对负责雌激素失活和消除的酶/蛋白质的调节知之甚少，例如在此期间由EST介导。

Steroid hormones are essential in orchestrating oocyte maturation, i.e. estrogens of follicular origin support the development of the female gamete and fertilization. In this project the concentration of free and conjugated estrogens during follicular development will be analysed and compared to local concentrations in the developing follicle. Cattle are suitable animal models because of the accessibility and suitability for frequent examination and sampling. Furthermore, it has been useful for understanding several features of human reproduction including follicular dynamics, the fate of the emerging follicles is orchestrated mainly by gonadotropins and steroid hormones in a similar manner. Ovarian SULT1E1 participates locally in the regulation of follicular estrogen activity. The ESTcatalysed down-regulation of estrogen activity enables normal ovulation. Conversely, sulfoconjugated estrogens may also be precursors of the production of free estrogens depending on estrogen sulfatase (StS) acitivity. In mammals, follicular luteinisation/ovulation is triggered by a surge in LH and is characterised by numerous physical and biochemical changes, including the decreased production of estradiol (E2). This loss in E2 biosynthetic capacity has been explained by a marked decrease in the expression of key steroidogenic enzymes involved in the follicular production of active estrogens. However, little is known about the regulation of enzymes/proteins responsible for the inactivation and elimination of estrogens, as mediated for example by EST during this period.