Steroid hormones and receptors play important roles in female reproduction, and their expression patterns affect follicular growth and development. To examine the expression of dihydrotestosterone (DHT) synthases (5α‐reductases (5α‐red1 and 5α‐red2)) and androgen receptor (AR) during follicular development, and the regulation of DHT signalling by follicle‐stimulating hormone (FSH) and luteinizing hormone (LH), we have used enzyme‐linked immunosorbent assays, quantitative real‐time polymerase chain reaction, immunohistochemical staining and Western blotting to examine DHT synthesis in small (≤2 mm), medium (2–5 mm) and large (≥5 mm) sheep follicles. Expression of 5α‐red1, 5α‐red2 and AR was observed in ovine ovaries, and with the development of follicles, the expressions of 5α‐red1 and 5α‐red2 mRNA and protein increased, but the levels of AR mRNA, protein and DHT level decreased. In addition, granulosa cells were treated with FSH (0.01, 0.1 and 1 international unit (IU)/ml), LH (0.01, 0.1 and 1 IU/ml) and testosterone (T, 10^–7 M) to evaluate the effects of FSH and LH on DHT and oestradiol (E2) synthesis and 5α‐red1, 5α‐red2 and AR expression. We found that FSH and LH upregulated 5α‐red1 and 5α‐red2 in sheep granulosa cells, but downregulated the concentration of DHT and expression of AR. Meanwhile, FSH and LH significantly upregulated the expression of aromatase (P450arom) and secretion of E2. This result indicates that although FSH and LH promote the expression of 5α‐red1 and 5α‐red2, T is not transformed into DHT, but E2. This study reveals the reason why DHT concentration is downregulated in large follicles and lays a foundation for further exploring the synthesis mechanism of DHT during follicular development.

中文翻译：

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促卵泡激素和黄体生成素调节绵羊颗粒细胞中双氢睾丸激素的合成机制

类固醇激素和受体在女性生殖中起重要作用，其表达方式影响卵泡的生长和发育。检查卵泡发育过程中二氢睾丸激素（DHT）合成酶（5α-还原酶（5α-red1和5α-red2））和雄激素受体（AR）的表达，以及通过卵泡刺激素（FSH）和黄体生成素对DHT信号的调节激素（LH），我们已经使用酶联免疫吸附测定，定量实时聚合酶链反应，免疫组化染色和蛋白质印迹法来检查小（≤2mm），中（2–5 mm）和大（≥ 5毫米）羊卵泡。在绵羊卵巢中观察到5α-red1、5α-red2和AR的表达，并且随着卵泡的发育，5α-red1和5α-red2的mRNA和蛋白的表达增加，但是AR mRNA的水平 蛋白质和DHT水平降低。此外，颗粒细胞用FSH（0.01、0.1和1国际单位（IU）/ ml），LH（0.01、0.1和1 IU / ml）和睾丸激素（T，10^–7  M）评估FSH和LH对DHT和雌二醇（E2）合成以及5α-red1、5α-red2和AR表达的影响。我们发现FSH和LH上调了绵羊颗粒细胞中的5α-red1和5α-red2，但下调了DHT的浓度和AR的表达。同时，FSH和LH显着上调了芳香化酶（P450arom）的表达和E2的分泌。该结果表明，尽管FSH和LH促进5α-red1和5α-red2的表达，但T不会转化为DHT，而是E2。这项研究揭示了大卵泡中DHT浓度下调的原因，并为进一步探索卵泡发育过程中DHT的合成机理奠定了基础。