Studies on 5α-reductase activity in human ovarian tissue

Melatonin regulates dihydrotestosterone formation via its membrane receptor in the epididymal epithelial cells of sheep

Both melatonin and androgen, which affect sperm fertility, are the important factors in epididymis of male animal. In the present study, we confirmed that melatonin regulates the formation of dihydrotestosterone (DHT) in sheep epididymides. Here, we investigated the localization and the expression levels of melatonin keys synthases AANAT and HIOMT, membrane receptors MT1 and MT2, and nuclear receptor RORα in sheep epididymides and testes. We also cultured epididymal epithelial cells and treated them with different concentrations of melatonin (10^-11-10^-7 M) and luzindole (10^-5 M) and 4P-PDOT (10^-5 M) to investigate whether melatonin is involved in the regulation of DHT formation and whether these effects are mediated through its receptor pathways. The results showed that AANAT, HIOMT, MT1, MT2, and RORα were differentially expressed between sheep epididymides and testes. In addition, melatonin is involved in mediating the formation of DHT in epididymal epithelial cells, and its influence on DHT is at least partially regulated by the melatonin receptor pathway. Our findings showed that melatonin regulates the functions of the testes and epididymides through an autocrine mechanism and regulates the formation of androgen in sheep epididymides via the receptor pathway. These results provide a basis for further exploring the regulatory mechanisms of melatonin in animal reproduction.

Follicle-stimulating hormone and luteinizing hormone regulate the synthesis mechanism of dihydrotestosterone in sheep granulosa cells

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.

Dihydrotestosterone synthesis in the sheep corpus luteum and its potential mechanism in luteal regression

Corpus luteum (CL) regression is a complex physiological process. Previous studies have shown that dihydrotestosterone (DHT) may be involved in regulating CL regression, but the mechanism is still unclear. In this study, we evaluated the localization of the two isoforms of DHT synthetase 5α-reductase (5α-red1 and 5α-red2) and androgen receptor (AR) in sheep CL, and investigated 5α-red1, 5α-red2, AR, and DHT levels at different luteal stages of CL (early, middle, and late phase) by immunohistochemistry, quantitative real-time polymerase chain reaction, and western blot analysis. Moreover, we cultured luteal cells from middle phase CL and treated them with different concentrations of DHT (10^-10 -10 ^-6  M) and the AR antagonist flutamide (10 ^-5  M), to evaluate whether DHT is involved in the regulation of progesterone (P4) secretion and progesterone nuclear receptor (PGR) expression and whether these effects are regulated by the AR pathway. We also investigated the effects of DHT and flutamide on prostaglandin F2α (PGF2α) secretion and apoptotic gene and protein expression. Our results showed that 5α-red1, 5α-red2, and AR were expressed in the CL, and their expression and DHT levels were changed during the luteal phase. DHT was involved in mediating P4 and PGF2α secretion and PGR and apoptotic gene and protein expression. The effects of DHT on CL were at least partially regulated by the AR pathway. This study reveals the mechanism of action of DHT on sheep CL regression and lays the foundation for further exploration of androgen regulation of CL function.