Greater Conversion of Testosterone to 5α-Dihydrotestosterone, Reflecting Increased Peripheral 5α-Reductase Activity in Nude Mice Treated with High Doses of Cyclosporine A

The study investigated the effects of cyclosporine A (CsA) on hair growth and testosterone metabolism in nude mice. Three groups of 5 female nude mice were treated with varying doses of CsA (5 mg/kg, 25 mg/kg, and 100 mg/kg), and their results were compared to a control group. The study found that high doses of CsA significantly increased the conversion of testosterone to 5α-dihydrotestosterone (5α-DHT) and other 5α-reduced products, indicating increased 5α-reductase activity. Specifically, the highest dose group showed a 44.4% increase in 5α-DHT formation compared to the control group, suggesting that CsA may enhance hair growth by increasing peripheral 5α-reductase activity.