Sertoli Cell Capacity to Metabolize C19Steroids: Variation with Age and the Effect of Follicle-Stimulating Hormone*

Sertoli cells from rats 6–60 days of age were examined for their in vitro capacity to convert androstenedione (A) to testosterone (T), androstenedione to 3α, 17β-dihydroxy-5α-androstane (DIOL), and 17β-hydroxy-5α-androstan-3-one (DHT) to DIOL. The influence of FSH on these conversions was also examined. The A to T conversion rate, indicative of 17β- oxidoreductase (17β-HSD) activity, increased from less than 10 ng/h/mg in cells from 6-day-old rats to over 60 ng/h/mg in cells from 16-day-old rats and then declined to about the 6-day level in 32-day-old rats; the rate of 17β-HSD activity remained low in Sertoli cells from rats older than 32 days. FSH resulted in significant increases in A to T conversions in Sertoli cells from 10-, 16-, and 20-day-old rats but not in cells from younger or older rats. The conversion of A to T was highly favored over the reverse reaction; the T to A conversion rate was not influenced by FSH. The 17β-HSD activity showed a response to purified (Papkoff) FSH which was dose dependent between 1–100 ng/ml medium. The conversion rates of A to DIOL and DHT to DIOL, indicative of 5α-reductase and 3α-HSD activities, respectively, varied with age in a manner similar to the 17β-HSD activity. However, FSH caused a significant increase in 5areductase and 3α-HSD activities only in cells from 10- day-old rats. FSH caused a significant reduction of the enzyme activities in Sertoli cells from rats 20 to 24 days old. Recrystallization data indicated an absence of 3β- HSD activity in Sertoli cells from young rats; no 3β- androstanediol was found. The results indicate that at the onset of meiosis, Sertoli cells possess enhanced 17β- HSD, 5α-reductase, and 3α-HSD activities which may be responsive to FSH. The FSH response is not present in Sertoli cells from older rats.