Evidence for a direct in vitro action of sex steroids on rabbit cartilage cells during skeletal growth: influence of age and sex.

A direct effect of sex steroid hormones on in vitro cartilage cell metabolism was demonstrated. Cells were derived from rabbit fetuses on day 20 of gestation, and from male and female rabbits aged from 2 to 80 days. Testosterone (T), dihydrotestosterone (DHT), or 17 beta-estradiol (E2) (10(-9) -10(-9) M) were added to primary culture of epiphyseal articular chondrocytes. They showed an age-dependent stimulatory effect on [35S]sulfate incorporation into newly synthesized proteoglycans. In cultured rabbit fetal cartilage cells, the maximum active concentration of T and DHT was 10(-9) M with a 40% stimulating effect over control values. E2 was even more active with 80% stimulating effect when added at 10(-8) M. Chondrocytes from animals aged up to 5 days responded poorly and those from animals aged 5-30 days not at all. The response of cells from older animals varied with animal age and sex. T and DHT stimulated chondrocytes from males aged 32-55 days and females aged 40-52 days to about the same extent. E2 stimulated cells from animals of the same ages, but the response of female-derived cells was twice that of male-derived cells. The stimulating effect was dose dependent from 10(-11) to 10(-8) M and maximal at 10(-9) M for T and DHT and at 10(-8) M for E2. Puromycin completely abolished the effect.