Short-term effect of cyproterone acetate on testicular FSH binding in immature rats

Male rats, aged 19 days, were injected with 1 mg cyproterone acetate, an antiandrogen, and killed 24 h later. In 9 out of 10 experiments this increased the apparent FSH-binding capacity by testicular tissue in vitro. In 4 out of 5 similar experiments, injection of 500 micrograms testosterone propionate caused a significant reduction in FSH binding. Observed changes were small but this does not preclude the possibility that androgens contribute to the physiological control of FSH receptor numbers.