Sexual behaviour in castrated rabbits treated with testosterone, oestradiol, dihydrotestosterone or oestradiol in combination with dihydrotestosterone.

Sexual behaviour and the function of the accessory sexual glands were studied in castrated rabbits injected with testosterone benzoate (TB), oestradiol benzoate (OEB), dihydrotestosterone benzoate (DHTB) or OEB in combination with DHTB. Testosterone benzoate (1 mg daily for 90 days) stimulated the sexual behaviour more than any of the other steroids. The combination of OEB (0-33 mg) and DHTB (1 mg) was no more effective than either of these steroids given alone. The function of the accessory sexual glands was stimulated to a level comparable to that of intact animals given TB. Dihydrotestosterone benzoate was, however, not very effective in this respect. Oestradiol benzoate alone or in combination with DHTB caused hypertrophy and very low secretory activity of the seminal vesicles. These results suggest that testosterone itself is active both in the brain and in the accessory sexual glands in rabbits. This is in contrast to the rat, in which aromatization to oestradiol in the brain and reduction to DHT in the periphery seems to be important.