Studies on the reproductive function in the male rat following combined administration of progestin and androgen

Experiments were designed to test the effects of megestrol acetate (MA) and medroxyprogesterone acetate (provera) in combination with methyltestosterone (MT) and testosterone enanthate (TE), respectively, on sperm population and motility of spermatozoa in the ductus deferens, circulating androgens, mating behaviour, and fertility in male rats. One milligram of progestin and 100 micrograms of androgen, when administered for 70 days, impaired the fertility without any apparent effect on mating behaviour. Azoospermia or severe oligospermia coupled with asthenospermia was achieved in the majority of animals. Spermatozoa revealed changes in their pattern of motility after different medication intervals and these have been discussed in relation to androgen dependency of the reproductive tract. Transitory decline in serum androgen is observed after withdrawal of treatment.