Effect of Hypophysectomy, Castration and Androgen Replacement upon the Fertilizing Ability of Rat Epididymal Spermatozoa

It has been demonstrated that in the rat, spermatozoa become able to fertilize ova when they reach the proximal region of the cauda epididymidis. Epididymal spermatozoa lose this ability 3 days after castration and 4 days after hypophysectomy. Ligation of the ductuli efferentes or sham hypophysectomy has no effect. Testosterone propionate (2 mg/kg/day) prevents the effect of castration or hypophysectomy. Cyproterone acetate (20 mg/kg/day) successfully inhibits the effect of exogenous testosterone (2 mg/ kg/day). Spermatozoa from the distal cauda epididymidis lose their fertilizing ability within 4 days after castration (9%) and 6 days after hypophysectomy (13%). Testosterone propionate (2 mg/kg/day) maintains the fertilizing ability of the spermatozoa from the distal cauda. Procedures (castration or hypophysectomy) which cause a decline in circulating androgen levels, hasten sperm transit through the epididymis. Castration interferes with the acquisition by the spermatozoa of their mature progressive pattern of motility. Hypophysectomy has no effect during the time period studied. It is concluded that sperm maturation and sperm survival are adversely affected by procedures which either cause a rapid decline in circulating androgen or inhibit the action of androgen on the target cells. (Endocrinology93: 391, 1973)