Suppression of human spermatogenesis by depot androgen: Potential for male contraception

Abstract

The gonadotropic hormones, LH and FSH, are required for normal sperm production. Inhibition of gonadotropin secretion by exogenously administered sex steroids represents one possible approach for male contraception. In the present study testosterone enanthate (TE) was administered IM to 39 normal adult men (age 21–39) to assess its efficacy as a suppressor of spermatogenesis and to determine possible adverse effects. Seventeen subjects (Group A) received TE (200 mg/wk) for 16–20 weeks. 16 17 lowered sperm counts to less than 5 million/cc; 11 17 to less than 300,000; and 10 17 became azoospermic. Group B received TE (200 mg/2 wk). In 10 22 , sperm counts were less than 5 million/cc at 16 weeks; 9 22 were less than 300,000; and 5 22 were azoospermic. When those with sperm counts greater than 5 million/cc were switched at 16 weeks to weekly treatment (additional 3–16 weeks), 9 12 lowered sperm counts to less than 5 million/cc. Overall, 19 22 of Group B attained this level. Serum LH and FSH were decreased on both regimens. These effects were dose-related. Mean serum testosterone was elevated above baseline (+64%) at 1 week after injection (Group A), but remained at basal levels 2 weeks after TE injection in Group B. Serum oestradiol levels parallel those of serum testosterone. Decreasing the frequency of TE (3 or 4 weeks) resulted in a rebound of FSH and LH above baseline and increased sperm counts. After discontinuing treatment, sperm counts and hormonal measurements returned to normal in all subjects. Modest increase in body weight, red cell mass, oiliness of skin and mild acne were seen in some subjects. Liver function tests, glucose tolerance, blood lipids and renal function were unchanged. Based on these data, testosterone enanthate demonstrates significant suppression of spermatogenesis. Further refinement of dose and/or delivery system, as well as investigation of combination hormonal regimens show promise for the development of a safe, effective male contraceptive agent.