Is high dosage testosterone an effective male contraceptive agent?

In male contraceptive trials, approximately half of normal men become azoospermic on high dosages of testosterone enanthate (TE), whereas the other half of men become severely oligozoospermic. To determine whether sperm function is reduced in men with severe oligozoospermia induced by TE, we studied sperm function in six normal men whose sperm counts were reduced to less than or equal to 5 X 10(6)/ml but not to azoospermia by high-dosage TE administration for 5 to 6 months and five normal men who received placebo (sesame oil) injections for the same period of time. Seminal fluid analysis and sperm function (as assessed by zona pellucida-free hamster ova penetration test, HOPT) were performed during a pretreatment period and after at least 3 months of TE or placebo treatment. HOPT was severely reduced in all six men, whose sperm counts were suppressed to severe oligozoospermia during TE (0.8 +/- 0.8% compared to 37 +/- 14% during the pretreatment period, P less than 0.05). Five men failed to penetrate any hamster ova, while the remaining man penetrated only 5% of ova during TE treatment. There were no significant changes in other seminal fluid measurements during high-dosage TE. The five men who received placebo injections did not demonstrate any significant changes in HOPT or seminal fluid analysis during the treatment period. In summary, we found that the fertilizing capacity of sperm is markedly diminished when sperm production is severely reduced by high-dosage TE administration. These findings suggest that male contraception may be achievable by reduction of spermatogenesis to severe oligozoospermia.(ABSTRACT TRUNCATED AT 250 WORDS)