Feeding adult male rats with gossypol acetic acid at a dose of 15 nig/kg/day for 50 days led to infertility. Spermatogenesis and sperm motility were impaired ( table 1 ) . However, testosterone, K+ and Na+ concentsrations in serum and RTF were found to be unchanged (table 2, 3 ) . It suggests that at low antifertility doses gossypol disrupts spermatogenesis in the seminiferous epithelium without affecting testosterone, K+ and Na+ secretion and translation in testis.

OBJECTIVETo observe depot medroxyprogesterone acetate (DMPA) and testosterone undecanoate (TU) injected at 8-week intervals for the suppression of spermatogenesis in healthy Chinese men.

METHODSAfter screening, 30 healthy volunteers were enrolled and randomly assigned to 3 dosage-groups (n = 10/group): 1000 mg TU (Group A), 1000 mg TU plus 150 mg DMPA (Group B), 1000 mg TU plus 300 mg DMPA (Group C). All dosages were given as intramuscular injections at 8-week intervals. The study consisted of an 8-week control (baseline) period, a 24-week treatment period and a 24-week recovery period.

RESULTSConsistent azoospermia or severe oligozoospermia was achieved and maintained in all the volunteers during the treatment period, except 2 in the mere TU group who experienced a "rebound" in sperm concentrations. An 8-week regimen of TU plus DMPA at both tested combination dosages effectively suppressed spermatogenesis to azoospermia. All volunteers tolerated the injections; no serious adverse effects were reported.

CONCLUSIONThe lower combined dosage is recommended for further testing in an expanded clinical trial or contraceptive efficacy study.

Adult ; Androgens ; pharmacology ; China ; Gonadotropin-Releasing Hormone ; biosynthesis ; Humans ; Hypothalamo-Hypophyseal System ; metabolism ; Male ; Medroxyprogesterone Acetate ; pharmacology ; Prospective Studies ; Sperm Count ; Spermatogenesis ; drug effects ; Testosterone ; analogs & derivatives ; pharmacology