Abstract
Aflatoxin B1 (150 .mu.g) were injected i.p. to male rats on 3 occasions at intervals of 48 h. Sperm production and plasma and testicular testosterone concentrations were determined in rats killed 24 h after the last dose of aflatoxin with or without stimulation with human chorionic gonadotropin (HCG). Neither sperm production nor testosterone secreting capacity was significantly depressed by the acute aflatoxin treatment. The Leydig cell function was however impaired as indicated by the extremely reduced responsiveness of the Leydig cells of the aflatoxin-pretreated rats to HCG stimulation. The disruption of spermatogenesis by chronic aflatoxin treatment is preceded and caused by the impairment of the Leydig cell function and the resultant drop in testosterone in the testis.