Diethylstilbestrol-Treated Adult Rats with Altered Epididymal Sperm Numbers and Sperm Motility Parameters, but Without Alterations in Sperm Production

In this study, we characterized estrogenic effects of diethylstilbestrol (DES) on reproductive parameters in male rats to identify a minimal dose level that alters epididymal and sperm functions but has little or no effect on sperm production and/ or spermatogenesis. Adult rats (five animals/group) received s.c. injections of 0.2 ml of corn oil containing DES at a rate of 1.0 mg, 200 mg, 40 mg, 8 mg, 1.6 mg, or 320 ng rat 21 day 21 for 12 days. The control group received corn oil only. DES effects were similar in the 8-mg group and higher dose groups and included significant (P # 0.05) reductions in 1) absolute and relative weights of the head and body of the epididymis (EP), tail of the EP, and seminal vesicle, 2) numbers of sperm in both regions of the EP, and 3) motility characteristics in sperm collected from the tail of the EP. Conversely, no significant changes were observed in relative testis weight, daily sperm production, spermatogenesis, seminiferous epithelial height in stage VII, and sperm morphology. All of the above parameters in the 1.6-mg group (except seminal vesicle weight) and 320-ng group were comparable to those of controls. Plasma testosterone (T) level was reduced to an almost undetectable level in the $8-mg groups and to a very low level in the 1.6-mg group (0.35 vs. 2.36 ng/ml in controls or 320-ng group), but LH level was unaltered. In a parallel fertility study, males received DES at a rate of 40,