Testicular effects of the Leydig cell toxicant ethane dimethanesulphonate given to neonatal rats

Neonatal rats were injected with either 50 mg/kg ethane dimethanesulphonate (EDS) or vehicle on days 1 to 5 inclusive or on day 1 alone. Studies were made on days 6, 28, and 63 of testicular structure; related endocrinologic parameters were measured in the day 1 to 5 treated animals only. Leydig cells and their activities were identified by cell counts using sections stained for 3 beta-hydroxysteroid dehydrogenase, hCG binding to LH receptors in testicular homogenates, and assays of intratesticular testosterone, plus pituitary and/or serum concentrations of testosterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH). Given on days 1 to 5, EDS reduced Leydig cell populations estimated by morphometry and 125I-HCG binding, and testicular and body weights between days 6 and 63, and permanently retarded the development of the seminiferous epithelium. Decreases of serum and intratesticular testosterone occurred with homeostatic rises in FSH and LH. Injection on day 1 reduced Leydig cell numbers only on day 6 although body weight remained retarded. The data illustrate the susceptibility of the developing rat testis to the cytotoxicant EDS; whether this is related to withdrawal of androgen production or nonspecific cytotoxicity remains to be evaluated.