Testicular effects of dinoseb in rats

Abstract

Diets containing the herbicide dinoseb (2-sec- butyl 4,6-dinitrophenol) were fed to adult male Sherman rats for 11 weeks. One-half the survivors were killed for terminal studies during the eleventh week and the remainder bred to untreated females during posttreatment, and then killed for terminal studies. Interim sacrifices were made in groups fed 0 and 300 ppm. In rats fed 300 ppm, differential classification of spermatozoa from the cauda epididymidis indicated 90% of the cells were atypical by 20 days of treatment. By 30 days, bizarre and amorphous forms were observed and epididymal sperm counts were decreased. Histologic changes in the testes included abnormal spermatozoa and spermatids and multinucleated spermatogenic cells at 20 and 30 days and severe damage to spermatogenic cells by 50 days. Dietary levels of 225 and 300 ppm produced marked oligospermia and extensive loss of spermatogenic cells in rats fed dinoseb for 11 weeks. Evidence of necrotic spermatogenic cells was seen in some tubules, and in many tubules, only Sertoli cells remained. Reproductive failure occurred at 225 and 300 ppm, although mating behavior and libido were unaffected. There was little or no remission of these effects during the 16-week post-treatment period. Decreased epididymal sperm counts, atypical epididymal spermatozoa, and minimal testicular changes were seen in rats fed 150 ppm, but reproduction was unaffected and the anomalies were reversible. No effects were detected in animals fed 75 ppm.