Uterotrophic and Hershberger assays for n-butylbenzene in rats

We performed the uterotrophic and Hershberger assays proposed by the OECD to investigate the estrogenic and androgenic effects of n-butylbenzene (nBB). For the uterotrophic assay, nBB was injected subcutaneously at doses of 0, 40, 200, 1000 and 2000 mg/kg to 19-day-old rats for 3 days. In some rats, ethynylestradiol (EE) was also injected subcutaneously at a dose of 0.6 microg/kg after the administration of nBB. There were essentially no differences in the uterine wet or blotted weights between the control and any of the nBB-treated groups, or between the control and any of the nBB plus EE-treated groups. For the Hershberger assay, nBB was administered orally at doses of 0, 200 and 600 mg/kg to 56-day-old castrated rats for 10 days. In some rats, 0.4 mg/kg testosterone propionate (TP) was also administered by subcutaneous injection after the administration of nBB. Doses of 0, 200 and 600 mg/kg nBB were also administered orally to non-castrated rats. The weights of the accessory sex organs of the castrated rats showed no significant differences between the control and any of the nBB-treated groups or between the control and the nBB plus TP-treated groups. No significant differences in the weights of the accessory sex organs of the non-castrated rats were observed between the control and the nBB-treated groups. These findings suggest that nBB does not have any endocrine-disrupting properties on in vivo screening tests.