Binding of the aliphatic halides 1,2-dibromoethane and chloroform in the rodent vaginal epithelium

Whole-body and light microscopic autoradiography were used to study the binding of 1,2-dibromo(14C)ethane (14C-DBE) and 14C-chloroform (14C-CF) in the mouse and rat vaginal epithelium in vitro and in vivo. In pregnant mice, mice pretreated with pregnant mare's serum gonadotropin (PMSG) or ovariectomized mice primed with medroxyprogesterone, a high level of bound 14C-DBE metabolites were present in the epithelium, while in ovariectomized oestradiol-primed mice or intact oestradiol-primed mice, the binding was low. Similar results were obtained with 14C-CF, although the level of binding generally was lower than that observed after 14C-DBE-exposure. No binding of 14C-DBE-metabolites was observed in the juvenile rat vaginal epithelium, whereas a high binding was present in the PMSG-primed adult rat vaginal epithelium. Collectively, these data show that 14C-DBE and 14C-CF are transformed in situ to metabolites that are irreversibly bound to the vaginal epithelium. The results also suggest that the activating enzyme is under endocrine control and has a low activity in the juvenile and oestradiol-primed adult animal.