Irreversible binding and adrenocorticolytic activity of the DDT metabolite3-methylsulfonyl-DDE examined in tissue-slice culture

The persistent adrenocorticolytic DDT metabolite 3-methylsulfonyl-DDE (MeSO 2-DDE) was originally identified in Baltic grey seals, a population sufferi ng from adrenocortical hyperplasia. In mice, MeSO2-DDE induces mitochondria l degeneration and cellular necrosis in the adrenal zona fasciculata. In th is study, we used precision-cut tissue slice culture to examine local CYP11 B1-catalyzed irreversible binding of MeSO2-DDE in the murine adrenal cortex . We also examined effects on steroid hormone secretion, histology, and ult rastructure. As determined by microautoradiography, selective binding occur red in zona fasciculata of slices exposed to MeSO2-[C-14]-DDE. Quantificati on of binding by phosphorautoradiography revealed a 3-fold reduction of bin ding in slices co-exposed to the CYP11B1 inhibitor metyrapone. As measured by HPLC, corticosterone and 11-deoxycorticosterone secretion to the medium increased linearly for at least 24 hr. Addition of the ACTH analog tetracos actide caused an 8-fold increase in corticosterone secretion. Addition of m etyrapone reduced corticosterone secretion 4-fold. Exposure of slices to Me SO2-DDE (50 muM) reduced the rate of corticosterone secretion by 90% after 24 hr of incubation. As determined by electron microscopy, vacuolated mitoc hondria were present in zona fasciculata of slices exposed to MeSO2-DDE (50 muM) for 24 hr. Our findings show that all effects of MeSO2-DDE previously reported in vivo could be reproduced in adrenal slice culture ex vivo. Thi s test system allows analysis of zone-specific irreversible binding and eff ects on steroid hormone secretion and target cell ultrastructure. We propos e adrenal slice culture as a simple ex vivo test system with which to exami ne the adrenocorticolytic activity of xenobiotics in human and wild animal tissue.