The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in primary rat astroglia: identification of biochemical and cellular targets.

This paper reports the results from in vitro experiments utilizing vital fluorescent probes and biochemical assays to examine the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and related compounds in primary rat astroglia in an effort to identify the cellular site(s) involved in toxicity. Application of 100 nM 2,3,7,8-TCDD, a strong Ah receptor agonist, resulted in altered astroglial intracellular Ca2+, a significant decrease in glutathione, a disrupted mitochondrial membrane potential, a significant decrease in glutamine synthetase immunoreactivity and eventual loss of pH maintenance. In contrast, application of 10 microM 1,2,3,4-TCDD, a weak Ah receptor agonist, had no effect on any parameters measured. These findings, coupled with the identification of the 9-10S cytosolic Ah receptor in cultured rat astroglia, are consistent with typical structure-activity relationships observed for other Ah receptor mediated responses. However, the time course of the Ca2+, as well as other responses observed in this study, suggest that the above effects may not necessarily involved the formation of the nuclear Ah receptor complex.