2,3,7,8-Tetrachlorodibenzo-p-dioxin (
TCDD), a highly toxic environmental contaminant, interferes with
retinoid homeostasis. To elucidate the underlying mechanism, the activities of
lecithin :
retinol and
acyl-CoA : retinol acyltransferase (LRAT and ARAT) were determined in liver, kidney, and hepatic parenchymal and nonparenchymal cell fractions from rats 7 days after a single oral dose of 10 μg
TCDD/kg
body weight (b.w). Severely depressed LRAT activity in hepatic stellate cells, and greatly increased LRAT activity in kidneys, as well as decreased ARAT activity in stellate cells, were seen in
TCDD-treated rats. Although the relevance of decreased ARAT activity under physiological conditions is not clear, the changed LRAT activities most likely contributes significantly to the
TCDD-induced effects on tissue
retinyl ester levels. It is intriguing that
TCDD affects LRAT activity in hepatic stellate cells and kidney in opposite directions. The results suggest that effects of
TCDD on
retinyl ester tissue levels could be due to a specific interaction with
retinoid metabolism.