Alterations in retinoid concentrations in several extrahepatic organs of rats by 3,4,3′,4′-tetrachlorobiphenyl

In this study, the effect of polychlorinated biphenyls on retinoid homeostasis was investigated in Sprague—Dawley rats, by analysing ³H]retinoid concentrations in peripheral organs, following exposure to 3,4,3′,4′-tetrachlorobiphenyl (TCB). The rats were rendered retinoid-deficient through dietary restriction, followed by dietary supplementation with ³H]retinol for 14 days, in order to facilitate determination of retinoid concentrations in various tissues. At day 7 of ³H]retinol supplementation the rats were exposed to a single i.p. dose of 15 mg TCB dissolved in corn oil/kg body weight. In corn oil-treated control rats, the highest concentrations of ³H]retinoid radioactivity, consisting mainly of retinol and several retinylesters, were obtained in the liver ( > 10⁶ cpm/g), followed by the kidney and the lung, while only minor concentrations were found in skin and heart. Exposure to TCB resulted in a significant reduction of both retinol and retinylester concentrations in the liver (to 25% of controls) and the lung (to 44% of controls), while in the heart a reduction of retinol to 35% of controls was observed. No significant alterations in retinoid concentrations were observed in the skin and kidney. It is suggested that the reductions in retinoid concentrations might contribute to the toxicological alterations reported in these organs upon exposure to TCB.