Effects of Aroclor 1242 and different fish-based diets on vitamins A1 (retinol) and A2 (3,4-didehydroretinol), and their fatty acyl esters in mink plasma

The effects of a 21-week exposure to Aroclor 1242 (1 mg per day in feed) on plasma concentrations of vitamins A1 (retinol) and A2 (3,4-didehydroretinol) and their principal fatty acyl esters (A1-16:0, A2-16:0 (palmitates), A1-18:1n-9; A2-18:1n-9 (oleates), and A1-18:0; A2-18:0 (stearates)) were studied in young female mink (Mustela vison) fed a diet based on freshwater smelt. These vitamin levels were also examined in mink fed diets containing Baltic herring or fatty marine fish. In the Aroclor-exposed smelt-fed mink, the plasma concentrations of A1 and A2 esters were significantly lower than the levels in controls fed the uncontaminated smelt diet. In addition, the A2 esters reacted more sensitively to the polychlorinated biphenyls than did A1 esters. In contrast, in the plasma of the exposed mink the level of alcoholic A1 was normal, and transport of thyroxine (T4) and nonspecific lipoprotein transport of major lipids were not impaired. Despite the large dietary supply of vitamin A2 and high levels of plasma A2 esters, the mink fed freshwater smelt had only trace amounts of alcoholic vitamin A2 in their plasma. The concentrations of A1 and A2 esters in the plasma of all the mink studied correlated with the hepatic total concentrations of the vitamins. Thus, in carnivores that have nonspecific lipoprotein transport of vitamin A esters, determination of plasma levels of the esterified vitamins may be a useful nondestructive way to estimate stores of the vitamin A analogs in the body and to assess the organochlorine-induced decrease in the vitamin stores.