Hepatic histopathology of a vitamin A overdose in mouse liver.

The effect of vitamin A on peroxisomal catalase in liver of male ICR mice was studied electron microscopically after a single subcutaneous injection of retinyl acetate. A significant proliferation of peroxisomes in hepatocytes was observed up to 3 days after a single injection of 80,000 IU of retinyl acetate. This was followed by a significant decrease up to 21 days and increase above control levels at 60 days after the injection. Histopathological alterations, such as focal necrosis of hepatocytes in the peripheral zone of hepatic lobules, release of their membrane-bound bodies from Disse's space and the appearance of large vacuoles around the nucleus, were observed from early stages onwards. These findings indicated that alterations on lipid metabolism in the liver were induced when a subacute dose of retinyl acetate was administered. Histopathological alterations were probably attributable either to accumulation of retinyl esters or effect of mediators released from activated leucocytes at an early stage.