Hepatoprotective effect of vitamin B12 on dimethylnitrosamine-induced liver injury.

Vitamin B(12) contains a cobalt complex and accumulates at high levels in the liver. Vitamin B(12) was examined for its hepatoprotective effect on dimethylnitrosamine-induced liver injury in mice. Vitamin B(12) decreased the blood levels of aspartate aminotransferase and alanine aminotransferase, and clearly inhibited the overaccumulation of collagen fibrils. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of the liver showed that the gene expression of alpha-smooth muscle actin and heat-shock protein 47, which are markers of fibrosis, were suppressed by vitamin B(12) administration. Our findings indicate that vitamin B(12) could be an effective hepatoprotective agent.