Vitamin B12 supplement alleviates N′-nitrosodimethylamine-induced hepatic fibrosis in rats

Context: Altered vitamin B-12 levels have been correlated with hepatotoxicity; however, further evidence is required to establish its protective role. Objective: To evaluate the effects of vitamin B12 supplement in protecting N'-nitrosodimethylamine (NDMA)-induced hepatic fibrosis in Wistar rats. Materials and methods: Hepatic fibrosis was induced by administering NDMA in doses of 10 mg/kg body weight thrice a week for 21 days. Another group received equal doses (10 mg/kg body weight) of vitamin B12 subsequent to NDMA treatment. Animals from either group were sacrificed weekly from the start of the treatment along with their respective controls. Progression of hepatic fibrosis, in addition to the effect of vitamin B12, was assessed biochemically for liver function biomarkers, liver glycogen, hydroxyproline (HP) and B12 reserves along with histopathologically by hematoxylin and eosin (H & E) as well immunohistochemical staining for alpha-SMA expression. Results and discussion: Elevation in the levels of aminotransferases, SALP, total bilirubin and HP was observed in NDMA treated rats, which was concomitant with remarkable depletion in liver glycogen and B-12 reserves (p<0.05). Liver biopsies also demonstrated disrupted lobular architecture, collagen amassing and intense fibrosis by NDMA treatment. Immunohistochemical staining showed the presence of activated stellate cells that was dramatically increased up to day 21 in fibrotic rats. Following vitamin B-12 treatment, liver function biomarkers, glycogen contents and hepatic vitamin B-12 reserves were restored in fibrotic rats, significantly. Vitamin B-12 administration also facilitated restoration of normal liver architecture. Conclusion: These findings provide interesting new evidence in favor of protective role for vitamin B-12 against NDMA-induced hepatic fibrosis in rats.