Preventive Effects of Vitamin C on Diethylnitrosamine-induced Hepatotoxicity in Smp30 Knockout Mice

Vitamin C (L-ascorbic acid) is well known as a free radical scavenger that protects cells against damage from oxidative stress. Herein, we investigated the effects of vitamin C against diethylnitrosamine (DEN)-induced hepatotoxicity. Male wild-type (C57BL/6) and senescence marker protein-30 (Smp30) knockout (KO) mice were used and divided in the following four groups: WT group (n=15): Wild-type (WT) mice fed vitamin C-free diet with tap water; WV group (n=14): WT mice fed vitamin C-free diet with water supplemented with 1.5 g/kg vitamin C; KT group (n=12): Smp30 KO mice fed vitamin C-free diet with tap water; and KV group (n=13): Smp30 KO mice fed vitamin C-free diet with water supplemented with 1.5 g/kg vitamin C. A single intraperitoneal injection of DEN (5 mg/kg body weight) was injected in the second week during the experimental period. Mice were sacrificed after 17 weeks of treatment to investigate the effect of dietary vitamin C on DEN-induced hepatotoxicity. The results showed that vitamin C significantly increased the mean lifespan (p<0.05) in the WT, WV and KV groups compared with the KT group. The serum concentrations of gamma-glutamyl transpeptidase, alanine aminotransferase, and aspartate aminotransferase did not significantly differ among groups. The WT group exhibited significantly more acute cellular swelling accompanied by centrilobular necrosis, focal lymphocyte infiltration, and eosinophilic intracytoplasmic inclusion bodies as compared with the WV and KV groups, suggesting that vitamin C had a hepatoprotective effect. Dysplastic, large, and binucleated hepatocytes were also observed in the WT group, but these pathological signs were absent from the WV and KV groups. Our experimental evidence suggests that vitamin C supplementation in Smp30 KO mice was effective for the treatment of DEN-induced hepatotoxicity.