Effect of vitamin C on oxidative liver injury due to isoniazid in rats

The aim of the present study was to investigate the effect of different doses of vitamin C on oxidative liver injury due to isoniazid (INH) in rats.

Rats were divided into four subgroups, each containing 10 rats. Group 1 was the control group; group 2, INH 50 mg/kg per day; group 3, INH 50 mg/kg per day + low-dose vitamin C (100 mg/kg per day); group 4, INH 50 mg/kg per day + high-dose vitamin C (1000 mg/kg per day). INH and vitamin C were administered into their stomachs through an oral tube. After 21 days, measurements were made in both serum and homogenized liver tissues. The levels of glutathione (GSH), superoxide dismutase (SOD) and other biochemical variables were measured. Malondialdehyde (MDA), glutathione peroxidase (GSH-px) and vitamin C were measured using commercial kits.

Aspartate amino transferase and alanine aminotransferase in group 2 were higher than those in groups 1, 3 and 4 (P < 0.008 for both). Serum and tissue levels of MDA in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). There was no difference in the SOD levels between the four groups (P= 0.095). Erythrocyte and tissue GSH in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). Interestingly, erythrocyte and tissue GSH in group 4 were lower than those in group 1 (P < 0.008 for both). Erythrocyte level of GSH-px in group 2 was higher than that in groups 1 and 3 (P < 0.008 for both).

INH-induced liver injury is associated with oxidative stress, and co-administration of low-dose vitamin C may reduce this damage effectively in a rat model. The antioxidant effect of high-dose vitamin C does not seem more potent compared to the low dose.