Abstract:

Objective To prepare a stable mouse model of chronic liver fibrosis induced by dietary vitamin A (VA) deficiency combined with CCl₄ injections. Methods A total of 126 Balb/c mice were randomized into 3 groups for feeding with a normal VA diet or a VA-deficient diet containing 500 or 200 IU/kg VA. After 4 weeks of feeding, half of the mice in each group were given intraperitoneal injections of 5% CCl₄ (10 mL/kg, twice a week) for 8 weeks. Serum retinol, ALT/AST and liver index of the mice were examined, liver tissue pathologies were observed with HE and Masson staining, and liver fibrosis score and oxidative stress level were evaluated. Results Four weeks of VA-deficient feeding, especially at 200 IU/kg, significantly lowered serum retinol level of the mice. CCl₄ injections for 8 weeks obviously increased liver index and ALT/AST and caused obvious liver fibrosis in all the mice, but liver pathologies were more severe in the 2 VA-deficient groups; severe liver necrosis with inflammatory cell infiltration was observed in 200 IU/kg VA group, where 2 mice died. After discontinuation of CCl₄, the mice with normal dietary VA showed gradual recovery of the liver index, ALT/AST, liver cord structure and liver fibrosis; the mice with VA deficiency, however, showed no significant improvements in these parameters, and the mice with 200 IU/kg VA still had serious abdominal adhesion, false lobules and massive inflammatory cell infiltration with a fibrosis stage score of 3. The oxidative damage index 8-OHdG was significantly higher in 500 IU/kg VA group than in normal VA group after CCl₄ modeling. Conclusion Feeding with diet containing 500 IU/kg VA for 4 weeks and 10 mL/kg CCl₄ injections for 8 weeks can result in stable moderate to severe liver fibrosis in mice without spontaneous reversal at 8 weeks of drug withdrawal.

Key words: vitamin A deficiency, CCl₄, chronic liver fibrosis, animal models