Effects of vitamins E and C supplementation on hepatic glutathione peroxidase activity and tissue injury associated with ethanol ingestion in malnourished rats.

BACKGROUND

Oxidative stress has been associated with tissue injury in alcoholic liver disease. Although this close association is well known, whether prevention of oxidative stress retards tissue injury has not been thoroughly investigated.

OBJECTIVE

The aim of this study was to determine the effects of supplementation with vitamins E and C on antioxidant enzyme status and histologic changes in hepatic tissue in a rat model of alcoholic liver disease.

METHODS

This 8-week, blinded, controlled study was conducted at the Department of Internal Medicine, Trakya University, Edirne, Turkey. Weanling albino female protein-deficient Wistar rats weighing ∼200 g were randomly assigned to 1 of 6 groups: (1) liquid diet+ethanol+vitamin E 15 mg/kg PO (LDetvitE); (2) liquid diet+ethanol+vitamin C 10 mg/kg PO (LDetvitC); (3) liquid diet+ethanol+vitamin E 15 mg/kg+vitamin C 10 mg/kg PO (LDetvitEC); (4) liquid diet+ethanol (LDet); (5) liquid diet+isocaloric sucrose (LDS); and (6) normal diet (control). The primary end point of the study was to determine whether antioxidant vitamin E/C combination therapy prevents development of hepatic fibrosis (ie, cirrhosis in a period of 1 year). After being euthanized at week 8, the rats were weighed, and their livers and spleens were weighed. Hepatic tissue specimens were histopathologically assessed according to the Brunt system. Hepatic tissue glutathione peroxidase, superoxide dismutase, and catalase activities were determined. Biochemical tissue collagen concentrations were measured to determine the presence of hepatic fibrosis.

RESULTS

Seventy-two rats were included in the study (mean [SE] weight, 205 [21] g) (12 rats per group). Initially planned to last 48 weeks, the study was terminated at 8 weeks due to the death of 3 rats in each group (except the LDS group and control group). The relative liver weight was significantly lower in the LDetvitEC group compared with that in the LDet group (mean [SE], 3.7% [0.5%] vs 4.8% [0.9%]; P<0.01). Mean (SE) hepatic tissue glutathione peroxidase activity was significantly reduced in the LDet-treated rats compared with controls (1.2 [0.2] vs 2.6 [0.3] U/mg protein; P<0.001). The groups that received supplementation with vitamin E, vitamin C, and vitamins E and C combined had significantly more hepatic glutathione peroxidase activity (mean [SE], 2.1 [0.5], 2.5 [0.2], and 2.6 [0.7] U/mg protein, respectively) compared with the LDet group (1.2 [0.2] U/mg protein) (all, P<0.001). No significant between-group differences in hepatic superoxide dismutase or catalase activities were found. Compared with controls (14.5 [1.9] μg collagen/mg protein), the mean (SE) histologic hepatic collagen concentration was significantly higher in all groups (19.2 [1.2], 19.5 [3.3], 18.5 [3.0], 25.9 [3.3], and 21.6 [1.5] μg collagen/mg protein in the LDetvitE, LDetvitC, LDetvitEC, LDet, and LDS groups, respectively; P<0.01, P<0.01, P<0.05, P<0.001, and P<0.001, respectively). Compared with the LDet group, the mean hepatic collagen concentration was significantly lower in the LDetvitE, LDetvitC, and LDetvitEC groups (P<0.01, P<0.05, and P<0.01, respectively). The LDetvitEC group had a significantly lower mean (SE) hepatic inflammatory score compared with the LDet group (0.8 [0.1] vs 1.3 [0.2]; P<0.05). The LDetvitEC group had a significantly lower mean (SE) hepatic necrosis score compared with that in the LDet group (1.5 [0.2] vs 2.4 [0.3]; P<0.05).

CONCLUSIONS

The results of this study in protein-deficient rats fed with a high-fat liquid diet suggest that supplementation with vitamin E, vitamin C, and a combination of vitamins E and C was associated with decreased ethanol-induced hepatic glutathione peroxidase activity and hepatic fibrosis, and that supplementation with vitamins E and C might have attenuated the development of hepatomegaly and hepatic necroinflammation, whereas this result was not found in the group given a liquid diet and ethanol in this 8-week study. (Curr Ther Res Clin Exp. 2006;67:118-137) Copyright © 2006 Excerpta Medica, Inc.