Influence of resveratrol on liver fibrosis induced by dimethylnitrosamine in male rats

Abstract

Liver fibrosis is a significant health problem which represents the liver's scarring process and response to injury through deposition of collagen and extracellular matrix, and ultimately leads to cirrhosis. Resveratrol is a naturally occurring phytoalexin found predominantly in grapes. This study aimed to investigate the antifibrotic role of resveratrol on dimethylnitrosamine (DMN)-induced liver fibrosis in rats. Rats were divided into four groups and treated for three weeks; control, resveratrol administered orally (20 mg/kg daily), DMN intraperitoneally injected (10 mg/kg 3 days/week), and the last group was pre-treated daily with resveratrol then injected with DMN, 3 days/week. DMN administration induced severe liver pathological alterations. However, oral administration of resveratrol before DMN significantly prevented the induced loss in body weight, as well as the increase in liver weight which arise from DMN administration. Resveratrol has also inhibited the elevation of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin levels. Furthermore, resveratrol significantly increased hepatic reduced glutathione (GSH) levels and reduced the levels of malondialdehyde (MDA) due to its antioxidants effect as well as increased serum protein levels. In addition, DMN induced elevation in hydroxyproline content. On the other hand, hydroxyproline level was significantly reduced in the resveratrol pretreated rats. Resveratrol has also remarkably maintained the normal liver lobular architecture. Moreover, resveratrol had displayed potent potentials to prevent collagen deposition, lymphocytic infiltration, necrosis, steatosis, vascular damage, blood hypertention, cholangiocyte proliferation. It can be concluded that resveratrol has a marked protective role on DMN-induced liver fibrosis in rats, and can be considered as antiproliferative, antihypertensive, as well as antifibrotic agent and may be used to block the development of liver fibrosis.

Keywords: Antifibrotic role; Dimethylnitrosamine; Liver fibrosis; Rats; Resveratrol.

Fig. 1

Body and liver weights of all experimental groups. Statistical analysis of rats body and liver weights during DMN intoxication (G3) and resveratrol (Resvtrl) pre-treatment (G4). Body and liver weight were measured weekly throughout the study. Results were analyzed by ANOVA one way and are presented as mean ± SEM P ≤ 0.01.* indicates a significant difference between G1 and G3. ** indicates a significant difference between G3 and G4.

Fig. 2

Serum and homogenate levels of liver biomarkers. The mean difference is significant at the 0.05 level by ANOVA one way p ≤ 0.05. * indicates a significant difference between G1 and G3. ** indicates a significant difference between G3 and G4.

Fig. 3

Light micrographs of rat liver sections showing (A) control, (B) resveratrol, the histology is the same as the control with normal lobular structure; (C) DMN with central veins dilatation and disrupted vascular architecture (arrows), collagen deposition (stained in blue) around the central vein and portal area; (D and F) resveratrol pretreated group, exhibiting minimal fibrosis, with normal central veins and portal areas. Thickening of collagen fiber bundles and central vein dilatation is markedly reduced by resveratrol pretreatment. (E) DMN, bridging fibrosis between two portal areas with marked increase in collagen content. Note bile ducts proliferation (arrows) and muscular hypertrophy of a hepatic artery (*). Central vein (CV) and portal area (PA). Masson's trichrome stain (A, B, C and D X40; E and F X 200).

Fig. 4

Histological analysis of rat liver sections showing (A) control, normal liver structure with polygonal hepatocytes (H), prominent nucleus (N), sinusoids (S) and central vein (CV); (B) resveratrol treatment, normal structure with organized plates of hepatocytes separated by sinusoids (S). (C) DMN, early cirrhosis with dilated, congested portal vein and the extension of inflammatory cells from the portal tract into the periportal parenchyma (arrows). (D) Resveratrol pretreatment, tissue architecture appears to be similar to that of control rats. (E) DMN, typical lymphocytic inflammation spotty necrosis (N) and damage to bile ducts in portal tracts (*). Note, proliferation of bile ductules (BD), fat droplets (thick arrow) inside ducts, veins, and hepatocytes. Most of the hepatocytes (H) are swollen and hydropic, but some are shrunken and necrotic (arrows); (F) resveratrol pretreatment shows preserved and organized hepatocyte plates and sinusoids. Necrosis is rare. (G) DMN. Dilated and thickened fibrotic portal vein (arrow) with eosinophilic material (E) and large amount of fat droplets inside the vein (short arrow), hepatocytes show ballooning and steatosis. Note the large number of fibroblasts lining the vein wall, and liver cell regeneration (head arrows). (H) Resveratrol pretreatment. Note the big difference in the wall thickness of the portal vein between (G and H), the fat inside the vein, and the eosinophilic material. (H&E) stain (A, B, C, and D ×100; E, F, G and H ×400).