Hypertension exacerbates liver injury and hepatic fibrosis induced by a choline-deficient L-amino acid-defined diet in rats.

The effect of hypertension on non-alcoholic fatty liver disease (NAFLD) remains unclear at the molecular level. In this study, we investigated the effects of hypertension on the degree of hepatic steatosis, liver injury and hepatic fibrosis induced by a choline-deficient L-amino acid-defined (CDAA) diet in spontaneously hypertensive rats (SHRs). Seven-week-old male SHRs were fed standard chow with high or normal salt concentrations for 7 weeks, followed by a CDAA diet containing high or normal salt for an additional 8 or 24 weeks. Hepatic steatosis was assessed using hepatic triglyceride levels and Oil red O staining. Hepatic fibrosis was evaluated using Sirius red and Azan staining. Systolic blood pressure (SBP) gradually increased with a high-salt diet and was significantly higher after 7 weeks of feeding with high-salt vs. normal-salt chow. After 8 weeks on the CDAA diet, the degree of hepatic steatosis did not differ between the high-salt and normal-salt groups; however, alanine aminotransferase and fasting blood glucose levels were significantly higher and hepatic mRNA levels for interleukin (IL)-10 and heme oxygenase (HO)-1 were significantly lower in the high-salt group compared with the normal-salt group. After 24 weeks on the CDAA diet, the high-salt group had significantly more severe hepatic fibrosis and a higher hepatic mRNA expression of α-smooth muscle actin and lower hepatic IL-10 and HO-1 mRNA levels compared with the normal-salt group. In conclusion, our results indicate that hypertension is a potential risk factor for liver injury and hepatic fibrosis through glucose intolerance and decreased IL-10-mediated or HO-1-induced anti-inflammatory mechanisms.

Dietary fructose enhances the incidence of precancerous hepatocytes induced by administration of diethylnitrosamine in rat.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a risk for hepatocellular carcinoma (HCC), but the association between a high-fructose diet and HCC is not fully understood. In this study, we investigated whether a high-fructose diet affects hepatocarcinogenesis induced by administration of diethylnitrosamine (DEN). METHODS: Seven-week-old male Sprague-Dawley rats were fed standard chow (controls), a high-fat diet (54% fat), or a high-fructose diet (66% fructose) for 8 weeks. All rats were given DEN at 50 µg/L in drinking water during the same period. Precancerous hepatocytes were detected by immunostaining of the placental form of glutathione-S-transferase (GST-P). The number of GST-P-positive hepatocytes was assessed in liver specimens. RESULTS: Serum levels of total cholesterol were similar among the three groups, but serum triglyceride, fasting blood glucose, and insulin levels were higher in the high-fructose group compared to the high-fat group. In contrast, hepatic steatosis was more severe in the high-fat group compared with the high-fructose and control groups, but the incidence of GST-P-positive specimens was significantly higher in the high-fructose group compared to the other two groups. The average number of GST-P-positive hepatocytes in GST-P positive specimens in the high-fructose group was also higher than those in the other two groups. This high prevalence of GST-P-positive hepatocytes was accompanied by higher levels of 8-hydroxydeoxyguanosine in serum and liver tissue. CONCLUSIONS: These results indicate that dietary fructose, rather than dietary fat, increases the incidence of precancerous hepatocytes induced by administration of DEN via insulin resistance and oxidative stress in rat. Thus, excessive fructose intake may be a potential risk factor for hepatocarcinogenesis.

Liver regeneration after partial hepatectomy in rat is more impaired in a steatotic liver induced by dietary fructose compared to dietary fat.

Hepatic steatosis (HS) has a negative effect on liver regeneration, but different pathophysiologies of HS may lead to different outcomes. Male Sprague-Dawley rats were fed a high fructose (66% fructose; H-fruc), high fat (54% fat; H-fat), or control chow diet for 4 weeks. Based on hepatic triglyceride content and oil red O staining, HS developed in the H-fruc group, but was less severe compared to the H-fat group. Hepatic mRNA expression levels of fatty acid synthase and fructokinase were increased and those of carnitine palmitoyltransferase-1 and peroxisome proliferator-activated receptor-α were decreased in the H-fruc group compared to the H-fat group. Liver regeneration after 70% partial hepatectomy (PHx) was evaluated by measuring the increase in postoperative liver mass and PCNA-positive hepatocytes, and was impaired in the H-fruc group compared to the H-fat and control groups on days 3 and 7. Serum levels of tumor necrosis factor-α, interleukin-6 and hepatocyte growth factor did not change significantly after PHx. In contrast, serum TGF-ß1 levels were slightly but significantly lower in the control group on day 1 and in the H-fat group on day 3 compared to the level in each group on day 0, and then gradually increased. However, the serum TGF-ß1 level did not change after PHx in the H-fruc group. These results indicate that impairment of liver regeneration after PHx in HS is related to the cause, rather than the degree, of steatosis. This difference may result from altered metabolic gene expression profiles and potential dysregulation of TGF-ß1 expression.