Sorafenib prevents liver fibrosis in a non-alcoholic steatohepatitis (NASH) rodent model

Liver fibrosis occurring as an outcome of non-alcoholic steatohepatitis (NASH) can precede the development of cirrhosis. We investigated the effects of sorafenib in preventing liver fibrosis in a rodent model of NASH. Adult Sprague-Dawley rats were fed a choline-deficient high-fat diet and exposed to diethylnitrosamine for 6 weeks. The NASH group (n=10) received vehicle and the sorafenib group (n=10) received 2.5 mg·kg-1·day-1 by gavage. A control group (n=4) received only standard diet and vehicle. Following treatment, animals were sacrificed and liver tissue was collected for histologic examination, mRNA isolation, and analysis of mitochondrial function. Genes related to fibrosis (MMP9, TIMP1, TIMP2), oxidative stress (HSP60, HSP90, GST), and mitochondrial biogenesis (PGC1α) were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR). Liver mitochondrial oxidation activity was measured by a polarographic method, and cytokines by enzyme-linked immunosorbent assay (ELISA). Sorafenib treatment restored mitochondrial function and reduced collagen deposition by nearly 63% compared to the NASH group. Sorafenib upregulated PGC1α and MMP9 and reduced TIMP1 and TIMP2 mRNA and IL-6 and IL-10 protein expression. There were no differences in HSP60, HSP90 and GST expression. Sorafenib modulated PGC1α expression, improved mitochondrial respiration and prevented collagen deposition. It may, therefore, be useful in the treatment of liver fibrosis in NASH.

Liver mitochondrial dysfunction and oxidative stress in the pathogenesis of experimental nonalcoholic fatty liver disease

Oxidative stress and hepatic mitochondria play a role in the pathogenesis of nonalcoholic fatty liver disease. The aim of the present study was to evaluate the role of hepatic mitochondrial dysfunction and oxidative stress in the pathogenesis of the disease. Fatty liver was induced in Wistar rats with a choline-deficient diet (CD; N = 7) or a high-fat diet enriched with PUFAs-omega-3 (H; N = 7) for 4 weeks. The control group (N = 7) was fed a standard diet. Liver mitochondrial oxidation and phosphorylation were measured polarographically and oxidative stress was estimated on the basis of malondialdehyde and glutathione concentrations. Moderate macrovacuolar liver steatosis was observed in the CD group and mild liver steatosis was observed in the periportal area in the H group. There was an increase in the oxygen consumption rate by liver mitochondria in respiratory state 4 (S4) and a decrease in respiratory control rate (RCR) in the CD group (S4: 32.70 ± 3.35; RCR: 2.55 ± 0.15 ng atoms of O2 min-1 mg protein-1) when compared to the H and control groups (S4: 23.09 ± 1.53, 17.04 ± 2.03, RCR: 3.15 ± 0.15, 3.68 ± 0.15 ng atoms of O2 min-1 mg protein-1, respectively), P < 0.05. Hepatic lipoperoxide concentrations were significantly increased and the concentration of reduced glutathione was significantly reduced in the CD group. A choline-deficient diet causes moderate steatosis with disruption of liver mitochondrial function and increased oxidative stress. These data suggest that lipid peroxidation products can impair the flow of electrons along the respiratory chain, causing overreduction of respiratory chain components and enhanced mitochondrial reactive oxygen species. These findings are important in the pathogenesis of nonalcoholic fatty liver disease.

Hepatic damage during acute pancreatitis in the rat

We studied the alterations in the metabolism of liver mitochondria in rats with acute pancreatitis. Male Wistar rats were allocated to a control group (group I) and to five other groups corresponding to 2,4, 12,24 and 48 h after the induction of acute pancreatitis by the injection of 5 per cent sodium taurocholate into the pancreatic duct. Sham-operated animals were submitted to the same surgical steps except for the induction of acute pancreatitis. Mitochondrial oxidation and phosphorylation were measured polarographically by determining oxygen consumption without ADP (basal respiration, state 4) and in the presence of ADP (activated respiration, state 3). Serum amylase, transaminases (ALT and AST) and protein were also determined. Ascitic fluid, contents of amylase, trypsin and total protein were also determined and arterial blood pressure was measured in all groups. In ascitic fluid, trypsin and amylase increased reaching a maximum at 2 and 4h, respectively. Serum amylase increased at 2 h reaching a maximum at 4 h. Serum transaminase levels increased at 12 and 24 h. After 2 h (and also 4 h) there was an increase in state 4 respiration (45.65 + 1.79 vs 28.96 + 1.50) and a decrease in respiration control rate (3.53 + 0.09 vs 4.45 + 0.08) and in the ADP/O ratio (1.77 + 0.02 vs 1.91 + 0.01) compared to controls (P<0.05). These results indicate a disruption of mitochondrial function, which recovered after 12 h. In the 48-h groups there was mitochondrial damage similar to that occurring in ischemic lesion. Beat-to-beat analysis (30 min) showed that arterial blood pressure remained normal up to 24 h (111 + 3 mmHg) while a significant decrease occurred in the 48-h group (91 + 4 mmHg). These data suggest biphasic damage in mitochondrial function in acute pancreatitis: an inital uncoupled phase, possibly secondary to enzyme activity, followed by a temporary recovery and then a late and final dysfunction, associated with arterial hypotension, possibly related to ischemic damage.

Reduction of pancreatic enzyme content and mortality in experimental acute pancreatitis in rats

A previous report has shwon that undernutrition reduces the mortality of acute experimental pancreatitis probably by decreasing pancreatic enzyme content of the pancreas without any harmful effect on the organ. The aim of the present study was to assess the effect of acute reduction of pancreatic enzyme content on the outcome of acute pancreatitis. Two groups of males Wistar rats weighing 230-250 g were studied: group I, 12-h fasted animals, and group II, add libitum-fed animals who received cerulein at the inframaximal dose (0.2 µg kg-1h-1) for 2 h. Cerulein adminsitration resulted in the reduction of the pancreatic contents of chymotrypsinogen (71 percent), trypsinogen (55 percent), proelastase (60 percent), amylase (62 percent) and cathepsin B (45 percent) (P<0.05). However, no significant reduction in pancreatic phospholipase content was observed. Acute pancreatitis wass induced in group I after 12-h fasting and in group II at the end of cerulein infusion by retrograde injection of 0.5 ml of 2.5 percent Na+ taurocholate into the pancreatic duct. Ascites volume and the degree of histologically observed lesions were similar in both groups, but 72-h mortality was 56 percent in the control group (10/18) and 23 percent (5/22) in the cerulein group (P<0.05). We speculate that the reduction of pancreatic enzyme content may exert its beneficial effect in acute pancreatitis by decreasing the quantity of pancreatic enzymes reaching the circulation and consequently their pathogenic effects