The Effects of a Fat- and Sugar-Enriched Diet and Chronic Stress on Nonalcoholic Fatty Liver Disease in Male Wistar Rats

The pathogenesis of nonalcoholic fatty liver disease (NAFLD) is still under debate. The aim of this study was to investigate the effects of a long-term fat- and sugar-enriched diet (FSED) and chronic stress (CS) on NAFLD. Male Wistar rats were fed on either a standard diet or a FSED and given CS, a random electric foot shock (2 hr/morning and afternoon per day), or not for 12 weeks. After the experimental period, epididymal adipose tissue weight, sign of visceral obesity (VO), and hepatic index (HI) were measured. At sacrifice blood samples and liver were obtained. Histology of the liver was blindly determined by a pathologist. Histopathologically, moderate to severe steatosis, ballooning hepatocytes, and portal or lobules inflammation were observed in the FSED+CS group. However, mild to moderate steatosis with a few portal inflammation in the FSED group and mild steatosis or not with a few portal inflammation in the CS group were found correspondingly. In addition, more severe blood-fat disorder, high HI, fatty metabolic dysfunction, oxidative stress, high expressions of C-reactive protein mRNA and low expressions of peroxisome proliferator-activated receptor alpha mRNA in the liver were also revealed in the FSED+CS group. But, the degree of VO was not different between the FSED and FSED+CS groups. The observations strongly suggest that chronic stress can aggravate fat- and sugar-enriched diet-induced NAFLD from steatosis to steatohepatitis in male Wistar rats, although VO is not changed.