The expression and significance of autophagy related gene in rats with non-alcoholic fatty liver disease

Objective To investigate the expression and significance of autophagy related gene in rats with non-alcoholic fatty liver disease (NAFLD). Methods In vivo model of NAFLD was established in SD rats by high fat diet (model group, n=24), while the rats with normal food were set as control group(n=18). The rats of each group were sacrificed at the end of 4, 8, 12 weeks respectively. Body weight, liver wet weight, liver function, liver lipid metabolism and other indicators were measured. Hepatic histology was evaluated by hematoxylin-eosin (HE) staining and oil red O staining. The identification of autophagy were morphologically visualized by transmission electron microscopy (TEM). The expression of autophagy related gene ATG7, beclin1, microtubule-associated protein 1 lightchain3(LC3)were detected by real-time quantitative RT-PCR (qRT-PCR) for mRNA levels. Result ①Compared with the control group at the corresponding time point, the weights of the mice and their livers.②Hepatic oil red O staining areas and density in high fat diet group all increased. HE staining revealed different degrees of macrosteatosis accompanied with intralobular inflammatary foci. With a remarkable histological change of NASH (typical hepatocellular ballooning and perisinusoidal fibrosis)about 80% of mice from high fat diet group had NASH [NAFLD activity score (NAS)≥5] at the end of 12 weeks.③ TEM pictures showed that autophagy bubble appeared since high fat diet feeding for 4 weeks.④ The relative expression of ATG7, Beclin1, LC3-I, LC3-II at mRNA level were up-regulated after high fat diet, and reached their peak at the end of 8 weeks when compared with the control group. The differences can be applied to statistical significance(P<0.05). The expression of these autophagy related genes in rats of high fat diet group were down-regulated at the end of 12 weeks, which had no difference the control group. Conclusion ①High fat diet feeding is able to induce a rat model of NAFLD.②The expression level of autophagy related genes is altered during high fat diet treatment. ③Autophagy may take part in the occurrence and development of NAFLD. Key words: Fatty liver; Genes; Rats