Objective      To investigate the expression and significance of autophagy related gene 7 (ATG7) and Calpain 2 in nonalcoholi

c fatty liver disease (NAFLD).       Methods     

In vivo

model of NAFLD was established in SD rats by high fat diet

while the rats fed with normal food were set as control group. The rats were killed at 4

8

12 and 16 weeks after feeding. Blood samples were collected to check serum aspartate transaminase (AST)

alanine aminotransferase (ALT)

and free fatty acid(FFA). Steatosis of liver tissues were observed by HE staining. The expression of Calpain 2 and ATG7 was detected by real-time PCR and Western blotting respectively for mRNA and protein levels.       Results      HE staining implicated that the degree of hepatic steatosis was increased with the time of high fat diet feeding. Compared with the control group

the serum contents of ALT

AST

and FFA in NAFLD rats were increased with different degree

and significantly increased at 16th week (165.95±7.24 U/L

249.52±4.20 U/L

0.83±0.05 mmol/L

respectively

P

<

0.01). The relative expression of Calpain 2 at mRNA level was increased after high fat diet feeding and reached its peak at the 16th week

and was 9.83±0.85 fold higher as compared with the control group (

P

<

0.01). While the relative expression of ATG7 began to decrease at the 4th week (0.82±0.02)

and reached its lowest level at the 16th week (0.20±0.03

P

<

0.01) when compared with the control group. As with mRNA level

the protein level of Calpain 2 began to increase at the 4th week (2.32±0.45)

and was 9.87±1.20 fold higher as the control group (

P

<

0.01). While the expression of ATG7 at protein level was decreased with progress of steatosis

and was significantly reduced at 16th week (0.18±0.05

P

<

0.01).       Conclusion      The up-regulation of Calpain 2 inhibits the expression of ATG7

which further attenuates the cell protection through autophagy

and then induces injury of hepatocyte in NAFLD. Autophagy may take part in the incidence of NAFLD.