[NASH -- nonalcoholic steatohepatitis]

Preventive effect of pioglitazone against nonalcoholic fatty liver disease in Sprague-Dawley rats and its mechanism

AIM: To explore the prevention effect and mechanism of pioglitazone (PIO) on nonalcoholic fatty liver disease (NAFLD) in rats.

METHODS: Seventy two Sprague-Dawley rats were randomly divided into three groups: normal diet group (NG), high fat diet group (HG) and PIO group (PIOG), with 24 rats in every group. PIOG were fed with high fat diet and PIO for eight weeks. IR was tested by euglycemic-hyperinsulinemic clamp; TG, ALT, AST, FFAs, FINS and TNF-α were tested by biochemistry automatic analyzer or RIA; mRNA expression of peroxisome proliferator-activated receptor (PPARγ) was detected using RT-PCR. The expression of PPARγ and c-Jun amino-terminal kinase 1 (JNK1) were detected by Western blot.

RESULTS: The glucose infusion rate (GIR) decreased and JNK1 increased in HG rats in a time-dependent manner from 1st to 8th week (P < 0.05). Compared with NG, at the end of 8th week, the hepatic steatosis was significant in HG group. The weight, liver index, serum levels of TG, ALT, AST, FFAs, FINS and TNF-α increased, while IR was aggravated. Meanwhile, the JNK1 protein expression in liver tissue was up-regulated, while expression of PPARγ was decreased (TG: 1.23 ± 0.08 vs 0.62 ± 0.12; ALT: 92.80 ± 7.09 vs 51.34 ± 8.12; AST: 153.22 ± 20.65 vs 119.26 ± 13.61; FFAs: 511.94 ± 24.88 vs 335.31 ± 15.71; FINS: 41.23 ± 1.84 vs 22.65 ± 2.25; TNF-α: 1.02 ± 0.12 vs 0.34 ± 0.07, all P < 0.05). In PIOG, all the indexes were improved, but didn't completely return to the same as those of NG group.

CONCLUSION: PIO could prevent NAFLD induced by a high-fat diet and other IR-related diseases.