The ameliorating effect of rosiglitazone on experimental nonalcoholic steatohepatitis is associated with regulating adiponectin receptor expression in rats

Abstract

Although nonalcoholic steatohepatitis (NASH) is associated with insulin resistance partly due to reduced levels of circulating adiponectin, the role of adiponectin receptors including adiponectin receptor 1 and adiponectin receptor 2 in adipose tissues in NASH remains controversial. The present study showed that there was a marked decline in adiponectin receptor 1 and adiponectin receptor 2 expressions in liver and visceral fat, and these expressions were elevated in muscle of NASH rats 12weeks after oral administration of a high-fat diet. An 8-week continuous treatment with rosiglitazone, a peroxisome proliferator-activated receptors γ (PPAR γ) agonist improved the histological lesions markedly in liver of NASH rats, and concurrently increased mRNA and protein expressions of adiponectin receptor 1 and adiponectin receptor 2 in liver and visceral fat, with down-regulation of the two receptors in muscle. There was a negative correlation between the ratio of adiponectin receptors/β-actin protein and serum TNF-α in the liver and visceral fat, and a positive correlation in muscle. Additionally, rosiglitazone increased circulating adiponectin, which was negatively correlated with serum TNF-α. These results indicated that rosiglitazone improved NASH by directly modulating adiponectin receptor 1 and adiponectin receptor 2 in various adipose tissues, or indirectly possibly via decreasing serum TNF-α.