Longdan Xiegan Tang attenuates liver injury and hepatic insulin resistance by regulating the angiotensin-converting enzyme 2/Ang (1?7)/Mas axis-mediated anti-inflammatory pathway in rats

Ethnopharmacological relevance: The ancient Chinese herbal formula Longdan Xiegan Tang (LXT, also called Gentiana Longdancao Decoction to Drain the Liver) treats insulin resistance- and inflammation-associated liver injuries in clinical practice. Aim of the study: To investigate the molecular mechanisms underlying LXT-elicited improvement of the liver injuries. Materials and methods: Male rats were co-treated with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) for eight weeks. Blood parameters were determined enzymatically or by ELISA. Gene/protein expression was analyzed by Real-Time PCR, Western blot and/or immunohistochemistry. Results: LXT attenuated olanzapine-induced liver injury manifested by hyperactivities of plasma alanine aminotransferase and aspartate aminostransferase, hyperbilirubinemia and hypoalbuminemia. Furthermore, LXT improved hepatic insulin resistance that was indicated by hyperinsulinemia, the increased HOMA-IR index, and hepatic over-phosphorylation of Ser307 in insulin receptor substrate (IRS)1, Ser731 in IRS2, Tyr607 in phosphoinositide 3-kinase p85? and Ser473 in AKT at baseline. Mechanistically, LXT inhibited olanzapine-triggered hepatic over-phosphorylation of both I?B kinase (IKK)?/? and nuclear factor (NF)?B p65 proteins, and mRNA overexpression of tumor necrosis factor ?, interleukin 6, interleukin 1? and CD68. More importantly, LXT restored the decreases in angiotensin-converting enzyme 2 (ACE2) protein level, and its downstream targets Ang (1?7) content and Mas receptor expression. Conclusions: The present results demonstrate that LXT attenuates liver injury and hepatic insulin resistance by regulating the ACE2/Ang (1?7)/Mas axis-mediated anti-inflammatory pathway in rats. Our findings provide a better understanding of LXT for treatment of insulin resistance- and inflammation-associated liver injuries.

Automated summary

The study revealed that Longdan Xiegan Tang attenuates liver injury and hepatic insulin resistance in rats by regulating the ACE2/Ang (1–7)/Mas axis-mediated anti-inflammatory pathway.