RESUMO
Objective To investigate the effect of emodin on insulin resistance and leptin in rat with nonalcoholic fatty liver disease (NAFLD) and to explore the mechanisms of emodin treating NAFLD.Methods Forty two Spraque-Dawley rats were numbered according to their body weights,and were randomly divided into two groups(group A:8 rats; group M:34 rats) by random number table method.The rats in group A was fed with ordinary diets and Group M with improved high fat diets.Four weeks later,when hepatic steatosis in group M were identified,the remaining 32 rats in group M were numbered according to their body weights,and were divided randomly into 4 subgroups (group M1,M2,M3 and M4) by random number table method,with 8 rats in each subgroup.The feeding of all rats was unchanged.The rats in group M2,M3 and M4 were separately intervened with emodin by low doses,emodin by high doses and metformin.Emodin and metformin were dissolved by 0.5％ sodium carboxymethyl cellulose.The rats in group A and M1 was fed with 0.5％ sodium carboxymethyl cellulose by gavage.Four weeks later,all rats were executed.The serum glucose was measured with automatic biochemical analyzer.The serum insulin and leptin were measured by radioimmunoassay (RIA).Insulin resistance was estimated by insulin resistance index of homeostasis model assessment (HOMA-IR) and insulin sensitivity index (ISI).Liver biopsy tissues were treated by Hematoxylin-eosin (HE) staining to evaluate the degree of steatosis and inflammation of liver.Results Compared with group M1,the low and high dosage emodin improved insulin resistance which was represent by serum insulin,HOMA-IR,and ISI(P ＜0.05,P ＜0.01).The serum leptin in group M1 was higher than that in group A (P ＜0.01).The serum leptin in groups M2 and M3 was lower than that in group M1(P ＜0.05,P ＜0.01).Correlation analysis showed that the serum leptin was positively correlated with HOMA-IR(r =0.746,P ＜0.05),and negatively correlated with ISI(r =-0.731,P ＜ 0.05)in group M1.Compared with group M1,the low and high dosage emodin together had the respective effect of ameliorating steatosis(P ＜0.05,P ＜0.01),and they also reduced the hepatic inflammatory activity(P ＜ 0.01).Conclusions Reducing serum leptin and improving insulin resistance may be the mechanisms of emodin treating NAFLD.
