FXR activation reverses insulin resistance and lipid abnormalities and protects against liver steatosis in Zucker (fa/fa) obese rats.
The farnesoid X receptor (FXR) is a bile acid activated nuclear receptor. Zucker (fa/fa) rats, harboring a loss of function mutation of the leptin receptor, develop diabetes, insulin resistance, obesity, and liver steatosis. In this study, we investigated the effect of FXR activation by 6-ethyl-chenodeoxycholic acid, (6E-CDCA, 10 mg/kg) on insulin resistance and liver and muscle lipid metabolism in fa/fa rats and compared its activity with rosiglitazone (10 mg/kg) alone or in combination with 6E-CDCA (5 mg/kg each). In comparison to lean (fa/+), fa/fa rats on a normal diet developed insulin resistance and liver steatosis. FXR activation protected against body weight gain and liver and muscle fat deposition and reversed insulin resistance as assessed by insulin responsive substrate-1 phosphorylation on serine 312 in liver and muscles. Activation of FXR reduced liver expression of genes involved in fatty acid synthesis, lipogenesis, and gluconeogenesis. In the muscles, FXR treatment reduced free fatty acid synthesis. Rosiglitazone reduced blood insulin, glucose, triglyceride, free fatty acid, and cholesterol plasma levels but promoted body weight gain (20%) and liver fat deposition. FXR activation reduced high density lipoprotein plasma levels. In summary, FXR administration reversed insulin resistance and correct lipid metabolism abnormalities in an obesity animal model.
Dipartimento di Medicina Clinica e Sperimentale, Università di Perugia, Via E. dal Pozzo, Perugia, Italy.
Sabrina
S
Cipriani
Andrea
A
Mencarelli
Giuseppe
G
Palladino
Stefano
S
Fiorucci
D000818:Animals; D002635:Chenodeoxycholic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination; D005234:Fatty Liver / Q000097:blood / Q000473:pathology / Q000517:prevention & control*; D005786:Gene Expression Regulation / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D000960:Hypolipidemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007333:Insulin Resistance; D050356:Lipid Metabolism / Q000187:drug effects* / Q000235:genetics; D008055:Lipids / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009765:Obesity / Q000097:blood / Q000150:complications*; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D011924:Rats, Zucker; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000008:administration & dosage / Q000627:therapeutic use; D013997:Time Factors; D000099150:Receptor, Farnesoid X-Activated
D002635:Chenodeoxycholic Acid; D007004:Hypoglycemic Agents; D000960:Hypolipidemic Agents; D055504:Insulin Receptor Substrate Proteins; D008055:Lipids; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D000077154:Rosiglitazone; D045162:Thiazolidinediones; D000099150:Receptor, Farnesoid X-Activated; C526296:Irs1 protein, rat; C464660:obeticholic acid