title: Troglitazone improves GLUT4 expression in adipose tissue in an animal model of obese type 2 diabetes mellitus.
abstract: Troglitazone has been shown to improve peripheral insulin resistance in type 2 diabetic patients and animal models. We examined the effect of troglitazone on the expression of glucose transporter 4 (GLUT4) in muscle and adipose tissue from Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of obese type 2 diabetes mellitus. In addition, the effects of troglitazone on GLUT4 translocation and on glucose transport activity in adipocytes were also evaluated. Muscle and adipose tissues were isolated from 35-week-old male troglitazone-treated and untreated OLETF rats at a dose of 150 mg/kg per day for 14 days. In skeletal muscle, the protein and mRNA levels of GLUT4 were not significantly different between OLETF and control rats and they were not affected by troglitazone. On the other hand, GLUT4 protein and mRNA levels in adipose tissue from OLETF rats were significantly decreased (P<0.01) compared with control rats and they were significantly increased (1.5-fold, P<0.01) by troglitazone. Troglitazone had no major effect on GLUT4 translocation in adipocytes, but it significantly increased (1.4-fold, P<0.05) the basal and insulin-induced amounts of GLUT4 in plasma membrane (PM) in adipocytes from OLETF rats. Consistent with these results, the basal and insulin-induced glucose uptakes in adipocytes from troglitazone-treated OLETF rats were significantly increased (1.5-fold, P<0.05) compared with untreated OLETF rats. Our results suggest that troglitazone may exert beneficial effects on insulin resistance by increasing the expression of GLUT4 in adipose tissue.
authors.affiliation: Third Department of Internal Medicine, Mie University School of Medicine, Edobashi 2-174, Tsu, Mie 514-8507, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Furuta
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yano
authors.forename: Esteban C
authors.initials: EC
authors.lastname: Gabazza
authors.forename: Rika
authors.initials: R
authors.lastname: Araki-Sasaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Akira
authors.initials: A
authors.lastname: Katsuki
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Hori
authors.forename: Kaname
authors.initials: K
authors.lastname: Nakatani
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Sumida
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Adachi
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D002839:Chromans / Q000494:pharmacology*; D003920:Diabetes Mellitus / Q000235:genetics / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005786:Gene Expression Regulation / Q000187:drug effects*; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009124:Muscle Proteins; D009765:Obesity; D051381:Rats; D020334:Rats, Inbred OLETF; D020318:Rats, Long-Evans; D012016:Reference Values; D013844:Thiazoles / Q000494:pharmacology*; D045162:Thiazolidinediones; D014280:Triglycerides / Q000097:blood; D000077288:Troglitazone
chemical_list: D001786:Blood Glucose; D002839:Chromans; D005230:Fatty Acids, Nonesterified; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D013844:Thiazoles; D045162:Thiazolidinediones; D014280:Triglycerides; D002784:Cholesterol; D000077288:Troglitazone