Pioglitazone induces in vivo adipocyte differentiation in the obese Zucker fa/fa rat.
Thiazolidinediones are potent antidiabetic compounds, in both animal and human models, which act by enhancing peripheral sensitivity to insulin. Thiazolidinediones are high-affinity ligands for peroxisome proliferator-activated receptor-gamma, a key factor for adipocyte differentiation, and they are efficient promoters of adipocyte differentiation in vitro. Thus, it could be questioned whether a thiazolidinedione therapy aimed at improving insulin sensitivity would promote the recruitment of new adipocytes in vivo. To address this problem, we have studied the in vivo effect of pioglitazone on glucose metabolism and gene expression in the adipose tissue of an animal model of obesity with insulin resistance, the obese Zucker (fa/fa) rat. Pioglitazone markedly improves insulin action in the obese Zucker (fa/fa) rat, but doubles its weight gain after 4 weeks of treatment. The drug induces a large increase of glucose utilization in adipose tissue, where it stimulates the expression of genes involved in lipid metabolism such as the insulin-responsive GLUT, fatty acid synthase, and phosphoenolpyruvate carboxykinase genes, but decreases the expression of the ob gene. These changes are related to both an enhanced adipocyte differentiation, as shown by the large increase in the number of small adipocytes in the retroperitoneal fat pad, and a direct effect of pioglitazone on specific gene expression (phosphoenolpyruvate carboxykinase and ob genes) in mature adipocytes.
Hallakou
S
S
Institut National de la Santé et de la Recherche Médicale, Unit 465, Paris, France.
Doaré
L
L
Foufelle
F
F
Kergoat
M
M
Guerre-Millo
M
M
Berthault
M F
MF
Dugail
I
I
Morin
J
J
Auwerx
J
J
Ferré
P
P
D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002454:Cell Differentiation; D064429:Fatty Acid Synthases / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007333:Insulin Resistance; D020738:Leptin; D050356:Lipid Metabolism; D008053:Lipid Mobilization / Q000187:drug effects; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009124:Muscle Proteins; D009765:Obesity / Q000378:metabolism* / Q000473:pathology; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics; D000077205:Pioglitazone; D011506:Proteins / Q000235:genetics; D051381:Rats; D011922:Rats, Mutant Strains; D013844:Thiazoles / Q000627:therapeutic use*; D045162:Thiazolidinediones
D051275:Glucose Transporter Type 4; D020738:Leptin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D011506:Proteins; C495694:Slc2a4 protein, rat; D013844:Thiazoles; D045162:Thiazolidinediones; D064429:Fatty Acid Synthases; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D005947:Glucose; D000077205:Pioglitazone