Pioglitazone but not glibenclamide improves cardiac expression of heat shock protein 72 and tolerance against ischemia/reperfusion injury in the heredity insulin-resistant rat.
We tested the hypothesis that pioglitazone could restore expression of heat shock protein (HSP)72 in insulin-resistant rat heart. At 12 weeks of age, male Otsuka Long-Evans Tokushima Fatty (OLETF) rats and control (LETO) rats were treated with pioglitazone (10 mg x kg(-1) x day(-1)) or glibenclamide (5 mg x kg(-1) x day(-1)) for 4 weeks. Thereafter, hyperthermia (43 degrees C for 20 min) was applied. In response to hyperthermia, the activation of serine/threonine kinase Akt depending on phosphatidylinositol 3 (PI3) kinase was necessary for cardiac expression of HSP72. Hyperthermia-induced activation of Akt and HSP72 expression were depressed in OLETF rat hearts. Pioglitazone but not glibenclamide improved insulin sensitivity in OLETF rats, which was associated with the restoration of Akt activation and HSP72 expression. In experiments with isolated perfused heart, reperfusion-induced cardiac functional recovery was suppressed in OLETF rat hearts, which was improved by pioglitazone but not glibenclamide. Our results suggest that PI3 kinase-dependent Akt activation, an essential signal for HSP72 expression, is depressed in the heart in insulin-resistant OLETF rats, and the results suggest also that the restoration of HSP72 expression and tolerance against ischemia/reperfusion injury by treatment with pioglitazone might be due to an improvement of insulin resistance, leading to restoration of impaired PI3 kinase-dependent Akt activation in response to hyperthermia.
Taniguchi
Yayoi
Y
Department of Internal Cardiovascular Science, Facutly of Medicine, Oita University, Oita, Japan.
Ooie
Tatsuhiko
T
Takahashi
Naohiko
N
Shinohara
Tetsuji
T
Nakagawa
Mikiko
M
Yonemochi
Hidetoshi
H
Hara
Masahide
M
Yoshimatsu
Hironobu
H
Saikawa
Tetsunori
T
D000818:Animals; D015153:Blotting, Western; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy; D005334:Fever; D005951:Glucose Tolerance Test; D005905:Glyburide / Q000627:therapeutic use*; D050884:HSP72 Heat-Shock Proteins / Q000032:analysis*; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000235:genetics*; D007700:Kinetics; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D000077205:Pioglitazone; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D020334:Rats, Inbred OLETF; D045162:Thiazolidinediones / Q000627:therapeutic use*; D016277:Ventricular Function, Left / Q000187:drug effects
D050884:HSP72 Heat-Shock Proteins; D007004:Hypoglycemic Agents; D007328:Insulin; D045162:Thiazolidinediones; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D005905:Glyburide; D000077205:Pioglitazone