title: Effects of insulin resistance on geranylgeranylacetone-induced expression of heat shock protein 72 and cardioprotection in high-fat diet rats.
abstract: We investigated the effects of insulin resistance on the expression of heat-shock proteins (HSPs) and myocardial protection against ischemia/reperfusion injury. Male Sprague-Dawley rats received normal chow (CNT) or high-fat (HiF) diet. HiF diet for 6 weeks resulted in the development of insulin resistance, which was evaluated by oral glucose test and insulin tolerance test. Twenty-four hour after oral administration of geranylgeranylacetone (GGA) (200 mg/kg), the heart was isolated and perfused retrogradely with two different doses of insulin (0.1 or 1 mU/ml). Myocardial expression of HSP72 was examined using Western blot analysis. In the HiF group, the expression of HSP72 in response to GGA was decreased. The recovery of left ventricular developed pressure (LVDP) 30 min after reperfusion was tended to be lower in HiF group than in CNT group. Although GGA improved the recovery of LVDP in both CNT and HiF rats, LVDP during reperfusion period was significantly lower in HiF group than in CNT group. High-dose insulin perfusion caused deterioration of post-ischemic functional recovery and LVDP was not different between the two groups, but GGA-induced cardioprotection was preserved irrespective of the dose of insulin both in the CNT and HiF rats. This is the first demonstration that expression of HSP72 was depressed in the heart and that reduced HSP72 was related with less cardioprotection against ischemic insult in high-fat diet-induced insulin resistance rats.
authors.affiliation: Department of Laboratory Medicine, Faculty of Medicine, Oita University, 1-1, Hasama, Oita, 879-5593, Japan. TATSU@med.oita-u.ac.jp
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Ooie
authors.forename: Munetaka
authors.initials: M
authors.lastname: Kajimoto
authors.forename: Naohiko
authors.initials: N
authors.lastname: Takahashi
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Shinohara
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kouno
authors.forename: Osamu
authors.initials: O
authors.lastname: Wakisaka
authors.forename: Hironobu
authors.initials: H
authors.lastname: Yoshimatsu
authors.forename: Tetsunori
authors.initials: T
authors.lastname: Saikawa
mesh_terms: D000818:Animals; D004041:Dietary Fats / Q000008:administration & dosage*; D004224:Diterpenes / Q000494:pharmacology*; D005951:Glucose Tolerance Test; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D017202:Myocardial Ischemia / Q000188:drug therapy*; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004041:Dietary Fats; D004224:Diterpenes; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007328:Insulin; C031049:geranylgeranylacetone