title: Diabetes abolishes morphine-induced cardioprotection via multiple pathways upstream of glycogen synthase kinase-3beta.
abstract: The cardioprotective effect of opioids or glycogen synthase kinase (GSK) inhibitors given at reperfusion has not been investigated in diabetes models. Therefore, nondiabetic (NDBR) or streptozotocin-induced diabetic (DBR) rat hearts were subjected to 30 min of ischemia and 2 h of reperfusion. Groups of NDBR or DBR were administered either vehicle, morphine (0.3 mg/kg), or the GSK inhibitor SB216763 (0.6 mg/kg) 5 min before reperfusion. SB216763 (but not morphine) reduced infarct size in DBRs (44 +/- 1* and 55 +/- 2%, respectively), while both agents reduced infarct size in NDBRs versus untreated NDBRs or DBRs (44 +/- 3*, 42 +/- 3*, 60 +/- 2, and 56 +/- 2%, respectively, *P < 0.001). Morphine-induced phospho- (P-)GSK3beta was reduced 5 min after reperfusion in DBRs compared with NDBRs (0.83 +/- 0.29 and 1.94 +/- 0.12 [P < 0.05] pg/microg tissue, respectively). The GSK3beta mediators, P-Akt, P-extracellular signal-related kinase (ERK)1, and P-signal transducer and activator of transcription (STAT)3, were also significantly reduced in untreated DBR compared with NDBR rats. Morphine-induced elevations of P-Akt, P-ERK1, P-p70s6, P-janus-activated kinase-2, and P-STAT3 in NDBRs were also blunted in DBRs. H9C2 cells raised in 25 mmol/l compared with 5.56 mmol/l glucose media also demonstrated reduced morphine-induced P-GSK3beta, P-Akt, P-STAT3, and P-ERK1 after 15 min. Hence, acute GSK inhibition may provide a novel therapeutic strategy for diabetic patients during an acute myocardial infarction, whereas morphine is less effective due to signaling events that adversely affect GSK3beta.
authors.affiliation: Medical College of Wisconsin, Department of Pharmacology and Toxicology, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Gross
authors.forename: Anna K
authors.initials: AK
authors.lastname: Hsu
authors.forename: Garrett J
authors.initials: GJ
authors.lastname: Gross
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006339:Heart Rate / Q000187:drug effects; D006943:Hyperglycemia / Q000503:physiopathology; D053614:Janus Kinase 2 / Q000378:metabolism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010769:Phosphothreonine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D050794:STAT1 Transcription Factor / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; C494081:Stat1 protein, rat; C494088:Stat3 protein, rat; D010769:Phosphothreonine; D009020:Morphine; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3