Antiapoptosis and mitochondrial effect of pioglitazone preconditioning in the ischemic/reperfused heart of rat.
OBJECTIVE
Pioglitazone, used clinically in the treatment of type 2 diabetes mellitus, has been implicated as a regulator of cellular inflammatory and ischemic responses. The present study examined whether pioglitazone could inhibit cardiomyocyte apoptosis and reduce mitochondrial ultrastructure injury and membrane potential loss in the ischemic/reperfused heart of the rat. Furthermore, we investigated whether the protective effect of pioglitazone was related to opening of the mitochondrialATP-sensitive potassium channels.


METHODS
Adult male Sprague-Dawley rats were subjected to 30 min of ischemia followed by 4 h of reperfusion. At 24 h before ischemia, rats were randomized to receive 0.9% saline, 5-hydroxydecanoate (5-HD, 10 mg kg(-1), i.v.) plus pioglitazone (3 mg kg(-1), i.v.) or pioglitazone (3 mg kg(-1), i.v.). One group served as sham control. We investigated mitochondrial structure, apoptosis rate and Bcl-2, Bax and Caspase-3 proteins by immunohistochemistry staining. RT-PCR was used to determine the expression of P38MAPKmRNA and JNKmRNA. Western blotting was used to measure the expression of P38MAPK, JNK and NFkappaB P65. A second group of rats were randomly divided into sham-operated, ischemia/reperfusion (I/R), pioglitazone treatment, 5-HD + pioglitazone and 5-HD groups and the size of myocardial infarction was determined. Primary cultured cardiomyocytes of neonatal Sprague-Dawley rats were divided into control, hypoxia reoxygenation, different concentrations of pioglitazone and 5-HD + pioglitazone groups. JC-1 staining flowcytometry was used to examine mitochondrial membrane potential (DeltaPsim).


RESULTS
Pioglitazone decreased mitochondrial ultrastructural damage compared to I/R, and reduced infarct size from 34.93 +/- 5.55% (I/R) to 20.24 +/- 3.93% (P < 0.05). Compared with the I/R group, the apoptosis rate and positive cell index (PCI) of Bax and Caspase-3 proteins in the pioglitazone group were significantly decreased (P < 0.05), while the PCI of Bcl-2 protein was increased (P < 0.05). There was no significant difference between the I/R and 5-HD + pioglitazone groups. Compared with the sham-operated group, the expression of P38MAPK mRNA, JNK mRNA and protein of P38MAPK, JNK and NFkappaB P65 in I/R was increased (P < 0.05). Pioglitazone did inhibit the increase in expressions vs I/R (P < 0.05). The rate of loss DeltaPsim cells in the pioglitazone group was significantly lower than in the hypoxia reoxygenation group, while the addition of 5-HD inhibited the effect of pioglitazone.


CONCLUSIONS
Pioglitazone inhibited cardiomyocyte apoptosis and reduced mitochondrial ultrastructure injury and membrane potential loss in the ischemic/reperfused heart of rat. These protective effects of pioglitazone may be related to opening mitochondrial(ATP)-sensitive potassium channels.
Li
Jian
J
Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No.1277 Jiefang Road, Wuhan 430022, China. leerabbity@126.com
Lang
Ming-Jian
MJ
Mao
Xiao-Bo
XB
Tian
Li
L
Feng
Yi-Bai
YB
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D002317:Cardiovascular Agents / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D000077205:Pioglitazone; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D045162:Thiazolidinediones / Q000494:pharmacology*; D051996:Transcription Factor RelA / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
C494828:Bax protein, rat; D002317:Cardiovascular Agents; D015221:Potassium Channels; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D045162:Thiazolidinediones; D051996:Transcription Factor RelA; D051028:bcl-2-Associated X Protein; C117780:mitochondrial K(ATP) channel; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505410:Casp3 protein, rat; D053148:Caspase 3; D000077205:Pioglitazone