, Volume 22, Issue 4, pp 283-291
Date: 10 May 2008

Antiapoptosis and Mitochondrial Effect of Pioglitazone Preconditioning in the Ischemic/reperfused Heart of Rat

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Abstract

Purpose

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 cadiocyte 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 NFκB 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 (ΔΨm).

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 NFκB 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 ΔΨm 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.

Conclusion

Pioglitazone inhibited cadiocyte 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 mitochondrialATP-sensitive potassium channels.