DRD4 Mitigates Myocardial Ischemia/Reperfusion Injury in Association With PI3K/AKT Mediated Glucose Metabolism.

Xue-Song Liu,Ting Xiong,Geng-Ze Wu,Da-Xin Wang,Chun-Yu Zeng,Yu-Xue Yang,Jing Zeng,Chun-Lei Qi

doi:10.3389/fphar.2020.619426

Abstract

Ischemia-reperfusion (I/R) could cause heart irreversible damage, which is tightly combined with glucose metabolism disorder. It is demonstrated that GLUT4 (glucose transporter 4) translocation is critical for glucose metabolism in the cardiomyocytes under I/R injury. Moreover, DRD4 (dopamine receptor D4) modulate glucose metabolism, and protect neurocytes from anoxia/reoxygenation (A/R) injury. Thus, DRD4 might regulate myocardial I/R injury in association with GLUT4-mediated glucose metabolism. However, the effects and mechanisms are largely unknown. In the present study, the effect of DRD4 in heart I/R injury were studied ex vivo and in vitro. For I/R injury ex vivo, DRD4 agonist (PD168077) was perfused by Langendorff system in the isolated rat heart. DRD4 activated by PD168077 improved cardiac function in the I/R-injured heart as determined by the left ventricular developed pressure (LVDP), +dp/dt, and left ventricular end diastolic pressure (LVEDP), and reduced heart damage evidenced by infarct size, the release of troponin T (TNT) and lactate dehydrogenase (LDH). DRD4 activation diminished I/R injury induced apoptosis and enhanced cell viability impaired by I/R injury in cardiomyocyte, showed by TUNEL staining, flow cytometer and CCK8 assay. Furthermore, DRD4 activation did not change total GULT4 protein expression level but increased the membrane GULT4 localization determined by western blot. In terms of mechanism, DRD4 activation increased pPI3K/p-AKT but not the total PI3K/AKT during anoxia/reoxygenation (A/R) injury in vitro. Interestingly, PI3K inhibitor, Wortmannin, blocked PI3K/AKT pathway and depleted the membrane GULT4, and further promoted apoptosis showed by TUNEL staining, flow cytometer, western blot of cleaved caspase 3, BAX and BCL2 expression. Thus, DRD4 activation exerted a protective effect against I/R injury by promoting GLUT4 translocation depended on PI3K/AKT pathway, which enhanced the ability of glucose uptake, and ultimately reduced the apoptosis in cardiomyocytes.

Highlights

Ischemia-reperfusion (I/R) injury is a major problem after coronary revascularization by the percutaneous coronary intervention (PCI) (Fröhlich et al, 2013)
Our previous works found DRD4 was expressed on kidney renal proximal tubule (RPT) cells (Chen et al, 2015; Zhang et al, 2016), so it was used as a positive control
As shown by immunofluorescence data (Figure 1A), the DRD4 was detectable in the RPT cells, neonatal rat ventricular myocytes (NRVMs), Adult mice cardiomyocytes (AMCs) and heart tissue

Summary

Introduction

Ischemia-reperfusion (I/R) injury is a major problem after coronary revascularization by the percutaneous coronary intervention (PCI) (Fröhlich et al, 2013). In order to optimize cardiac energy metabolism and oxygen consumption, glycolysis becomes the main mechanism by using glucose as fuel instead of fatty acids (Ussher and Lopaschuk, 2008). In this process, limited ATPs production by glycolysis does not maintain the normal cardiac function and induces cells death (Depre et al, 1999; Harmancey et al, 2013). Mounting of evidences suggest that improvement of glucose metabolism in cardiomyocytes could increase the heart’s tolerance to I/R injury (Gandhi et al, 2008; Lucchinetti et al, 2011; Zhang et al, 2015), improve cardiac function recovery (Rowe et al, 2010), and promote cardiomyocytes survival (Apstein, 1998). Glucose metabolism plays a critical role in cardiomyocytes survival during I/R injury. How to treat heart I/R injury by regulating glucose metabolism is incompletely elucidated

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Conclusion