Regular paper

Involvement of GPR30 in protection effect of Dexmedetomidine against myocardial ischemia/reperfusion injury in rat via AKT pathway

Zheming Shao1#, Qihong Shen2#, Min Kong2, Huadong Ni2 and Xiaomin Hou2✉

1Department of Anesthesiology, Zhejiang Sian Internatinal Hospital, Jiaxing City, Zhejiang Province, 314000, China; 2Department of Anesthesiology-Jiaxing Key Discipline of Medicine-Anesthesiology (2019-zc-06), The Affiliated Hospital of Jiaxing University, The First Hospital of Jiaxing, Jiaxing City, Zhejiang Province, 314001, China

Acute myocardial infarction (AMI) is a heart disease that seriously threatens human health. Dexmedetomidine (DEX) has a certain protective effect on cardiac injury. This study investigated the cardioprotective effect of DEX and its potential molecular mechanism in vivo and in vitro. The results showed that DEX could significantly increase the viability of hypoxia/reoxygenation (H/R) treated cardiomyocytes and reduce oxidative damage and apoptosis. Further molecular mechanism analysis showed that the above cardiac protective effects may be related to Akt signaling pathway. In addition, the expression of G-Protein Receptor 30 (GPR30) was promoted after H/R treatment. However, knockdown of GPR30 by shRNA significantly counteracted the cardioprotective effect of DEX. Meanwhile, we constructed a rat model of AMI to investigate the role of GPR30 in vivo. The results showed that DEX significantly reduced the infarct size, and GPR30 agonist G1 enhanced the protective effect of DEX on heart. On the contrary, protein kinase B (AKT) inhibitor LY294002 counteracted the protective effect of DEX on heart, suggesting that GPR30 enhanced the protective effect of DEX on ischemia-reperfusion induced heart injury by regulating AKT related pathways. In conclusion, our study provides a potential target for the clinical treatment of AMI.

Keywords: acute myocardial infarction, Dexmedetomidine, G-protein receptor 30, myocardial ischemia/reperfusion injury, AKT pathway

Received: 01 September, 2020; revised: 19 October, 2020; accepted: 20 October, 2020; available on-line: 25 February, 2021

✉e-mail: houxiaomin0810@163.com

Acknowledgemnts of Financial Support: This research was supported by a grant from the Public Technology Application Research Program of Zhejiang Province of China (NO. LGD19C090001).

#These authors contributed equally to the work.

Abbreviations: AMI, acute myocardial infarction; DEX, Dexmedetomidine; H/R, hypoxia/reoxygenation; GPR30, G-Protein Receptor 30; AKT, protein kinase B; I/R, ischemia-reperfusion; PI3K, Phosphatidylinositol 3 kinase; ADCA, anterior descending coro­nary artery; AAR, area at risk; PBS, phosphate buffered solution; DMEM-F12, Dulbecco’s Modified Eagle Media: Nutrient Mixture F-12; FBS, fatal bovine serum; 5-BrdU, 5-bromodeox­yuridine; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; DMSO, dimethyl sulfoxide; OD, Optical density; SOD, superoxide dismutase; MDA, Malondialdehyde; RT-qPCR, Real time quantitative PCR; GAP­DH, glyceraldehyde-3-phosphate dehydrogenase; RIPA, Radioimmunoprecipitation assay; SDS–PAGE, sodium dodecyl sulfate polyacryla­mide gel electrophoresis; PVDF, polyvinylidene fluoride; siRNA, small interfering RNA; S.D., standard deviation; shRNA, short hairpin RNA; LDH, lactic dehydrogenase; SIRT1, silence information regulator1; mTOR, mam­malian target of rapamycin; Erα, estrogen receptor alpha; Erβ, estrogen receptor beta; EGFR, epidermal growth factor recep­tor; MAPK, mitogen activated protein kinase; PKA, protein kinase A; OVX, ovariectomized

Introduction

Acute myocardial infarction (AMI) is a heart disease that seriously threatens human health. With the change of people’s lifestyle and the aging of the population, cardiovascular diseases, especially congestive heart failure and malignant arrhythmias caused by myocardial infarction, have a very high morbidity and mortality all over the world (Lloyd-Jones et al., 2010; JENKO et al., 2019). In recent years, with the extensive development of thrombolysis and cardiac interventional surgery and the rapid development of drug therapy in the treatment of myocardial infarction, the prognosis of patients with myocardial infarction has been greatly improved, but there are still many patients who failed to carry out revascularization in time for various reasons. The irreversible death of myocardium leads to ventricular remodeling, which leads to deterioration of cardiac function and eventually to heart failure (Eapen et al., 2012).

Dexmedetomidine (DEX) is a novel highly selective α 2-adrenergic receptor agonist, which is widely used in intensive care unit and clinical anesthesia (Eltzschig & Eckle, 2011). Studies have found that DEX has a protective effect on lung, kidney and other organ injury, and can reduce apoptosis and inhibit inflammatory response (Vincent et al., 2013; Lin & Knowlton, 2014). In recent years, a number of studies have shown that DEX has a certain protective effect on cardiac injury, including reducing myocardial ischemia-reperfusion (I/R) injury, stabilizing heart rhythm, and reducing the incidence of complications of cardiac surgery (Peng et al., 2013; Xu et al., 2013; Chen et al., 2014) by regulating antioxidant and anti-inflammatory signals (Wang et al., 2020). However, the detailed mechanism still needs to be further explored.

G-Protein Receptor 30 (GPR30) is an estrogen receptor which plays an important role in the protection of myocardium against myocardial injury induced by I/R. It has been found that GPR30 agonist treatment can significantly reduce isolated myocardial I/R injury in male rats (Deschamps & Murphy, 2009; Bopassa et al., 2010). The activation of GPR30 promoted the recovery of rat cardiac function and reduced myocardial inflammation by increasing cell viability and inhibiting apoptosis (Weil et al., 2010). Our pre-experimental studies showed that DEX preconditioning increased the expression of GPR30 in I/R myocardium, so we speculate that the cardioprotective effect of DEX may be achieved through GPR30.

Phosphatidylinositol 3 kinase (PI3K)-protein kinase B (AKT) signaling pathway plays an important role in various diseases (Gu et al., 2020), including myocardial I/R injury (Yang et al., 2004). In I/R, it was initially found to be associated with pathways, such as mitochondrial dysfunction, oxygen free radical production, neutrophil aggregation, calcium overload etc. Further studies have shown that the protective mechanism in cardiomyocytes has played a role before serious consequences, and one of the important mechanisms is the PI3K-AKT signal pathway (Yang et al., 2005). Interestingly, Wei et al found that the activation of GPR30 may provide cardiac protection through downstream activation of PI3K-dependent pathways in I/R (Deschamps & Murphy, 2009). Therefore, the current study investigated the role of GPR30 in the protection of DEX against myocardial I/R injury in rats and its potential molecular mechanisms.

Material and methods

Animals and Experimental protocols

Animal experiments were approved by the Ethics Committee of Experimental Animals in Medical College of Jiaxing University and carried out in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Male Sprague–Dawley rats (300 g) were purchased from Shanghai Experimental Animal Center (Shanghai, China), and given humane care. Rats were anesthetized by intraperitoneal injection of pentobarbital sodium (80 mg/kg) and mechanical ventilation. The left chest was opened through the fourth intercostal space and the heart was revealed by pericardiotomy. To evaluate transient ischemia of the left ventricular, 6-0 Prolene ring was placed at the site of the first branch of the anterior descending coronary artery (ADCA), and the end of the suture passed through PE-50 to form a snare for reversible occlusion. Then, the heart was subjected to regional ischemia for 30 min, followed by reperfusion of area at risk (AAR) (ADCA dependent area) for 120 min. Sixty rats were randomly divided into 6 groups with 10 rats in each group: Sham group, AMI group (rats were given equal amount of normal saline before modeling), AMI+DEX group (rats were given 1 μg/kg/d DEX by intravenous injection for 30 min), AMI+DEX+G1 group (rats were given 1 μg/kg/d DEX and 100 nM G1 by intravenous injection for 30 min before modeling), AMI+LY294002 group (rats were given 1 μg/kg/d DEX and 20 μM G1 by intravenous injection before modeling) and AMI+DEX+G1+LY294002 group (rats were given 1 μg/kg/d DEX, 100 nM G1 and 20 μM LY294002 by intravenous injection for 30 min before modeling). After 10 weeks, animals were euthanized by intraperitoneal injection of 200 mg/kg pentobarbital sodium.

Isolation and treatment of primary cardiomyocytes

Primary cardiomyocytes were isolated as previously described (Gao & Meng 2017). In short, heart of neonatal rats (1–2 days old) was taken out and maintained in cold phosphate buffered solution (PBS). Ventricle was cut into small pieces (1~3 mm3) and digested with 0.1% type II collagenase at 37°C for 5 min, repeated five times. The supernatant was collected by centrifugation and resuspended with Dulbecco’s Modified Eagle Media: Nutrient Mixture F-12 (DMEM-F12) containing 15% fatal bovine serum (FBS) (C11330500 ETQ Gibco). Separate fibroblasts and cardiomyocytes by differential wall method, and the growth of fibroblasts was inhibited by 5-bromodeoxyuridine (5-BrdU) (B5002 pr. Louisjue USA). For in vitro hypoxia/reoxygenation (H/R) model, cells were pre-treated with different doses of DEX (0.1, 0.5, 1 and 5 μM), and then subjected to Na2S2O4 (4 mM) at 37°C for 1 h. Thereafter, the cells were cultured with normal medium for another 12 h to generate a reoxygenated wcondition.

MTT assay

Cell viability was monitored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In brief, cardiomyocytes were exposed to MTT (50 µM) at 37°C for 4 h. Thereafter, the medium was carefully removed and 100 μl of dimethyl sulfoxide (DMSO) was added. Optical density (OD) values of formazan crystals were determined at 570 nm using microplate reader
(BioTeck, Winooski, Vermont, USA).

Measurement of SOD and MDA

Enzymatic activity of superoxide dismutase (SOD) was detected using Total Superoxide Dismutase Assay Kit with NBT (S0109, Beyotime, Shanghai, China), while Malondialdehyde (MDA) were detected using Lipid Peroxidation MDA Assay Kit (S0131S, Beyotime, Shanghai, China) as per manufacturer’s instructions

Real time quantitative PCR (RT-qPCR)

Total RNA from cells was isolated and reversely transcribed using FastKing gDNA Dispelling RT SuperMix (Tiangen, Beijing, China). The expression of GPR30 was measured by RT-qPCR using Quant one step qRT-PCR Kit (SYBR Green, FP303, Tiangen, Beijing, China) in a Mastercycler EP realplex detection system (Roche, Indianapolis, IN). The expression of GPR30 was normalized by glyceraldehyde-3-phosphate dehydrogenase
(GAPDH), and analyzed using 2-ΔΔCT method (Schmittgen & Livak, 2008). Primers were as follows:

GPR30, F, 5’-GACCTGATATTGACCTTG-3’, R, 5’-CCACAATATCGACTTCAATC-3’.

GAPDH, F, 5’-AACTGAACCTGACCAACG-3’, R, 5’-TTCAAGGCTGCATGCCAAC-3’.

Western blotting

Proteins in infarcted heart tissue or cells were extracted using Radioimmunoprecipitation assay (RIPA) lysis buffer (Beyotime, Shanghai, China) with phosphatase inhibitors (Abcam, Cambridge, UK). Protein levels were measured by Western blotting. In brief, protein (20 μg) was separated by 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) and then transferred on to polyvinylidene fluoride (PVDF) membranes (Roche, Switzerland). The membranes were incubated with primary antibodies, such as anti-GPR30 (ab39742, 1:250, Abcam, Cambridge, UK), anti-Bcl2 (ab32124, 1:1000, Abcam, Cambridge, UK), anti-cleaved caspase 3 (ab32042, 1:500, Abcam, Cambridge, UK), anti-caspase 3 (ab13847, 1:500, Abcam, Cambridge, UK), anti-AKT (ab38449, 1:500, Abcam, Cambridge, UK), anti-p-GSK-3β (ab93926, 1:500, Abcam, Cambridge, UK), anti-GSK-3β (ab32391, 1:5000, Abcam, Cambridge, UK), anti-β-actin (ab8227, 1:1000, Abcam, Cambridge, UK) at 4°C overnight, and incubated with secondary antibody Goat Anti-Rabbit IgG H&L (HRP) secondary antibody (ab6721, 1:2000; Abcam, Cambridge, UK) for 1 h at room temperature. Blots were visualized using a FluroChem E Imager (ProteinSimple, Santa Clara, CA, USA) and protein levels were quantified with Quantity AlphaEaseFCTM (Alpha Innotech, San Leandro, CA, USA) imaging software.

GPR30 knockdown

To investigate the effect of GPR30 in vitro. The cells were infected with adenovirus vectors (VectorBuilder, Guangzhou, China) containing shGPR30 fragments for GPR30 silencing (shGPR30#1 or shGPR30#2) or shRNA as negative control. Sh-GPR30 was designed by annealing two pairs of small interfering RNA (siRNA) fragments. The sequences were as follows:

ShRNA1# (i) 5’-AAGTGGCTTCGTACATAACGTCCTGTCTC-3’ (sense), and 5’-AAGCCTACCAATGTAACTACGCCTGTCTC-3’ (antisense); (ii) 5’-AACCAAATGCTAGGAACTGCACCTGTCTC-3’ (sense)
and 5’-AACAACCAAACTGCCTCTGAACCTGTCTC-3’ (antisense).

ShRNA2# (i) 5’-AAGCCGGTAAACTGACAAATGCCTGTCTC-3’ (sense), and 5’-AAGTTGCTAGCTCAAATCGAGCCTGTCTC-3’ (antisense); (ii) 5’-AACCTAGCTGFATGCCTGGACCCTGTCTC-3’ (sense) and 5’-AACCGTAGCTTAGTGCCATGCCCTGTCTC-3’ (antisense)

Triphenyl tetrazolium chloride (TTC) staining

Myocardial infarction was detected by TTC staining. At the end of the reperfusion, hearts were quickly removed from mice and stored at –80°C. The myocardial tissue was sectioned (2 mm), and then incubated with 1% TTC solution (sigma Aldrich) at 37°C for 30 min. Kept away from light for 30 min. After washing and fixing, the photos were taken and analyzed by Image-Pro Plus6.0 software.

Statistical analysis

All data are presented as mean standard deviation (S.D.) Unpaired t-test was used for the difference between two groups, while one-way ANOVA followed by Bonferroni test was used for the difference between multiple groups. p<0.05 was considered statistically significant. GraphPad Prism 5 was used for statistical analysis.

Results

DEX up-regulated the expression of GPR30, which increased cell viability and reduced oxidative damage of cardiomyocytes treated with H/R

This study investigated the effect of DEX on the viability of cardiomyocytes. Cell viability was detected by MTT assay. As shown in Fig. 1A, different doses of DEX had little effect on the viability of cardiomyocytes. However, after the cardiomyocytes were treated with H/R, DEX had a significant effect on the viability of the cardiomyocytes. As shown in Fig. 1B, compared with the control group, H/R treatment significantly reduced the viability of cardiomyocytes. Notably, DEX (1 μM) reversed the inhibitory effect of H/R on cardiomyocyte viability. Compared with 1 μM, when the dose of DEX was 5 μM, the reversal effects of DEX were weakened. Besides, our study also showed that H/R treatment reduced the activity of SOD and increased the content of MDA. Interestingly, DEX (1 μM) reversed the reduction of SOD activity and the increase of MDA content by H/R. In addition to 1 μM of DEX, 0.5 μM of DEX also showed a reversal effect on the increase of MDA content. Compared with 1 μM, when the dose of DEX was 5 μM, the effects of DEX were weakened (Fig. 1C–D). Further analysis showed that different doses of DEX promoted the expression of GPR30 at the mRNA and protein level in a dose-dependent manner, which further promoted the expression of anti-apoptosis-related protein (Bcl2) and inhibited the expression of apoptosis-related protein (Cleaved caspase 3) (Fig. 1E–F). In summary, our findings demonstrated that DEX up-regulated the expression of GPR30, which increased cell viability and reduced oxidative damage of cardiomyocytes treated with H/R.

DEX activated the AKT signal pathway

PI3K-AKT signaling pathway plays a very important role in myocardial I/R injury. Therefore, this study explored the effect of DEX on AKT signal pathway. As shown in Fig. 2, the level of phosphorylation of AKT in cardiomyocytes treated with H/R was significantly lower than that of the control group, followed by a decrease in the level of phosphorylation of GSK-3β, a protein downstream of AKT. Interestingly, DEX significantly reversed the inactivation of AKT and its downstream protein GSK-3β in cardiomyocytes induced by H/R in a dose-dependent manner. All in all, our results showed that DEX activated the AKT signal pathway.

GPR30 knockdown reversed the protective effect of DEX on cardiomyocytes treated with H/R

To clarify whether the high expression of GPR30 is involved in the protective effect of DEX on cardiomyocytes, we first use short hairpin RNA (shRNA) to knock down GPR30. As shown in Fig. 3A–B, after knockdown of GPR30 by shGPR30#1 or shGPR30#2, the expression of GPR30 in cardiomyocytes was significantly inhibited, and the knockdown effect of shGPR30#1 was better than that of shGPR30#2. Therefore, the follow-up experiment was carried out by using shGPR30#1 with high knockout efficiency. Then we investigated the effect of low expression of GPR30 on cardiomyocytes treated with H/R. As shown in Fig. 3C, DEX significantly reversed the decrease in cardiomyocyte viability after H/R treatment, which was offset by GPR30 knockdown. Besides, GPR30 knockdown also offset the increase of SOD activity and the decrease of MDA content in H/R cardiomyocytes pretreated with DEX (Fig. 3D–E). In addition, GPR30 knockdown offset the increase of Bcl-2 and the decrease of cleaved caspase-3 in H/R cardiomyocytes pretreated with DEX. Further analysis showed that GPR30 knockdown reversed the activation of the AKT–GSK-3β pathway by DEX (Fig. 3F). Overall, our results showed that GPR30 knockdown reversed the protective effect of DEX on cardiomyocytes treated with H/R.

GPR30/AKT signal pathway plays a role in myocardial protection of DEX

As a supplement, we also confirmed the effect of GPR30 on myocardial protection induced by DEX in vivo. As shown in Fig. 4A, TTC staining showed that AMI rats had severe myocardial infarction compared with the sham group, and the degree of myocardial infarction in AMI rats was improved after DEX treatment. Compared with DEX alone, myocardial infarction was significantly improved in AMI rats treated with DEX and GPR30 agonist (G1). It is worth noting that compared with DEX alone, myocardial infarction was significantly aggravated in AMI rats treated with DEX and AKT inhibitor (LY294002). Besides, we detected the levels of lactic dehydrogenase (LDH) and MDA, as well as the activity of SOD in myocardial tissue of rats in each group. As shown in Fig. 4B–D, LDH and MDA in myocardium of AMI rats increased significantly, while SOD activity significantly decreased. After DEX treatment, the levels of LDH and MDA decreased significantly, while the activity of SOD increased. More importantly, compared with DEX alone, when AMI rats were treated with DEX and GPR30 agonist (G1), the levels of LDH and MDA were further decreased, while the activity of SOD was further increased. However, compared with DEX alone, when AMI rats were treated with DEX and AKT inhibitor (LY294002), the levels of LDH and MDA increased again, while the activity of SOD decreased as well. Taken together, these results suggest that GPR30/AKT signal pathway plays a role in myocardial protection of DEX.

Discussion

Ischemic heart disease remains the leading cause of global deaths, and its persistence is the main cause of high mortality and incidence rate worldwide (Mendis et al., 2015). Although great progress has been made in the treatment of ischemic heart disease, the injury caused by I/R still limits the recovery of myocardial injury and acute myocardial infarction (Spath et al., 2016). In patients with AMI, antiplatelet, antithrombotic therapy, revascularization and drug therapy such as blocking, statins and renin angiotensin aldosterone axis inhibitors improve cardiac remodeling and subsequent cardiac events, including myocardial ischemia and cardiac exhaustion (Hamm et al., 2011; Ibanez et al., 2018; Neumann et al., 2019).

DEX has the effects of sedation, analgesia and opioids, and is a routine perioperative drug, especially for short-term and long-term sedation in intensive care patients (Keating, 2015). Previous studies have shown that DEX has obvious cardioprotective effects on myocardial I/R rats (Cheng et al., 2016; Behmenburg et al., 2017; Bunte et al., 2020). For example, Tang and others (Tang et al., 2020) found that DEX preconditioning alleviated acute myocardial infarction, oxidative stress and myocardial injury after ischemia by regulating endoplasmic reticulum stress and reducing cell injury, thus achieving cardioprotective effect. Besides, Zhang and others (Zhang et al., 2020) found that DEX protected myocardium by up-regulating silence information regulator1 (SIRT1)/ mammalian target of rapamycin (mTOR) axis and reducing excessive autophagy to reduce cardiomyocyte apoptosis, oxidative stress and inflammation. Similarly, this study confirmed that DEX has a cardioprotective effect by elevating the vitality of H/R cardiomyocytes and inhibiting their apoptosis, reducing oxidative damage. Moreover, after treating AMI rat models with different doses of DEX, we found that DEX can reduce the area of myocardial infarction and reduce oxidative damage. Further mechanism analysis showed that the cardioprotective effect of DEX may be related to the AKT signaling pathway.

Estrogen is a steroid hormone with a wide range of biological activities. It is generally believed that estrogen plays a role through the downstream signaling pathway mediated by estrogen receptor alpha (ERα) and estrogen receptor beta (Erβ), but the activation of these pathways can lead to side effects such as breast cancer and endometrial hyperplasia (Robinson et al., 2013). In recent years, it has been found that GPR30, a subtype of ER located on cell membrane, has an important cardioprotective effect (Weil et al., 2010). Estrogen has high affinity for GPR30 and could induce rapid signal transduction through GPR30 and epidermal growth factor receptor (EGFR), including activation of mitogen activated protein kinase (MAPK), protein kinase A (PKA) and phosphatidylinositol 3 kinase (PI3K) (Prossnitz & Maggiolini 2009). Besides, Zhu and others (Zhu et al., 2020) found that GPR30 and its upstream regulatory genes, miR-2861 and miR-5115, were differentially expressed in myocardial I/R by microarray analysis of GES67308 and GES50885, in which the expression of GPR30 was suppressed, and miR-2861 and miR-5115 inhibited the expression of GPR30. Notably, overexpression of GPR30 alleviated pathological damage, myocardial infarction and apoptosis in mice. Moreover, GPR30 specific agonist G1 reduces I/R-induced myocardial infarction by reducing myocardial inflammation, improving immune suppression, and triggering a pro-survival signal cascade (De Francesco et al., 2017). On this basis, this study found the high expression of GPR30 in H/R cardiomyocytes, while DEX treatment could promote the expression of GPR30, suggesting that the myocardial injury induced by H/R may be related to the low expression of GPR30, and the cardioprotective effect of DEX may be related to GPR30. So, we designed shRNA to knock down GPR30. Surprisingly, knockdown of GPR30 reversed the increase of cardiomyocyte viability after DEX treatment, aggravated oxidative damage and accelerated cardiomyocyte apoptosis. On the contrary, in vivo studies have shown that GPR30 agonist G1 significantly enhanced the ameliorative effect of DEX on myocardial infarction. Therefore, this study found for the first time that GPR30 participates in the protective effect of DEX on myocardial I/R injury.

PI3K-AKT pathway is an important pathway in the process of myocardial I/R injury (Xin et al., 2020). In vivo and in vitro studies found that regulation of PI3K/Akt/mTOR signaling pathway inhibited autophagy of cardiomyocytes, thereby reducing myocardial I/R injury (Qiu et al., 2020). Previous studies have shown that activating GPR30 may regulate cell viability, apoptosis and inflammation by activating PI3K-dependent pathways, thereby alleviating heart injury induced by I/R (Deschamps & Murphy, 2009). Some other studies have shown that GPR30 reduced myocardial infarction and fibrosis in female ovariectomized (OVX) mice by activating PI3K/AKT pathway (Wang et al., 2019). In addition, Chang et al investigated the potential molecular mechanism of DEX on myocardial I/R injury, and found that preconditioning may activate PI3K/AKT signal pathway by relying on α-adrenoceptor, and further confirmed that DEX preconditioning may inhibit Imax R-induced apoptosis by activating PI3K/Akt signal pathway, thus has a cardioprotective effect on myocardial I/R injury in diabetic rats (Chang et al., 2020). Consistent with the above study, this study also found that DEX protected the heart by regulating AKT-related signaling pathways. Curiously, this study found that GPR30 participated in this process and enhanced the protective effect of DEX on myocardial I/R injury by enhancing the activation of AKT pathway.

In conclusion, in this study we investigated the cardioprotective effect of DEX and its potential molecular mechanism in vitro and in vivo. The results showed that DEX increased the viability of H/R cardiomyocytes and reduced apoptosis and myocardial infarction area by regulating AKT pathway. Further study found that GPR30 was involved in the protective effect of DEX on H/R and AMI. Our study provides a potential target for the clinical treatment of AMI.

Acknowledgements

Not applicable.

Competing interests

The authors state that there are no conflicts of interest to disclose.

Ethics approval

Ethical approval was obtained from the Ethics Committee of Experimental Animals in Medical College of Jiaxing University.

Statement of Informed Consent

Written informed consent was obtained from a legally authorized representative(s) for anonymized patient information to be published in this article.

Availability of data and materials

All data generated or analyzed during this study are included in this published article.

Authors’ contributions

Zheming Shao and Qihong Shen designed the study, supervised the data collection, Min Kong and Huadong Ni analyzed the data, interpreted the data, Xiaomin Hou prepare the manuscript for publication and reviewed the draft of the manuscript. All authors have read and approved the manuscript.

Reference

<ars.2009.2488.pdf>.

Behmenburg F, Pickert E, Mathes A, Heinen A, Hollmann MW, Huhn R, Berger MM (2017) The cardioprotective effect of dexmedetomidine in rats is dose-dependent and mediated by BKCa channels. J Cardiovasc Pharmacol 69: 228–235. https://doi.org/10.1097/fjc.0000000000000466

Bopassa JC, Eghbali M, Toro L, Stefani E (2010) A novel estrogen receptor GPER inhibits mitochondria permeability transition pore opening and protects the heart against ischemia-reperfusion injury. Am J Physiol Heart Circ Physiol 298: H16–H23. https://doi.org/10.1152/ajpheart.00588.2009

Bunte S, Behmenburg F, Majewski N, Stroethoff M, Raupach A, Mathes A, Heinen A, Hollmann MW, Huhn R (2020) Characteristics of dexmedetomidine postconditioning in the field of myocardial ischemia-reperfusion injury. Anesth Analg 130: 90–98. https://doi.org/10.1213/ane.0000000000004417

Chang JH, Jin MM, Liu JT (2020) Dexmedetomidine pretreatment protects the heart against apoptosis in ischemia/reperfusion injury in diabetic rats by activating PI3K/Akt signaling in vivo and in vitro. Biomed Pharmacother 127: 110188. https://doi.org/10.1016/j.biopha.2020.110188

Chen C, Zhang Z, Chen K, Zhang F, Peng M, Wang Y (2014) Dexmedetomidine regulates inflammatory molecules contributing to ventilator-induced lung injury in dogs. J Surg Res 187: 211–218. https://doi.org/10.1016/j.jss.2013.09.018

Cheng XY, Gu XY, Gao Q, Zong QF, Li XH, Zhang Y (2016) Effects of dexmedetomidine postconditioning on myocardial ischemia and the role of the PI3K/Akt-dependent signaling pathway in reperfusion injury. Mol Med Rep 14: 797–803. https://doi.org/10.3892/mmr.2016.5345

De Francesco EM, Rocca C, Scavello F, Amelio D, Pasqua T, Rigiracciolo DC, Scarpelli A, Avino S, Cirillo F, Amodio N, Cerra MC, Maggiolini M, Angelone T (2017) Protective role of GPER agonist G-1 on cardiotoxicity induced by doxorubicin. J Cell Physiol 232: 1640–1649. https://doi.org/10.1002/jcp.25585

Deschamps AM,Murphy E (2009) Activation of a novel estrogen receptor, GPER, is cardioprotective in male and female rats. Am J Physiol Heart Circ Physiol 297: H1806–H1813. https://doi.org/10.1152/ajpheart.00283.2009

Eapen ZJ, Tang WH, Felker GM, Hernandez AF, Mahaffey KW, Lincoff AM, Roe MT (2012) Defining heart failure end points in ST-segment elevation myocardial infarction trials: integrating past experiences to chart a path forward. Circ Cardiovasc Qual Outcomes 5: 594–600. https://doi.org/10.1161/circoutcomes.112.966150

Eltzschig HK, Eckle T (2011) Ischemia and reperfusion--from mechanism to translation. Nat Med 17: 1391–1401. https://doi.org/10.1038/nm.2507

Gao JM, Meng XW (2017) Dexmedetomidine protects cardiomyocytes against hypoxia/reoxygenation injury by suppressing TLR4-MyD88-NF-κB signaling. 2017: 1674613. https://doi.org/10.1155/2017/1674613

Gu Y, Wang T, Chen J, Zhou Z, Wang Y, Chen J, Liu N, Jiang Z (2020) The Chinese Herb Codonopsis pilosula Isolate Isorhapontigenin protects against oxidative stress injury by inhibiting the activation of PI3K/Akt signaling pathway. J Integr Neurosci 19: 333–340. https://doi.org/10.31083/j.jin.2020.02.1152

Hamm CW, Bassand JP, Agewall S, Bax J, Boersma E, Bueno H, Caso P, Dudek D, Gielen S, Huber K, Ohman M, Petrie MC, Sonntag F, Uva MS, Storey RF, Wijns W, Zahger D (2011) ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: The Task Force for the management of acute coronary syndromes (ACS) in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 32: 2999–3054. https://doi.org/10.1093/eurheartj/ehr236

Ibanez B, James S, Agewall S, Antunes MJ, Bucciarelli-Ducci C, Bueno H, Caforio ALP, Crea F, Goudevenos JA, Halvorsen S, Hindricks G, Kastrati A, Lenzen MJ, Prescott E, Roffi M, Valgimigli M, Varenhorst C, Vranckx P, Widimský P (2018) 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Kardiol Pol 76: 229–313. https://doi.org/10.5603/kp.2018.0041

Jenko M, Požar-Lukanović N, Perić M, Spindler-Vesel A (2019) Fluid optimisation in pancreas surgery. Signa Vitae: J Intesive Care Emergency Med 15: 45–51

Keating GM (2015) Dexmedetomidine: a review of its use for sedation in the intensive care setting. Drugs 75: 1119–1130. https://doi.org/10.1007/s40265-015-0419-5

Lin L, Knowlton AA (2014) Innate immunity and cardiomyocytes in ischemic heart disease. Life Sci 100: 1–8. https://doi.org/10.1016/j.lfs.2014.01.062

Lloyd-Jones D, Adams RJ, Brown TM, Carnethon M, Dai S, De Simone G, Ferguson TB, Ford E, Furie K, Gillespie C, Go A, Greenlund K, Haase N, Hailpern S, Ho PM, Howard V, Kissela B, Kittner S, Lackland D, Lisabeth L, Marelli A, McDermott MM, Meigs J, Mozaffarian D, Mussolino M, Nichol G, Roger VL, Rosamond W, Sacco R, Sorlie P, Stafford R, Thom T, Wasserthiel-Smoller S, Wong ND, Wylie-Rosett J; American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Executive summary: heart disease and stroke statistics – 2010 update: a report from the American Heart Association. Circulation 121: 948–954. https://doi.org/10.1161/circulationaha.109.192666

Mendis S, Davis S, Norrving B (2015) Organizational update: the world health organization global status report on noncommunicable diseases 2014; one more landmark step in the combat against stroke and vascular disease. Stroke 46: e121–e122. https://doi.org/10.1161/strokeaha.115.008097

Neumann FJ, Sousa-Uva M, Ahlsson A, Alfonso F, Banning AP, Benedetto U, Byrne RA, Collet JP, Falk V, Head SJ, Jüni P, Kastrati A, Koller A, Kristensen SD, Niebauer J, Richter DJ, Seferović PM, Sibbing D, Stefanini GG, Windecker S, Yadav R, Zembala MO (2019) 2018 ESC/EACTS Guidelines on myocardial revascularization. EuroIntervention 14: 1435–1534. https://doi.org/10.4244/eijy19m01_01

Peng M, Wang YL, Wang CY, Chen C (2013) Dexmedetomidine attenuates lipopolysaccharide-induced proinflammatory response in primary microglia. J Surg Res 179: e219–e225. https://doi.org/10.1016/j.jss.2012.05.047

Prossnitz ER, Maggiolini M (2009) Mechanisms of estrogen signaling and gene expression via GPR30. Mol Cell Endocrinol 308: 32–38. https://doi.org/10.1016/j.mce.2009.03.026

Qiu L, Xu C, Xia H, Chen J, Liu H, Jiang H (2020) Downregulation of P300/CBP-associated factor attenuates myocardial ischemia-reperfusion injury via inhibiting autophagy. Int J Med Sci 17: 1196–1206. https://doi.org/10.7150/ijms.44604

Robinson DR, Wu YM, Vats P, Su F, Lonigro RJ, Cao X, Kalyana-Sundaram S, Wang R, Ning Y, Hodges L, Gursky A, Siddiqui J, Tomlins SA, Roychowdhury S, Pienta KJ, Kim SY, Roberts JS, Rae JM, van Poznak CH, Hayes DF, Chugh R, Kunju LP, Talpaz M, Schott AF, Chinnaiyan AM (2013) Activating ESR1 mutations in hormone-resistant metastatic breast cancer. Nat Genet 45: 1446–1451. https://doi.org/10.1038/ng.2823

Schmittgen TD, Livak KJ (2008) Analyzing real-time PCR data by the comparative C(T) method. Nat Protocol 3: 1101–1108. https://doi.org/10.1038/nprot.2008.73

Spath NB, Mills NL, Cruden NL (2016) Novel cardioprotective and regenerative therapies in acute myocardial infarction: a review of recent and ongoing clinical trials. Future Cardiol 12: 655–672. https://doi.org/10.2217/fca-2016-0044

Tang C, Hu Y, Gao J, Jiang J, Shi S, Wang J, Geng Q, Liang X, Chai X (2020) Dexmedetomidine pretreatment attenuates myocardial ischemia reperfusion induced acute kidney injury and endoplasmic reticulum stress in human and rat. Life Sci 257: 118004. https://doi.org/10.1016/j.lfs.2020.118004

Vincent A, Lattuca B, Merlet N, Sportouch-Dukhan C, Barrère-Lemaire S (2013) New insights in research about acute ischemic myocardial injury and inflammation. Antiinflamm Antiallergy Agents Med Chem 12: 47–54. https://doi.org/10.2174/1871523011312010007

Wang X, Lu L, Tan Y, Jiang L, Zhao M, Gao E, Yu S, Liu J (2019) GPR 30 reduces myocardial infarct area and fibrosis in female ovariectomized mice by activating the PI3K/AKT pathway. Life Sci 226: 22–32. https://doi.org/10.1016/j.lfs.2019.03.049

Wang YG, Liu CZ, Li YZ, Peng Y, Yan S (2020) Cotreatments with Dex and Na(2)SeO(3) further improved antioxidant and anti-inflammatory protection of myocardial cells from I/R injury compared to their individual treatments. Free Radic Res 54: 76–90. https://doi.org/10.1080/10715762.2019.1707198

Weil BR, Manukyan MC, Herrmann JL, Wang Y, Abarbanell AM, Poynter JA, Meldrum DR (2010) Signaling via GPR30 protects the myocardium from ischemia/reperfusion injury. Surgery 148: 436–443. https://doi.org/10.1016/j.surg.2010.03.011

Xin G, Xu-Yong L, Shan H, Gang W, Zhen C, Ji-Jun L, Ping Y, Man-Hua C (2020) SH2B1 protects cardiomyocytes from ischemia/reperfusion injury via the activation of the PI3K/AKT pathway. Int Immunopharmacol 83: 105910. https://doi.org/10.1016/j.intimp.2019.105910

Xu L, Bao H, Si Y, Wang X (2013) Effects of dexmedetomidine on early and late cytokines during polymicrobial sepsis in mice. Inflamm Res 62: 507–514. https://doi.org/10.1007/s00011-013-0604-5

Yang XM, Philipp S, Downey JM, Cohen MV (2005) Postconditioning’s protection is not dependent on circulating blood factors or cells but involves adenosine receptors and requires PI3-kinase and guanylyl cyclase activation. Basic Res Cardiol 100: 57–63. https://doi.org/10.1007/s00395-004-0498-4

Yang XM, Proctor JB, Cui L, Krieg T, Downey JM, Cohen MV (2004) Multiple, brief coronary occlusions during early reperfusion protect rabbit hearts by targeting cell signaling pathways. J Am Coll Cardiol 44: 1103–1110. https://doi.org/10.1016/j.jacc.2004.05.060

Zhang X, Li Y, Wang Y, Zhuang Y, Ren X, Yang K, Ma W, Zhong M (2020) Dexmedetomidine postconditioning suppresses myocardial ischemia/reperfusion injury by activating the SIRT1/mTOR axis. Biosci Rep 40: https://doi.org/10.1042/bsr20194030

Zhu L, Li Q, Li Q, Qi D, Gao C, Yang H (2020) MicroRNA-2861 and microRNA-5115 regulates myocardial ischemia-reperfusion injury through the GPR30/mTOR signaling pathway by binding to GPR30. J Cell Physiol 235: 7791–7802 https://doi.org/10.1002/jcp.29427