Inhibition of endoplasm reticulum stress by ghrelin protects against ischemia/reperfusion injury in rat heart

doi:10.1016/j.peptides.2009.03.024

Peptides

Volume 30, Issue 6, June 2009, Pages 1109-1116

https://doi.org/10.1016/j.peptides.2009.03.024 Get rights and content

Abstract

Ghrelin is a multi-functional polypeptide with cardiovascular protective effects. We aimed to explore whether the cardioprotective effect of ghrelin is mediated by inhibiting myocardial endoplasmic reticulum stress (ERS). A Langendorff model of isolated rat heart was used with ischemia/reperfusion (I/R; 40/120 min). Cardiac function was monitored, and histomorphologic features, degree of myocardial injury, level of ERS markers, and number of apoptotic cardiomyocytes were determined. Compared with control group, the I/R group showed significantly decreased cardiac function, seriously damaged myocardial tissue, increased number of apoptotic cells, and overexpression of mRNA and protein of ERS markers. However, preadministration of ghrelin in vivo (10⁻⁸ mol/kg, intraperitoneal injection, every 12 h, twice in all) greatly ameliorated the damaged heart function, attenuated myocardial injury and apoptosis, and decreased the expression of ERS markers: it decreased the mRNA and protein levels of glucose-regulated protein78 (GRP78) and C/EBP homologous protein (CHOP), with reduced caspase-12 protein expression. Furthermore, in vitro, ghrelin directly inhibited the myocardial ERS response induced by tunicamycin or dithiothreitol in rat cardiac tissue. Ghrelin could protect the heart against I/R injury, at least in part, through inhibiting myocardial ERS.

Introduction

Numerous data have shown that ghrelin, a bioactive peptide with multi-functions, has broad-spectrum cardiovascular protective actions, including reducing heart injury induced by ischemia/reperfusion (I/R) [6], [11] or isoprenaline [7], improving the prognosis of myocardial infarction [34], [36], enhancing cardiac performance [25], ameliorating cardiac cachexia in heart failure [26], vasodilation [16], [24], and blunting vascular calcification [18]. The extensive homeostatic regulatory effect of ghrelin on the cardiovascular system can be attributed to its various beneficial functions in anti-inflammatory [8], [19] and anti-oxidative effects [15], protection of the vascular endothelium [32], [38], inhibition of apoptosis in myocardial and endothelial cells [2], and improvement of myocardial energy metabolism [5], [6]. However, the exact mechanism of ghrelin in cardioprotection needs to be further elucidated.

Endoplasmic reticulum stress (ERS) is a sub-cellular pathological process of misbalance in endoplasmic reticulum (ER) homeostasis and physical function disorder, which can be induced by various pathophysiological stimuli [14]. In the early stages of ERS, a series of signaling pathways are activated, and ER chaperone proteins such as glucose-regulated protein78 (GRP78) and GRP94 are overexpressed to help cells manage the stress; however, when ERS is prolonged and excessive, C/EBP homologous protein (CHOP), caspase-12 (an ERS-specific proapoptotic molecule) and cJUN NH₂-terminal kinase (JNK) are activated or upregulated, and the damaged cells undergo ERS-induced apoptosis [3]. ERS, extensively existing during many diseases, is considered an early or initial response of cells under stress or damage.

Previous studies have shown that ERS is involved in the pathogenesis of myocardial ischemia and I/R injury. In cultured cardiomyocytes, hypoxia/reoxygenation-induced injury was accompanied by overexpression of GRP78 protein and mRNA [21]. In isolated perfused rat hearts, GRP78, spliced X-box binding protein1 and phospho-JNK were increased in level with I/R (35/60 min) [31]. As well, myocardial GRP78 and GRP94 were overexpressed in mice hearts ex vivo with I/R (25/120 min) [22]. Serious myocardial ERS was also found in vivo in rats with I/R injury induced by ligation of the left anterior descending coronary artery [20], [35]. In addition, ERS extensively exists in other cardiovascular pathological processes, such as atherosclerosis, ischemic heart disease, cardiomyopathy, and heart failure. In these processes, ERS can cause cell damage and apoptosis while inhibiting or remodeling ERS response pathways may provide cardiovascular protection [39]. Ghrelin is a multi-functional polypeptide with cardiovascular protective effects. However, the relation between the cardiovascular protective effect of ghrelin and ERS has not been investigated.

The purpose of the present study was to verify whether ghrelin protect heart against I/R injury by inhibiting ERS. We studied the effect of ghrelin on myocardial ERS in an ex vivo heart I/R model and observed the direct effect of ghrelin on myocardial ERS in incubated cardiac tissue in vitro. And we found that ghrelin protects heart against I/R injury, at least partially by inhibiting myocardial ERS.

Section snippets

Materials

Male Sprague–Dawley (SD) rats (220 ± 10 g) were obtained from the Animal Center, Health Science Center, Peking University (Beijing, China). All animal care and experimental protocols complied with the Animal Management Rule of the Ministry of Health, People's Republic of China (documentation 55, 2001). Synthetic human ghrelin was produced by Phoenix Pharmaceuticals (Belmont, CA, USA). Dithiothreitol, tunicamycin and bovine serum albumin (BSA) were purchased from Sigma (St. Louis, MO, USA).

Ghrelin ameliorated the ex vivo I/R-induced depressed rat cardiac function

After preperfusion for 10 min (before ischemia), cardiac function parameters and CPF did not significantly differ among the three treatment groups (data not shown). Compared with the control group, the I/R group (40/120 min) showed significantly decreased left-ventricular pressure (ΔLVP, =LVESP − LVEDP, ±LVdp/dt_max, HR and CPF (all P < 0.01)) and significantly increased LVEDP (P < 0.01). Preadministration of ghrelin (in vivo 10⁻⁸ mol/kg, i.p. twice) significantly ameliorated the inhibited cardiac

Discussion

The endoplasmic reticulum (ER), one of the largest organelle in cell, plays an important role in the regulation of cellular homeostasis. It is responsible for protein synthesis, modification and processing; new peptide chain-folding, assembly and transportation; biosynthesis of steroids, cholesterol and many lipids; and intracellular calcium regulation [29]. Certain pathological conditions, such as hypoxia, ischemia, adenosine triphosphate depletion, viral infection, treatment with

Acknowledgments

This work was supported by the National Natural Science Foundation of China (30670847) and the State Major Basic Research Development Program of the People's Republic of China (2006CB503807).

References (46)

L. Chang et al.
Therapeutic effects of ghrelin on endotoxic shock in rats
Eur J Pharmacol
(2003)
S.O. Iseri et al.
Ghrelin alleviates biliary obstruction-induced chronic hepatic injury in rats
Regul Pept
(2008)
A. Kawczynska-Drozdz et al.
Ghrelin inhibits vascular superoxide production in spontaneously hypertensive rats
Am J Hypertens
(2006)
B. Kola et al.
Cannabinoids and ghrelin have both central and peripheral metabolic and cardiac effects via AMP-activated protein kinase
J Biol Chem
(2005)
G.Z. Li et al.
Ghrelin blunted vascular calcification in vivo and in vitro in rats
Regul Pept
(2005)
T. Momoi
Caspases involved in ER stress-mediated cell death
J Chem Neuroanat
(2004)
B.D. Obay et al.
Dose dependent effects of ghrelin on pentylenetetrazole-induced oxidative stress in a rat seizure model
Peptides
(2008)
X. Qi et al.
deltaPKC participates in the endoplasmic reticulum stress-induced response in cultured cardiac myocytes and ischemic heart
J Mol Cell Cardiol
(2007)
F. Rossi et al.
Ghrelin inhibits angiotensin II-induced migration of human aortic endothelial cells
Atherosclerosis
(2007)
K. Shintani-Ishida et al.
Ischemic preconditioning protects cardiomyocytes against ischemic injury by inducing GRP78
Biochem Biophys Res Commun
(2006)

K.A. Webster et al.

Cardioprotection in an in vitro model of hypoxic preconditioning

J Mol Cell Cardiol

(1995)

Z. Xu et al.

Ghrelin prevents doxorubicin-induced cardiotoxicity through TNF-alpha/NF-kappaB pathways and mitochondrial protective mechanisms

Toxicology

(2008)

J. Yang et al.

Identification of the acyltransferase that octanoylates ghrelin, an appetite-stimulating peptide hormone

Cell

(2008)

T. Askawa et al.

Thiobarbituric acid test for detecting lipid peroxide

Lipids

(1979)

G. Baldanzi et al.

Ghrelin and des-acyl ghrelin inhibit cell death in cardiomyocytes and endothelial cells through ERK1/2 and PI 3-kinase/AKT

J Cell Biol

(2002)

M. Boyce et al.

Cellular response to endoplasmic reticulum stress: a matter of life or death

Cell Death Differ

(2006)

J.P. Camina

Cell biology of the ghrelin receptor

J Neuroendocrinol

(2006)

L. Chang et al.

Protective effects of ghrelin on ischemia/reperfusion injury in the isolated rat heart

J Cardiovasc Pharmacol

(2004)

L. Chang et al.

Ghrelin protects myocardium from isoproterenol-induced injury in rats

Acta Pharmacol Sin

(2004)

V.D. Dixit et al.

Ghrelin inhibits leptin- and activation-induced proinflammatory cytokine expression by human monocytes and T cells

J Clin Invest

(2004)

E. El Eter et al.

In vivo and in vitro antioxidant activity of ghrelin: attenuation of gastric ischemic injury in the rat

J Gastroenterol Hepatol

(2007)

J.S. Elz et al.

Quantification of calcium paradox in neonatal rat hearts

Am J Physiol

(1987)

S. Frascarelli et al.

Effect of ghrelin and synthetic growth hormone secretagogues in normal and ischemic rat heart

Basic Res Cardiol

(2003)

Cited by (51)

Ghrelin as an anti-inflammatory and protective agent in ischemia/reperfusion injury
2020, Peptides
Ischemia/reperfusion (I/R) continue to be the most frequent cause of damaged tissues. Injured tissues resulted from the first ischemic insult, which is determined by the interruption in the blood supply, followed by subsequent impairment induced by reperfusion. In addition, ischemia-reperfusion injury is mediated by tumor necrosis factor (TNF) and other cytokines that activate complements and proteases responsible for free radical production. However, earlier studies have reported the protective roles of bioactive peptides during ischemia reperfusion injury. In fact, ghrelin is a peptide hormone discovered since 1999 as GH secretagogue and its production was identified in gastric X/A-like endocrine cells in rats and P/D1 type cells in humans. To date, this peptide receives growing attention due to its pleiotropic action in the organism and its role in maintaining energy homeostasis. Ghrelin is also involved in stress responses, assuming a modulatory action on immune pathways. Previous studies have identified many other functions related to an anti-inflammatory role in ischemia reperfusion injury. Under these challenging conditions, studies described acylated and unacylated ghrelin in activation and/or inhibition processes related to ischemia-reperfusion injury. The aim of this article is to provide a minireview about ghrelin mechanisms involved in the proinflammatory response of I/R injury. However, the regulatory processes of ghrelin in this pathologic event are still very limited and warrant further investigation.
The Homeostatic Force of Ghrelin
2018, Cell Metabolism
Citation Excerpt :
Furthermore, ghrelin exerts cytoprotective effects by suppressing ER stress. Ghrelin administration decreases myocardial apoptosis and ameliorates cardiac dysfunction after chemical or ischemic myocardial injury (Zhang et al., 2009, 2013). Ghrelin prevents ER stress and reduces apoptosis in primary rat cardiomyocytes (Zhang et al., 2013) (Figure 4C).
Ghrelin, a gastric-derived acylated peptide, regulates energy homeostasis by transmitting information about peripheral nutritional status to the brain, and is essential for protecting organisms against famine. Ghrelin operates brain circuits to regulate homeostatic and hedonic feeding. Recent research advances have shed new light on ghrelin's multifaceted roles in cellular homeostasis, which could maintain the internal environment and overcome metaflammation in metabolic organs. Here, we highlight our current understanding of the regulatory mechanisms of the ghrelin system in energy metabolism and cellular homeostasis and its clinical trials. Future studies of ghrelin will further elucidate how the stomach regulates systemic homeostasis.
Ghrelin ameliorates acute lung injury induced by oleic acid via inhibition of endoplasmic reticulum stress
2018, Life Sciences
Acute lung injury (ALI) is associated with excessive mortality and lacks appropriate therapy. Ghrelin is a novel peptide that protects the lung against ALI. This study aimed to investigate whether endoplasmic reticulum stress (ERS) mediates the protective effect of ghrelin on ALI.
We used a rat oleic acid (OA)-induced ALI model. Pulmonary impairment was detected by hematoxylin and eosin (HE) staining, lung mechanics, wet/dry weight ratio, and arterial blood gas analysis. Plasma and lung content of ghrelin was examined by ELISA, and mRNA expression was measured by quantitative real-time PCR. Protein levels were detected by western blot.
Rats with OA treatment showed significant pulmonary injury, edema, inflammatory cellular infiltration, cytokine release, hypoxia and CO₂ retention as compared with controls. Plasma and pulmonary content of ghrelin was reduced in rats with ALI, and mRNA expression was downregulated. Ghrelin (10 nmol/kg) treatment ameliorated the above symptoms, but treatment with the ghrelin antagonists D-Lys³ GHRP-6 (1 μmol/kg) and JMV 2959 (6 mg/kg) exacerbated the symptoms. ERS induced by OA was prevented by ghrelin and augmented by ghrelin antagonist treatment. The ERS inducer, tunicamycin (Tm) prevented the ameliorative effect of ghrelin on ALI. The decreased ratio of p-Akt and Akt induced by OA was improved by ghrelin treatment, and was further exacerbated by ghrelin antagonists.
Ghrelin protects against ALI by inhibiting ERS. These results provide a new target for prevention and therapy of ALI.
Ghrelin Ameliorates Asthma by Inhibiting Endoplasmic Reticulum Stress
2017, American Journal of the Medical Sciences
This study aimed to confirm the ameliorative effect of ghrelin on asthma and investigate its mechanism.
The murine model of asthma was induced by ovalbumin (OVA) treatment and assessed by histological pathology and airway responsiveness to methacholine. The total and differential leukocytes were counted. Tumor necrosis factor α, interferon γ, interleukin-5 and interleukin-13 levels in bronchoalveolar lavage fluid were quantified by commercial kits. The protein levels in pulmonary tissues were measured by Western blot analysis.
Ghrelin ameliorated the histological pathology and airway hyperresponsiveness in the OVA-induced asthmatic mouse model. Consistently, OVA-increased total and differential leukocytes and levels of tumor necrosis factor α, interferon γ, interleukin-5 and interleukin-13 in bronchoalveolar lavage fluid were significantly attenuated by ghrelin. Ghrelin prevented the increased protein levels of the endoplasmic reticulum stress markers glucose regulated protein 78 and CCAAT/enhancer binding protein homologous protein and reversed the reduced levels of p-Akt in asthmatic mice.
Ghrelin might prevent endoplasmic reticulum stress activation by stimulating the Akt signaling pathway, which attenuated inflammation and ameliorated asthma in mice. Ghrelin might be a new target for asthma therapy.
Inhibition of endoplasmic reticulum stress by neuregulin-1 protects against myocardial ischemia/reperfusion injury
2017, Peptides
Citation Excerpt :
Inhibition of ER stress and ER stress-associated apoptosis provides cardiovascular protection, including alleviating cardiac I/R injury [2,5,10]. Our previous data demonstrated that ghrelin and intermedin 1–53, two other myocardial protective auto/paracrine factors, protect the myocardium against I/R injury by inhibiting ER stress [8,9]. These data indicate that autocrine/paracrine factors of the cardiovascular system can play a cardioprotective role by regulating ER stress in myocardial physiologic and pathophysiologic processes.
Neuregulin-1 (NRG-1), an endogenously produced polypeptide, is the ligand of cardiomyocyte ErbB receptors, with cardiovascular protective effects. In the present study, we explored whether the cardioprotective effect of NRG-1 against I/R injury is mediated by inhibiting myocardial endoplasmic reticulum (ER) stress. In vitro, NRG-1 directly inhibited the upregulation of ER stress markers such as glucose-regulated protein 78, CCAAT/enhancer binding protein homologous protein and cleaved caspase-12 induced by the ER stress inducers tunicamycin or dithiothreitol in both neonatal and adult ventricular myocytes. Attenuating ErbB signals by an ErbB inhibitor AG1478 or ErbB4 knockdown and preincubation with phosphoinositide 3-kinase inhibitors all reversed the effect of NRG-1 inhibiting ER stress in cultured neonatal rat cardiomyocytes. Concurrently, cardiomyocyte ER stress and apoptosis induced by hypoxia-reoxygenation were decreased by NRG-1 treatment in vitro. Furthermore, in an in vivo rat model of myocardium ischemia/reperfusion (I/R), intravenous NRG-1 administration significantly decreased ER stress and myocardial infarct size induced by I/R. NRG-1 could protect the heart against I/R injury by inhibiting myocardial ER stress, which might be mediated by the phosphoinositide 3-kinase/Akt signaling pathway.
Gut-Derived Hormones-Cardiac Effects of Ghrelin and Glucagon-Like Peptide-1
2017, Endocrinology of the Heart in Health and Disease: Integrated, Cellular, and Molecular Endocrinology of the Heart
The effects of gut-derived hormones on the cardiovascular system have aroused the interest of numerous experimental and clinical investigators for decades. Among these hormones, ghrelin and glucagon-like peptide-1 (GLP-1) are certainly the most promising for their therapeutic potential. Ghrelin is a potent growth hormone secretogogue mainly produced by the stomach. It regulates feeding and metabolism and exerts also a number of beneficial actions on the cardiovascular system, such as cardiomyocyte cytoprotection, mitigation of inflammatory processes, and improvement of cardiac function. GLP-1 is an incretin hormone secreted by endocrine L-cells. It enhances glucose-dependent insulin secretion after food ingestion and, similar to ghrelin, exerts a number of actions on different organs, including the heart. GLP-1 administration to type 2 diabetic patients improves body weight and glycemic control, reduces inflammation, and protects the heart. In this chapter we will review the existing evidence supporting important cardiovascular effects of these two hormones and their potential therapeutic use.

View all citing articles on Scopus

View full text

Inhibition of endoplasm reticulum stress by ghrelin protects against ischemia/reperfusion injury in rat heart

Abstract

Introduction

Section snippets

Materials

Ghrelin ameliorated the ex vivo I/R-induced depressed rat cardiac function

Discussion

Acknowledgments

Eur J Pharmacol

Regul Pept

Am J Hypertens

J Biol Chem

Regul Pept

J Chem Neuroanat

Peptides

J Mol Cell Cardiol

Atherosclerosis

Biochem Biophys Res Commun

J Mol Cell Cardiol

Toxicology

Cell

Thiobarbituric acid test for detecting lipid peroxide

Lipids

Ghrelin and des-acyl ghrelin inhibit cell death in cardiomyocytes and endothelial cells through ERK1/2 and PI 3-kinase/AKT

J Cell Biol

Cellular response to endoplasmic reticulum stress: a matter of life or death

Cell Death Differ

Cell biology of the ghrelin receptor

J Neuroendocrinol

Protective effects of ghrelin on ischemia/reperfusion injury in the isolated rat heart

J Cardiovasc Pharmacol

Ghrelin protects myocardium from isoproterenol-induced injury in rats

Acta Pharmacol Sin

Ghrelin inhibits leptin- and activation-induced proinflammatory cytokine expression by human monocytes and T cells

J Clin Invest

In vivo and in vitro antioxidant activity of ghrelin: attenuation of gastric ischemic injury in the rat

J Gastroenterol Hepatol

Quantification of calcium paradox in neonatal rat hearts

Am J Physiol

Effect of ghrelin and synthetic growth hormone secretagogues in normal and ischemic rat heart

Basic Res Cardiol