Exenatide protects against hypoxia/reoxygenation-induced apoptosis by improving mitochondrial function in H9c2 cells

Abstract

Glucagon-like peptide-1 (GLP-1) analogues might exert the cardioprotective effects via attenuating apoptosis. This study aimed to determine the protective effects and mechanism of exenatide, a GLP-1 analogue, on cardiomyocyte apoptosis using an in vitro model of hypoxia/reoxygenation (H/R). H9c2 cells were employed to establish an in vitro model of H/R. 200 nM exenatide pretreatment significantly reduced apoptosis measured by flow cytometry. To further study the antiapoptotic mechanism of exenatide, we used flow cytometry in combination with laser confocal microscopy to determine the interaction between exenatide and the process of mitochondria-mediated apoptosis. We found that exenatide pretreatment reduced the intracellular reactive oxygen species (ROS) levels and decreased the mitochondrial calcium overload caused by H/R. Furthermore, an increase of total superoxide dismutase (T-SOD) levels, a decrease of malondialdehyde (MDA) levels, a preservation of mitochondrial membrane potential (ΔΨm), a reduction of cytochrome-c release, a decline of cleaved caspase-3 expression, and caspase-3 activation were observed in exenatide-pretreated cultures. These results suggest that exenatide exerts a protective effect on preventing against H/R-induced apoptosis. Importantly, the protective effects of exenatide may be attributed to its role in improving mitochondrial function in H9c2 cells subjected to H/R.

Geniposide Prevents Hypoxia/Reoxygenation-Induced Apoptosis in H9c2 Cells: Improvement of Mitochondrial Dysfunction and Activation of GLP-1R and the PI3K/AKT Signaling Pathway

“…Cardiomyocyte apoptosis induced by I/R is an essential process in the progression of heart failure. Mitochondria play a crucial role in cardiomyocyte apoptosis under hypoxic conditions [3,4]. This study showed that H/R treatment caused mitochondrial dysfunction and cardiomyocyte apoptosis, whereas, pretreatment with geniposide improved mitochondrial dysfunction and attenuated mitochondria-dependent cell apoptosis.…”

“…In addition to their significant role in cell apoptosis, mitochondria are also the primary sources of oxidative stress during H/R [3,10]. ROS and RNS are products of mitochondrial oxidative stress, and production of ROS is a vital step in the mitochondria-dependent apoptosis pathway [3,4,27].…”

“…Cardiomyocyte apoptosis caused by ischemia/reperfusion (I/R) injury can lead to myocardial cell loss, which further accelerates cardiac dysfunction, ventricular remodeling, and even heart failure [3][4][5][6]. Numerous studies have reported that inhibition of apoptosis could attenuate myocardial damage, decrease cardiomyocyte removal, and improve ventricular contractile function caused by I/R [7].…”

“…Cardiomyocyte apoptosis includes two major pathways, the extrinsic pathway via death receptors, and the intrinsic pathway involving mitochondria [8,9]. Notably, the mitochondria-dependent pathway plays a key role in I/R-induced myocardial cell apoptosis [3,4,10]. The most typical characteristic of myocardial ischemia is severe hypoxia, which could cause acidosis, energy depletion, and ion homeostasis rupture, ultimately resulting in cardiomyocyte death [11].…”

“…Geniposide, an extract of Gardenia jasminoides J. Ellis and a novel agonist for glucagon-like peptide-1 receptor (GLP-1R), has been shown to exert antinociception effects [15], promote β-cell regeneration, attenuate β-cell apoptosis [16,17], regulate insulin secretion in INS-1 cells [18], and prevent oxidative stress of PC12 cell [19]. Accumulating evidences has revealed that glucagon-like peptide 1 (GLP-1) and GLP-1 analogues exert anti-apoptotic effects by activating GLP-1R via the phosphatidylinositol 3 kinase (PI3K)/ AKT signaling pathway [3,[20][21][22]. Geniposide can also activate GLP-1R in response to oxidative stress in PC12 cells via the PI3K/AKT pathway [23], inhibit PC12 cell death by the mitochondrial pathway [24], and attenuate memory deficits in amyloid precursor protein (APP)/ presenilin 1(PS1) transgenic mice by improving mitochondrial dysfunction [25].…”