Exercise copes with prolonged stress-induced impairment of spatial memory performance by endoplasmic reticulum stress

Exploration of the Moderating Effects of Physical Activity and Early Life Stress on the Relation between Brain-Derived Neurotrophic Factor (BDNF) rs6265 Variants and Depressive Symptoms among Adolescents

Depression affects one in five persons at 18 years of age. Allele A of the brain-derived neurotrophic factor (BDNF) rs6265 is considered to be a risk factor for depression. Previous studies of the interaction between BDNF rs6265, early adversity, and/or physical activity have shown mixed results. In this study, we explored the relation between BDNF rs6265 polymorphism and childhood stress, as well as the moderating effect of physical activity in relation to depressive symptoms using binary logistic regressions and process models 1, 2 and 3 applied to data obtained at three times (waves 1, 2 and 3) from the Survey of Adolescent Life in Västmanland cohort study (SALVe). Results revealed that both childhood stress and physical activity had a moderation effect; physical activity in wave 1 with an R2 change = 0.006, p = 0.013, and the Johnson−Neyman regions of significance (RoS) below 1.259, p = 0.05 for 11.97%; childhood stress in wave 2 with the R2 change = 0.008, p = 0 002, and RoS below 1.561 with 26.71% and >4.515 with 18.20%; and a three-way interaction in wave 1 in genotype AA carriers. These results suggest that allele A is susceptible to physical activity (positive environment) and childhood stress (negative environment).

The Effect of Resistance Training and Berberine Chloride on the Apoptosis-related Unfolded Protein Response Signaling Pathway in the Hippocampus of Diazinon-poisoned Rats

Introduction:

Diazinon is one of the most widely-used organophosphate pesticides in the world. This toxin enters the body in various ways and induces oxidative stress in various tissues. It has been proved that activation of Unfolded Protein Response (UPR) under oxidative stress is a steady mechanism for maintaining cell function and survival. Therefore, the present study aimed to review the effect of Resistance Training (RT) and Berberine Chloride (BC) on the apoptosis-related UPR signaling pathway in the hippocampus of diazinon-poisoned rats.

Methods:

In this experimental study, 40 male Wistar rats weighing 250 ±50 g were randomly divided into eight groups of five rats of 1) diazinon + 2 mg/kg BC + RT, 2) diazinon + 15 mg/kg BC + RT, 3) diazinon, 4) diazinon + RT, 5) diazinon + 2 mg/kg BC, 6) diazinon + 15 mg/kg BC, 7) healthy control, and 8) sham. The groups were treated for 5 weeks. At the end of the fifth week, ATF-4, ATF-6, and CHOP gene expression in hippocampus tissue were measured by quantitative real-time RT-PCR.

Results:

Diazinon significantly increased the expression of ATF-4, ATF-6, and CHOP in the hippocampus tissue of rats. Administrating 15 mg/kg BC with RT significantly decreased these genes, indicating a decrease in the rate of apoptosis in the hippocampus.

Conclusion:

This study showed that RT and BC have a protective effect against diazinon-induced toxicity in the hippocampus.

Aerobic exercise ameliorates cardiac hypertrophy by regulating mitochondrial quality control and endoplasmic reticulum stress through M2 AChR

Aerobic exercise increases M2 AChR, which thus improves cardiac function in cardiovascular disease (CVD) rats. This study aimed to determine whether aerobic exercise could ameliorate pressure overload-induced heart hypertrophy through M2 AChR, and to elucidate the underlying mechanisms of action. Mice were used to establish the myocardial hypertrophy model by transverse aortic constriction (TAC), and subjected to 2, 4, and 8 weeks of moderate-intensity aerobic exercise and choline intervention (14 mg/kg/day). Our results showed that 4 and 8 weeks of exercise and choline intervention reduced excessive mitochondrial fission and autophagy of myocardial mitochondria, thereby improving the ultrastructure and function of mitochondria after TAC. Moreover, 8-week exercise and choline intervention have enhanced parasympathetic function and promoted the expression of M2 AChR. In addition, 8-week exercise and choline intervention also inhibited the protein expression of myocardial MFN2, PERK/eIF2α/ATF4, and NLRP3/caspase-1/IL-1β signaling pathways, thereby effectively reducing mitochondrial fusion, endoplasmic reticulum stress, and inflammation. Taken together, these data suggest that pressure overload led to cardiac hypertrophy, cardiac dysfunction, and decreased parasympathetic function in cardiac tissues. Aerobic exercise attenuated cardiac dysfunction by modulating the expression of proteins involved in mitochondrial quality control, and induced endoplasmic reticulum stress and inflammation, thereby reducing cardiac hypertrophy and improving cardiac function in impaired heart tissues following TAC, which was likely mediated by M2 AChR activation.

Nerve Growth Factor Protects Against Pyrethroid-Induced Endoplasmic Reticulum (ER) Stress in Primary Hippocampal Neurons

Neurotrophins are a family of growth factors crucial for growth and survival of neurons in the developing and adult brain. Reduction in neurotrophin levels is associated with reduced neurogenesis and cognitive deficits in rodents. Recently, we demonstrated that long-term exposure to low levels of the pyrethroid pesticide deltamethrin causes hippocampal endoplasmic reticulum (ER) stress and learning deficits in mice. Here, we found that nerve growth factor (NGF) mRNA and protein were selectively reduced in the hippocampus of deltamethrin-treated mice. To explore potential mechanisms responsible for this observation, we employed mouse primary hippocampal neurons. Exposure of neurons to deltamethrin (1-5 μM) caused ER stress as indicated by increased levels of C/EBP-homologous protein (CHOP) and glucose-regulated protein 78 (GRP78). These changes were accompanied by increased levels of caspase-12, activated caspase-3, and decreased levels of NGF. Inhibition of ER stress with the eukaryotic initiation factor 2 alpha (eIF2α) inhibitor salubrinal abolished deltamethrin-induced activation of caspase-12 and caspase-3, and restored NGF levels. Furthermore, deltamethrin decreased Akt (protein kinase B) phosphorylation, which was significantly prevented by co-treatment with NGF or SC-79 in cells. Collectively, these results demonstrate that the loss of NGF following ER stress may contribute to deltamethrin-induced apoptosis in the hippocampus through the Akt signaling pathway, and that this may provide a plausible mechanism for impaired learning and memory observed following exposure of mice to deltamethrin.

The chemical chaperon 4-phenyl butyric acid restored high-fat diet- induced hippocampal insulin content and insulin receptor level reduction along with spatial learning and memory deficits in male rats

This study assessed the effect of a chronic high-fat diet (HFD) on plasma and hippocampal insulin and corticosterone levels, the hippocampus insulin receptor amount, and spatial learning and memory with or without receiving 4-phenyl butyric acid (4-PBA) in male rats. Rats were divided into high-fat and normal diet groups, then each group was subdivided into dimethyl sulfoxide (DMSO) and 4-PBA groups. After weaning, the rats were fed with HFD for 20 weeks. Then, 4-PBA or DMSO were injected for 3 days. Subsequently, oral glucose tolerance test was done. On the following day, spatial memory tests were performed. Then the hippocampus Bip, Chop, insulin, corticosterone, and insulin receptor levels were determined. HFD increased plasma glucose, leptin and corticosterone concentrations, hippocampus Bip, Chop and corticosterone levels, food intake, abdominal fat weight and body weight along with impaired glucose tolerance. It decreased plasma insulin, and insulin content, and its receptor amount in hippocampus. HFD lengthened escape latency and shortened the duration spent in target zone. 4-PBA administration improved the HFD- induced adverse changes. Chronic HFD possibly through the induction of endoplasmic reticulum (ER) stress and subsequent changes in the levels of hippocampal corticosterone, insulin and insulin receptor along with possible leptin resistance caused spatial learning and memory deficits.

Up-regulation of Thioredoxin 1 by aerobic exercise training attenuates endoplasmic reticulum stress and cardiomyocyte apoptosis following myocardial infarction

Exercise training (ET) has been reported to reduce oxidative stress and endoplasmic reticulum (ER) stress in the heart following myocardial infarction (MI). Thioredoxin 1 (Trx1) plays a protective role in the infarcted heart. However, whether Trx1 regulates ER stress of the infarcted heart and participates in ET-induced cardiac protective effects are still not well known. In this work, H9c2 cells were treated with hydrogen peroxide (H₂O₂) and recombinant human Trx1 protein (TXN), meanwhile, adult male C57B6L mice were used to establish the MI model, and subjected to a six-week aerobic exercise training (AET) with or without the injection of Trx1 inhibitor, PX-12. Results showed that H₂O₂ significantly increased reactive oxygen species (ROS) level and the expression of TXNIP, CHOP and cleaved caspase12, induced cell apoptosis; TXN intervention reduced ROS level and the expression of CHOP and cleaved caspase12, and inhibited cell apoptosis in H₂O₂-treated H9c2 cells. Furthermore, AET up-regulated endogenous Trx1 protein expression and down-regulated TXNIP expression, restored ROS level and the expression of ER stress-related proteins, inhibited cell apoptosis as well as improved cardiac fibrosis and heart function in mice after MI. PX-12 partly inhibited the AET-induced beneficial effects in the infarcted heart. This study demonstrates that Trx1 attenuates ER stress-induced cell apoptosis, and AET reduces MI-induced ROS overproduction, ER stress and cell apoptosis partly through up-regulating of Trx1 expression in mice with MI.

Protective and therapeutic effects of exercise on stress-induced memory impairment

The objective of this paper was to systematically evaluate the potential preventive and therapeutic effects of exercise in attenuating stress-induced memory impairment. A systematic review was employed, searching PubMed, PsychInfo, Sports Discus and Google Scholar databases. For eligibility, studies had to be published in English, employ an experimental design, have the acute or chronic bout of exercise occur prior to, during or after the stressor, implement a psychophysiological stressor, and have an assessment of memory function occurring after the stressor. In total, 23 studies were evaluated, all of which were conducted among animal models. All 23 studies employed a chronic exercise protocol and a chronic stress protocol. Eight studies evaluated a preventive model, three employed a concurrent model, ten studies employed a therapeutic model, and two studies evaluated both a preventive and therapeutic model within the same study. Among the eight studies employing a preventive model, all eight demonstrated that the stress regimen impaired memory function. In all eight of these studies, when exercise occurred prior to the stressor, exercise attenuated the stress-induced memory impairment effect. Among the ten studies employing a therapeutic model, one study showed that the stress protocol enhanced memory function, one showed that the stress protocol did not influence memory, and eight demonstrated that the stress regimen impaired memory function. Among the eight studies showing that the stress protocol impaired memory function, all eight studies demonstrated that exercise, after the stressor, attenuated stress-induced memory impairment. Within animal models, chronic stress is associated with memory impairment and chronic exercise has both a preventive and therapeutic effect in attenuating stress-induced memory impairment. Additional experimental work in human studies is needed. Such work should also examine acute exercise and stress protocols.

Endoplasmic Reticulum Unfolded Protein Response, Aging and Exercise: An Update

The endoplasmic reticulum (ER) is a dynamic and multifunctional organelle responsible for protein biosynthesis, folding, assembly and modifications. Loss of protein folding regulation, which leads to unfolded or misfolded proteins accumulation inside the ER lumen, drives ER stress (ERS) and unfolded protein response (UPR) activation. During aging, there is a decline in the ability of the cell to handle protein folding, accumulation and aggregation, and the function of UPR is compromised. There is a progressive failure of the chaperoning systems and a decline in many of its components, so that the UPR activation cannot rescue the ERS. Physical activity has been proposed as a powerful tool against aged-related diseases, which are linked to ERS. Interventional studies have demonstrated that regular exercise is able to decrease oxidative stress and inflammation and reverse mitochondrial and ER dysfunctions. Exercise-induced metabolic stress could activate the UPR since muscle contraction is directly involved in its activation, mediating exercise-induced adaptation responses. In fact, regular moderate-intensity exercise-induced ERS acts as a protective mechanism against current and future stressors. However, biological responses vary according to exercise intensity and therefore induce different degrees of ERS and UPR activation. This article reviews the effects of aging and exercise on ERS and UPR, also analyzing possible changes induced by different types of exercise in elderly subjects.

Effect of Crocin, Exercise, and Crocin-accompanied Exercise on Learning and Memory in Rats under Chronic Unpredictable Stress

Background:

Stress affects brain functions and induces psychological disorders. Previous studies have indicated different effects of crocin and exercise on the improvement of memory in some types of stress. The present study investigated the effect of crocin, exercise, and crocin-accompanied exercise on learning, memory, and memory consolidation in rats under chronic unpredictable stress (CUS).

Materials and Methods:

Male rats were randomly allocated to different groups: control, sham, stress, stress-exercise, stress-crocin, and stress-crocin-accompanied exercise groups. The CUS and treadmill running were applied 2 h/day and 1 h/day, respectively, for 21 days. Crocin (30 mg/kg) was daily intraperitoneally injected to the rats and their behavioral variables were evaluated as a brain function using the passive avoidance test.

Results:

Results showed that the CUS significantly decreased learning and memory compared to the control group, while crocin alone and crocin-accompanied exercise significantly improved learning and memory compared to the stressed group. It was found that exercise alone caused learning but did not improve memory in unpredictable stress rats.

Conclusion:

The data indicated that unpredictable stress had very destructive effects on the brain functions. Furthermore, unlike exercise, crocin improved memory under unpredictable stress conditions. Overall, it seems that the beneficial effects of crocin-accompanied exercise on learning and memory were probably because of crocin, but not exercise.

A comprehensive review of genetic and epigenetic mechanisms that regulate BDNF expression and function with relevance to major depressive disorder

Major depressive disorder (MDD) is a mood disorder that affects behavior and impairs cognition. A gene potentially important to this disorder is the brain derived neurotrophic factor (BDNF) as it is involved in processes controlling neuroplasticity. Various mechanisms exist to regulate BDNF's expression level, subcellular localization, and sorting to appropriate secretory pathways. Alterations to these processes by genetic factors and negative stressors can dysregulate its expression, with possible implications for MDD. Here, we review the mechanisms governing the regulation of BDNF expression, and discuss how disease-associated single nucleotide polymorphisms (SNPs) can alter these mechanisms, and influence MDD. As negative stressors increase the likelihood of MDD, we will also discuss the impact of these stressors on BDNF expression, the cellular effect of such a change, and its impact on behavior in animal models of stress. We will also describe epigenetic processes that mediate this change in BDNF expression. Similarities in BDNF expression between animal models of stress and those in MDD will be highlighted. We will also contrast epigenetic patterns at the BDNF locus between animal models of stress, and MDD patients, and address limitations to current clinical studies. Future work should focus on validating current genetic and epigenetic findings in tightly controlled clinical studies. Regions outside of BDNF promoters should also be explored, as should other epigenetic marks, to improve identification of biomarkers for MDD.

Effects of repeated restraint stress and WiFi signal exposure on behavior and oxidative stress in rats

Today, due to technology development and aversive events of daily life, Human exposure to both radiofrequency and stress is unavoidable. This study investigated the co-exposure to repeated restraint stress and WiFi signal on cognitive function and oxidative stress in brain of male rats. Animals were divided into four groups: Control, WiFi-exposed, restrained and both WiFi-exposed and restrained groups. Each of WiFi exposure and restraint stress occurred 2 h (h)/day during 20 days. Subsequently, various tests were carried out for each group, such as anxiety in elevated plus maze, spatial learning abilities in the water maze, cerebral oxidative stress response and cholinesterase activity in brain and serum. Results showed that WiFi exposure and restraint stress, alone and especially if combined, induced an anxiety-like behavior without impairing spatial learning and memory abilities in rats. At cerebral level, we found an oxidative stress response triggered by WiFi and restraint, per se and especially when combined as well as WiFi-induced increase in acetylcholinesterase activity. Our results reveal that there is an impact of WiFi signal and restraint stress on the brain and cognitive processes especially in elevated plus maze task. In contrast, there are no synergistic effects between WiFi signal and restraint stress on the brain.

The Role of Endoplasmic Reticulum Stress in Cardiovascular Disease and Exercise

Endoplasmic reticulum (ER) stress, which is highly associated with cardiovascular disease, is triggered by a disturbance in ER function because of protein misfolding or an increase in protein secretion. Prolonged disruption of ER causes ER stress and activation of the unfolded protein response (UPR) and leads to various diseases. Eukaryotic cells respond to ER stress via three major sensors that are bound to the ER membrane: activating transcription factor 6 (ATF6), inositol-requiring protein 1α (IRE1α), and protein kinase RNA-like ER kinase (PERK). Chronic activation of ER stress causes damage in endothelial cells (EC) via apoptosis, inflammation, and oxidative stress signaling pathways. The alleviation of ER stress has recently been accepted as a potential therapeutic target to treat cardiovascular diseases such as heart failure, hypertension, and atherosclerosis. Exercise training is an effective nonpharmacological approach for preventing and alleviating cardiovascular disease. We here review the recent viewing of ER stress-mediated apoptosis and inflammation signaling pathways in cardiovascular disease and the role of exercise in ER stress-associated diseases.

Nupr1 Modulates Methamphetamine-Induced Dopaminergic Neuronal Apoptosis and Autophagy through CHOP-Trib3-Mediated Endoplasmic Reticulum Stress Signaling Pathway

Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH exposure causes detrimental effects on multiple organ systems, primarily the nervous system, especially dopaminergic pathways, in both laboratory animals and humans. In this study, we hypothesized that Nuclear protein 1 (Nupr1/com1/p8) is involved in METH-induced neuronal apoptosis and autophagy through endoplasmic reticulum (ER) stress signaling pathway. To test this hypothesis, we measured the expression levels of Nupr1, ER stress protein markers CHOP and Trib3, apoptosis-related protein markers cleaved-caspase3 and PARP, as well as autophagy-related protein markers LC3 and Beclin-1 in brain tissues of adult male Sprague-Dawley (SD) rats, rat primary cultured neurons and the rat adrenal pheochromocytoma cells (PC12 cells) after METH exposure. We also determined the effects of METH exposure on the expression of these proteins after silencing Nupr1, CHOP, or Trib3 expression with synthetic small hairpin RNA (shRNA) or siRNA in vitro, and after silencing Nupr1 in the striatum of rats by injecting lentivirus containing shRNA sequence targeting Nupr1 gene to rat striatum. The results showed that METH exposure increased Nupr1 expression that was accompanied with increased expression of ER stress protein markers CHOP and Trib3, and also led to apoptosis and autophagy in rat primary neurons and in PC12 cells after 24 h exposure (3.0 mM), and in the prefrontal cortex and striatum of rats after repeated intraperitoneal injections (15 mg/kg × 8 injections at 12 h intervals). Silencing of Nupr1 expression partly reduced METH-induced apoptosis and autophagy in vitro and in vivo. These results suggest that Nupr1 plays an essential role in METH-caused neuronal apoptosis and autophagy at relatively higher doses and may be a potential therapeutic target in high-dose METH-induced neurotoxicity.

Levels of Hepatic Activating Transcription Factor 6 and Caspase-3 Are Downregulated in Mice after Excessive Training

Recently, we demonstrated that different running overtraining (OT) protocols with the same external load, but performed downhill (OTR/down), uphill (OTR/up), and without inclination (OTR), led to hepatic fat accumulation. As the disruption of endoplasmic reticulum (ER) homeostasis is linked to animal models of fatty liver disease, we investigated the effects of these OT models on the proteins related to ER stress (i.e., BiP, inositol-requiring enzyme 1, protein kinase RNA-like endoplasmic reticulum kinase, eIF2alpha, ATF6beta, and glucose-regulated protein 94) and apoptosis (C/EBP-homologous protein, Caspase-3, 4, and 12, Bax, and tumor necrosis factor receptor-associated factor 2) in livers of C57BL/6 mice. Also, aerobic training can attenuate cardiac ER stress and improve exercise capacity. Therefore, we investigated whether the decrease in performance induced by our OT protocols is linked to ER stress and apoptosis in mouse hearts. The rodents were divided into six groups: naïve (N, sedentary mice), control (CT, sedentary mice submitted to the performance evaluations), trained (TR), OTR/down, OTR/up, and OTR groups. Rotarod, incremental load, exhaustive, and grip force tests were used to evaluate performance. After the grip force test, the livers and cardiac muscles (i.e., left ventricle) were removed and used for immunoblotting. All of the OT protocols led to similar responses in the performance parameters and displayed significantly lower hepatic ATF6beta values compared to the N group. The OTR/down group exhibited lower liver cleaved caspase-3 values compared to the CT group. However, the other proteins related to ER stress and apoptosis were not modulated. Also, the cardiac proteins related to ER stress and apoptosis were not modulated in the experimental groups. In conclusion, the OT protocols decreased the levels of hepatic ATF6beta, and the OTR/down group decreased the levels of hepatic cleaved caspase-3. Also, the decrease in performance induced by our OT models is not associated with ER stress and apoptosis in mice hearts.

Physical exercise alleviates ER stress in obese humans through reduction in the expression and release of GRP78 chaperone

BACKGROUND AND OBJECTIVES

Perturbation of the endoplasmic reticulum (ER) homeostasis has emerged as one of the prominent features of obesity and diabetes. This occurs when the adaptive unfolded protein response (UPR) fails to restore ER function in key metabolic tissues. We previously reported increased inflammation and impaired heat shock response (HSR) in obese human subjects that were restored by physical exercise. Here, we investigated the status of ER stress chaperone; glucose-regulated protein 78 (GRP78) and its downstream UPR pathways in human obese, and their modulation by a supervised 3-month physical exercise.

METHODS

Subcutaneous adipose tissue (SAT) and blood samples were collected from non-diabetic adult human lean (n=40) and obese (n=40, at baseline and after 3months of physical exercise). Transcriptomic profiling was used as a primary screen to identify differentially expressed genes and it was carried out on SAT samples using the UPR RT(2) Profiler PCR Array. Conventional RT-PCR, immunohistochemistry, immunofluorescence, Western blot and ELISA were used to validate the transcriptomic data. Correlation analyses with the physical, clinical and biochemical outcomes were performed using Pearson's rank correlation coefficient.

RESULTS

Levels of GRP78 and its three downstream UPR arms; activating transcription factor-6 (ATF6), inositol-requiring enzyme-1α (IRE1α) and protein kinase RNA-like endoplasmic reticulum kinase (PERK) were increased in obese subjects. More interestingly, higher levels of circulating GRP78 protein were found in obese compared to lean subjects which correlated negatively with maximum oxygen uptake (VO2 Max) but positively with high-sensitivity C-reactive protein (hsCRP) and obesity indicators such as BMI, percentage body fat (PBF) and waist circumference. GRP78 increased secretion in obese was further confirmed in vitro using 3T3-L1 preadipocyte cells under ER stress. Finally, we showed that physical exercise significantly attenuated the expression and release of GRP78 with a concomitant reduction in the phosphorylation of IRE1α and eukaryotic initiation factor-2α (eIF2α).

CONCLUSION

Our results suggest that physical exercise alleviates ER stress in human obese through attenuation of GRP78 signaling network.

Nupr1/Chop signal axis is involved in mitochondrion-related endothelial cell apoptosis induced by methamphetamine

Methamphetamine (METH) abuse has been a serious global public health problem for decades. Previous studies have shown that METH causes detrimental effects on the nervous and cardiovascular systems. METH-induced cardiovascular toxicity has been, in part, attributed to its destructive effect on vascular endothelial cells. However, the underlying mechanism of METH-caused endothelium disruption has not been investigated systematically. In this study, we identified a novel pathway involved in endothelial cell apoptosis induced by METH. We demonstrated that exposure to METH caused mitochondrial apoptosis in human umbilical vein endothelial cells and rat cardiac microvascular endothelial cells in vitro as well as in rat cardiac endothelial cells in vivo. We found that METH mediated endothelial cell apoptosis through Nupr1–Chop/P53–PUMA/Beclin1 signaling pathway. Specifically, METH exposure increased the expression of Nupr1, Chop, P53 and PUMA. Elevated p53 expression raised up PUMA expression, which initiated mitochondrial apoptosis by downregulating antiapoptotic Bcl-2, followed by upregulation of proapoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. Interestingly, increased Beclin1, upregulated by Chop, formed a ternary complex with Bcl-2, thereby decreasing the dissociative Bcl-2. As a result, the ratio of dissociative Bcl-2 to Bax was also significantly decreased, which led to translocation of cyto c and initiated more drastic apoptosis. These findings were supported by data showing METH-induced apoptosis was significantly inhibited by silencing Nupr1, Chop or P53, or by PUMA or Beclin1 knockdown. Based on the present data, a novel mechanistic model of METH-induced endothelial cell toxicity is proposed. Collectively, these results highlight that the Nupr1–Chop/P53–PUMA/Beclin1 pathway is essential for mitochondrion-related METH-induced endothelial cell apoptosis and may be a potential therapeutic target for METH-caused cardiovascular toxicity. Future studies using knockout animal models are warranted to substantiate the present findings.