Aged Rat Heart Research Articles

Protective Effect of Carvacrol against Oxidative Damage in Aged Rats.

Aging affects cellular functions and impairs tissue homeostasis. Carvacrol, a polyphenolic compound, has been shown to exert a wide range of pharmacological effects, such as antioxidant, anti-inflammatory, and anticancer characteristics. This investigation aimed to evaluate the effect of carvacrol in elderly male rats. Carvacrol at a dose of 15 or 30 mg/kg was administrated daily per os for 60 days to aged rats. The liver, heart, and kidney samples were taken for the analysis of oxidative stress markers. Serum samples were used to evaluate liver enzymes (alanine transaminase (ALT) and aspartate aminotransferase (AST)). The levels of malondialdehyde (MDA) in the liver, heart, and kidney tissues of aged rats were higher. Conversely, the level of thiol was lower in the mentioned tissues than in the young control group. The levels of MDA in the liver, heart, and kidney tissues of aged rats were significantly reduced by carvacrol, which was accompanied by increased levels of total thiol. ALT and AST levels were higher in the serum of aged rats than in the young control ones. Carvacrol decreased ALT and AST levels in the serum of aged rats versus aged control rats. Carvacrol can be effective in protecting susceptible aged tissues and organs by increasing antioxidant defenses and decreasing liver enzymes.

Light transmittance in human atrial tissue and transthoracic illumination in rats support translatability of optogenetic cardioversion of AF

Abstract Background Optogenetics could offer a solution to the current lack of an ambulatory method for rapid automated cardioversion of AF, but key translational aspects remain to be studied. Objective To investigate whether optogenetic cardioversion of AF is effective in the aged heart and whether sufficient light penetrates the human atrial wall. Methods Atria of adult (7 weeks old) and aged (2 years old) rats were optogenetically modified to express light-gated ion channels (i.e. ReaChR), followed by AF induction and atrial illumination to determine effectivity of optogenetic cardioversion. The irradiance level was determined by light transmittance measurements on human atrial tissue. Results AF could be effectively terminated in remodelled atria of aged rats (97%, n=6). Next, in terms of ReaChR activation, it was shown that light pulses of 25mW/mm2 are expected to fully penetrate the human atrial wall (∼2 mm). Applying such irradiation onto the chest of adult rats resulted in full transthoracic illumination (also ∼2 mm) as evidenced by optogenetic cardioversion of AF (90%, n=4). Conclusion Optogenetic cardioversion of AF is effective in the aged rat heart and can also be realized with irradiation levels compatible with human atrial transmural light penetration.

Light transmittance in human atrial tissue and transthoracic illumination in rats support translatability of optogenetic cardioversion of atrial fibrillation.

Optogenetics could offer a solution to the current lack of an ambulatory method for the rapid automated cardioversion of atrial fibrillation (AF), but key translational aspects remain to be studied. To investigate whether optogenetic cardioversion of AF is effective in the aged heart and whether sufficient light penetrates the human atrial wall. Atria of adult and aged rats were optogenetically modified to express light-gated ion channels (i.e., red-activatable channelrhodopsin), followed by AF induction and atrial illumination to determine the effectivity of optogenetic cardioversion. The irradiance level was determined by light transmittance measurements on human atrial tissue. AF could be effectively terminated in the remodeled atria of aged rats (97%, n=6). Subsequently, ex vivo experiments using human atrial auricles demonstrated that 565-nm light pulses at an intensity of 25mW/mm2 achieved the complete penetration of the atrial wall. Applying such irradiation onto the chest of adult rats resulted in transthoracic atrial illumination as evidenced by the optogenetic cardioversion of AF (90%, n=4). Transthoracic optogenetic cardioversion of AF is effective in the aged rat heart using irradiation levels compatible with human atrial transmural light penetration.

Age-related increases in cardiac excitability, refractoriness and impulse conduction favor arrhythmogenesis in male rats.

The effects of excitability, refractoriness, and impulse conduction have been independently related to enhanced arrhythmias in the aged myocardium in experimental and clinical studies. However, their combined arrhythmic effects in the elderly are not yet completely understood. Hence, the aim of the present work is to relate relevant cardiac electrophysiological parameters to enhanced arrhythmia vulnerability in the in vivo senescent heart. We used multiple-lead epicardial potential mapping in control (9-month-old) and aged (24-month-old) rat hearts. Cardiac excitability and refractoriness were evaluated at numerous epicardial test sites by means of the strength-duration curve and effective refractory period, respectively. During sinus rhythm, durations of electrogram intervals and waves were prolonged in the senescent heart, compared with control, demonstrating a latency in tissue activation and recovery. During ventricular pacing, cardiac excitability, effective refractory period, and dispersion of refractoriness increased in the aged animal. This scenario was accompanied by impairment of impulse propagation. Moreover, both spontaneous and induced arrhythmias were increased in senescent cardiac tissue. Histopathological evaluation of aged heart specimens revealed connective tissue deposition and perinuclear myocytolysis in the atria, while scattered microfoci of interstitial fibrosis were mostly present in the ventricular subendocardium. This work suggests that enhanced arrhythmogenesis in the elderly is a multifactorial process due to the joint increase in excitability and dispersion of refractoriness in association with enhanced conduction inhomogeneity. The knowledge of these electrophysiological changes will possibly contribute to improved prevention of the age-associated increase in cardiac arrhythmias.

Exercise improves cardiac function in the aged rats with myocardial infarction.

Exercise can improve the cardiovascular health. However, the mechanism contributing to its beneficial effect on elderly patients with myocardial infarction is obscure. 20-month-old male Sprague-Dawley rats were used to establish myocardial infarction (MI) model by permanent ligation of the left anterior descending coronary artery (LAD) of the heart, followed by 4-week interval exercise training on a motor-driven rodent treadmill. The cardiac function, myocardial fibrosis, apoptosis, oxidative stress, and inflammatory responses were determined by using pressure transducer catheter, polygraph physiological data acquisition system, Masson's trichrome staining, and ELISA to evaluate the impact of post-MI exercise training on MI. Western blot were performed to detect the activation of AMPK/SIRT1/PGC-1alpha signaling in the hearts of aged rats. Exercise training significantly improved cardiac function and reduced the cardiac fibrosis. In infarcted heart, the apoptosis, oxidative stress, and inflammation were significantly reduced after 4-week exercise training. Mechanistically, AMPK/SIRT1/PGC-1alpha pathway was activated in the myocardial infarction area after exercise training, which might participate in the protection of cardiac function. Exercise training improves cardiac function in MI rats through reduction of apoptosis, oxidative stress, and inflammation, which may mediate by the activation of AMPK/SIRT1/PGC-1alpha signaling pathway.

The additive effects of nicotinamide mononucleotide and melatonin on mitochondrial biogenesis and fission/fusion, autophagy, and microRNA-499 in the aged rat heart with reperfusion injury.

The prognosis of myocardial ischemia/reperfusion (I/R) injury is poor in elderly patients. Aging increases the susceptibility of the heart to cell death from I/R injury and prevents the optimal effectiveness of cardioprotective modalities. Since the interaction of aging with cardioprotection is multifactorial, combination therapy may overcome the above-mentioned burden through correcting various components of the injury. Here, we explored the effects of nicotinamide mononucleotide (NMN)/melatonin combination therapy on mitochondrial biogenesis and fission/fusion, autophagy, and microRNA-499 in the aged rat heart with reperfusion injury. Ex vivo model of myocardial I/R injury was established by coronary occlusion and re-opening in 30 aged male Wistar rats (400-450g, 22-24months old). NMN (100mg/kg/48h, intraperitoneally) was administered over 28days before I/R, and melatonin (50µM) was added to the perfusion solution at early reperfusion. CK-MB release and expression of mitochondrial biogenesis genes and proteins, mitochondrial fission/fusion proteins, autophagy genes, and microRNA-499 were assessed. NMN/melatonin combination therapy concomitantly decreased CK-MB release in aged reperfused hearts (P < .001). It also upregulated SIRT1/PGC-1α/Nrf1/TFAM profiles at both gene and protein levels, Mfn2 protein, and microRNA-499 expression, and downregulated Drp1 protein and Beclin1, LC3, and p62 genes (P < .05 to P < .001). The effect of combination therapy was greater than individual ones. Co-application of NMN/melatonin within the setting of I/R injury in the aged rat heart induced noticeable cardioprotection through modulation of a coordinated network including microRNA-499 expression along with mitochondrial biogenesis associated with SIRT1/PGC-1α/Nrf1/TFAM profiles, mitochondrial fission/fusion, and autophagy, therefore, appears to prevent the burden of myocardial I/R injury in elderly patients.

Liraglutide provides cardioprotection through the recovery of mitochondrial dysfunction and oxidative stress in aging hearts.

Glucagon-like peptide-1 receptor (GLP-1R) agonists improve cardiovascular dysfunction via the pleiotropic effects behind their receptor action. However, it is unknown whether they have a cardioprotective action in the hearts of the elderly. Therefore, we examined the effects of GLP-1R agonist liraglutide treatment (LG, 4weeks) on the systemic parameters of aged rats (24-month-old) compared to those of adult rats (6-month-old) such as electrocardiograms (ECGs) and systolic and diastolic blood pressure (SBP and DBP). At the cellular level, the action potential (AP) parameters, ionic currents, and Ca2+ regulation were examined in freshly isolated ventricular cardiomyocytes. The LG treatment of aged rats significantly ameliorated the prolongation of QRS duration and increased both SBP and DBP together with recovery in plasma oxidant and antioxidant statuses. The prolonged AP durations and depolarized membrane potentials of the isolated cardiomyocytes from the aged rats were normalized via recoveries in K+ channel currents with LG treatment. The alterations in Ca2+ regulation including leaky-ryanodine receptors (RyR2) could be also ameliorated via recoveries in Na+/Ca2+ exchanger currents with this treatment. A direct LG treatment of isolated aged rat cardiomyocytes could recover the depolarized mitochondrial membrane potential, the increase in both reactive oxygen and nitrogen species (ROS and RNS), and the cytosolic Na+ level, although the Na+ channel currents were not affected by aging. Interestingly, LG treatment of aged rat cardiomyocytes provided a significant inhibition of activated sodium-glucose co-transporter-2 (SGLT2) and recoveries in the depressed insulin receptor substrate 1 (IRS1) and increased protein kinase G (PKG). The recovery in the ratio of phospho-endothelial nitric oxide (pNOS3) level to NOS3 protein level in LG-treated cardiomyocytes implies the involvement of LG-associated inhibition of oxidative stress-induced injury via IRS1-eNOS-PKG pathway in the aging heart. Overall, our data, for the first time, provide important information on the direct cardioprotective effects of GLP-1R agonism with LG in the hearts of aged rats through an examination of recoveries in mitochondrial dysfunction, and both levels of ROS and RNS in left ventricular cardiomyocytes.

Aging-associated susceptibility to stress-induced ventricular arrhythmogenesis is attenuated by tetrodotoxin

Aging is associated with increased prevalence of life-threatening ventricular arrhythmias, but mechanisms underlying higher susceptibility to arrhythmogenesis and means to prevent such arrhythmias under stress are not fully defined. We aimed to define differences in aging-associated susceptibility to ventricular fibrillation (VF) induction between young and aged hearts. VF induction was attempted in isolated perfused hearts of young (6-month) and aged (24-month-old) male Fischer-344 rats by rapid pacing before and following isoproterenol (1 μM) or global ischemia and reperfusion (I/R) injury with or without pretreatment with low-dose tetrodotoxin, a late sodium current blocker. At baseline, VF could not be induced; however, the susceptibility to inducible VF after isoproterenol and spontaneous VF following I/R was 6-fold and 3-fold higher, respectively, in old hearts (P < 0.05). Old animals had longer epicardial monophasic action potential at 90% repolarization (APD90; P < 0.05) and displayed a loss of isoproterenol-induced shortening of APD90 present in the young. In isolated ventricular cardiomyocytes from older but not younger animals, 4-aminopyridine prolonged APD and induced early afterdepolarizations (EADs) and triggered activity with isoproterenol. Low-dose tetrodotoxin (0.5 μM) significantly shortened APD without altering action potential upstroke and prevented 4-aminopyridine-mediated APD prolongation, EADs, and triggered activity. Tetrodotoxin pretreatment prevented VF induction by pacing in isoproterenol-challenged hearts. Vulnerability to VF following I/R or catecholamine challenge is significantly increased in old hearts that display reduced repolarization reserve and increased propensity to EADs, triggered activity, and ventricular arrhythmogenesis that can be suppressed by low-dose tetrodotoxin, suggesting a role of slow sodium current in promoting arrhythmogenesis with aging.

The effect of six weeks High Intensity Interval Swimming Training and Resveratrol supplementation on the level of SIRT3 in left ventricular heart of aged rats

زمینه و هدف: شناسایی و تجزیه‌وتحلیل اجزایی که در به تأخیر انداختن پیری و افزایش طول عمر نقش دارند، بسیار ضروری است. سیرتوئین‌ها از تنظیم‌کننده‌های اصلی بقای سلولی و طول عمر هستند. هدف پژوهش حاضر بررسی تأثیر شش هفته فعالیت ورزشی HIIT شنا و مکمل رزوراترول بر مقدار SIRT3 در بافت بطن چپ قلب موش‌های صحرایی پیر بود. مواد و روش‌ها: در این پژوهش، 30 سر موش صحرایی 20 ماهه (پیر) نر نژاد ویستار تصادفی به پنج گروه (کنترل (C)، گروه تمرین (EX)، گروه تمرین+مکمل (EXR)، گروه مکمل (R) و گروه حلال (M)) تقسیم شدند. گروه EX، تمرین HIIT شنا را به مدت شش هفته انجام دادند. گروه C، تمرین نمی‌کردند. گروه R، فقط مکمل رزوراترول دریافت کردند. گروه EXR، تمرین HIIT شنا را همراه با دریافت رزوراترول انجام دادند. گروه M فقط حلال دریافت کردند. SIRT3 با استفاده از روش آزمایشگاهی وسترن بلات سنجیده شد. داده‌های حاصله توسط آزمون آماری تحلیل واریانس یکطرفه و آزمون تعقیبی توکی تجزیه‌وتحلیل شدند.نتایج: پس از شش هفته، تفاوت معناداری بین میانگین میزان پروتئین SIRT3 در پنج گروه مشاهده شد. بنابراین، آزمون تعقیبی توکی نشان داد که مقدار SIRT3 در گروه EX و EXR در مقایسه با گروه C، R و M، به‌طور معناداری بیشتر بود (001/0P=)، اما این تفاوت بین دو گروه EX و EXR معنادار نبود (05/0P>). همچنین، مقدار SIRT3 در گروه R به‌طور معناداری در مقایسه با گروه C و M بیشتر بود.نتیجه‌گیری: افزایش SIRT3، نشان‌دهندة دخیل بودن این پروتئین در مسیرهای سوخت‌وسازی، دفاع ضداکسایشی و بهبود وضعیت سلول است. همچنین می‌توان از تمرین تناوبی شدید همراه با مصرف مکمل رزوراترول برای تعدیل فشار اکسایشی و تأخیر روند پیری و سالمندی بهره برد.

Resveratrol as a Promising Polyphenol in Age-Associated Cardiac Alterations.

According to a widely accepted theory, oxidative stress is considered to be the number one trigger of aging-associated degenerative processes including cardiovascular diseases. In the context of aging-research, resveratrol receives special attention with its surprising number of health benefits. The aim of our study was to examine the anti-inflammatory and antioxidant effects of this dietary polyphenol in aging rat heart. 20-month-old female and male Wistar rats were divided into control (untreated) and resveratrol-treated groups. Resveratrol was administered at a dose of 0.05 mg/ml for 12 weeks dissolved in drinking water, while the control rats received ad libitum water. Cardiac level of reactive oxygen species (ROS), nuclear factor kappa B (NFκB), tumor necrosis factor alpha (TNF-α), and glutathione (GSH) parameters, as well as the activity of myeloperoxidase (MPO) and heme oxygenase (HO) enzymes were detected. Together with the biochemical measurements, hearts were isolated and used for an exposure of ischemic-reperfusion injury via Langendorff perfusion system. 12 week of resveratrol treatment suppressed the age-related inflammatory pathways including the expression of TNF-α, NFκB, and the activity of MPO while intensified the endogenous antioxidant defenses through the induction of GSH and HO system. Presumably, as a result of these processes, the necrotic area of the heart in response to an acute injury was also significantly reduced in the resveratrol-treated groups. Our findings confirmed that resveratrol has cardioprotective effects at several points by counteracting the aging-associated cellular malfunctions in the heart.

Effect of exercise and curcumin on cardiomyocyte molecular mediators associated with oxidative stress and autophagy in aged male rats

AimAging can origin changes in the heart that may increase risk of developing cardiovascular disease. This study aimed to characterize autophagy alterations and related molecular mediators in the heart tissue in the aging alone or in combination with exercise and curcumin treatment. MethodsSeven young and twenty-eight elderly male Wistar rats were assigned into five groups, namely: young control, age, exercise, curcumin, and curcumin+exercise. Aged rats in exercise group run on treadmill (17 m/min) and in the curcumin group received curcumin (50 mg/kg) by gavage daily for 8 weeks for 2 months. At the end, heart samples were collected and used for determination of autophagy by immunostaining for LC3-phosphatidylethanolamine conjugate (LC3-II), apoptosis by TUNEL assay, Malondialdehyde (MDA) level by enzymatic assay and determination of mediators' molecules by ELISA for NADPH Oxidase 4 (NOX4), sirtuin 1 (SIRT-1), phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-Ƙb) protein levels and Sequestosome-1 (P62). Also, histological changes such as fibrosis evaluated by Masson trichrome staining. ResultsOur results showed that autophagy, SIRT-1 level were significantly decreased and MDA, NOX4, p-NF-Ƙb and P62 levels were significantly increased in heart of aged group compared to young group. Also, significant increased apoptosis and fibrosis levels in the heart of aged rats were observed compared with young rats, whereas, these undesirable changes were improved by exercise and curcumin. Also, combination therapy of aged rats with curcumin and exercise showed more significant prominent effect on molecular mediators and histological changes in the heart compared with monotherapy. ConclusionThese findings indicate that stress oxidative increase and autophagy decrease in the heart tissue of aged rats. The age induced the mentioned changes in the heart may in part be associated with down-expression of SIRT-1 and overexpression of NOX4 proteins. It was also showed that these age induced effects can be alleviated by treatment with exercise and curcumin. Since NF-Ƙb increased in both the age and treatment groups, it seems the age heart increased NF-Ƙb to be due to a compensatory mechanism.

Aronia melanocarpa Fruit Juice Modulates ACE2 Immunoexpression and Diminishes Age-Related Remodeling of Coronary Arteries in Rats.

The aim of the study is to evaluate the effect of Aronia melanocarpa fruit juice (AMJ) supplementation on age-related coronary arteries remodeled in aged rat hearts. Male Wistar rats (n = 24) were divided into three groups: (1) young controls (CY), aged 2 months, without AMJ supplementation; (2) old controls (CO), aged 27 months, without AMJ supplementation; and (3) the AMJ group (A), which used 27-month old animals, supplemented orally with AMJ for 105 days. AMJ supplementation did not influence the wall-to-diameter parameter (Kernohan index) of the coronary arteries of test animals. Aged rats supplemented with AMJ showed a significant decrease in the amount of collagen fibers in their coronary tunica media, as compared with the old controls. The intensity of the immunoreaction for alpha smooth muscle actin (αSMA) in the coronary tunica media was significantly lower in the supplemented group than in the old controls. The intensity of the angiotensin-converting enzyme 2 (ACE2) immunoreaction in the coronary tunica media of the supplemented group was significantly higher than the one observed in the old controls. These results indicate the positive effects of AMJ supplementation on the age-dependent remodeling of coronary arteries and support for the preventive potential of antioxidant-rich functional food supplementation in age-related diseases.

Pretreatment with nicotinamide mononucleotide increases the effect of ischaemic postconditioning on cardioprotection and mitochondrial function following ex vivo myocardial reperfusion injury in aged rats.

The present study aims to evaluate the combined effect of ischaemic postconditioning (IPostC) and nicotinamide mononucleotide (NMN) on cardioprotection and mitochondrial function in aged rats subjected to myocardial ischaemia-reperfusion (IR) injury. Sixty aged Wistar rats were randomly divided into fivegroups (n=12), including sham, control, NMN, IPostC, and NMN+IPostC. Regional ischaemia was induced by 30-min occlusion of the left anterior descending coronary artery (LAD) followed by 60-min reperfusion. IPostC was applied at the onset of reperfusion, by six cycles of 10-s reperfusion/ischaemia. NMN (100mg/kg) was intraperitoneally injected every other day for 28days before IR. Myocardial haemodynamics and infarct size (IS) were measured, and the left ventricles samples were harvested to assess cardiac mitochondrial function. The results showed that all treatments reduced lactate dehydrogenase release compared to those of the control group. IPostC alone failed to reduce IS and myocardial function. However, NMN and combined therapy could significantly improve myocardial function and decrease the IS compared to the control animals. Moreover, the effects of combined therapy on the decrease of IS, mitochondrial reactive oxygen species (ROS), and improvement of mitochondrial membrane potential (MMP) were greater than those of stand-alone treatments. These results demonstrated that cardioprotection by combined therapy with NMN+IPostC was superior to individual treatments, and pretreatment of aged rats with NMN was able to correct the failure of IPostC in protecting the hearts of aged rats against IR injury.

Effects of Aging on Cardiac Oxidative Stress and Transcriptional Changes in Pathways of Reactive Oxygen Species Generation and Clearance.

BackgroundAge‐related heart diseases are significant contributors to increased morbidity and mortality. Emerging evidence indicates that mitochondria within cardiomyocytes contribute to age‐related increased reactive oxygen species (ROS) generation that plays an essential role in aging‐associated cardiac diseases.Methods and ResultsThe present study investigated differences between ROS production in cardiomyocytes isolated from adult (6 months) and aged (24 months) Fischer 344 rats, and in cardiac tissue of adult (18–65 years) and elderly (>65 years) patients with preserved cardiac function. Superoxide dismutase inhibitable ferricytochrome c reduction assay (1.32±0.63 versus 0.76±0.31 nMol/mg per minute; P=0.001) superoxide and H2O2 production, measured as dichlorofluorescein diacetate fluorescence (1646±428 versus 699±329, P=0.04), were significantly higher in the aged versus adult cardiomyocytes. Similarity in age‐related alteration between rats and humans was identified in mitochondrial‐electron transport chain‐complex‐I‐associated increased oxidative‐stress by MitoSOX fluorescence (53.66±18.58 versus 22.81±12.60; P=0.03) and in 4‐HNE adduct levels (187.54±54.8 versus 47.83±16.7 ng/mg protein, P=0.0063), indicative of increased peroxidation in the elderly. These differences correlated with changes in functional enrichment of genes regulating ROS homeostasis pathways in aged human and rat hearts. Functional merged collective network and pathway enrichment analysis revealed common genes prioritized in human and rat aging‐associated networks that underlay enriched functional terms of mitochondrial complex I and common pathways in the aging human and rat heart.ConclusionsAging sensitizes mitochondrial and extramitochondrial mechanisms of ROS buildup within the heart. Network analysis of the transcriptome highlights the critical elements involved with aging‐related ROS homeostasis pathways common in rat and human hearts as targets.

Chlorpyrifos with Age-Dependent Effects in Cardiac Tissue of Male Rats.

Age-dependent toxic effects of organophosphorus pesticides (OPs) have not been fully understood. The current study aimed to investigate the cardiotoxic damage of chlorpyrifos (CPF) by evaluating oxidative modifications in young (2-month old), middle-aged (10- month old), and aged (20-month old) rats. Five mg/kg of CPF was administered orally for 45 days to young, middle-aged, and aged male Wistar rats. In the end, animals were anesthetized and the heart of each rat was dissected for biochemical assay. Malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH), total antioxidant capacity (TAC), and superoxide dismutase (SOD) were assessed in the cardiac tissue of rats. The results indicated an increase in the levels of MDA and NO, and also a decline in the levels of GSH and TAC as well as a decrease in the SOD activity in the heart of aged rats compared with young rats. CPF administration deteriorated these changes in the heart of exposed rats compared with the age-matched controls. Additionally, these oxidative modifications were more severe in aged rats versus other age. In conclusion, advancing age may increase oxidative changes in the heart of animals exposed to CPF. It is suggested that aging can affect cardiac toxicity induced by OPs.

Melatonin postconditioning combined with sitagliptin exerts full cardioprotection in diabetic hearts of aged rats through an AMPK-dependent mechanism

The presence of multiple comorbidities in patients facing myocardial ischemia-reperfusion (IR) injury is the main obstacle for cardioprotection. This study investigated the effect of melatonin postconditioning combined with sitagliptin pretreatment on cardioprotection in diabetic aged rats by evaluating oxidative stress, apoptosis and involvement of the AMPK/SIRT1 pathway. The type-2 high-fat/streptozotocin experimental model in aged Sprague-Dawley rats (n=78) was used. The animals underwent left coronary occlusion for 30 min, followed by 3 h reperfusion. Diabetic rats were pretreated with sitagliptin (20 mg/kg, i.p.) and received melatonin (10 mg/kg, i.p.) early in reperfusion. Myocardial infarct size, histological changes, oxidative markers, mitochondrial reactive oxygen species (mitoROS) and expression of proteins regulating apoptosis and AMPK/SIRT1 activity were measured. The infarct size-sparing effect of the combination of melatonin plus sitagliptin was greater than that observed in individual treatments (P&lt;0.01). Combination therapy significantly reduced IRinduced elevation of 8-isoprostane, mitoROS and proapoptotic proteins Bax and cleaved caspase-3, and increased IR-induced downregulation of mitochondrial superoxide-dismutase, glutathione, anti-apoptotic protein Bcl2, phosphorylated AMPK and SIRT1 (P&lt;0.01, P&lt;0.001). Inhibition of AMPK via compound-C completely reversed combination-induced cardioprotection. Thus, improving cardiac antioxidative and antiapoptotic responses via upregulation of AMPK/SIRT1 activity may represent a central mechanism through which melatonin plus sitagliptin attenuate myocardial IR injury in diabetic-aged rats.

Cardiac Pacemaker Dysfunction Arising From Different Studies of Ion Channel Remodeling in the Aging Rat Heart.

The function of the sinoatrial node (SAN), the pacemaker of the heart, declines with age, resulting in increased incidence of sinoatrial node dysfunction (SND) in older adults. The present study assesses potential ionic mechanisms underlying age associated SND. Two group studies have identified complex and various changes in some of membrane ion channels in aged rat SAN, the first group (Aging Study-1) indicates a considerable changes of gene expression with up-regulation of mRNA in ion channels of Cav1.2, Cav1.3 and KvLQT1, Kv4.2, and the Ca2+ handling proteins of SERCA2a, and down-regulation of Cav3.1, NCX, and HCN1 and the Ca2+-clock proteins of RYR2. The second group (Aging Study-2) suggests a different pattern of changes, including down regulation of Cav1.2, Cav1.3 and HCN4, and RYR2, and an increase of NCX and SERCA densities and proteins. Although both data sets shared a similar finding for some specific ion channels, such as down regulation of HCN4, NCX, and RYR2, there are contradictory changes for some other membrane ion channels, such as either up-regulation or down-regulation of Cav1.2, NCX and SERCA2a in aged rat SAN. The present study aims to test a hypothesis that age-related SND may arise from different ionic and molecular remodeling patterns. To test this hypothesis, a mathematical model of the electrical action potential of rat SAN myocytes was modified to simulate the functional impact of age-induced changes on membrane ion channels and intracellular Ca2+ handling as observed in Aging Study-1 and Aging Study-2. The role and relative importance of each individually remodeled ion channels and Ca2+-handling in the two datasets were evaluated. It was shown that the age-induced changes in ion channels and Ca2+-handling, based on either Aging Study-1 or Aging Study-2, produced similar bradycardic effects as manifested by a marked reduction in the heart rate (HR) that matched experimental observations. Further analysis showed that although the SND arose from an integrated action of all remodeling of ion channels and Ca2+-handling in both studies, it was the change to ICaL that played the most important influence.

Cardiac function and tolerance to ischemia/reperfusion injury in a rat model of polycystic ovary syndrome during the postmenopausal period

AimsThere is much controversy regarding whether cardiovascular events increase in women with polycystic ovary syndrome (PCOS) with aging. Considering the lack of possibility of certain investigations in humans, animal models of PCOS may be suitable resources to obtain the useful data needed. In this study; we aimed to investigate whether cardiac function and tolerance to ischemia/reperfusion (I/R) injury worsen in postmenopausal rats, who had PCOS at younger ages, compared to controls. Main methodsThe hearts of aged rats with a history of PCOS and their controls were isolated and perfused in a Langendorff apparatus. Values of hemodynamic parameters, including left ventricular systolic pressure (LVSP), left ventricular developed pressure (LVDP), rate pressure product (RPP) and peak rates of positive and negative changes in left ventricular pressure (±dp/dt) were recorded using a power lab system. Blood serum levels of total testosterone (TT) and estradiol (E2) were determined by ELISA kits. Generalized Estimating Equation Model and t-student unpaired test results were used to compare the findings documented between two groups. Key findingsNo statistically significant differences were observed in hemodynamic parameters of the heart including, LVSP, LVDP, RPP and ±dp/dt, between the rats of two groups of study, at baseline or before ischemia and after I/R. Nor were any significant differences observed in the levels of two hormones between the two groups (p > 0.05). SignificanceHistory of PCOS during reproductive ages should not be considered an important risk factor for reduction in cardiac contractile function or less tolerance to I/R injury during the postmenopausal period.

D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus fortified adipose-derived mesenchymal stem cells.

This study addresses the effect of D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus (AOF; Alpinia oxyphylla Miq) extracts fortified with adipose-derived mesenchymal stem cells (ADMSCs) in rats. Male 18 week-old Wistar Kyoto (WKY) rats were used in this study. We analyzed cardiac fibrosis by Masson's trichrome staining. The tissue sections were dyed using hematoxylin and eosin (H&E). Tissue sections were stained for the restoration of Nrf2 expression in treatment groups by immunohistochemistry. Immunohistochemistry and western blotting analysis showed that AOF with ADMSCs could significantly reduce aging-induced oxidative stress in D-galactose-induced aging rat hearts by inducing Nrf2 pathway. Reduction in ROS resulted in the suppression of inflammatory signals (p-NF-κB and IL-6). Histopathological studies were showed an increased interstitium and collagen accumulation in aging-induced heart sections. However, AOF and ADMSCs treated hearts were recovered from cardiac remodeling. Furthermore, hypertrophy and fibrosis associated markers were also significantly reduced (P < .05) in treatment groups. We speculate that ADMSCs might activate certain paracrine factors, which could target the upstream activator of aging associated cardiac complications and AOF might provide homing for these stem cells.

Exercise improves aging-related decreased angiogenesis through modulating VEGF-A, TSP-1 and p-NF-Ƙb protein levels in myocardiocytes.

Introduction: Aging-dependent decline in the angiogenesis of heart is a risk factor for cardiovascular disease. This study was aimed to characterize effect of exercise on angiogenesis alterations and molecular mediators which are related to angiogenesis in the heart under aging condition. Methods: Twenty-one male Wistar rats were assigned into three groups: young, aged, and exercise. Aged animals in the exercise group run on treadmill for 8 weeks. At the end, heart samples were collected and used for histological evaluation , determination of angiogenesis by immunostaining for PECAM-1/ CD31 and expressions of vascular endothelial growth factor-A (VEGF-A), thrombospondin-1 (TSP-1) and nuclear factor kappa B (NF-κB) levels by ELISA. P<0.05 is considered as statistically significant. Results: Our results showed that angiogenesis, and VEGF-A levels were significantly decreased, TSP1 (P >0.0001) and p-NF-κB (P >0.001) levels were significantly increased in the heart of aged group compared to young group. Exercise group showed significant increase in angiogenesis, VEGF-A (P >0.0001), and p-NF-κB (P >0.001) and showed significant decrease in TSP-1 levels (P >0.001) compared to aged group. Moreover, compared to the young group, aged group showed histological changes in the heart, such as interstitial edema, and congestion, whereas, treatment with exercise improved these undesirable changes in the heart of exercise groups. Conclusion: These findings indicated that aging-related decrease in angiogenesis in the heart may mediated by downexpression of VEGF-A and overexpression of TSP-1 proteins. Also, we showed that p-NF-κB protein was increased in the heart of aged rats, this probably mediated by compensatory mechanism. It was also showed that exercise as novel non-pharmacological therapy modifies VEGF-A and TSP-1 and increases p-NF-κB protein levels in the aged heart.