Ventricle Of Rats Research Articles

ИЗУЧЕНИЕ АКТИВНОСТИ Na/K-АТФазы В МИОКАРДЕ КРЫС В ЭКСПЕРИМЕНТАЛЬНЫХ УСЛОВИЯХ ПРЕДДИАБЕТА И САХАРНОГО ДИАБЕТА

Cardiac disruption and development of a diabetic cardiomyopathy (DCM) are a direct consequence of diabetes. In work activity Na/K-ATPase in a myocardium of rats with different extent of diabetic impairment was studied. Suppression of activity of Na/K-ATPase in the cardiomyocytes the left ventricle of rats was revealed at strongly developed diabetes, but not at a prediabetes stage. It was concluded, that development of DCM breaks transport processes in a membrane of rats cardiomyocytes, and the expressiveness of observed changes depends on diabetes degree.

Protective effect of hypoxia inducible factor-1α gene therapy using recombinant adenovirus in cerebral ischaemia-reperfusion injuries in rats

Context Hypoxia-inducible factor-1α (HIF-1α)-induced genes can improve blood circulation. Objective To investigate brain protective effect of recombinant adenovirus-mediated HIF-1α (AdHIF-1α) expression and its mechanism. Materials and methods Male SD rats were used to establish focal cerebral ischaemia-reperfusion (CIR) injury models and randomly divided into normal, sham, CIR, Ad and AdHIF-1α groups. Ad or AdHIF-1α (108 pfu/10 µL) were administered into lateral ventricle of rats in Ad and AdHIF-1α groups. Modified neurological severity score (mNSS), brain water content (BWC) and cerebral infarct volumes (CIVs) were analyzed, and HE staining was performed using the brain tissues. Furthermore, the expression of caspase-3 and HSP90 was analyzed using qRT-PCR and Western blotting. Results Compared to CIR (mNSS, 8.52 ± 0.52; CIV, 0.22 ± 0.01) and Ad groups (mNSS, 8.83 ± 0.41; CIV, 0.22 ± 0.02), mNSS and CIV were significantly decreased in AdHIF-1α group (mNSS, 6.03 ± 0.61; CIV, 0.11 ± 0.01) at 72 h (p < 0.05). With prolonged reperfusion time (6 h to 72 h), BWC of all rats increased gradually, although the increase was markedly less in AdHIF-1α group (78.15 ± 0.16 to 87.01 ± 0.31) compared to that in CIR (78.77 ± 0.60 to 89.74 ± 0.34) and Ad groups (78.77 ± 0.35 to 89.71 ± 0.27) (p < 0.01). There were significantly greater pathological changes in the neurons in AdHIF-1α group at 72 h following CIR. Furthermore, expression of caspase-3 (p < 0.01) down-regulated and HSP90 up-regulated (p < 0.05) at mRNA and protein levels in AdHIF-1α group. Discussion and conclusions HIF‑1α gene therapy is neuroprotective towards the CIR rat model. HIF-1α may be a candidate gene for the treatment of ischaemic brain injury.

Protective Effects of Quercetin on Anxiety‐Like Symptoms and Neuroinflammation Induced by Lipopolysaccharide in Rats

Recently, neuroinflammation is thought to be one of the important causes of many neuropsychiatric diseases. Quercetin (QUER) is a natural flavonoid, and it is well known that QUER has antioxidative, anti-inflammatory, and neuroprotective effects. In our study, lipopolysaccharide (LPS) was injected into the lateral ventricle of rats to induce anxiety-like behaviors and neuroinflammation, and it was confirmed that chronic administration of QUER could improve anxiety-like symptoms. We also investigated the effects of QUER on inflammatory markers and its major mechanisms associated with inflammation in the hippocampus. Daily administration of QUER (10, 50, and 100 mg/kg) daily for 21 days significantly improved anxiety-like behaviors in the elevated plus-maze test and open field test. QUER administration significantly reduced inflammatory markers such as interleukin-6, interleukin-1β, cyclooxygenase-2, and nuclear factor-kappaB levels in the brain. In addition, QUER significantly increased the brain-derived neurotrophic factor (BDNF) mRNA level and decreased the nitric oxide synthase (iNOS) mRNA level. Therefore, our results have shown that QUER can improve anxiety-like behaviors caused by chronic neuroinflammation. This anxiolytic effect of QUER has been shown to be due to its anti-inflammatory effects and appropriate regulation of BDNF and iNOS expression. Thus, QUER provides the potential as a therapeutic agent to inhibit anxiety-like symptoms in neuropsychiatric diseases, such as anxiety.

Inhibitory effect of carvacrol on lipopolysaccharide-induced memory impairment in rats.

Neuroinflammation is an important process underlying a wide variety of neurodegenerative diseases. Carvacrol (CAR) is a phenolic monoterpene commonly used as a food additive due to its antibacterial properties, but it has also been shown to exhibit strong antioxidative, anti-inflammatory, and neuroprotective effects. Here, we sought to investigate the effects of CAR on inflammation in the hippocampus and prefrontal cortex, as well as the molecular mechanisms underlying these effects. In our study, lipopolysaccharide was injected into the lateral ventricle of rats to induce memory impairment and neuroinflammation. Daily administration of CAR (25, 50, and 100 mg/kg) for 21 days improved recognition, discrimination, and memory impairments relative to untreated controls. CAR administration significantly attenuated expression of several inflammatory factors in the brain, including interleukin-1β, tumor necrosis factor-α, and cyclooxygenase-2. In addition, CAR significantly increased expression of brain-derived neurotrophic factor (BDNF) mRNA, and decreased expression of Toll-like receptor 4 (TLR4) mRNA. Taken together, these results show that CAR can improve memory impairment caused by neuroinflammation. This cognitive enhancement is due to the anti-inflammatory effects of CAR medicated by its regulation of BDNF and TLR4. Thus, CAR has significant potential as an inhibitor of memory degeneration in neurodegenerative diseases.

The influence of non-opiate analogue of leu-enkephalin to the cardiac consequences of intrauterine hypoxia of albino rats

Objective ― Our study aimed to evaluate the possibility of correcting cardiac consequences of intrauterine hypoxia (IUH) by injecting leu-enkephalin analog, lacking affinity for opiate receptors, in the early postnatal period. Material and Methods ― To model IUH, we placed pregnant Wistar rats in a hypobaric chamber with an oxygen partial pressure of 52 mmHg. The procedure was repeated for 4 h daily over the 15th-19th days of gestation. From the 2nd through the 6th days of their lives, the offspring were injected intraperitoneally with non-opiate leu-enkephalin analog at a dose of 100 μg/kg (NALE: Phe-D-Ala-Gly-Phe-Leu-Arg). This analog did not have affinity for opiate receptors. The 7- and 60-day old offspring of female rats subjected to IUH were investigated. The control group included the descendants of intact animals. We investigated gravimetric indicators, DNA-synthetic activity of cardiomyocytes (CMC) by tritium-labeled thymidine autoradiography method, the size of the CMC nuclei, as well as size and amount of nucleoli in the CMC nuclei. The activity of free radical oxidation was evaluated in cardiac homogenates by chemiluminescence. Results ― In 7-day old rats subjected to IUH vs. control animals, we observed decreases in body mass by 32.6%, in heart mass by 27.3%; in the proportion of 3Н-thymidine labeled CMC nuclei by 32.7% in the left ventricle and by 30.4% in the right ventricle; in the number of nucleoli in the CMC nuclei (in the left ventricle: control – 2.384±0.027, IUH – 2.282±0.027*, p&lt;0.05; in the right ventricle: control – 2.409±0.038; IUH – 2.240±0.012*, p&lt;0, 05). Increase in CML indices of cardiac homogenates was revealed, indicating the activation of free radical oxidation. In 7-day old rats subjected to IUH and administration of the NALE peptide from the 2nd through the 6th days of their lives, the proportion of 3H-thymidine labeled nuclei in the CMC did not differ from the control (in the left ventricle: control – 12.79±0.89%, IUH + NALE – 10.98±0.95%, p&gt;0.05; in the right ventricle: control – 11.61±0.78%; IUH + NALE – 11.26±0.58%, p&gt;0.05). The number of nucleoli in the CMC nuclei of the left and right ventricles in the heart of 7-day old animals in the IUH + NALE group did not differ from the control too. The CML indices of heart homogenates in the IUH + NALE group were significantly lower than those in the IUH group. In 60-day old male rats exposed to IUH, there was a decrease in heart mass by 18.5%, sizes of CMC nuclei by 7.5% and 16.1% in the left and right ventricles, respectively, and in the total nucleoli area in the CMC nuclei of the left ventricle (control – 3.953±0.085; IUH – 3.372±0.078*; p&lt;0.05). In 60-day old male rats subjected to IUH and injections of the NALE peptide from the 2nd to the 6th days of their lives, heart mass (control – 692.73±26.81 mg; IUH + NALE – 631.0±29.79 mg; p&gt;0.05) and the size of the CMC nuclei of the right ventricle (control – 54.25±0.84; IUH + NALE – 55.24±0.94; p&gt;0.05) did not differ significantly from the control. The size of the nuclei, the number and size of the nucleoli in the CMC of the left ventricle, as well as the area of the nucleoli in the CMC of the right ventricle in 60-day old male rats of the IUH + NALE group significantly exceeded control group values. Conclusion ― Administration of the NALE peptide to albino rats subjected to IUH normalized DNA-synthetic activity and the number of nucleoli in the nuclei of CMC in 7-day old animals, and also reduced the severity of oxidative stress in the heart tissue. In 60-day old albino male rats exposed to IUH, injecting NALE from the 2nd to the 6th days of their lives eliminated declines in heart mass and sizes of the CMC nuclei and nucleoli, and also led to an increase in the values of the nucleus-and-nucleolus complex indices compared with the control.

Isolation and characterization of cluster of differentiation 9-positive ependymal cells as potential adult neural stem/progenitor cells in the third ventricle of adult rats

Ependymal cells located above the ventricular zone of the lateral, third, and fourth ventricles and the spinal cord are thought to form part of the adult neurogenic niche. Many studies have focused on ependymal cells as potential adult neural stem/progenitor cells. To investigate the functions of ependymal cells, a simple method to isolate subtypes is needed. Accordingly, in this study, we evaluated the expression of cluster of differentiation (CD) 9 in ependymal cells by in situ hybridization and immunohistochemistry. Our results showed that CD9-positive ependymal cells were also immunopositive for SRY-box 2, a stem/progenitor cell marker. We then isolated CD9-positive ependymal cells from the third ventricle using the pluriBead-cascade cell isolation system based on antibody-mediated binding of cells to beads of different sizes and their isolation with sieves of different mesh sizes. As a result, we succeeded in isolating CD9-positive populations with 86% purity of ependymal cells from the third ventricle. We next assayed whether isolated CD9-positive ependymal cells had neurospherogenic potential. Neurospheres were generated from CD9-positive ependymal cells of adult rats and were immunopositve for neuron, astrocyte, and oligodendrocyte markers after cultivation. Thus, based on these findings, we suggest that the isolated CD9-positive ependymal cells from the third ventricle included tanycytes, which are special ependymal cells in the ventricular zone of the third ventricle that form part of the adult neurogenic and gliogenic niche. These current findings improve our understanding of tanycytes in the adult third ventricle in vitro.

Cardiac myocyte functional and biochemical changes after hypothermic preservation in vitro. Protective effects of storage solutions.

In this study, we evaluated cardiac myocyte viability and function under hypothermic conditions with four types of storage solutions, saline solution, Euro-Collins solution, University of Wisconsin solution, and MCDB 107 medium. Cardiac myocytes were isolated from neonatal rat ventricles by collagenase dispersion and cultured for 4 days with MCDB 107 medium. A total of 12.5 x 10(5) myocytes per culture dish was used and the myocytes were incubated at 4 degrees C for 6, 12, 18, and 24 hours in the various storage solutions. After each incubation time, creatine kinase and lactate dehydrogenase were measured in the storage solutions. The myocytes were then incubated for 24 hours at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the MCDB 107 group (n = 7), the recovery ratio of myocyte beating rate was complete by 12 hours, then decreased to 44.8% of control (beating rate before hypothermic incubation) at 24 hours. The saline, Euro-Collins, and University of Wisconsin groups (n = 7 each) had significantly lower recovery ratios than the MCDB 107 group (at 12 hours: 61.0%, 32.2%, and 48.9%; at 18 hours: 0.0%, 5.5%, and 15.1% of control, respectively). Release of creatine kinase and lactate dehydrogenase in the MCDB 107 group gradually increased and at 24 hours was 143.2 mIU/flask and 486.2 mIU/flask, respectively. However, the saline and University of Wisconsin groups had significantly increased creatine kinase and lactate dehydrogenase values at 24 hours (creatine kinase: 334.6 and 319.6 mIU/flask; lactate dehydrogenase: 821.6 and 654.4 mIU/flask, respectively). The Euro-Collins group showed the greatest increase in both markers (creatine kinase: 1587.5, lactate dehydrogenase: 2106.9 mIU/flask). In summary, saline and University of Wisconsin solutions showed a beneficial effect on recovery of myocyte viability at 12 hours compared with Euro-Collins solution, however MCDB 107 medium had the best overall protective effect on cultured myocytes. Accordingly, alternate hypothermic storage solutions, such as cell-culture medium, may have protective characteristics that are suitable for cardiac preservation.

Speckle tracking echocardiography in early detection of myocardial injury in a rat model with stress cardiomyopathy.

Studies on the usefulness of speckle tracking echocardiography (STE) in the evaluation of the left ventricle in rats with stress cardiomyopathy (SCM) are limited. Our aim was to investigate whether strain values by STE and cardiac troponin I (cTnI) could predict early myocardial injury in rats with SCM. SCM was induced in Sprague-Dawley female rats using immobilization (IMO) stress. Biomarkers and echocardiographic parameters were evaluated and compared among groups (group 1 - 30 minutes after IMO stress, group 2 - 24 hours after IMO stress, and control group). We defined myocardial injury as a left ventricular ejection fraction <50%. Possible predictors of early myocardial injury were determined by univariate logistic regression, and independent predictors of early myocardial injury were investigated with multivariable logistic regression. A total of 44 rats with a mean weight of 426±33 g were evaluated. Group 1 had the highest plasma epinephrine and norepinephrine levels (p<0.001) and the highest heart rate (p<0.001). In univariate logistic regression, cTnI (OR=2.61 [1.02‒10.25], p=0.043) and global longitudinal strain (GLS) (OR=2.13 [1.12‒6.26], p=0.022) were predictive of early myocardial injury. When GLS and cTnI were included in a multivariate analysis, only GLS remained an independent predictor of early myocardial injury (OR=2.67 [1.14‒14.76], p=0.027). STE is useful for the quantitative detection of subtle myocardial abnormalities in rats with SCM. GLS may provide a reliable and non-invasive method to predict early myocardial injury.

One year of exercise training promotes distinct adaptations in right and left ventricle of female Sprague-Dawley rats.

Aerobic exercise training induces a unique cardioprotective phenotype, but it is becoming clear that it does not promote the same structural, functional, and molecular adaptations in both ventricles. In the present study, we aimed to better characterize and compare the molecular pathways involved in the exercise-induced remodeling of both ventricles. Female Sprague-Dawley rats were randomly assigned to control and exercise groups. Animals in the exercise group were submitted to low-intensity treadmill exercise for 54weeks. After the experimental period, biventricular hemodynamic analysis was performed and right and left ventricles were harvested for morphological and biochemical analyses. Data showed that long-term low-intensity exercise training improves cardiac function, especially left ventricular diastolic function; however, the expression of connexin-43, CCAAT-enhancer binding protein β, and c-kit did not change in none of the ventricles. In the right ventricle, long-term exercise training induced an increase of manganese superoxide dismutase and sirtuin 3 protein expression, suggestive of improved antioxidant capacity. Our results also support that long-term aerobic exercise training imposes greater metabolic remodeling to the right ventricle, mainly by increasing mitochondrial ability to produce ATP, with no association to estrogen-related receptor α regulation.

Cardiac wall mechanics analysis in hypertension-induced heart failure rats with preserved ejection fraction

Although cardiac wall mechanics is of importance for understanding heart failure with preserved ejection fraction (HFpEF), there is a lack of relevant mechanics studies. The aim of this study was to analyze the changes in stress and strain in the left ventricle (LV) in hypertension-induced HFpEF rats. Based on experimental measurements in DSS rats fed with high-salt (HS) and low-salt (LS) diets, LV stress and strain were computed throughout the cardiac cycle using Continuity software. HS-feeding increased myofiber stress and strain along both the transmural and longitudinal directions at the end-diastolic state but resulted in a lower absolute value of strain and relatively unchanged stress at the end-systolic state. Moreover, the end-diastolic stress and strain decreased with increasing radial position from the endocardial towards the epicardial walls despite negligible changes along the longitudinal direction. The changes in LV wall mechanics characterized the elevated diastolic LV stiffness and slow LV relaxation in HS-fed rats of HFpEF. These findings denote that a vicious cycle of increased stress and strain and diastolic dysfunction can prompt the development of HFpEF.

Investigation of the Role of Myocyte Orientations in Cardiac Arrhythmia Using Image-Based Models

Cardiac electrical excitation-propagation is influenced by myocyte orientations (cellular organization). Quantitatively understanding this relationship presents a significant research challenge, especially during arrhythmias in which excitation patterns become complex. Tissue-scale simulations of cardiac electrophysiology, incorporating both dynamic action potential behavior and image-based myocardial architecture, provide an approach to investigate three-dimensional (3D) propagation of excitation waves in the heart. In this study, we aimed to assess the importance of natural variation in myocyte orientations on cardiac arrhythmogenesis using 3D tissue electrophysiology simulations. Three anatomical models (i.e., describing myocyte orientations) of healthy rat ventricles—obtained using diffusion tensor imaging at 100 μm resolution—were registered to a single biventricular geometry (i.e., a single cardiac shape), in which the myocyte orientations could be represented by each of the diffusion tensor imaging data sets or by an idealized rule-based description. The Fenton-Karma cellular excitation model was modified to reproduce rat ventricular action potential duration restitution to create reaction-diffusion cardiac electrophysiology models. Over 250 3D simulations were performed to investigate the effects of myocyte orientations on the following: 1) ventricular activation, 2) location-dependent arrhythmia induction via rapid pacing, and 3) dynamics of re-entry averaged over multiple episodes. It was shown that 1) myocyte orientation differences manifested themselves in local activation times, but the influence on total activation time was small; 2) differences in myocyte orientations could critically affect the inducibility and persistence of arrhythmias for specific stimulus-location/cycle-length combinations; and 3) myocyte orientations alone could be an important determinant of scroll wave break, although no significant differences were observed in averaged arrhythmia dynamics between the four myocyte orientation scenarios considered. Our results show that myocyte orientations are an important determinant of arrhythmia inducibility, persistence, and scroll wave break. These findings suggest that where specificity is desired (for example, when predicting location-dependent, patient-specific arrhythmia inducibility), subject-specific myocyte orientations may be important.

Intracranial lymphatic drainage discharges iron from the ventricles and reduce the occurrence of chronic hydrocephalus after intraventricular hemorrhage in rats

Background: The discovery of intracranial lymphatic system provides a new theory about cerebrospinal fluid circulation. In order to investigate the role of lymphatic drainage in hydrocephalus after intraventricular hemorrhage (IVH), three parts of experiments were performed.Methods: IVH model was produced by 200ul autologous blood injection into lateral ventricle of SD male rats. Perls Prussian blue reaction was used to confirm the ability of iron drainage through deep cervical lymph nodes (DCLNs) in part I. The part II measured the volume of ventricles by MR scanner , and the part III compared the ferritin level of area surrounding ventricles by Western blotting after IVH.Results: The ability of iron drainage through DCLNs was confirmed. DCLNs-excised rats got a 19.6% higher incidence of hydrocephalus than DCLNs-preserved rats at day 28 after IVH. And DCLNs-excised group showed higher ferritin level than DCLNs-preserved group at day 3 after IVH.Conclusion: The whole experiments revealed the role of intracranial lymphatic system in discharging iron out of central nervous system at acute phase of IVH, and proved the function in alleviating and avoiding hydrocephalus at chronic phase after IVH.

Direct and Indirect Suppression of Scn5a Gene Expression Mediates Cardiac Na+ Channel Inhibition by Wnt Signalling

BackgroundMyocardial infarction and heart failure are associated with reduced voltage-gated Na+ current (INa) that promotes arrhythmias and sudden deaths. We have previously shown that the Wnt/β-catenin signalling (Wnt signalling), which is active in heart disease, reduces cardiac INa, suggesting that Wnt signalling may be a potential therapeutic target. However, because Wnt signalling is required for the homeostasis of many noncardiac tissues, administration of Wnt inhibitors to heart patients would cause significant side effects. The present study aims to elucidate the molecular mechanisms of cardiac INa inhibition by Wnt, which would identify cardiac-specific therapeutic targets. MethodsWnt signalling was activated in neonatal rat ventricular myocytes by Wnt3a protein. Adenovirus expressing Wnt3a was injected into the adult rat ventricle. CRISPR/Cas9 and chromatin immunoprecipitation were used for mechanistic studies. ResultsWnt signalling activation in neonatal rat ventricular myocytes reduced Nav1.5 protein and Scn5a mRNA, but increased Tbx3, a known suppressor of Scn5a. Chromatin immunoprecipitation showed that Wnt signalling inhibits Scn5a expression through downstream mediator (TCF4) binding to both Tbx3 and Scn5a promoters. Overexpression or knockdown of Tbx3 directly modified Nav1.5 and INa, whereas CRISPR/Cas9-induced mutations at TCF4 binding sites within the Scn5a promoter attenuated Wnt inhibition of Scn5a and Nav1.5. In adult rat hearts, adenovirus expressing Wnt3a reduced Nav1.5, increased QRS duration in electrocardiogram, and increased the susceptibility to ventricular tachycardia. ConclusionsWnt signalling inhibits the Na+ channel by direct and indirect (via Tbx3) suppression of Scn5a transcription. Strategies to block TCF4 binding to the Tbx3 and Scn5a promoters would represent novel strategies for cardiac-specific inhibition of the Wnt pathway to rescue INa and prevent sudden cardiac deaths.

P6300Endothelial cell activation by pro-inflammatory cytokines exerts novel paracrine effects on co-cultured cardiomyocytes

Abstract Background Anti-inflammatory therapies have failed to meet expectations in recent clinical trials for heart failure, despite the number of studies demonstrating pro-fibrotic, arrhythmogenic and hypertrophic effects of inflammation. To enlighten this, we sought to examine the contribution of non-myocytes in the cardiac inflammatory response. Endothelial cells (EC) can regulate cardiomyocyte (CM) function with multiple soluble factors. While many studies have shown the effects of pro-inflammatory cytokines on EC or CM separately, it is still unclear how the activation of EC can affect CM function. Purpose We studied the effect of pro-inflammatory pre-conditioning of EC on CM in indirect co-culture systems and in an ex vivo model of cardiac tissue. We hypothesised that pro-inflammatory activation of EC would alter the contractility of co-cultured CM. Methods Human cardiac microvascular EC were first pre-conditioned for 24h with Cytomix (1 ng/ml TNF-α, 1 ng/ml IL-1β, 25 ng/ml IL-6 Rα/IL-6 chimera) and co-cultured in a transwell system (pore size: 0.4μm) with adult rat ventricular CM. Co-culture supernatants were screened using a Cytokine Profiler Array. In vitro analysis of calcium handling in CM utilised the optical mapping technique and Fluo-4. Contractility of cardiac tissue was measured ex vivo using myocardial slices of 300 μm, prepared from left ventricles of adult rat and cultured for 24h with field stimulation and a fixed stretch producing a sarcomeric length of 2.2 μm. Results Treatment of EC by Cytomix prior to co-cultures induced a release of CC and CXC chemokines, G-/GM-CSF, ST2 and the adhesion molecule ICAM-1. Using published RNAseq datasets we noticed that adult CM do not constitutively express the receptors for the chemokines identified with the Profiler Array. However, duration of calcium transients in CM was significantly reduced from 454 to 322 ms in co-cultures with EC pre-conditioned by Cytomix, compared to untreated EC. Amplitude and time to peak were unchanged. In contrast, myocardial slices treated with Cytomix demonstrated a significant increase in contractility compared to control (from 3.3 to 5.3 mN/mm2) but no significant change in the duration of contraction (from 467 to 434 ms) or the rate of relaxation. Conclusions Pre-conditioned EC exert paracrine effects on the calcium handling of isolated CM, suggesting pro-inflammatory activation of proximal EC can affect CM function. In myocardial slices, pro-inflammatory stimulation provoked an inotropic response. The divergence of effect with findings in isolated cells may reflect differences in experimental design and multicellularity. Future work will aim to characterise the soluble mediators involved, and selectively target EC in slices to contextualise the effects described in co-cultures. Ultimately, this may inform the development of novel anti-inflammatory strategies for clinical use. Acknowledgement/Funding British Heart Foundation

Effects of exercise training and stem cell therapy on the left ventricle of infarcted rats

Introduction and ObjectivesStem cell therapy and aerobic exercise are non-pharmacological therapies following myocardial infarction. The aim of this study was to test whether aerobic exercise training enhances the benefits of mesenchymal stem cell (MSC) therapy on remodeling of the extracellular matrix and fetal gene expression in the left ventricle of infarcted rats. MethodsMyocardial infarction was surgically induced in six-week old male Wistar rats. Animals were divided into four groups: sedentary control (SC) and sedentary and stem cell treated (SCMSC); exercised (EX) and exercised and stem cell treated (EXMSC). Bone marrow-derived MSCs were immediately transplanted via the tail vein (concentration: 1×106 cells). Exercise training (five days/week, 60 min/day; 60% of maximal running speed) started 24 hours after myocardial infarction and lasted for 12 weeks. ResultsExercise capacity was higher in exercised than in sedentary groups. Animals in the SCMSC, EX and EXMSC groups exhibited better cardiac function than those in SC. Collagen content was lower in the SCMSC, EX and EXMSC groups than in SC and skeletal α-actin expression was lower in EX and EXMSC than in SC. The α/β-MHC ratio was higher in EX and EXMSC than in SC. The combination of therapies further reduced collagen content in the remote region of the infarct (∼24%) and skeletal α-actin expression (∼30%). ConclusionAerobic exercise training appears to enhance the beneficial effects of stem cell therapy on remodeling of the extracellular matrix and fetal gene expression in the left ventricle of rats with moderate infarction.

Effects of exercise training and stem cell therapy on the left ventricle of infarcted rats

Stem cell therapy and aerobic exercise are non-pharmacological therapies following myocardial infarction. The aim of this study was to test whether aerobic exercise training enhances the benefits of mesenchymal stem cell (MSC) therapy on remodeling of the extracellular matrix and fetal gene expression in the left ventricle of infarcted rats. Myocardial infarction was surgically induced in six-week old male Wistar rats. Animals were divided into four groups: sedentary control (SC) and sedentary and stem cell treated (SCMSC); exercised (EX) and exercised and stem cell treated (EXMSC). Bone marrow-derived MSCs were immediately transplanted via the tail vein (concentration: 1×10 6 cells). Exercise training (five days/week, 60 min/day; 60% of maximal running speed) started 24 hours after myocardial infarction and lasted for 12 weeks. Exercise capacity was higher in exercised than in sedentary groups. Animals in the SCMSC, EX and EXMSC groups exhibited better cardiac function than those in SC. Collagen content was lower in the SCMSC, EX and EXMSC groups than in SC and skeletal α-actin expression was lower in EX and EXMSC than in SC. The α/β-MHC ratio was higher in EX and EXMSC than in SC. The combination of therapies further reduced collagen content in the remote region of the infarct (∼24%) and skeletal α-actin expression (∼30%). Aerobic exercise training appears to enhance the beneficial effects of stem cell therapy on remodeling of the extracellular matrix and fetal gene expression in the left ventricle of rats with moderate infarction. Terapia com células estromais e exercício aeróbio são estratégias não farmacológicas no tratamento pós-enfarte do miocárdio. O objetivo foi testar se o treinamento aeróbio amplia os benefícios da terapia com células mesenquimais estromais (CME) na remodelagem da matriz extracelular e na expressão de genes fetais no ventrículo esquerdo de ratos enfartados. O enfarte do miocárdio foi induzido cirurgicamente em ratos com seis semanas de idade, divididos em quatro grupos: sedentário controle (SC) e tratado com CME (SCCME); exercício (EX) e exercício tratado com CME (EXCME). CME derivadas da medula óssea foram transplantadas através da veia caudal (concentração: 1 x 106 células). O treinamento aeróbio (5 dias/semana; 60 min/dia; 60% da velocidade máxima de corrida) iniciou 24 h após enfarte do miocárdio e durou 12 semanas. A capacidade de exercício foi maior nos grupos exercitados que nos sedentários. Os grupos SCCME, EX e EXCME apresentaram melhor função cardíaca do que o SC. O conteúdo de colagénio foi menor nos grupos SCCME, EX e EXCME que no SC. A expressão da α-actina esquelética foi menor nos grupos EX e EXCME, comparada à do SC. A razão miosina de cadeia pesada α/β foi maior nos grupos EX e EXCME, comparada à do SC. A combinação das terapias reduziu ainda mais o conteúdo de colagénio na região remota (∼24%) e a expressão de α-actina esquelética (∼30%). O treinamento aeróbio parece potencializar os benefícios da terapia com células mesenquimais estromais na remodelagem da matriz extracelular do ventrículo esquerdo e expressão de genes fetais em ratos com enfarte moderado.

Crocin Improves Cognitive Behavior in Rats with Alzheimer's Disease by Regulating Endoplasmic Reticulum Stress and Apoptosis.

Aim To investigate the effect of crocin on the learning and memory acquisition of AD rats and its underlying mechanisms. Methods A total of 48 healthy male SD rats were randomly divided into control group, AD model group, resveratrol group, and crocin group, with 12 rats per group. AD model was established by injecting Aβ25–35 to the lateral ventricle of rats, and thereafter the rats were administrated with resveratrol (40 mg/kg), crocin (40 mg/kg), or PBS daily for 14 days. Y-maze test and sucrose preference test were used to detect the learning and memory acquisition of rats. Neuronal apoptosis was detected by TUNEL staining and Western blot for apoptosis-related proteins Bax, Bcl-2, and Caspase-3. Immunofluorescence staining and Western blot tests were used to detect the expression of glucose regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) in hippocampal CA1 region (Hippo) and prefrontal cortical neurons (PFC). Results The learning and memory abilities of AD rats were significantly decreased, which was significantly rescued by resveratrol and crocin. The apoptotic cell number of Hippo and PFC neurons in AD model group was significantly higher than that in control group (P<0.01), while resveratrol and crocin significantly decreased the apoptotic cell number in AD group (P<0.01). Compared with the control group, the expression of Bcl2 in PFC and hippo of AD model group was significantly decreased (P<0.01), while those of Bax, Caspase3, GRP78, and CHOP were significantly increased (P<0.01). Resveratrol and crocin could significantly reverse the expression of these proteins in AD rats (P<0.05). Conclusion Crocin can improve the learning and memory ability of AD rats possibly by reducing endoplasmic reticulum stress and neuronal apoptosis.

Electrophysiological remodeling of the right ventricle in experimental heart failure of different etiologies

The aim of the study was to evaluate electrophysiological remodeling of the right ventricle in rats in experimental heart failure of different etiologies. Materials and methods. Isadrin-, doxorubicin- and monocrotaline-induced heart failure models were developed. Unipolar epicardial electrograms of the ventricles (256 recording sites) were recorded using a 144-channel system. The cardiac output and pressure in both ventricles of the heart were measured. Activation-recovery intervals were used as an index of duration of local repolarization, and the general and local dispersions of activation-recovery intervals were used as an index of heterogeneity of ventricular repolarization. Results. In all models of heart failure, the following were identified: 1) non-uniform prolongation of repolarization with the greatest elongation at the apex of the right ventricle; 2) an increase in apicobasal differences of repolarization with the greatest change in the right ventricle; 3) an increase in the heterogeneity of the repolarization of the epicardial layer of the ventricles with heterogeneous changes in the local heterogeneity of repolarization and a decrease in the interregional differences in the heterogeneity of the electrophysiological properties of the myocardium; 4) more pronounced changes in the repolarization of the right ventricle than in the repolarization of the left ventricle. Conclusion. Thus, irrespective of the cause of the heart failure, the following changes occur: 1) prolongation of the right ventricular repolarization occurs non-uniformly (mostly due to the apical area), which results in an increase in the right ventricular repolarization heterogeneity; 2) an increase in the heterogeneity of right ventricular repolarization is observed, which causes an increase in the overall heterogeneity of the ventricular epicardial surface.

Abstract 606: Stimulation of Cardiomyocyte a- and b-Adrenoceptors Uniquely Regulates Exosome Generation and miRNA Content

Background and Purpose: Influence of adrenoceptor (AR) signaling for the regulation of exosomes secreted from cardiomyocytes is unknown and since catecholamines are increased in heart failure (HF), there is interest in uncovering whether α- or β-ARs can induce specific changes in circulating blood exosomes in HF. In this study, we have evaluated whether α- or β-AR stimulation of neonatal rat ventricle myocytes (NRVMs) can alter the number, size or microRNA (miR) content of secreted exosomes. Methods and Results: The number and size distribution of exosomes from NRVMs were evaluated by Nanosight NS300. Phenylephrine (PE, 10 uM for 3 days), an α-AR agonist, increased exosome number significantly of NRVM compared than vehicle (PBS) treatment group (Veh: 7.82X10 8 ± 5.06X10 7 and PE: 10.09X10 8 ± 15.0 X10 7 / 1X10 6 NRVMs, n=3) but Isoproterenol (ISO, 1uM), a β-AR agonist, did not. Both agonists had no effect on exosome size distribution. After purifying total RNA from secreted exosomes, we evaluated the expression level of 37 candidate miR’s, which were selected from previous microarray data. ISO treatment decreased 14 miR’s (miR-222, -106a, -292a, -181b, -210, -489, -214, -1947, -195, -17, -7b, -93, -532 and -19a) and PE increased 5 miR’s (miR-20a, -210, -17-1, -Let7a, and 146b). Importantly, PE or ISO regulated any identical miR’s. As a control for treatment effects, we found that PE and ISO elevated myocyte mRNA levels of ANP and BNP to similar degrees. Conclusions: Both α- and β-AR agonists are can stimulate cardiomyocyte hypertrophy to similar degrees, however they have distinct regulatory patterns for secreted exosomes. This includes the number produced and more importantly, miR content. These miR’s and exosomes found in circulating blood may be able to distinguish and be biomarkers for different modes of maladaptive cardiac hypertrophy and HF.

Abstract 425: Role of MLF1 in Cardiomyocyte Cell Cycle Regulation

The neonatal mammalian heart is capable of significant regeneration after cardiac injury. However, that ability is lost in the early postnatal period, coinciding with the development of cardiomyocyte cell cycle arrest. Myeloid leukemia factor 1 (MLF1) is a protein expressed in hematopoietic cells, skeletal muscle and cardiac muscle. In hematopoietic cells, MLF1 is thought to be a negative cell cycle regulator, possibly acting through a p53-dependent mechanism. However, the role of MLF1 in the cardiovascular system is not well understood. Here, we describe MLF1 as a regulator of cardiomyocyte cell cycle progression. We first examined the expression pattern of MLF1 in neonatal mouse heart. MLF1 protein specifically expresses in the nucleus, and the expression level increases from P1 to P7 as revealed by quantitative PCR and Western Blot. To elucidate a potential role of Mlf1 in cardiomyocyte proliferation, we silenced Mlf1 in neonatal rat ventricle myocytes (NRVMs) which showed increased cardiomyocyte proliferation by staining with a mitosis marker phospho-Histone 3 (pH3). Then we generated an inducible cardiac-specific Mlf1 knockout mouse model and assessed for the prolongation of the proliferative window by echocardiography, cell size analysis, and immunostaining for cell cycle markers. Staining the Mlf1 KO hearts with proliferation markers, pH3 to determine mitosis and Aurora B kinase to determine cytokinesis, indicated that deletion of Mlf1 resulted in increased cardiomyocyte proliferation. It also showed improvement in left ventricular systolic function following myocardial infarction by echocardiography. In contrast, overexpression of MLF1 in heart showed decreased cardiac function as quantified by ejection fraction. These results identify MLF1 as a negative cell cycle regulator of cardiomyocyte proliferation.