Left Ventricle Collagen Research Articles

O70 INVOLVEMENT OF MICRORNAs-146a-5P, -155-5P, AND -29b-5P IN CARDIAC REMODELLING AND DYSFUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS

Background: MicroRNAs have been implicated in the pathogenesis of cardiovascular disease. However, the contribution of microRNAs remain poorly understood in the context of hypertensive cardiac pathology. Aim: We investigated the role of miR-146a-5p, -155-5p, and -29b-5p in the development of cardiac hypertrophy and dysfunction in male and female spontaneously hypertensive rats (SHR). Methods: Seven (7)-month-old SHR (n=7 male, n=10 female), and age- and sex-matched normotensive Wistar Kyoto rats (WKY, n=7 male, n=9 female) were used for the study. Cardiac geometry and function were determined from echocardiography. Plasma levels of inflammatory markers were measured by ELISA. Collagen fraction area was determined from histological sections of the left ventricle (LV). MicroRNA, and mRNA expression of target genes was determined in the LV by RT-qPCR. Group differences were ascertained from 2-way ANOVA. Associations were determined from pearson's correlation. Results: In SHR, normalised heart and LV masses, LVPWTd, RWT, E, A, E/e’, and collagen fraction area were significantly greater compared to WKY. MidFS, e’, and a’ were significantly lower in SHR versus WKY. Female rats exhibited significantly greater LV mRNA expression of Lox1, Col1a/Col3a ratio, and plasma levels of CRP, IL-6, and TNF-α compared to males. MiR-29b-5p showed similar expression levels across experimental groups. MiR-146a-5p was upregulated in SHR and exhibited positive associations with BP, normalised heart and LV masses, RWT, collagen fraction area, and E/e’ ratio, but negative associations with e’. Conversely, miR-155-5p was downregulated in females and only positively associated with absolute heart, LV, kidney masses, and stroke volume. Conclusion: Upregulation of miR-146a-5p was associated with indices of concentric LVH, diastolic dysfunction, reactive fibrosis, and may be involved in the hypertensive-induced LV remodelling; whereas, changes in expression of miR-155-5p may be involved with a cardiac phenotype related to sexual dimorphism.

Beneficial Consequences of One-Month Oral Treatment with Cannabis Oil on Cardiac Hypertrophy and the Mitochondrial Pool in Spontaneously Hypertensive Rats.

Introduction: It has been demonstrated the dysregulation of the cardiac endocannabinoid system in cardiovascular diseases. Thus, the modulation of this system through the administration of phytocannabinoids present in medicinal cannabis oil (CO) emerges as a promising therapeutic approach. Furthermore, phytocannabinoids exhibit potent antioxidant properties, making them highly desirable in the treatment of cardiac pathologies, such as hypertension-induced cardiac hypertrophy (CH). Objective: To evaluate the effect of CO treatment on hypertrophy and mitochondrial status in spontaneously hypertensive rat (SHR) hearts. Methods: Three-month-old male SHR were randomly assigned to CO or olive oil (vehicle) oral treatment for 1 month. We evaluated cardiac mass and histology, mitochondrial dynamics, membrane potential, area and density, myocardial reactive oxygen species (ROS) production, superoxide dismutase (SOD), and citrate synthase (CS) activity and expression. Data are presented as mean ± SEM (n) and compared by t-test, or two-way ANOVA and Bonferroni post hoc test were used as appropriate. p < 0.05 was considered statistically significant. Results: CH was reduced by CO treatment, as indicated by the left ventricular weight/tibia length ratio, left ventricular mass index, myocyte cross-sectional area, and left ventricle collagen volume fraction. The ejection fraction was preserved in the CO-treated group despite the persistence of elevated systolic blood pressure and the reduction in CH. Mitochondrial membrane potential was improved and mitochondrial biogenesis, dynamics, area, and density were all increased by treatment. Moreover, the activity and expression of the CS were enhanced by treatment, whereas ROS production was decreased and the antioxidant activity of SOD increased by CO administration. Conclusion: Based on the mentioned results, we propose that 1-month oral treatment with CO is effective to reduce hypertrophy, improve the mitochondrial pool and increase the antioxidant capacity in SHR hearts.

Doxycycline Attenuates Doxorubicin-Induced Cardiotoxicity by Improving Myocardial Energy Metabolism in Rats.

Aim: Evaluate the influence of doxycycline, an anti-inflammatory and matrix metalloproteinase (MMP) inhibitor, on the attenuation of chronic doxorubicin-induced cardiotoxicity in rats. Methods: We allocated male Wistar rats into four groups: control (C), doxorubicin (D), doxycycline (inhibitor of MMP, IM), and Dox + doxycycline (DIM). Groups IM and DIM received doxycycline (5 mg/kg, IP) once a week for 4 weeks. In addition, 48 h after every doxycycline injection, groups D and DIM received Dox (5 mg/kg, IP). We performed echocardiogram and evaluated TIMP-4 and collagen I protein expression, MMP-2 activity, and oxidative stress and myocardial metabolism. Results: Doxorubicin promotes left atrium (LA) and left ventricle (LV) dilatation and decreases in LV fractional shortening, which was improved by doxycycline. Moreover, doxycycline attenuated the LV cardiomyocyte hypertrophy and collagen type I expression. Doxorubicin increased phosphofructokinase and decreased beta-hydroxyacyl Co-A dehydrogenase, pyruvate dehydrogenase, citrate synthase, and ATP synthase activity, which was partially attenuated by doxycycline. Lastly, doxycycline improved antioxidant enzyme activity in the DIM group. Conclusion: Doxorubicin increases oxidative stress and promotes changes in myocardial energy metabolism, accompanied by structural and functional changes. Doxycycline attenuated the doxorubicin-induced cardiotoxicity, at least in part, through changes in myocardial energy metabolism.

Analysis of age-related left ventricular collagen remodeling in living donors: Implications in arrhythmogenesis

SummaryAge-related fibrosis in the left ventricle (LV) has been mainly studied in animals by assessing collagen content. Using second-harmonic generation microscopy and image processing, we evaluated amount, aggregation and spatial distribution of LV collagen in young to old pigs, and middle-age and elder living donors. All collagen features increased when comparing adult and old pigs with young ones, but not when comparing adult with old pigs or middle-age with elder individuals. Remarkably, all collagen parameters strongly correlated with lipofuscin, a biological age marker, in humans. By building patient-specific models of human ventricular tissue electrophysiology, we confirmed that amount and organization of fibrosis modulated arrhythmia vulnerability, and that distribution should be accounted for arrhythmia risk assessment. In conclusion, we characterize the age-associated changes in LV collagen and its potential implications for ventricular arrhythmia development. Consistency between pig and human results substantiate the pig as a relevant model of age-related LV collagen dynamics.

Effect of neuregulin-1 on cardiac glucose metabolism in rats with experimental myocardial infarction

Objective: To investigate the effect of neuregulin-1(NRG-1) on cardiac glucose metabolism in Sprague Dawley (SD) rats with experimental myocardial infarction (MI). Methods: Adult male SD rats were randomly divided into three groups: the sham-operated group, MI group, and MI+NRG1 group. The rat MI model was established via ligation of the left anterior descending coronary artery. Two weeks after operation, echocardiography was performed, MI rats with left ventricular ejection fraction (LVEF) between 0.3-0.5 were selected and randomly assigned to MI group and MI+NRG-1 group. Rats in MI+NRG-1 group were treated with recombinant human NRG-1β (100 μg/kg) via tail vein at 2 weeks after operation (twice per week for 6 weeks); while rats in sham-operated group and MI group received equal volume of physiological saline. By the end of administration, echocardiography and small animal positron emission tomography (PET) were performed to detect cardiac function and myocardial glucose uptake. Myocardial morphology and collagen volume fraction, cardiomyocyte apoptosis and reactive oxygen species (ROS) production were evaluated by histopathologic analysis. Myocardial pyruvate dehydrogenase (PDH) and citrate synthase (CS) activity, as well as ATP production were detected by commercial kits. The mRNA and protein expression levels of NRG-1, p-ErbB4, and key factors involved in glucose metabolism (including Glut-4, HK2, PDK4, PDH, CS) were detected by quantitative real-time PCR (qRT-PCR) and Western blot assay, respectively. Results: With the MI model successfully established, the left ventricular ejection fraction(LVEF) and left ventricular shortening fraction(LVFS) were significantly lower in MI group and MI+NRG-1 group than that in sham group (both P<0.01), while there was no significant difference between MI group and MI+NRG-1 group(all P>0.05). After 6 weeks of NRG-1β intervention, the LVEF and LVFS were significantly higher in MI+NRG-1 group than in MI group (both P<0.01). By the end of experiment, PET imaging showed that the mean standardized uptake value (SUVmean) were lower in MI+NRG-1 group than in the sham group (4.06±0.28 vs. 5.18±0.37, P<0.01), while significantly higher than that in MI group (4.06±0.28 vs.2.86±0.49, P<0.01). Histopathological analysis showed that compared with MI group, rats in MI+NRG-1 group exhibited significantly decreased left ventricle collagen volume fraction ((7.83±1.24) % vs. (18.31±3.58) %, P<0.01), cardiomyocyte apoptosis((37.98±4.26)% vs. (67.04±5.38)%, P<0.01), and DHE fluorescence intensity(0.057 28±0.007 06 vs. 0.076 94±0.008 46, P<0.01), indicating that NRG-1β could reduce ROS production. PDH activity, CS activity, and ATP production were significantly higher in MI+NRG-1 group than in MI group (all P<0.05). qRT-PCR demonstrated an upregulated Glut-4, HK2 and CS, but downregulated PDK4 mRNA expression in MI+NRG-1 group compared with MI group (all P<0.01). Western blot assay showed significantly higher protein expression of NRG-1, p-ErbB4, Glut-4, HK2, PDH, CS in MI+NRG-1 group than in MI group (all P<0.01). Conclusion: NRG-1 could improve glucose uptake and utilization in myocardium by activating phosphorylation of myocardial ErbB4 receptor in MI rats, thus providing a therapeutic option for improving energy metabolism after MI.

Abstract P363: Annexin-A1 Deficiency Exaggerates Cardiac Remodeling In Angiotensin II-induced Hypertension

Introduction: We have previously demonstrated that the naturally-occurring anti-inflammatory and pro-resolving protein Annexin-A1 (Anx-A1) limits the acute inflammatory response post myocardial infarction, but its impact on chronic inflammation, such as hypertension, has not been explored. This study aims to investigate the role of Anx-A1 in a preclinical model of hypertension, induced by angiotensin-II (Ang-II). Methods: 15-week-old male C57BL/6 or ANXA1 -/- were anesthetized (isoflurane, 2-4% v/v) and implanted with an osmotic minipump randomly assigned to receive Ang-II (0.7mg/kg/day) or vehicle (saline). Radiotelemetry recordings of blood pressure were taken at 10 intermittent timepoints from baseline to the end of the 29-day infusion period. Animals were euthanized with pentobarbitone (100mg/kg; i.p.) at endpoint and organ weights recorded and normalized to bodyweight. Left ventricle (LV) samples were stained with picrosirius red to assess total LV collagen deposition. Results: Ang II-induced mice at the end of the study had elevated mean arterial pressure (MAP), cardiac hypertrophy and fibrosis compared to normotensive mice (Table). Anx-A1 deficient mice given Ang II had an even greater increase in MAP and cardiac remodeling compared to WT. Interestingly, MAP of Anx-A1 deficient mice at baseline is significantly higher compare to C57BL/6 counterparts (Table). Conclusion: This is the first study to demonstrate that deficiency of Anx-A1 exaggerates cardiac remodeling in AngII-induced hypertension, suggesting that endogenous Anx-A1 might play previously unappreciated physiological role in regulating blood pressure. This supports the development of Anx-A1 based pharmacotherapy against hypertension-induced cardiac damage.

Abstract MP04: Interleukin-33 Drives Cardiac Remodeling And Alters Macrophage Polarization In Doca-salt Hypertension

Interleukin-33 (IL-33) is an alarmin critical for alternative macrophage activation and has been linked to hypertension in humans. The goal of this study was to evaluate whether IL-33 contributes to (deoxycorticosterone acetate) DOCA-salt induced cardiac remodeling and macrophage polarization. C57Bl/6J (WT, n=8) and IL33-deficient (IL-33 KO, n=8) mice underwent uninephrectomy, implantation of a DOCA pellet, and 1% NaCl supplementation of drinking water for three weeks. A control group of WT mice (n=10) underwent a sham procedure and were maintained on normal water. Systolic blood pressure measured by tail cuff showed a significant increase in WT DOCA-salt mice (128±9 mmHg; mean±SD) and IL-33 KO DOCA-salt mice (129±11) compared to WT sham (103±11). Hypertension was accompanied by significantly increased heart to body weight ratios in WT DOCA-salt (7.0±1.0 mg/g) and IL-33 KO DOCA-salt (6.8±0.6) compared to WT sham (5.3±0.3) mice. Glomerular injury was assessed by urine albumin-to-creatinine ratios, which were similarly increased in WT DOCA-salt (0.92±0.4) and IL-33 KO DOCA-salt (0.42±0.09) mice compared to WT controls (0.03±0.003). Echocardiography was performed to assess left ventricle (LV) dimensions and systolic function. IL-33 KO DOCA-salt mice exhibited a significantly higher cardiac output (22±2 mL/min) compared to WT sham (16±3) and WT DOCA-salt (15±3) mice, driven by increased stroke volume. No significant changes in heart rate or ejection fraction were observed between groups. Additionally, IL33-KO DOCA-salt mice had an increased diastolic LV internal dimension (3.2±0.2 mm) compared to WT sham (2.7±0.3) and WT DOCA-salt (2.7±0.3). DOCA-salt induced increased mRNA expression of alternative macrophage activation markers in both LV ( Chil3, Il10) and isolated peritoneal macrophages ( Arg1, Retnla, Tgfb1 ). Peritoneal macrophages deficient in IL-33 expressed less Il10 compared to WT. Cardiac fibrosis evaluated by Masson’s trichrome showed a significant increase in LV collagen deposition in WT DOCA-salt mice (1.09±0.8% trichrome positive) compared to WT sham (0.43±0.3) but no increase in IL-33 KO DOCA-salt mice (0.54±0.3). In conclusion, IL-33 deficiency alters macrophage and cardiac function in the DOCA-salt model of hypertension.

Effects of aerobic exercise training and açai supplementation on cardiac structure and function in rats submitted to a high-fat diet

This study evaluated the effect of aerobic exercise training (AET) and supplementation with açai on cardiac structure and function in rats submitted to a high-fat diet. Two-month old Fischer male rats were divided into 5 groups: Control (C), High-fat Diet (H), High-fat Diet + Açai (HA), High-fat Diet + AET (HT), High-fat Diet + Açai + AET (HAT). The high-fat diet had 21.8% lard and 1% cholesterol (H and HT), or supplemented with 1% lyophilized açai pulp (HA and HAT). The HT and HAT groups performed AET on a treadmill (5 days/week, 1 h/day, 60% of the maximum running speed) for 8 weeks. Exercise tolerance test were performed, and adiposity index calculated. After euthanasia, the left ventricle (LV) was dissected and processed for histological, single myocyte intracellular calcium ([Ca2+]i) transient and contractility, oxidative stress and gene expression analysis. AET improved running capacity and reduced the adiposity index. Both AET and açai supplementation inhibited the increase in the LV collagen content, the deleterious effects on the [Ca2+]i transient and contractility in cardiomyocytes and the increment in oxidative stress, caused by the consumption of a high-fat diet. Aerobic exercise training and açai supplementation can mitigate damage caused by high-fat diet in cardiac structure and function, though the combination of treatments had no additional effects.

Effects of Stress Stimulation on Protein Folding/Degradation Pathway Related Proteins in Different Levels of Exhaustive Exercise

The pathways related to cell protein folding and degradation need to be elucidated because of training was set. The results showed that chaperonin containing tailless complex polypeptide the large number of proteins involved, the complex relationship between proteins and the lack of research on the effects of movement and cell protein folding and degradation. In order to analyze the effect of stress stimulation on protein folding/degradation pathway related proteins under different levels of exhaustive exercise, C57 Black 6 male mice of 4 w old were selected from the experimental animal center of the Academy of Military Medical Sciences and different intensity of treadmill exercise 1 beta, protein subunit alpha type-1 and protein subunit beta type-7 protein in insulin resistance mice bone increased significantly and insulin resistance improved significantly after 6 w of aerobic treadmill exercise. High intensity endurance exercise increased the expression of collagen volume fraction and type I collagen in right atrium and right ventricle (p<0.01) and the longer exercise time, the greater the increased range, and had no significant effect on the expression of collagen volume fraction and type I collagen in left ventricle. Although moderate intensity exercise promoted the expression of collagen volume fraction and collagen I in myocardium, there was no statistical significance.

Inflammatory cardiac fibroblast phenotype underlies chronic alcohol-induced cardiac atrophy and dysfunction

AimsThe purpose of this study was to investigate mechanisms of chronic alcohol-induced cardiac remodeling and dysfunction. We also sought to determine the role of cardiac fibroblasts, which play a dynamic role in cardiac remodeling, in mediating these effects. Main methodsAdult male Wistar rats were exposed to ethanol (EtOH) vapor inhalation for 16 weeks. Echocardiography was performed to assess terminal cardiac structure and function. Cardiac fibroblasts were isolated from the left ventricle (LV) for both ex vivo and in vitro analysis. Cultured H9C2 cells were also exposed to conditioned media from alcohol-exposed cardiac fibroblasts. Gene expression in whole LV tissue, isolated cardiac fibroblasts, or cultured H9C2 cells was determined by real-time PCR, and protein expression was determined by Western blot. Key findingsEtOH led to LV wall thinning and impaired systolic function, and decreased contractile protein mRNA levels. EtOH increased LV inflammatory markers, JNK and Akt activation, and decreased mTOR expression. EtOH induced myofibroblast activation as assessed by flow cytometry, and increased LV collagen III expression. EtOH increased expression of several inflammatory mediators in cardiac fibroblasts both ex vivo and in vitro. Administration of conditioned media from EtOH-treated fibroblasts decreased contractile protein mRNA levels and impaired Akt and mTOR signaling in differentiated H9C2 cardiomyocytes. SignificanceOur results indicate that EtOH-induced cardiac atrophy and dysfunction is associated with activation of inflammatory pathways. Furthermore, EtOH may induce a pro-inflammatory cardiac fibroblast phenotype, leading to aberrant fibroblast-myocyte cross-talk. Thus, EtOH may promote cardiac muscle wasting in part by activation of pro-inflammatory fibroblasts.

Altered Antioxidant and Inflammatory Signaling by Fibroblasts in the Hypertensive Heart

In response to hypertensive stimuli, like angiotensin II (AngII), cardiac fibroblasts (CFs) transform into an activated phenotype, which triggers increased collagen deposition and pro‐inflammatory signals. Transforming growth factor beta 1 (TGF‐β1) and reactive oxygen species are important modulators of AngII‐induced cardiac fibrosis and CF activation. The extent to which the AngII‐induced changes in CF phenotype persist in the absence of ongoing stimulation is not known. The objective of the present study was to determine the persistent impact of chronic AngII infusion on CF phenotype. Specifically, we performed an in vitro characterization of CFs isolated from rats chronically treated with AngII (in vivo) or saline (vehicle) and investigated acute (in vitro) responses to AngII thereafter. Adult male SD rats were administered AngII (200 ng/kg/min) or saline for 4 weeks. In half of the rats in each group, we measured mean arterial pressure (MAP), weighed the left ventricle (LV), and fixed a section of LV for assessment of collagen deposition (Sirius Red). In remaining rats, CFs were isolated and passaged to P1. CFs were treated in vitro with AngII (1uM) or vehicle for 72 hr. TGF‐β1 and monocyte chemoattractant protein 1 (MCP‐1) were assessed in culture media. Expression of pro‐/anti‐oxidant proteins NADPH oxidase 2 (Nox2), catalase and superoxide dismutase 1 (SOD1) were determined by western blot. Ang II increased MAP (43%, p&lt;0.05), LV/BW (30%, p&lt;0.05), and LV collagen deposition. TGF‐β1 release was not different from CFs isolated from saline vs. AngII infused rats. However, in vitro incubation with AngII significantly increased TGF‐β1 secretion in all CFs. CFs isolated from AngII‐infused rats secreted elevated levels of MCP‐1 (p&lt;0.05), when compared to control CFs. MCP‐1 levels were not further modified by acute AngII treatment. Basal expression of Nox2, SOD1, and catalase was similar between CFs isolated from control vs. AngII‐infused rats. Acute AngII tended to increase Nox2 expression in CFs isolated from vehicle and AngII‐treated rats, whereas AngII only increased SOD1 expression (46%, p&lt;0.05) in CFs from AngII‐infused rats. In vitro stimulation with AngII tended to increase catalase in CFs isolated from control rats, but reduced (20%, p&lt;0.05) expression in CFs isolated from AngII infused rats. Taken together, these data demonstrate that CFs isolated from an actively remodeling myocardium continue to secrete elevated levels of MCP‐1, but not TGF‐β1, in vitro. Moreover, CFs from AngII‐infused rats displayed altered expression of antioxidant enzymes following AngII in vitro, which may play a role in worsened inflammatory signaling and resultant pro‐fibrotic activity. Future studies will further elucidate the fibrotic and inflammatory characteristics of CFs from the remodeling myocardium and determine the extent to which this persistent phenotype alters the future responsiveness to a pathogenic stimulus.Support or Funding InformationSpringboard Grant, UA College of Medicine – PhoenixThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Influence of Creatine Supplementation and High Intensity Interval Training on Glycemic Profile and Cardiac Morphology in Rats

BackgroundCreatine supplementation may induce insulin resistance, a condition associated with cardiac remodeling and also a risk factor for cardiovascular disease. High intensity interval training (HITT) improves glucose tolerance and promotes cardiac changes. This study evaluated the influence of creatine supplementation and HITT on glycemic profile and cardiac morphology in rats.MethodsMale Wistar rats (n=60) were allocated into four groups: sedentary control (C), control + creatine supplementation (Cr), control + physical exercise (Ex), and creatine supplementation + physical exercise (ECr). C and Ex groups were treated with standard commercial chow; Cr and ECr received the same chow supplemented with creatine 2%. Rats from Ex and ECr groups underwent into a treadmill‐HIIT protocol, 5 times per week, for 12 weeks. At the end of the experiment, glycemic profile was analyzed by glucose and insulin tolerance tests (GTT and ITT, respectively), and functional capacity was assessed by maximal exercise test on treadmill. Cardiomyocyte cross‐sectional area and myocardial collagen interstitial fraction were evaluated in left ventricle histological sections stained with hematoxylin‐eosin and Picrosirius red, respectively. Statistics: two‐way ANOVA and Tukey.ResultsFunctional capacity was improved in exercised groups compared to respective controls. Considering glycemic response in GTT, the area under curve (AUC) was lower in Ex and ECr than in C and Cr. In ITT, AUC was lower in Ex than C and ECr. Atria weight and atria weight‐to‐body weight ratio were higher in ECr than Ex and atria weight‐to‐body weight ratio was higher in Cr than C. Heart weight‐to‐body weight ratio was higher in ECr than Cr and Ex. Left and right ventricle weight was similar between the groups. Myocyte cross‐sectional area (C 227±26, Cr 216±22, Ex 284±27, ECr 297±7 μm2) and left ventricle collagen interstitial fraction (C 1.96±1.79, Cr 1.98±1.28, Ex 2.36±2.00, ECr 2.49±1.80 %) were higher in Ex and ECr than C and Cr.ConclusionHIIT improves glucose and insulin tolerance. Creatine supplementation impairs insulin tolerance in exercised rats. HIIT promotes cardiomyocyte hypertrophy and increases myocardial collagen interstitial fraction without significant influence of creatine supplementation.Support or Funding InformationCAPESThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

QRS Shortens after Left Ventricular Assist Device Implantation

QRS Shortens after Left Ventricular Assist Device Implantation

MYOCARDIAL REACTION TO ENERGY DRINKS IN A GUINE A PIG: STRUCTURAL CHANGES

The aim of this study was to evaluate myocardial changes in a short-haired guinea pig (Cavia porcellus L) after everyday use of energy drinks for 60 days. The experiments were carried out on 11 male gui- nea pigs, age of 2 months, with a mean weight of 220±0.2 g. The guinea pigs were randomly grouped into a control group of 5 guinea pigs and experimen- tal group of 6. Experimental group guinea pigs were orally administered energy drinks 4 ml per day as a single oral dose. After the 60 days experiment, the quantitatively evaluated structures of myocardial in- terstitial collagen in the left ventricle using automa- ted image analysis system, which was connected to Olympus BXx51 microscope. Assessment was per- formed with Image-Pro Plus 5.1 analysis system. We calculated volume and perimeter of the interstitial fibrillar collagen in the left ventricular myocardium, the number of separate fibers in the field of view were counted. In total, there was evaluated 100 fields of view in the control group and 120 fields of view in the experimental group. Statistical analysis was per- formed using statistical package SPSS Statistics 20 and Microsoft Excel. We used bifactorial analysis of variance (ANOVA) to compare histomorphometric parameters between the two groups. We assessed that the difference between parameters was up to 1% and the individual specific effect was counting for 50% (p &amp;lt; 0.05). Variation of the featu- res was much larger within the experimental group, when compared to the control group. Maximum ave- rage values of the fibrillar collagen volume, perimeter and the number of separate fibers in the field of view were 1.2 times larger in the experimental group than in the control group. Repeated energy drink consumption acts as external factor stimulating adaptive remodeling processes. Quantative structural changes of fibrillar collagen in left ventricle of experimental group animals are reaction to a stress factor. Unbalanced changes of fi- brillar collagen may determine inadequate remodeling and become a reason for pathogenesis.

Magnesium valproate ameliorates type 1 diabetes and cardiomyopathy in diabetic rats through estrogen receptors

Estrogen is known to exhibit cardioprotective and antihyperlipidemic action. Valproic acid has been shown to upregulate estrogen receptors (ERs) in breast and prostate cancer tissues. No pharmacological evaluations for magnesium valproate (MgV) so far have been done for diabetic cadio-lipidemic complications. Based on the above context, current study was undertaken to evaluate the therapeutic effectiveness of MgV in cardiac complications associated with type-1 diabetes mellitus in rats wherein diabetes was induced by single tail vein injection of streptozotocin (STZ, 45mg/kg, IV) in female Sprague Dawley rats and treatment of MgV (210mg/kg, PO) was given for eight weeks to diabetic animals, after which, various biochemical and cardiac biomarkers, hypertrophic, hemodynamic and histological parameters along with immunohistochemistry of ERs in the left ventricle (LV) were estimated. MgV treatment significantly controlled hyperglycemia and dyslipidemia, reduced elevated cardiac biomarkers and C-reactive protein(CRP), significantly improved hemodynamic functions and increased the rate of pressure development and decay. MgV also significantly reduced left ventricular hypertrophy index and cardiac hypertrophy index, LV wall thickness, LV collagen, cardiomyocyte diameter and prevented the oxidative stress with significant increase in Na+-K+-ATPase activity in LV. Moreover, MgV reversed STZ-induced histological alterations and decreased glycogen content in LV and increased the ERβ expressions in LV as evidenced by immunohistochemistry. The result indicated that MgV prevented disease progression in the early stage of diabetic cardiomyopathy which seems to be mediated by upregulation of estrogen receptors in LV tissue.

Reduced collagen accumulation and augmented MMP-2 activity in left ventricle of old rats submitted to high-intensity resistance training.

Progressive fibrosis is a hallmark of the aging heart. Age-related fibrosis is modulated by endurance exercise training; however, little is known concerning the influence of resistance training (RT). Therefore we investigated the chronic effects of high-intensity RT on age-associated alterations of left ventricle (LV) structure, collagen content, matrix metalloproteinase-2 (MMP-2), and extracellular matrix-related gene expression, including transforming growth factor-β (TGF-β). Young adult (3 mo) and aged (21 mo) male Wistar rats were submitted to a RT protocol (ladder climbing with 65, 85, 95, and 100% load), three times a week for 12 wk. Forty-eight hours posttraining, arterial systolic and diastolic pressure, LV end-diastolic pressure (LVEDP) and dP/dt were recorded. LV morphology, collagen deposition, and gene expression of type I (COL-I) and type III (COL-III) collagen, MMP-2, tissue inhibitor of metalloproteinases-1 (TIMP-1), and TGF-β1 were analyzed by quantitative reverse transcriptase-PCR. MMP-2 content was assessed by zymography. Increased collagen deposition was observed in LV from aged rats. These parameters were modulated by RT and were associated with increased MMP-2 activity and decreased COL-I, TGF-β1, and TIMP-1 mRNA content. Despite the effect of RT on collagen accumulation, there was no improvement on LVEDP and maximal negative LV dP/dt of aged rats. Cardiomyocyte diameter was preserved in all experimental conditions. In conclusion, RT attenuated age-associated collagen accumulation, concomitant to the increase in MMP-2 activity and decreased expression of COL-I, TGF-β1, and TIMP-1 in LV, illustrating a cardioprotective effect of RT on ventricular structure and function.NEW & NOTEWORTHY We demonstrated the beneficial resistance-training effect against age-related left ventricle collagen accumulation in the left ventricle, which was associated with decreased type I collagen (COL-I), transforming growth factor-β1 (TGF-β1), and tissue inhibitor of metalloproteinases-1 (TIMP-1) gene expression and matrix metalloproteinase-2 (MMP-2) activity. Our findings suggest for the first time the potential effects of resistance training in modulating collagen accumulation and possibly fibrosis in the aging heart.

Dietary Salba (Salvia hispanica L) improves the altered metabolic fate of glucose and reduces increased collagen deposition in the heart of insulin-resistant rats

This study reports the effects of dietary Salba (chia) seeds on the mechanisms underlying impaired glucose metabolism in the heart of dyslipemic insulin-resistant rats fed a sucrose-rich diet (SRD). Wistar rats were fed a SRD for 3 months. Afterwards, half the animals continued with the SRD; in the other half's diet chia seeds replaced corn oil (CO) for three months (SRD+chia). In the control group, corn starch replaced sucrose. The replacement of CO by chia seeds in the SRD restored the activities of key enzymes involved in heart glucose metabolism decreasing fatty acid oxidation. Chia seeds normalized insulin stimulated GLUT-4 transporter, the abundance of IRS-1 and pAMPK, changed the profile of fatty acid phospholipids, reduced left-ventricle collagen deposition and normalized hypertension and dyslipidemia. New evidence is provided concerning the effects of dietary chia seeds in improving the altered metabolic fate of glucose in the heart of dyslipemic insulin-resistant rats.

Insulin replacement limits progression of diabetic cardiomyopathy in the low-dose streptozotocin-induced diabetic rat.

Diabetic cardiomyopathy is a major contributor to the increasing burden of heart failure globally. Effective therapies remain elusive, in part due to the incomplete understanding of the mechanisms underlying diabetes-induced myocardial injury. The objective of this study was to assess the direct impact of insulin replacement on left ventricle structure and function in a rat model of diabetes. Male Sprague-Dawley rats were administered streptozotocin (55 mg/kg i.v.) or citrate vehicle and were followed for 8 weeks. A subset of diabetic rats were allocated to insulin replacement (6 IU/day insulin s.c.) for the final 4 weeks of the 8-week time period. Diabetes induced the characteristic systemic complications of diabetes (hyperglycaemia, polyuria, kidney hypertrophy) and was accompanied by marked left ventricle remodelling (cardiomyocyte hypertrophy, left ventricle collagen content) and diastolic dysfunction (transmitral E/A, left ventricle-dP/dt). Importantly, these systemic and cardiac impairments were ameliorated markedly following insulin replacement, and moreover, markers of the diabetic cardiomyopathy phenotype were significantly correlated with the extent of hyperglycaemia. In summary, these data suggest that poor glucose control directly contributes towards the underlying features of experimental diabetic cardiomyopathy, at least in the early stages, and that adequate replacement ameliorates this.

Adenosine A2A receptor agonist prevents cardiac remodeling and dysfunction in spontaneously hypertensive male rats after myocardial infarction.

BackgroundThis work evaluated the hypothesis that 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294), an agonist of adenosine A2A receptor, could be beneficial for preventing cardiac dysfunction due to hypertension associated with myocardial infarction (MI).MethodsMale spontaneously hypertensive rats (SHR) were randomly divided into four groups (six animals per group): sham-operation (SHR-Sham), and myocardial infarction rats (SHR-MI) were treated orally either with vehicle or LASSBio-294 (10 and 20 mg.kg−1.d−1) for 4 weeks. Echocardiography and in vivo hemodynamic parameters measured left ventricle (LV) structure and function. Exercise tolerance was evaluated using a treadmill test. Cardiac remodeling was accessed by LV collagen deposition and tumor necrosis factor α expression.ResultsEarly mitral inflow velocity was significantly reduced in the SHR-MI group, and there was significant recovery in a dose-dependent manner after treatment with LASSBio-294. Exercise intolerance observed in the SHR-MI group was prevented by 10 mg.kg−1.d−1 of LASS-Bio-294, and exercise tolerance exceeded that of the SHR-Sham group at 20 mg.kg−1.d−1. LV end-diastolic pressure increased after MI, and this was prevented by 10 and 20 mg.kg−1.d−1 of LASSBio-294. Sarcoplasmic reticulum Ca2+ ATPase levels were restored in a dose-dependent manner after treatment with LASSBio-294. Fibrosis and inflammatory processes were also counteracted by LASSBio-294, with reductions in LV collagen deposition and tumor necrosis factor α expression.ConclusionIn summary, oral administration of LASSBio-294 after MI in a dose-dependent manner prevented the development of cardiac dysfunction, demonstrating this compound’s potential as an alternative treatment for heart failure in the setting of ischemic heart disease with superimposed chronic hypertension.

AT1 Receptor Modulator Attenuates the Hypercholesterolemia-Induced Impairment of the Myocardial Ischemic Post-Conditioning Benefits

Background and ObjectivesIschemic post-conditioning (PostC) has been demonstrated as a novel strategy to harness nature's protection against myocardial ischemia-reperfusion (I/R). Hypercholesterolemia (HC) has been reported to block the effect of PostC on the heart. Angiotensin II type-1 (AT1) modulators have shown benefits in myocardial ischemia. The present study investigates the effect of a novel inhibitor of AT1, azilsartan in PostC of the heart of normocholesterolemic (NC) and HC rats.Materials and MethodsHC was induced by the administration of high-fat diet to the animals for eight weeks. Isolated Langendorff's perfused NC and HC rat hearts were exposed to global ischemia for 30 min and reperfusion for 120 min. I/R-injury had been assessed by cardiac hemodynamic parameters, myocardial infarct size, release of tumor necrosis factor-alpha troponin I, lactate dehydrogenase, creatine kinase, nitrite in coronary effluent, thiobarbituric acid reactive species, a reduced form of glutathione, superoxide anion, and left ventricle collagen content in normal and HC rat hearts.ResultsAzilsartan post-treatment and six episodes of PostC (10 sec each) afforded cardioprotection against I/R-injury in normal rat hearts. PostC protection against I/R-injury was abolished in HC rat hearts. Azilsartan prevented the HC-mediated impairment of the beneficial effects of PostC in I/R-induced myocardial injury, which was inhibited by L-N5-(1-Iminoethyl)ornithinehydrochloride, a potent inhibitor of endothelial nitric oxide synthase (eNOS).ConclusionAzilsartan treatment has attenuated the HC-induced impairment of beneficial effects of PostC in I/R-injury of rat hearts, by specifically modulating eNOS. Azilsartan may be explored further in I/R-myocardial injury, both in NC and HC conditions, with or without PostC.