Myocardial Injury In Rats Research Articles

Combined Bisoprolol and Trimetazidine ameliorate Arsenic trioxide -Induced Acute Myocardial Injury in Rats: Targeting PI3K/GSK-3β/Nrf2/HO-1 and NF-κB/iNOS Signaling Pathways, Inflammatory Mediators and Apoptosis

Background Arsenic-trioxide (ATO) is an effective therapy for acute promyelocytic leukemia. Unfortunately, its utility is hindered by the risk of myocardial injury. Both bisoprolol (BIS) and trimetazidine (TMZ) have various pharmacological features, including anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Aim The cardioprotective effects of BIS and TMZ were studied, and their mechanistic role in ameliorating ATO-induced myocardial injury. Materials and Methods Forty male Wistar rats were randomly allotted into five groups as follows: normal control group (received normal saline, orally), ATO group (7.5 mg/kg, orally), BIS (8 mg/kg, orally), TMZ (60 mg/kg, orally), and finally combination group (BIS + TMZ + ATO). Following 21 days, samples of serum and cardiac tissues were obtained to perform biochemical, molecular, and histopathological investigations. Results The present study showed that ATO caused myocardial injury evidenced by changes in serum biomarkers (Aspatate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase-MB, and cardiac troponin-1), electrolyte imbalance, and lipid profiles alongside histopathologic changes. In addition, ATO administration significantly elevated malondialdehyde, nicotinamide adenine dinucleotide phosphate hydrogen oxidase, myloperoxidase, total nitrite, inducible nitric oxide synthase, tumor necrosis factor-alpha, interleukin-1β, interleukin-6, 8-Hydroxy-2'-deoxyguanosine, nuclear factor NF-kappa-B p65 subunit, glycogen synthase kinase-3 beta, and caspase-3 expression contemporaneously with down-regulation of reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase, heme oxygenase 1, nuclear factor erythroid 2–related factor 2, phosphatidylinositol-3 kinase, p-PI3K, and Bcl-2 expression. Interestingly, pre-treatment with BIS and TMZ significantly reversed the detrimental effects of ATO-induced myocardial injury at both cellular and molecular levels. Otherwise, combining the two drugs displayed more enhancement than each drug alone. Conclusion The present research depicted that BIS and TMZ have the potential to protect the heart and provide therapeutic benefits by preventing acute heart injury induced by ATO. This is achieved by reversing the redox-sensitive pathway, reducing inflammation, and inhibiting apoptosis.

Colchicine prevents perioperative myocardial injury in cardiac surgery by inhibiting the formation of neutrophil extracellular traps: evidence from rat models.

Colchicine, an anti-inflammatory agent, has been reported to improve myocardial infarction prognosis by inhibiting neutrophil extracellular traps (NETs) release. However, its role in cardiac surgery and the mechanisms behind NETs suppression remain unclear. This study aimed to explore colchicine's cardioprotective effects against perioperative myocardial injury in cardiac surgery, focusing on NETs inhibition as a novel therapeutic strategy. Male Sprague-Dawley rats were pre-treated with colchicine (0.1 mg/kg/day) or CI-amidine (10 mg/kg/day) for 7 days before undergoing cardiopulmonary bypass and myocardial ischaemia/reperfusion injury. The model was created by subjecting the rats to cardiopulmonary bypass and myocardial ischaemia/reperfusion injury. Under 4.0% sevoflurane anaesthesia, cardiopulmonary bypass was initiated by cannulating the tail artery and right atrium, and perfusion was maintained for 4 h. Immunofluorescence detected NETs, and haematoxylin and eosin staining assessed inflammatory cell. We found colchicine treatment significantly reduced perioperative myocardial injury in rats. Furthermore, we observed a notable elevation of NETs in the myocardial tissue of animal models. Moreover, suppressing peptidylarginine deiminase 4 was found to markedly diminish perioperative myocardial injury in rats. Additionally, colchicine can mitigate the release of NETs by inhibiting peptidylarginine deiminase 4. NETs were significantly elevated during the perioperative period of cardiac surgery. Colchicine significantly mitigated myocardial injury in cardiac surgery by inhibiting NETs formation, with peptidylarginine deiminase 4 inhibition being one of its mechanisms.

Effect of phosphatase and tensin homolog-induced putative kinase 1/ E3 ubiquitin ligase Parkin mediated mitochondrial autophagy on chronic kidney disease myocardial injury and the intervention mechanism of Shenshuai recipe.

To study whether Shenshuai recipe (, SSR) can play a protective role on chronic kidney disease myocardial injury model through phosphatase and tensin homolog-induced putative kinase 1 (PINK1)/E3 ubiquitin ligase Parkin (Parkin) mitochondrial autophagy pathway. Forty-eight nephrectomized rats were randomly divided into six groups: sham-operated group, model group, Benazepril group, low, medium and high-dose groups of SSR. The rats were given the cor-responding intervention for six weeks, then were sacrificed. Serum was examined by enzyme linked immunosorbent assay (ELISA). Cardiac ultrasound was used to detect cardiac function in 5/6 nephrectomized rats. Myocardial tissue was examined by light and electron microscopy; PINK1, Parkin, microtubule-associated protein1 light chain 3 II (LC3B), sequestosome 1 (P62), BECN1 (Beclin-1) and dynamin-related protein 1 (Drp-1) were measured by real time polymerase chain reaction (RT-PCR), Western blot (WB) and immunohistochemistry (IHC). The expression levels of blood urea nitrogen (BUN) and creatinine (SCr) in the model group were significantly higher than those in the sham-operated group, indicating that modeling was successful. SSR can protect myocardium by reducing the relative expression of creatine kinase myocardial isoenzyme and hypersensitivity cardiac troponin I (P<0.05). SSR can improve cardiac function in rats after ultrasound testing. SSR can improve the pathological manifestations of myocardial tissue after Masson staining. SSR can increase the number of autophagosomes and autophagiclysosomes in 5/6 nephrectomized rats (P<0.05). Determined by RT-PCR, WB and IHC, SSR can increase the relative expression of PINK1, Parkin, and LC3B (P<0.05), and decrease the relative expression of P62, Beclin-1 and Drp-1 (P<0.05). The PINK1/Parkin mitochondrial autophagy pathway in myocardial tissues in 5/6 nephrectomy CKD myocardial injury rats was inhibited. SSR can activate PINK1/Parkin mitochondrial autophagy to enhance mitochondrial autophagy, and play a protective role in myocardial tissues.

Cardioprotective Effects of Ursodeoxycholic Acid in Isoprenaline-Induced Myocardial Injury in Rats.

Patients suffering from cholelithiasis have an increased risk of developing cardiovascular complications, particularly ischemic myocardial disease. Ursodeoxycholic acid (UDCA), already used in clinical practice for the treatment of cholelithiasis and related conditions, has proven antioxidative, anti-inflammatory, and cytoprotective effects. Therefore, the aim of this study was to investigate the cardioprotective effect of UDCA pre-treatment on isoprenaline-induced myocardial injury in rats. Male Wistar albino rats were randomized into four groups. Animals were pre-treated for 10 days with propylene glycol + saline on days 9 and 10 (control), 10 days with propylene glycol + isoprenaline on days 9 and 10 (I group), 10 days with UDCA + saline on days 9 and 10 (UDCA group), and 10 days with UDCA + isoprenaline on days 9 and 10 (UDCA + I group). UDCA pre-treatment significantly reduced values of high-sensitivity troponin I (hsTnI) and aspartate aminotransferase (AST) cardiac markers (p < 0.001 and p < 0.01, respectively). The value of thiobarbituric acid reactive substances (TBARS) was also decreased in the UDCA + I group compared to the I group (p < 0.001). UDCA also significantly increased glutathione (GSH) levels, while showing a tendency to increase levels of superoxide dismutase (SOD) and catalase (CAT). The level of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, a key regulatory gene of inflammation, was diminished when UDCA was administered. A reduction of cardiac damage was also observed in the UDCA pre-treated group. In conclusion, UDCA pre-treatment showed a cardioprotective effect on isoprenaline-induced myocardial injury in rats, primarily by reducing oxidative stress and inflammation.

17β-Estradiol Nanoparticles Increase Endothelial Nitric Oxide Synthase Expression Through Akt Pathway in Rats with Myocardial Infarction

17β-estradiol can effectively slow down progression of myocardial infarction (MI), and is expected to have more curative effects. Therefore, this study investigated the mechanism underlying cardioprotective role of 17β-estradiol NPs in rats with MI. After construction of rat MI model and preparation of 17β-estradiol NPs, the rats were administered with 17β-estradiol alone, 17β-estradiol NPs and Akt agonist or inhibitor. Distribution of 17β-estradiol NPs was observed by fluorescence microscope and release curve was detected. After treatment, echocardiography was conducted to measure the cardiac function indicators. With HE staining to observe myocardial tissue, RT-qPCR and Western blot determined levels of AKT and eNOS. The NPs were relatively uniform in size and round in shape; and cumulative release rate and concentration of 17β-estradiol in rats reached highest level on 30th day. Treatment with 17β-estradiol or 17β-estradiol NPs importantly increased survival rate of MI rats and decreased MI area while improving LVSP, LVDP, and HR. Moreover, the 17β-estradiol NPs had the smallest MI area. The myocardial tissue of rats in the 17β-estradiol NP group was closely arranged, and myocardial collagen was significantly reduced. The 17β-estradiol NPs increased the mRNA level of eNOS and Akt when eNOS expression was related to Akt expression. 17β-estradiol NPs can therefore increase the expression of eNOS by activating Akt signaling pathway, thereby relieving the myocardial injury in rats, hindering progression of MI.

Melatonin mitigates the lipopolysaccharide-induced myocardial injury in rats by blocking the p53/xCT pathway-mediated ferroptosis.

This article examined the therapeutic effect of melatonin (MT) on the lipopolysaccharide (LPS)-induced myocardial injury, and the mechanisms involved. Septic rat model was constructed by exposing to lipopolysaccharide (LPS), and treated by MT, Ferrostatin-1 (Fer-1) and Erastin (Era). Hematoxylin-eosin staining was executed to appraise myocardial injury. H9c2 cells that exposed to LPS to induce in vitro sepsis cell model were treated by MT. p53 overexpression vectors were transfected into H9c2 cells. Inflammation- and ferroptosis-related indicators were examined by enzyme-linked immunosorbent assay. Expression of p53, xCT and GPX4 was scrutinized by quantitative real-time polymerase chain reaction and Western blot. MT relieved myocardial injury in septic rats. It decreased IL-6 and TNF-α, elevated GPX4 and GSH, and reduced MDA and Fe2+ in myocardial tissues of septic rats. LPS induced p53 elevation and xCT reduction in rats' myocardial tissues. Nevertheless, MT treatment declined p53 and increased xCT in myocardial tissues of septic rats. Interestingly, the relieving effect of MT on myocardial injury in septic rats was enhanced by Fer-1, but reversed by Era. The LPS-induced H9c2 cell damage was relieved by MT treatment. Besides, MT decreased LDH, IL-6 and TNF-α, elevated xCT, GPX4 and GSH, and reduced MDA and Fe2+ in the LPS-induced H9c2 cells. Conversely, these influences of MT on the LPS-induced H9c2 cells were reversed by p53 overexpression. MT is proposed to be a promising agent for treating the LPS-induced myocardial injury, as it relieves myocardial injury by hindering the p53/xCT-mediated ferroptosis in the LPS-induced septic rats.

Sacubitril/valsartan alleviates sepsis-induced myocardial injury in rats via dual angiotensin receptor-neprilysin inhibition and modulation of inflammasome/caspase 1/IL1β pathway

Sepsis is a life-threatening situation that ultimately affects cardiac function, leading to cardiomyopathy and myocardial injury as a result of uncontrolled response to infection.Till now, there is limited effective treatment to rescue those cases. Thus, novel therapeutic strategies should be identified to achieve better outcomes for septic patients. For the first time, we aimed to evaluate the effect of sacubitril/valsartan (Sac/Val) on sepsis-induced cardiac injury. Wistar male adult albino rats were randomly divided into four groups; Group I received the vehicle; Group II was given the vehicle plus 1 ml saline containing viable Escherichia coli (E. coli) (2.1 × 109 cfu) by intraperitoneal (i.p.) injection on the 1st and 2nd days; Group III received i.p. injection as group II plus oral administration of Sac/Val (30 mg/kg/day) and Nitro- ω-L-arginine (L-NNA) (25 mg/kg/day) for 7 days. Group IV was administered i.p. injection as group II plus oral administration of Sac/Val (30 mg/kg/day) for 7 days. Our data (n = 10) revealed successful induction of sepsis as it showed a significant increase in the measured cardiac enzymes, malondialdehyde (MDA), angiotensin II (Ang II), neprilysin, inflammasome, caspase 1, interleukin (IL)1β, and caspase 3 with cardiac histopathological changes, but there was a significant decrease in the antioxidants and blood pressure (BP). Co-administration of Sac/Val could obviously improve these changes. Interestingly, L-NNA given group showed a decrease in the cardioprotective effect of Sac/Val. Sac/Val could ameliorate sepsis induced cardiac damage via inhibition of Ang II and neprilysin with anti-inflammatory, anti-oxidant and anti-apoptotic properties.

Betulin protects against isoproterenol-induced myocardial injury by inhibiting NF-κB signaling and attenuating cardiac inflammation and oxidative stress in rats

Objective: To investigate the cardioprotective potential of betulin in isoproterenol (ISO)-induced myocardial injury in rats. Methods: Wistar rats were divided into five groups (n=10): normal, ISO, nebivolol 5 mg/kg, and betulin (20 &amp; 40 mg/kg). Nebivolol and betulin were administered orally for 29 days. ISO (85 mg/kg) was administered subcutaneously on day 27 and day 28 to induce myocardial injury. On day 29, blood was collected for determination of cardiac markers, and hemodynamic parameters were investigated. The levels of oxidative stress markers and the gene expressions of apoptotic markers and inflammatory mediators were evaluated. Moreover, 2,3,5-triphenyltetrazolium chloride staining and histopathological analysis were also performed. Results: Betulin reduced the size of myocardial infarction, decreased elevated levels of cardiac enzymes, and maintained hemodynamic functions. It also inhibited ISO-induced upregulation of Bax, caspase-3, NF-κB, and 1L-6, enhanced endogenous antioxidant enzymes, and reduced lipid peroxidation. Additionally, pretreatment with betulin alleviated myocardial ischemic damage, as reflected by reduced myonecrosis, edema, and inflammatory changes. Conclusions: Betulin exhibits strong cardioprotective activity against ISO-induced myocardial injury by anti-inflammatory, anti-apoptotic, and antioxidant activities.

Protective effect and mechanism of methylene blue on myocardial injury in rats with sepsis

To explore the protective effect of methylene blue (MB) on myocardial injury in sepsis and its possible signaling pathway. A total of 32 female Wistar rats were randomly divided into sham operation group, sepsis model group, MB prevention group, and MB treatment group, with 8 rats in each group. The MB prevention group was injected with 15 mg/kg MB in the peritoneal cavity 6 hours before modeling; the other 3 groups were injected with 4 mL/kg saline in the peritoneal cavity. The sepsis model was established by cecal ligation puncture (CLP); the sham operation group was only subjected to an exploratory incision without ligation or puncture of the caecum. The MB treatment group was injected with 15 mg/kg MB in the peritoneal cavity 0.5 hours after modeling; the other 3 groups were injected with 4 mL/kg saline in the peritoneal cavity. Peripheral blood and myocardial tissue were collected from each group at 6 hours and 12 hours after modeling. Histological changes in the myocardial tissue were observed under the microscope; the levels of serum cardiac troponin I (cTnI), MB isoenzyme of creatine kinase (CK-MB), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were detected by enzyme-linked immunosorbent assay (ELISA); and the expressions of inducible nitric oxide synthase (iNOS), light chain 3 (LC3), and p62 in the myocardial tissue were detected by Western blotting. Under light microscopy, no obvious abnormalities were found in the myocardium of the sham operation group; the myocardium of the sepsis model group showed obvious inflammatory changes; the myocardium of the MB prevention group showed mild inflammatory changes at 6 hours after modeling, severe inflammatory changes at 12 hours but less severe than the sepsis model group; the myocardium of the MB treatment group showed more obvious inflammatory changes at 6 hours after modeling but less severe than the MB prevention group at 12 hours after modeling, and the inflammatory changes at 12 hours after modeling were alleviated but more severe than the 6 hours after modeling in MB prevention group. Compared with the sham operation group, the levels of cTnI, CK-MB, TNF-α and IL-6 in the MB prevention group at 6 hours and 12 hours after modeling were not significantly changed; compared with the sepsis model group, the cTnI, CK-MB, TNF-α and IL-6 levels in the MB treatment group at 6 hours and 12 hours after modeling were significantly lower [cTnI (ng/L): 175.03±12.26, 411.24±21.20 vs. 677.79±43.95 at 6 hours of modeling, 159.52±6.44, 412.46±32.94 vs. 687.61±55.09 at 12 hours of modeling; CK-MB (ng/L): 8.38±0.49, 16.87±1.41 vs. 24.87±1.74 at 6 hours of modeling, 7.94±0.30, 16.66±2.03 vs. 25.02±7.29 at 12 hours of modeling; TNF-α (ng/L): 26.98±3.31, 46.95±3.74 vs. 112.60±6.64 at 6 hours of modeling, 31.31±5.83, 90.97±5.14 vs. 149.30±4.67 at 12 hours of modeling; IL-6 (ng/L): 40.86±4.48, 128.90±3.14 vs. 248.90±12.76 at 6 hours of modeling, 80.13±7.94, 190.40±9.56 vs. 288.90±6.01 at 12 hours of modeling; all P < 0.05]. Western blotting showed that compared with the sham operation group, the protein expressions of iNOS, LC3, and p62 in the sepsis model group were significantly higher at 6 hours and 12 hours after modeling; compared with the sepsis model group, the protein expressions of iNOS, LC3, and p62 in the MB treatment group and MB prevention group were significantly lower at 6 hours and 12 hours after modeling (iNOS/GAPDH: 0.38±0.04, 0.60±0.04 vs. 0.77±0.04 at 6 hours of modeling; 0.38±0.02, 0.66±0.04 vs. 0.79±0.05 at 12 hours of modeling; LC3/GAPDH: 0.13±0.07, 0.42±0.07 vs. 1.05±0.16 at 6 hours of modeling; 0.08±0.02, 0.25±0.03 vs. 0.48±0.09 at 12 hours of modeling; p62/GAPDH: 0.17±0.05, 0.44±0.10 vs. 1.19±0.07 at 6 hours of modeling; 0.07±0.00, 0.28±0.08 vs. 0.69±0.02 at 12 hours of modeling; all P < 0.05). MB can reduce myocardial oxidative stress by inhibiting iNOS expression and mitochondrial autophagy in septic rats, thereby alleviating myocardial damage in sepsis, and has protective effect on myocardial damage in sepsis.

Quercetin Ameliorates Myocardial Injury in Diabetic Rats by Regulating Autophagy and Apoptosis through AMPK/mTOR Signaling Pathway.

A high-glucose environment is involved in the progression of diabetes mellitus (DM). This study aims to explore the regulatory effects of quercetin (QUE) on autophagy and apoptosis after myocardial injury in rats with DM. The type 2 DM rat models were constructed using low-dose streptozotocin (STZ) treatment combined with a high-carbohydrate (HC) diet in vivo. Compared with the control group, the body weight was decreased, whereas blood pressure, blood glucose, and the LVW/BW ratio were increased in the diabetic group. The results showed that the myocardial fibers were disordered in the diabetic group. Moreover, we found that the myocardial collagen fibers, PAS-positive cells, and apoptosis were increased, whereas the mitochondrial structure was destroyed and autophagic vacuoles were significantly reduced in the diabetic group compared with the control group. The expression levels of autophagy-related proteins LC3 and Beclin1 were decreased, whereas the expression levels of P62, Caspae-3, and Bax/Bcl-2 were increased in the diabetic group in vitro and in vivo. Moreover, QUE treatment alleviated the cellular oxidative stress reaction under high-glucose environments. The results of immunoprecipitation (IP) showed that the autophagy protein Beclin1 was bound to Bcl-2, and the binding capacity increased in the HG group, whereas it decreased after QUE treatment, suggesting that QUE inhibited the binding capacity between Beclin1 and Bcl-2, thus leading to the preservation of Beclin1-induced autophagy. In addition, the blood pressure, blood glucose, and cardiac function of rats were improved following QUE treatment. In conclusion, QUE suppressed diabetic myocardial injury and ameliorated cardiac function by regulating myocardial autophagy and inhibition of apoptosis in diabetes through the AMPK/mTOR signaling pathway.

The protective effect of Macrostemonoside T from Allium macrostemon Bunge against Isoproterenol-Induced myocardial injury via the PI3K/Akt/mTOR signaling pathway

Myocardial injury (MI) signifies a pathological aspect of cardiovascular diseases (CVDs) such as coronary artery disease, diabetic cardiomyopathy, and myocarditis. Macrostemonoside T (MST) has been isolated from Allium macrostemon Bunge (AMB), a key traditional Chinese medicine (TCM) used for treating chest stuffiness and pains. Although MST has demonstrated considerable antioxidant activity in vitro, its protective effect against MI remains unexplored. To investigate MST's effects in both in vivo and in vitro models of isoproterenol (ISO)-induced MI and elucidate its underlying molecular mechanisms. This study established an ISO-induced MI model in rats and assessed H9c2 cytotoxicity to examine MST's impact on MI. Various assays, including histopathological staining, TUNEL staining, immunohistochemical staining, DCFH-DA staining, JC-1 staining, ELISA technique, and Western blot (WB), were utilized to explore the potential molecular mechanisms of MI protection. In vivo experiments demonstrated that ISO caused myocardial fiber disorders, elevated cardiac enzyme levels, and apoptosis. However, pretreatment with MST significantly mitigated these detrimental changes. In vitro experiments revealed that MST boosted antioxidant enzyme levels and suppressed malondialdehyde (MDA) production in H9c2 cells. Concurrently, MST inhibited ISO-induced reactive oxygen species (ROS) production and mitigated the decline in mitochondrial membrane potential, thereby reducing the apoptosis rate. Moreover, pretreatment with MST elevated the expression levels of p-PI3K, p-Akt, and p-mTOR, indicating activation of the PI3K/Akt/mTOR signaling pathway and consequent protection against MI. MST attenuated ISO-induced MI in rats by impeding apoptosis through activation of the PI3K/Akt/mTOR signaling pathway. This study presents potential avenues for the development of precursor drugs for CVDs.

Correlation of circulating fibroblast growth factor 21 levels with inflammatory factors and the degree of coronary artery stenosis in patients with acute myocardial infarction

BackgroundFibroblast growth factor 21 (FGF21) is a secreted protein that plays an important role in atherosclerosis and pathological cardiac remodeling. However, the correlation between FGF21 and the degree of coronary artery stenosis and its potential role in acute myocardial infarction (AMI) remain unclear. We examined whether changes in FGF21 levels in AMI correlate with the degree of coronary artery stenosis and the levels of inflammatory factors, and preliminarily investigated the effects of FGF21 on inflammatory factor levels and myocardial injury in rats with AMI. MethodsSerum levels of FGF21 and inflammatory factors in the AMI group and control group were measured, and the correlation between FGF21 and clinical indicators and inflammatory factors was analyzed. The effects of FGF21 on cardiac function and inflammatory response were evaluated through echocardiography and measurement of inflammatory factors. ResultsMultivariate logistic regression analysis showed that neutrophil percentage (NEUT%, odds ratio [OR]: 1.232; 95 % confidence interval [CI]: 1.028–1.477; p = 0.024) and FGF21 levels (OR: 2.063; 95 % CI: 1.187–3.586; p = 0.01) had independent effects on AMI. Spearman's rank correlation test showed that FGF21 levels were positively correlated with leukocyte count, NEUT%, neutrophil count, neutrophil to lymphocyte ratio, C-reactive protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1) and Gensini scores (p < 0.01), but negatively correlated with lymphocyte count (p < 0.01). FGF21 levels in myocardial tissues and serum levels of FGF21, IL-6, TNF-a, and MCP-1 were significantly higher in AMI rats than in the sham-operated group (p < 0.01). After overexpression of FGF21, serum levels of IL-6, TNF-a, and MCP-1 in rats were significantly decreased (p < 0.01), and cardiac function improved significantly. ConclusionsFGF21 levels were independently associated with AMI and may be related to the severity of coronary artery stenosis. Overexpression of FGF21 reduced serum inflammatory factor levels and improved cardiac function in AMI rats.

Effect of folic acid on isoprenaline-induced myocardial injury in rats.

Isoprenaline (ISO), a synthetic catecholamine and a β-adrenoceptor agonist, is widely used to develop an experimental model of myocardial injury (MI) in rats. The leading hypothesis for ISO-induced MI in rats is that it results from catecholamine overstimulation, oxidative stress, inflammatory responses, and development of cardiomyopathy during ISO administration. Folic acid (FA) reduces oxidative stress, improves endothelial function and prevents apoptosis, thereby contributing to cardiovascular protection. This study aimed to investigate the potentially protective effect of FA pretreatment on ISO-induced MI in rats. For 7 days, adult male Wistar albino rats were pretreated with 5 mg/kg/day of FA. On the sixth and seventh days, MI in rats was induced by administering 85 mg/kg/day of ISO. Prooxidant markers in plasma samples, antioxidant capacity in erythrocyte lysates, cardiac damage markers, lipid profile, electrocardiography (ECG) and histopathological analysis were evaluated. FA pretreatment significantly alleviated changes induced by ISO; it decreased the homocysteine and high-sensitivity troponin I level. FA moderately decreased the reactive oxygen species (ROS) levels (superoxide anion radical, hydrogen peroxide and thiobarbituric acid reactive substances) and improved the antioxidant activities of catalase, superoxide dismutase and reduced glutathione. ISO reduced the nitrite level and FA significantly alleviated this change. It can be concluded that FA, as a mild antioxidant, could be an appropriate cardioprotective substance in the rat model of ISO-induced MI.

16α-OHE1 alleviates hypoxia-induced inflammation and myocardial damage via the activation of β2-Adrenergic receptor

ObjectiveMyocardial injuries resulting from hypoxia are a significant concern, and this study aimed to explore potential protective strategies against such damage. Specifically, we sought to investigate the cardioprotective effects of 16α-hydroxyestrone (16α-OHE1). MethodsMale Sprague‒Dawley (SD) rats were subjected to hypoxic conditions simulating high-altitude exposure at 6000 m in a low-pressure chamber for 7 days. Before and during hypoxic exposure, estradiol (E2) and various doses of 16α-OHE1 were administered for 14 days. Heart weight/body weight (HW/BW), myocardial structure, Myocardial injury indicators and inflammatory infiltration in rats were measured. H9C2 cells cultured under 5% O2 conditions received E2 and varying doses of 16α-OHE1; Cell viability, apoptosis, inflammatory infiltration, and Myocardial injury indicators were determined. Expression levels of β2AR were determined in rat hearts and H9C2 cells. The β2AR inhibitor, ICI 118,551, was employed to investigate β2AR's role in 16α-OHE1's cardioprotective effects. ResultsHypoxia led to substantial myocardial damage, evident in increased heart HW, CK-MB, cTnT, ANP, BNP, structural myocardial changes, inflammatory infiltration, and apoptosis. Pre-treatment with E2 and 16α-OHE1 significantly mitigated these adverse changes. Importantly, the protective effects of E2 and 16α-OHE1 were associated with the upregulation of β2AR expression in both rat hearts and H9C2 cells. However, inhibition of β2AR by ICI 118,551 in H9C2 cells nullified the protective effect of 16α-OHE1 on myocardium. ConclusionOur findings suggest that 16α-OHE1 can effectively reduce hypoxia-induced myocardial injury in rats through β2ARs, indicating a promising avenue for cardioprotection.

REDUCED CX43 EXPRESSION INDUCES AUTOPHAGY THROUGH ACTIVATION OF THE AMPK-MTOR-ULK1 SIGNALING PATHWAY IN THE COMMON BILE DUCT LIGATION RAT HEART.

Backgrounds: This study aimed to investigate the relationship between Cx43 expression and autophagy mediated by the AMPK-mTOR-Ulk1 signaling pathway in jaundice heart. Methods: In this study, a jaundice model was established in common bile duct ligation (CBDL) rats. Cardiac injury was assessed using various methods including myocardial injury indicators, echocardiography, transmission electron microscopy, hematoxylin and eosin staining, Masson staining, immunohistochemical analyses, and immunofluorescence staining. We investigated the regulatory relationship between Cx43, autophagy, and the AMPK-mTOR-ULK pathway in vivo by administering autophagy agonists (Rapa), autophagy inhibitors (3-MA), and Cx43 inhibitors (Gap 26). In vitro , we observed the relationship between autophagy and the AMPK-mTOR-ULK1 pathway in cells by exposing them to the AMPK inhibitor Compound C and the AMPK activator AICAR. Results: We found that CBDL induced autophagy through the AMPK-mTOR-ULK pathway, leading to the inhibition of myocardial dysfunction. Rapamycin pretreatment with CBDL3d exhibited a protective effect against myocardial injury and promoted autophagy. In contrast, 3-MA had no impact. Pretreatment with rapamycin at CBDL2w enhanced autophagy and aggravated cardiac injury; however, inhibition of autophagy using 3-MA attenuated cardiac injury. Cell viability was enhanced by AMPK inhibitors and inhibited by AMPK agonists. In addition, we observed that increased autophagy led to decreased Cx43 expression, which negatively affected cardiac function. Conclusions: CBDL induces myocardial injury in rats and activates autophagy through the AMPK-mTOR-ULK pathway, resulting in decreased Cx43 protein levels. A moderate increase in early autophagy in CBDL can improve cardiac injury, while late inhibition of autophagy can reduce myocardial injury.

The Effect of HIF1-α/NF-κB/MMP2 Signaling Pathways Mediated by ALDH2 on Chronic Intermittent Hypoxia Induced Myocardial Injury in Rats

(1) Objective: To investigate the effect of HIF1-α/NF-κB/MMP2 signaling pathways mediated by ALDH2 on chronic intermittent hypoxia induced myocardial injury in rats. (2) Methods: Thirty SD rats were randomly assigned to three groups (10 rats in each group): control group (CONTROL), chronic intermittent hypoxia group (CIH), and CIH + ALDH2 group. Rats in the CIH + ALDH2 group were established by an intraperitoneal injection of the ALDH2 activator, Alda-1 (20 mg/kg), once a day for three consecutive days. After three months, changes in ventricular function were determined by ultrasound. The expressions of HIF1-α, NF-κB, and MMP2 proteins were detected by protein blotting, and the concentration of 4-HNE in myocardial tissue was measured. (3) Results: Compared with the control group, echocardiography showed that rats in the CIH group had significantly reduced myocardial function, elevated protein levels of HIF1-α, NF-κB, and MMP2 in myocardial tissues, and increased the expression of 4-HNE in myocardial tissues (P&lt;0.01); Compared with the CIH group, rats in the CIH + ALDH2 group showed significant improvement in myocardial function, decreased protein levels of HIF1-α, NF-κB, and MMP2 in myocardial tissue, and decreased the expression of 4-HNE in myocardial tissue (P&lt;0.01). (4) Conclusion: Chronic intermittent hypoxia increases the expression of HIF1-α to damage the myocardium and affect cardiac function, and ALDH2 inhibits the expression of HIF1-α to protect the myocardium.

Development and validation of cardiac diffusion weighted magnetic resonance imaging for the diagnosis of myocardial injury in small animal models

Cardiac diffusion weighted-magnetic resonance imaging (DWI) has slowly developed due to its technical difficulties. However, this limitation could be overcome by advanced techniques, including a stimulated echo technique and a gradient moment nulling technique. This study aimed to develop and validate a high-order DWI sequence, using echo-planar imaging (EPI) and second-order motion-compensated (M012) diffusion gradient applied to cardiac imaging in small-sized animals with fast heart and respiratory rates, and to investigate the feasibility of cardiac DWI, diagnosing acute myocardial injury in isoproterenol-induced myocardial injury rat models. The M012 diffusion gradient sequence was designed for diffusion tensor imaging of the rat myocardium and validated in the polyvinylpyrrolidone phantom. Following sequence optimization, 23 rats with isoproterenol-induced acute myocardial injury and five healthy control rats underwent cardiac MRI, including cine imaging, T1 mapping, and DWI. Diffusion gradient was applied using a 9.4-T MRI scanner (Bruker, BioSpec 94/20, gradient amplitude = 440 mT/m, maximum slew rate = 3440 T/m/s) with double gating (electrocardiogram and respiratory gating). Troponin I was used as a serum biomarker for myocardial injury. Histopathologic examination of the heart was subsequently performed. The developed DWI sequence using EPI and M012 provided the interpretable images of rat hearts. The apparent diffusion coefficient (ADC) values were significantly higher in rats with acute myocardial injury than in the control group (1.847 ± 0.326 * 10–3 mm2/s vs. 1.578 ± 0.144 * 10–3 mm2/s, P < 0.001). Troponin I levels were increased in the blood samples of rats with acute myocardial injury (P < 0.001). Histopathologic examinations detected myocardial damage and subendocardial fibrosis in rats with acute myocardial injury. The newly developed DWI technique has the ability to detect myocardial injury in small animal models, representing high ADC values on the myocardium with isoproterenol-induced injury.

The New Nano-Resuscitation Solution (TPP-MR) Attenuated Myocardial Injury in Hemorrhagic Shock Rats by Inhibiting Ferroptosis.

Hemorrhagic shock was a leading cause of death worldwide, with myocardial injury being a primary affected organ. As commonly used solutions in fluid resuscitation, acetated Ringer's (AR) and Lactate Ringer's solution (LR) were far from perfect for their adverse reactions such as lactic acidosis and electrolyte imbalances. In previous studies, TPP@PAMAM-MR (TPP-MR), a novel nanocrystal resuscitation fluid has been found to protect against myocardial injury in septic rats. However, its role in myocardial injury in rats with hemorrhagic shock and underlying mechanism is unclear. The hemorrhagic shock rats and hypoxia-treated cardiomyocytes (H9C2) were utilized to investigate the impact of TPP-MR on cardiac function, mitochondrial function, and lipid peroxidation. The expressions of ferritin-related proteins glutathione peroxidase 4 (GPX4), Acyl CoA Synthase Long Chain Family Member 4 (ACSL4), and Cyclooxygenase-2(COX2) were analyzed through Western blotting to explore the mechanism of TPP-MR on hemorrhagic myocardial injury. TPP-MR, a novel nanocrystalline resuscitation fluid, was synthesized using TPP@PAMAM@MA as a substitute for L-malic acid. We found that TPP-MR resuscitation significantly reduced myocardial injury reflected by enhancing cardiac output, elevating mean arterial pressure (MAP), and improving perfusion. Moreover, TPP-MR substantially prolonged hemorrhagic shock rats' survival time and survival rate. Further investigations indicated that TPP-MR improved the mitochondrial function of myocardial cells, mitigated the production of oxidative stress agents (ROS) and increased the glutathione (GSH) content. Additionally, TPP-MR inhibited the expression of the ferroptosis-associated GPX4 protein, ACSL4 and COX2, thereby enhancing the antioxidant capacity. The results showed that TPP-MR had a protective effect on myocardial injury in rats with hemorrhagic shock, and its mechanism might be related to improving the mitochondrial function of myocardial cells and inhibiting the process of ferroptosis.

Xinfeng Capsule Inhibits Pyroptosis and Ameliorates Myocardial Injury in Rats with Adjuvant Arthritis via the GAS5/miR-21/TLR4 Axis.

This study probed the mechanism of action of Xinfeng Capsule (XFC) in myocardial injury in rats with adjuvant arthritis (AA) via the growth arrest-specific transcript 5 (GAS5)/microRNA-21 (miR-21)/Toll-like receptor 4 (TLR4) axis. Rats were injected with Freund's complete adjuvant to establish a rat model of AA. Then, some modeled rats were given normal saline or drugs only, and some modeled rats were injected with adeno-associated viruses or necrosulfonamide (NSA; a pyroptosis inhibitor) before drug administration. Toe swelling and arthritis index (AI) were calculated. Pathological and morphological changes in synovial and myocardial tissues were analyzed with hematoxylin-eosin staining, and pyroptotic vesicles and the ultrastructural changes of myocardial tissues were observed with transmission electron microscopy. The serum levels of interleukin (IL)-1β, IL-18, IL-6, and tumor necrosis factor (TNF)-α were detected, and lactate dehydrogenase (LDH) release was measured in myocardial tissues, accompanied by the examination of GAS5, miR-21, TLR4, nuclear factor-kB (NF-κB) p65, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), Caspase-1, and Gasdermin D (GSDMD) expression in myocardial tissues. After AA modeling, rats presented with significantly increased toe swelling and AI scores, synovial and myocardial tissue damage, elevated pyroptotic vesicles, and markedly enhanced serum levels of IL-1β, IL-18, IL-6, and TNF-α, accompanied by significantly diminished GAS5 expression, substantially augmented miR-21, TLR4, NF-κB p65, NLRP3, Caspase-1, and GSDMD expression, greatly increased LDH release in myocardial tissues. XFC treatment significantly declined toe swelling, AI scores, synovial and myocardial tissue damage, and the serum levels of IL-1β, IL-18, IL-6, and TNF-α in AA rats. Additionally, XFC treatment markedly elevated GAS5 expression and substantially lowered LDH release and miR-21, TLR4, NF-κB p65, NLRP3, Caspase-1, and GSDMD expression in myocardial tissues of AA rats. Moreover, the above effects of XFC in AA rats were further promoted by GAS5 overexpression or NSA treatment. XFC alleviated myocardial injury in AA rats by regulating the GAS5/miR-21/TLR4 axis and inhibiting pyroptosis and pro-inflammatory cytokine secretion.

Elucidation for the pharmacological effects and mechanism of Shen Bai formula in treating myocardial injury based on energy metabolism and serum metabolomic approaches

Ethnopharmacological relevanceShen Bai formula (SBF) is a proven effective traditional Chinese medicine for treating viral myocarditis (VMC) sequelae in clinic, and myocardial injury is the pathological basis of VMC sequelae. However, the pharmacological action and mechanism of SBF have not been systematically elucidated. Aim of the studyIn present research, the doxorubicin-induced myocardial injury rat model was used to evaluate the efficacy of SBF, and energy metabolism and metabolomics approaches were applied to elucidate the effects of SBF on myocardial injury. Materials and methodsThrough energy metabolism measurement system and UPLC-Q-TOF-MS/MS oriented blood metabolomics, directly reflected the therapeutic effect of SBF at a macro level, and identified biomarkers of myocardial injury in microcosmic, revealing its metabolomic mechanism. ResultsResults showed that SBF significantly improved the electrocardiogram (ECG), heart rate (HR), extent of myocardial tissue lesion, and ratio of heart and spleen. In addition, the serum levels of AST, CK, LDH, α-HBDH, cTnI, BNP, and MDA decreased, whereas SOD and ATP activity and content increased. Moreover, SBF increased locomotor activity and basic daily metabolism in rats with myocardial injury, restoring their usual level of energy metabolism. A total of 45 potential metabolomic biomarkers were identified. Among them, 44 biomarkers were significantly recalled by SBF, including representative biomarkers arachidonic acid (AA), 12-HETE, prostaglandin J2 (PGJ2), 15-deoxy-Δ-12,14-PGJ2, 15-keto-PGE2, 15(S)-HPETE, 15(S)-HETE, 8,11,14-eicosatrienoic acid and 9(S)-HODE, which involved AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism. ConclusionWe successfully replicated a myocardial injury rat model with the intraperitoneal injection of doxorubicin, and elucidated the mechanism of SBF in treating myocardial injury. This key mechanism may be achieved by targeting action on COX, Alox, CYP, and 15-PGDH to increase or decrease the level of myocardial injury biomarker, and then emphatically interven in AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism, and participate in regulating purine metabolism, sphingolipid metabolism, primary bile acid biosynthesis, and steroid hormone synthesis.