Comparative Study Among Three Different Models for Induction of Acute Myocardial Infarction in Rats

Aim Laboratory study of Acute Myocardial Infarction (AMI) has become of great importance for further investigations about prevention, diagnosis and treatment of the increasing number of patients worldwide. In this study, we are seeking the best experimental AMI model by comparing three methods by which AMI can be experimentally induced in rats to illuminate the most reliable model to use in further studies. Methods and Results Experimentally, AMI can be produced by either drug induced methods or surgical methods. Here, we compared two drug induced methods (isoproterenol and doxorubicin) and a surgical model to find out which method is best simulating human AMI. 50 male sprague dowley rats were put into 5 groups, each contained 10 rats as follows. Surgical group in which the proximal left anterior descending coronary artery (LADCA) was dissected and ligated. Isoproterenol group in which Isoproterenol (300 gm/kg) was injected in ten rats subcutaneously on 2 doses a day apart. Doxorubicin group in which doxorubicin (2.5 mg/kg) was given intraperitonially every other day for total cumulative dose of 15 mg/kg. Control group where rats received only 2 ml of saline intraperitonially or subcutaneously. Sham group where rats underwent a similar surgery, but without LADAC ligation. After the induction, the biochemical parameter (serum Troponin I) at 12, 24, 36, 48 and 72 hours and histopathological changes (using hematoxylin, eosin and Mallory's trichrome stains) in all groups on days 1, 7, 14 and 21 were recorded. Data were statically analyzed, and Troponin curves were designed for each group to be correlated with that of AMI in human. After 7 days, histopathological studies of the surgical group exhibited wide areas of focal fibrosis at the apex and scattered mononuclear inflammatory cells infiltration. While the isoproterenol group showed moderate degree of inflammation with multifocal areas of fibrosis and scattered mononuclear inflammatory cells. However, the doxorubicin group showed more or less normal histology of cardiomyocytes. Biochemical studies reflected a significant difference in serum Troponin levels and peak timing among the groups. The surgical and isoproterenol groups Troponin peaked around 24 hours after the intervention, with higher levels in the surgical group. However, the doxorubicin group showed lower peaks around 36 hours post intervention. Correlations with human AMI histopathology and biochemical markers show more mimicking changes in the surgical group when compared to the other models, followed by the isoproterenol group and least similar in the doxorubicin- induced group. However, the survival rate of rats in the isoproterenol group was superior, followed by the surgical group and the doxorubicin group showed the lowest survival rates. Conclusions Surgical induction of AMI in rats achieves the high similarity to AMI in human but the low survival rates jeopardize the reliability of the model. However, isoproterenol shows sufficient levels of mimicking and higher survival indicating the highest reliability in simulation. Doxorubicin based models are the least reliable.

Nicorandil Ameliorates Doxorubicin-Induced Cardiotoxicity in Rats, as Evaluated by 7 T Cardiovascular Magnetic Resonance Imaging

Purpose Doxorubicin-induced cardiotoxicity (DIC) is a common side effect of doxorubicin chemotherapy, and a major mechanism of DIC is inflammation. However, no effective method exists to prevent DIC. In the present study, we investigated the cardioprotective effects of nicorandil against DIC using multiparametric cardiac magnetic resonance (CMR) imaging and elucidated the anti-inflammatory properties of nicorandil in rat models. Methods Male Sprague-Dawley rats received four weekly intraperitoneal doxorubicin doses (4 mg/kg/injection) to establish the DIC model. After treatment with or without nicorandil (3 mg/kg/day) or diazoxide (10 mg/kg/day) orally, all the groups underwent weekly CMR examinations, including cardiac function and strain assessment and T2 mapping, for 6 weeks. Additionally, blood samples and hearts were collected to examine inflammation and histopathology. Results According to our results, the earliest DIC CMR parameter in the doxorubicin group was T2 mapping time prolongation compared with the DIC rats treated with nicorandil (doxorubicin+nicorandil group) at week 2. Subsequently, the left ventricular ejection fraction (LVEF) and global peak systolic myocardial strain in the doxorubicin group were significantly reduced, and nicorandil effectively inhibited these effects at week 6. Our results were confirmed by histopathological evaluations. Furthermore, nicorandil treatment had a protective effect against the doxorubicin-induced inflammatory response. Interestingly, similar protective results were obtained using the KATP channel opener diazoxide. Conclusion Collectively, our findings indicate that nicorandil application ameliorates DIC in rats with significantly higher cardiac function and myocardial strain and less fibrosis, apoptosis and inflammatory cytokine production. Nicorandil prevents T2 abnormalities in the early stages of DIC, showing a high clinical value for early nicorandil treatment in chemotherapy patients.

[123I]MIBG is a better early marker of anthracycline cardiotoxicity than [18F]FDG: a preclinical SPECT/CT and simultaneous PET/MR study

Background During anthracycline treatment of cancer, there is a lack for biomarkers of cardiotoxicity besides the cardiac dysfunction. The objective of the present study was to compare [18F]FDG and [123I]MIBG (metaiodobenzylguanidine) in a longitudinal study in a doxorubicin-induced cardiotoxicity rat model. Methods Male Wistar Han rats were intravenously administered 3 times at 10 days’ interval with saline or doxorubicin (5 mg/kg). [123I]MIBG SPECT/CT (single photon emission computed tomography-computed tomography) and simultaneous [18F]FDG PET (positron emission tomography)/7 Tesla cardiac MR (magnetic resonance) imaging acquisitions were performed at 24 h interval before first doxorubicin / saline injection and every 2 weeks during 6 weeks. At 6 weeks, the heart tissue was collected for histomorphometry measurements. Results At week 4, left ventricle (LV) end-diastolic volume was significantly reduced in the doxorubicin group. At week 6, the decreased LV end-diastolic volume was maintained, and LV end-systolic volume was increased resulting in a significant reduction of LV ejection fraction (47 ± 6% vs. 70 ± 3%). At weeks 4 and 6, but not at week 2, myocardial [18F]FDG uptake was decreased compared with the control group (respectively, 4.2 ± 0.5%ID/g and 9.2 ± 0.8%ID/g at week 6). Moreover, [18F]FDG cardiac uptake correlated with cardiac function impairment. In contrast, from week 2, a significant decrease of myocardial [123I]MIBG heart to mediastinum ratio was detected in the doxorubicin group and was maintained at weeks 4 and 6 with a 45.6% decrease at week 6. Conclusion This longitudinal study precises that after doxorubicin treatment, cardiac [123I]MIBG uptake is significantly reduced as early as 2 weeks followed by the decrease of the LV end-diastolic volume and [18F]FDG uptake at 4 weeks and finally by the increase of LV end-systolic volume and decrease of LV ejection fraction at 6 weeks. Cardiac innervation imaging should thus be considered as an early key feature of anthracycline cardiac toxicity.

Doxorubicin-Induced Cardio Toxicity in Albino Rats Protected by Adansonia Digitata (Baobab) Leaf Extract

Cardiovascular disease is the world's leading cause of death, killing 17 to 19 million people each year. The usage of traditional drugs was influenced by the need for effective medications for the treatment of cardiovascular disease without side effects. The current study investigated the cardio-protective effects of Adansonia digitata leaf extract on doxorubicin-mediated cardiotoxicity in laboratory rats. Thirty-five albino rats were divided into five groups, each consisting of seven rats. Group 1 was given filtered water as a control, while Group 2 was given saline and doxorubicin, Group 3 received doxorubicin and Vitamin E, and Groups IV and V were myocardial oxidative animals treated with Adansonia digitata leaf extract (150 and 300 mg/kg/wt) for two weeks. After the rats were sacrificed, their hearts were collected and homogenized for biochemical assays. The results on the activities of creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate amino transferase (AST), nitric oxide synthase (NOS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde were determined. Histopathology examination was used in addition to assays to validate myocardial damage. In comparison to the control group, rats provided doxorubicin showed a significant increase in the activities of cardiac marker enzymes (CK, LDH, and AST), as well as a significant increase in malondialdehyde concentration with a concomitant decrease in antioxidant enzymes (SOD, CAT, and NOS), implying cardiotoxicity. In rats with doxorubicin-induced myocardial infection, pretreatment with Adansonia digitata leaf extract reduced myocardial damage, these biochemical results were confirmed by histopathology. Finally, the new study demonstrates that Adansonia digitata has cardioprotective properties.

Cardioprotective Roles of β-Hydroxybutyrate Against Doxorubicin Induced Cardiotoxicity

Background: β-Hydroxybutyrate (BHB) is produced by fatty acid oxidation in the liver under the fasting state and confirmed to play a cardioprotective role in ischemia and hypertensive settings. Doxorubicin (DOX) is an effective chemotherapeutic drug, but limited by serious irreversible cardiotoxicity. However, whether BHB can protect from DOX-induced cardiotoxicity remains unknown.Methods and Results: C57BL/6 mice were intraperitoneally injected with DOX to induce cardiac toxicity and intragastrically administered into BHB for treatment. They were randomly divided into three groups, namely a sham group (Sham), a doxorubicin group (DOX), and a doxorubicin+β-Hydroxybutyrate group (DOX + BHB). Echocardiography and pathological staining were performed to evaluate cardiac function and fibrosis. H9c2 cardiomyocyte was treated with DOX or BHB for in vitro experiments. Cell apoptosis and ROS were determined by flow cytometry. BHB significantly restored DOX-induced cardiac function decline and partially prevented cardiac reverse remodeling, characterized by increased cell size and decreased fibrosis. In vitro, BHB treatment decreased cellular injury and apoptosis. Also, BHB alleviated oxidative stress level and increased mitochondrial membrane potential.Conclusion: Our results suggested that BHB could protected from DOX-induced cardiotoxicity by inhibiting cell apoptosis and oxidative stress and maintaining mitochondrial membrane integrity.

Prevention of doxorubicin-induce renal function abnormalities by turmeric in Wistar rats

Doxorubicin is an anthracycline antibiotic with anti-neoplastic potentials mediated mainly by affecting the DNA synthetic machinery of the cell. It is found to be effective against a wide range of cancers including the ovary, uterus, lung, breast etc. Doxorubicin exerts its nephrotoxicity on the kidney by inducing inflammatory changes leading to increased capillary porousness and glomerular shrinking. This study investigated the effect of turmeric on the renal function biomarkers in doxorubicin-induced oxidative stress in Wistar rats. 54 adult Wistar rats were divided into 9 groups of six animals each. Group 1 animals served as control (normal saline), group 2 animals served as negative control, and received doxorubicin, group 3 animals were given doxorubicin and turmeric, group 4 animals received doxorubicin and vitamin C, group 5 animals received doxorubicin and vitamin E, group 6 animals received doxorubicin, vitamins C and turmeric, group 7 animals received doxorubicin, vitamin E and turmeric, while group 8 animals received doxorubicin, vitamin C and vitamin E and finally, group 9 animals receive doxorubicin, vitamin C, vitamin E and turmeric. The experiment lasted for 28 days and blood samples were collected from each animal from the various groups for renal function assay. Doxorubicin caused significant increase in the serum levels of urea, creatinine, sodium (Na+), calcium (Ca2+), and decrease serum levels of chloride (Cl-), magnesium (Mg2+) and potassium (K+). These abnormal electrolyte imbalances were prevented by administration of turmeric alone or in combination with vitamins C and or E along with doxorubicin concomitantly.

Antioxidant and Anti-Inflammatory Effects of Crocin Ameliorate Doxorubicin-Induced Nephrotoxicity in Rats

Doxorubicin is a drug that belongs to the anthracycline antibiotics. Nephrotoxicity is one of the serious side effects of doxorubicin treatment. Crocin, which is one of the most bioactive components of saffron, has antioxidant, anti-inflammatory, and antitumor effects. The current study was aimed at investigating the possible protective effects of crocin against doxorubicin-induced nephrotoxicity to elucidate the underlying mechanism of this effect. The study included four groups, six rats in each group: normal control, crocin control, doxorubicin, and crocin/doxorubicin. Doxorubicin and crocin/doxorubicin groups received intraperitoneal injections of doxorubicin (3.5 mg/kg twice weekly for 3 weeks). Rats in the crocin control group and the crocin/doxorubicin group were treated with intraperitoneal injections of crocin (100 mg/kg body weight per day) for 3 weeks. Biomarkers of kidney function and oxidative stress as well as the abundance of mRNA for nuclear factor-κβ and inducible nitric oxide synthase were evaluated. In addition, the abundance of cyclooxygenase 2 and tumor necrosis factor α immunoreactivity was evaluated. Crocin treatment had renoprotective effects manifested by significant improvement in kidney function as well as a reduction in the abundance of biomarkers of oxidative stress markers and inflammatory mediators. In conclusion, crocin has a protective effect against doxorubicin-induced nephrotoxicity in rats by serving as an antioxidant and attenuating the expression of NF-κB, iNOS, COX2, and TNFα.

miR-34a Reverses Doxorubicin Resistance in Breast Cancer

Chemotherapy is effectively used for treating breast cancer, but the problem of tumor resistance to chemotherapy drugs has been plaguing scientists. Our study investigated miR-34a?s effect on the sensitivity of drug-resistant strains to chemotherapeutic drugs using doxorubicin-resistant strains of breast cancer cells. Cell survival rate was detected by MTT assay. The doxorubicin-resistant strain rMCF-7 was obtained. The cell scratching method and CCK-8 method were used to detect cell migration and proliferation.Western Blot was performed for measuring SIRT1, p-AKT, AKT, p-mTOR and mTOR level. miR-34a significantly reduced the survival rate o doxorubicin-resistant breast cancer cell line rMCF-7 and significantly enhanced doxorubicin?s effect on inhibiting cell proliferation and cell migration. Compared with the doxorubicin group alone, miR-34a and doxorubicin combination group significantly downregulated SIRT1, p-AKT/AKT and p-mTOR/mTOR related proteins in rMCF-7 cells. miR-34a can reverse the resistance of doxorubicin in breast cancer in vitro and the mechanism may be through inhibition of SIRT and AKT signaling.

Pirfenidone and Vitamin D Ameliorate Cardiac Fibrosis Induced by Doxorubicin in Ehrlich Ascites Carcinoma Bearing Mice: Modulation of Monocyte Chemoattractant Protein-1 and Jun N-terminal Kinase-1 Pathways

Treatment of breast cancer with doxorubicin causes numerous side effects, of which cardiac fibrosis is considered the main one. This study was designed to investigate the underlying molecular mechanisms for the potential anti-fibrotic effect of pirfenidone and vitamin D against doxorubicin-induced cardiac fibrosis. Seventy mice carrying solid Ehrlich’s ascites carcinoma (EAC) discs on the ventral side were treated with orally administered pirfenidone (500 mg/kg) and intraperitoneal injection of vitamin D (0.5 µg/kg) either individually or in combination with a doxorubicin (15 mg/kg; i.p.) single dose. All treatments commenced one week post-tumor inoculation and continued for 14 days. Compared to control EAC mice, the doxorubicin group showed a significant increase in heart and left ventricle weights, troponin T, and creatinine kinase serum levels. Furthermore, the doxorubicin group depicts a high expression of monocyte chemoattractant protein (MCP-1), nuclear factor-kappa B (NF-κB), transforming growth factor-beta 1 (TGF-β1), smad3, Jun N-terminal Kinase-1 (JNK1), and alpha-smooth muscle actin (α-SMA). Treatment with pirfenidone or vitamin D significantly decreased all of these parameters. Furthermore, the expression of smad7 was downregulated by doxorubicin and improved by pirfenidone or vitamin D. Furthermore, all treated groups showed a marked decrease in tumor weight and volume. Current data demonstrate that pirfenidone and vitamin D represent an attractive approach to ameliorate the cardiac fibrosis produced by doxorubicin through inhibiting both JNK1 signaling and MCP-1 inflammatory pathways, thus preserving heart function. Further, this combination demonstrated an anti-tumor effect to combat breast cancer.

Cardioprotective effect of grape polyphenol extract against doxorubicin induced cardiotoxicity

Doxorubicin is a chemotherapeutic agent known to cause cardiotoxicity that is thought to be associated with oxidative stress. The aim of the current study is to investigate the role of grape polyphenols’ antioxidant property as cardioprotective against doxorubicin-induced cardiotoxicity. Adult Wistar rats weighing 200 ± 20 g were divided into 3 different groups: a doxorubicin group that received a single intraperitoneal administration of doxorubicin (8.0 mg/kg body weight), an experimental group that received doxorubicin and grape polyphenol concentrate (25 mg/kg) via intragastric route, and the third group was a negative control group that received water only. On day 8, blood samples and tissues were harvested for analyses. The results indicated that grape polyphenol concentrate was able to reduce the signs of cardiotoxicity of doxorubicin through the reduction of aspartate aminotransferase activation, increasing the plasma antioxidant levels and decreasing the level of free radicals. The results also showed that grape polyphenol concentrate was able to reverse doxorubicin-induced microscopic myocardial damage. The myocardial protective effect of grape polyphenol might likely be due to the increase in the level and activity of the antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. In conclusion, grape polyphenol concentrate displayed cardioprotective effect and was able to reverse doxorubicin-induced-cardiomyopathy in experimental rats.