The repercussion of the heated dispute on cyclooxygenase-2 (COX-2) selective nonsteroidal anti-inflammatory drugs (NSAIDs) led to the national and international withdrawal of several of the recently introduced coxibs. Further debate and research have highlighted risks of the classical NSAIDs too. There is much controversy about the cardiovascular safety of a nonselective NSAID naproxen (NAP) and its possible cardioprotective effect.
The study was undertaken to determine the cardiovascular effects of NAP on doxorubicin-induced cardiomyopathy in rats.
Materials and Methods:
Male albino rats received a single i.p. injection of normal saline (normal control group) and doxorubicin (DOX) 15 mg/kg (toxic control group). Naproxen was administered alone (50 mg/kg/day, p.o.) and in combination with DOX and DOX + trimetazidine (TMZ) (10 mg/kg/day, p.o.) for 5 days after 24 h of DOX treatment. DOX-induced cardiomyopathy was assessed in terms of increased activities of serum lactate dehydrogenase (LDH), tissue thiobarbituric acid reactive substances (TBARS) and decreased activities of myocardial glutathione, superoxide dismutase and catalase, followed by transmission electron microscopy of the cardiac tissue.
Doxorubicin significantly increased oxidative stress as evidenced by increased levels of LDH and TBARS and decreased antioxidant enzymes levels. Both biochemical and electron microscopic studies revealed that NAP itself was cardiotoxic and aggravated DOX-induced cardiomyopathy and abolished the protective effect of TMZ in rats.
This study indicates that NAP has the potential to worsen the situation in patients with cardiovascular disease. Therefore, it should be used cautiously in patients with compromised cardiac function.
Apoptosis; cardiomyopathy; enzyme (kinetics); free radicals; nonsteroidal anti-inflammatory drugs
Objective: To study the possible effect of angiotensin II type 1 Receptor blocker (AT1 blocker) on renal function, arterial blood pressure and parathyroid hormone related protein over expression in cadmium induced nephrotoxicity in adult male rats. Forty five rats were divided randomly into a control (group I), group II, received cadmium chloride at a dose of 5 mg/kg/day, orally, for nine weeks, group III received telmisartan (TEL) treatment (1 mg/kg/day, orally) one week before cadmium administration and continued for ten weeks. Results: Telmisartan significantly reduced blood urea nitrogen (BUN) and serum creatinine levels which were increased significantly by cadmium. Telmisartan significantly suppressed lipid peroxidation, compensated deficits in the antioxidant defenses (super oxide dismutase (SOD) level and catalase activity), decreased the elevations of nitric oxide (NO) and cadmium ion concentrations in renal tissue observed in Cd-treated rats. Group III had a significant decrease of urinary levels of total protein, N-acetyl-β-d-glucosaminidase (NAG), alkaline phosphatase (ALP) and γ-glutamyl-transpeptidase (GGT) and urinary 8-isoprostanes than those of group II. Telmisartan decreased the systolic blood pressure significantly than those of group II. Histopathological examination revealed that cadmium-induced renal tissue damage was ameliorated by telmisartan treatment. Immunohistochemical analysis revealed that telmisartan significantly decreased the cadmium-induced overexpression of parathyroid hormone receptor 1 (PTHR1) in renal tissue. RT-PCR analysis showed that Cd increased renal expression of PTHrP; however telmisartan could decrease the expression of PTHrP in group III. Conclusion: Blocking AT1 receptors significantly decreases PTHrP over expression and ameliorates renal dysfunction in Cd induced nephrotoxicity. These data suggest that Ang II might contribute to pathophysiology and deleterious effects in cadmium nephrotoxicity.
Cadmium; parathyroid hormone related protein; nephrotoxicity; telmisartan
Background and Purpose
AT1 receptor antagonists decrease body weight gain in models of murine obesity. However, fewer data are available concerning the anti-obesity effects of these antagonists, given as a treatment after obesity had been established.
In spontaneously hypertensive rats, obesity was established by cafeteria diet (CD) feeding for 19 weeks. Rats were then were treated with telmisartan (8 mg·kg−1·d−1) or amlodipine (10 mg·kg−1·d−1; serving as blood pressure control) or telmisartan + amlodipine (2 + 10 mg·kg−1·d−1; to control for dose-dependency) for 17 weeks. Rats receiving only chow (Cchow) or CD-fed rats treated with vehicle (CCD) served as controls.
The CD feeding induced obesity, hyperphagia, hyperlipidaemia, and leptin and insulin resistance. Telmisartan reduced the CD-induced increase in body weight and abdominal fat mass. Whereas energy intake was higher rather than lower, the respiratory ratio was lower. After telmisartan, leptin-induced energy intake was reduced and respiratory ratio was increased compared with CCD rats. Telmisartan also decreased plasma levels of triglycerides, free fatty acids and low-density lipoprotein. Amlodipine alone or the combination telmisartan + amlodipine did not affect body weight and eating behaviour. Telmisartan, but not amlodipine and telmisartan + amlodipine, improved glucose utilization. The decrease in BP reduction was almost the same in all treatment groups.
Conclusions and Implications
Telmisartan exerted anti-obesity effects and restored leptin sensitivity, given as a treatment to rats with obesity. Such effects required high doses of telmisartan and were independent of the decrease in blood pressure.
obesity; AT1-receptor blockade; telmisartan; weight loss; leptin resistance; metabolic syndrome; rat
Chemotherapy with doxorubicin is limited by cardiotoxicity. Free radical generation and mitochondrial dysfunction are thought to contribute to doxorubicin-induced cardiac failure. In this study we wanted to investigate if opening of mitochondrial KATP-channels by diazoxide is protective against doxorubicin cardiotoxicity, and if 5-hydroxydecanoate (5-HD), a selective mitochondrial KATP-channel antagonist, abolished any protection by this intervention.
Wistar rats were divided into 7 groups (n = 6) and followed for 10 days with 5 intervention groups including the following treatments: (1) Diazoxide and doxorubicin, (2) diazoxide and 5-hydroxydecanoate (5-HD), (3) 5-HD and doxorubicin, (4) diazoxide and saline and (5) 5-HD and saline. On day 1, 3, 5 and 7 the animals received intraperitoneal (i.p.) injections with 10 mg/kg diazoxide and/or 40 mg/kg 5-HD, 30 minutes before i.p. injections with 3.0 mg/kg doxorubicin. One control group received only saline injections and the other control group received saline 30 minutes prior to 3.0 mg/kg doxorubicin. On day 10 the hearts were excised and Langendorff-perfused. Cardiac function was assessed by an intraventricular balloon and biochemical effects by release of hydrogen peroxide (H2O2) and troponin-T (TnT) in effluate from the isolated hearts, and by myocardial content of doxorubicin.
Doxorubicin treatment produced a significant loss in left ventricular developed pressure (LVDP) (p < 0.05) and an increase in both H2O2 and TnT release in effluate (p < 0.05). Diazoxide significantly attenuated the decrease in LVDP (p < 0.05) and abolished the increased release of H2O2 and TnT (p < 0.05). 5-HD abolished the effects of pretreatment with diazoxide, and these effects were not associated with reduced myocardial accumulation of doxorubicin.
Pretreatment with diazoxide attenuates doxorubicin-induced cardiac dysfunction in the rat, measured by physiological indices and TnT and H2O2 in effluate from isolated hearts. The effect could be mediated by opening of mitochondrial KATP-channels, reduced doxorubicin-associated free radical generation and decreased cardiomyocyte damage. Diazoxide represents a promising protective intervention against doxorubicin-induced acute cardiotoxicity.
Doxorubicin; Troponin T; Hydrogenperoxide; Doxorubicinol; Heart; Rat; 5-hydroxydecanoate; Cardiotoxicity; Ex vivo; Diazoxide
Doxorubicin (DOX) is a commonly used chemotherapeutic agent. It is associated with serious dose-limiting cardiotoxicity, which is at least partly caused by generation of reactive oxygen species (ROS). Supplementations with bilberries were effective in reducing oxidative stress in many tissue injuries due their high content of antioxidants. The present study investigated the potential protective effect of bilberry extract against DOX-induced cardiotoxicity in rats.
Rats were treated orally with a methanolic extract of bilberry for 10 days. DOX was injected intraperitoneally on day 7. Twenty-four hours after the last bilberry administration, rats were subjected to ECG study. Blood was then withdrawn and cardiac tissues were dissected for assessment of oxidative stress and cardiac tissue injury. Cardiac tissues were also subjected to histopathological examination.
Bilberry extract significantly inhibited DOX-provoked reduced glutathione depletion and accumulation of oxidized glutathione, malondialdehyde and protein carbonyls in cardiac tissues. This was accompanied by significant amelioration of reduced cardiac catalase, superoxide dismutase, and glutathione peroxidase activities; and increased cardiac myeloperoxidase activity in response to DOX challenge. Pretreatment with bilberry significantly guarded against DOX-induced increase in serum activities of lactate dehydrogenase, creatine phosphokinase and creatine kinase-MB, as well as the level of troponin I. Bilberry alleviated ECG changes in rats treated with DOX and attenuated its pathological changes.
Bilberry protects against DOX-induced cardiotoxicity in rats. This can be attributed, at least in part, to its antioxidant activity.
bilberry; doxorubicin; cardiotoxicity; antioxidant; rats
Angiotensin-converting enzyme-2 (ACE-2) is a homolog of ACE that preferentially forms angiotensin-(ANG)-1-7 from angiotensin II (ANG II). We investigated the cardioprotective effects of telmisartan, a well-known angiotensin receptor blockers (ARBs) against experimental autoimmune myocarditis (EAM). EAM was induced in Lewis rats by immunization with porcine cardiac myosin. The rats were divided into two groups and treated with telmisartan (10 mg/kg/day) or vehicle for 21 days. Myocardial functional parameters were significantly improved by treatment with telmisartan compared with vehicle-treated rats. Telmisartan lowered myocardial protein expressions of NADPH oxidase subunits 3-nitrotyrosine, p47phox, p67 phox, Nox-4 and superoxide production significantly than vehicle-treated rats. In contrast myocardial protein levels of ACE-2, ANG 1-7 mas receptor were upregulated in the telmisartan treated group compared with those of vehicle-treated rats. The myocardial protein expression levels of tumor necrosis factor receptor (TNFR)-associated factor (TRAF)-2, C/EBP homologous protein (CHOP) and glucose-regulated protein (GRP) 78 were decreased in the telmisartan treated rats compared with those of vehicle-treated rats. In addition, telmisartan treatment significantly decreased the protein expression levels of phospho-p38 mitogen-activated protein kinase (MAPK), phospho-JNK, phospho-ERK and phospho (MAPK) activated protein kinase-2 than with those of vehicle-treated rats. Moreover, telmisartan significantly decreased the production of proinflammatory cytokines, myocardial apoptotic markers and caspase-3 positive cells compared with those of vehicle-treated rats. Therefore, we suggest that telmisartan was beneficial protection against heart failure in rats, at least in part by suppressing inflammation, oxidative stress, ER stress as well as signaling pathways through the modulation of ACE2/ANG1-7/Mas receptor axis.
Experimental autoimmune myocarditis; endoplasmic reticulum stress; inflammation; telmisartan; oxidative stress; signaling pathways
Doxorubicin (DOX) is the most active cytotoxic agents having efficacy in malignancies either alone or combined with other cytocidal agents. The clinical usefulness of the anthracycline drug has been precluded by cardiac toxicity. Many therapeutic interventions have been attempted to improve the therapeutic benefits of the drug. This study is based on the possible protective effects of combination of p-coumaric acid (PC) and naringenin (NR) on DOX induced cardiac toxicity in male Swiss albino rats.
Total nine groups of Swiss albino rats were used, Group I (vehicle control) receive saline solution daily and Group II (disease control) receive saline solution daily up to 29th day and at 30th day a single dose of DOX (15 mg/kg i.p.) is given. PC alone (100 mg/kg/day p.o.) and (200 mg/kg/day p.o.) also NR alone (15 mg/kg/day) orally administer for 30 days. Similarly a standard drug Vit. E (100 mg/kg/day) administers alone for 30 days. Group PC/DOX and PC and NR/DOX receive PC (200 mg/kg/day) and combine PC (200 mg/kg/day).
Doxorubicin induced marked biochemical alterations characteristic of cardiac toxicity including increase in MDA level and decrease SOD, CAT & GSH level but prior administration of combination of PC & NR ahead of doxorubicin challenge ameliorated all these biochemical markers.
The study proves the beneficial effects of combination of PC and NR in protecting animal against DOX induced cardiotoxicity.
Antioxidents; cardiotoxicity; doxorubicine; naringenin; p-coumaric acid
Doxorubicin (DOX) is an effective antineoplastic drug; however, clinical use of DOX is limited by its dose-dependent cardiotoxicity. It is well known that reactive oxygen species (ROS) play a vital role in the pathological process of DOX-induced cardiotoxicity. For this study, we evaluated the protective effects of guggulsterone (GS), a steroid obtained from myrrh, to determine its preliminary mechanisms in defending against DOX-induced cytotoxicity in H9C2 cells.
In this study, we used a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release measurements, and Hoechst 33258 staining to evaluate the protective effect of GS against DOX-induced cytotoxicity in H9C2 cells. In addition, we observed the immunofluorescence of intracellular ROS and measured lipid peroxidation, caspase-3 activity, and apoptosis-related proteins by using Western blotting.
The MTT assay and LDH release showed that treatment using GS (1–30 μM) did not cause cytotoxicity. Furthermore, GS inhibited DOX (1 μM)-induced cytotoxicity in a concentration-dependent manner. Hoechst 33258 staining showed that GS significantly reduced DOX-induced apoptosis and cell death. Using GS at a dose of 10–30 μM significantly reduced intracellular ROS and the formation of MDA in the supernatant of DOX-treated H9C2 cells and suppressed caspase-3 activity to reference levels. In immunoblot analysis, pretreatment using GS significantly reversed DOX-induced decrease of PARP, caspase-3 and bcl-2, and increase of bax, cytochrome C release, cleaved-PARP and cleaved-caspase-3. In addition, the properties of DOX-induced cancer cell (DLD-1 cells) death did not interfere when combined GS and DOX.
These data provide considerable evidence that GS could serve as a novel cardioprotective agent against DOX-induced cardiotoxicity.
Guggulsterone; Doxorubicin; Cardiotoxicity; Cytokines; Reactive oxygen species
To investigate the preventive and curative role of ascorbic acid on doxorubicin (dox)-induced myocardial toxicity in rats.
Materials and Methods:
Animals were divided into five groups of six animals each. Group I served as normal control and received saline 5 ml/kg/day intraperitoneal (i.p.) for a period of 15 days. Group II animals received ascorbic acid 20 mg/kg per oral (p.o.) for 15 days as a pretreatment control (PR). Group III animals received dox 2.5 mg/kg body weight (b.w.), i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg b.w. Group IV animals received ascorbic acid 20 mg/kg p.o. for 15 days as a pretreatment followed by dox 2.5 mg/kg b.w., i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg body weight. Group V animals received dox 2.5 mg/kg b.w., i.p., in six equal injections for two weeks for a total cumulative dose of 15 mg/kg b.w. followed by ascorbic acid 20 mg/kg p.o for 15 days as post-treatment control (CR). The biochemical parameters such as tissue glutathione (GSH), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), and enzyme biomarkers such as creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were monitored.
Pretreatment with ascorbic acid (20 mg/kg p.o.) significantly protected the myocardium from the toxic effect of dox (PR), by increasing the levels of antioxidant enzymes such as GSH, SOD, and CAT toward normal and decreased the levels of MDA, CPK, LDH, AST, and ALT as compared with dox-treated rats. Post-treatment with ascorbic acid to dox-treated group (CR) significantly increased the levels of tissue GSH, SOD, CAT and significantly decreased the level of MDA as compared with dox-treated group. It also reduced the severity of cellular damage of the myocardium as confirmed by histopathology. The restoration of the endogenous antioxidant system clearly depicts that ascorbic acid produced its protective effect by scavenging the reactive oxygen species.
The results obtained in this study provide evidence for the usefulness of the ascorbic acid as a cardioprotective agent.
Ascorbic acid; cardiotoxicity; doxorubicin; free radicals
Background and Objective
Sodium glucose cotransporter 2 (SGLT2) is the main luminal glucose transporter in the kidney. SGLT2 inhibition results in glycosuria and improved glycaemic control. Drugs inhibiting this transporter have recently been approved for clinical use and have been suggested to have potential renoprotective benefits by limiting glycotoxicity in the proximal tubule. We aimed to determine the renoprotective benefits of empagliflozin, an SGLT2 inhibitor, independent of its glucose lowering effect.
Research Design and Methods
We induced diabetes using a low dose streptozotocin protocol in 7–8 week old endothelial nitric oxide (eNOS) synthase knockout mice. We measured fasting blood glucose on a monthly basis, terminal urinary albumin/creatinine ratio. Renal histology was assessed for inflammatory and fibrotic changes. Renal cortical mRNA transcription of inflammatory and profibrotic cytokines, glucose transporters and protein expression of SGLT2 and GLUT1 were determined. Outcomes were compared to diabetic animals receiving the angiotensin receptor blocker telmisartan (current best practice).
Diabetic mice had high matched blood glucose levels. Empagliflozin did not attenuate diabetes-induced albuminuria, unlike telmisartan. Empagliflozin did not improve glomerulosclerosis, tubular atrophy, tubulointerstitial inflammation or fibrosis, while telmisartan attenuated these. Empagliflozin did not modify tubular toll-like receptor-2 expression in diabetic mice. Empagliflozin did not reduce the upregulation of macrophage chemoattractant protein-1 (MCP-1), transforming growth factor β1 and fibronectin mRNA observed in the diabetic animals, while telmisartan decreased transcription of MCP-1 and fibronectin. Empagliflozin increased GLUT1 mRNA expression and telmisartan increased SGLT2 mRNA expression in comparison to untreated diabetic mice. However no significant difference was found in protein expression of GLUT1 or SGLT2 among the different groups.
Hence SGLT2 inhibition does not have renoprotective benefits independent of glucose lowering.
Oxidative stress and disorders in calcium balance play a crucial role in the doxorubicin-induced cardiotoxicity. Moreover, many cardiotoxic targets of doxorubicin are regulated by iodothyronine hormones. The aim of the study was to evaluate effects of tetraiodothyronine (0.2, 2 mg/L) on oxidative stress in the cardiac muscle as well as contractility and cardiomyocyte damage markers in rats receiving doxorubicin (1.5 mg/kg) once a week for ten weeks. Doxorubicin was administered alone (DOX) or together with a lower (0.2T4 + DOX) and higher dose of tetraiodothyronine (2T4 + DOX). Two groups received only tetraiodothyronine (0.2T4, 2T4). Coadministration of tetraiodothyronine and doxorubicin increased the level of lipid peroxidation products and reduced RyR2 level when compared to untreated control and group exposed exclusively to doxorubicin. Insignificant differences in SERCA2 and occasional histological changes were observed. In conclusion, an increase of tetraiodothyronine level may be an additional risk factor of redox imbalance and RyR2 reduction in anthracycline cardiotoxicity.
To test the effect of 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) on doxorubicin (DOX)-induced cardiotoxicity.
We used neonate rat cardiomyocytes and an acute mouse model of DOX-induced cardiotoxicity to examine the protective effect of THSG.
In the mouse model, administration of THSG significantly reduced DOX-induced cardiotoxicity, including animal mortality, histopathological changes, and levels of serum creatine kinase (CK) and lactate dehydrogenase (LDH). Moreover, THSG was able to attenuate the increased malondialdehyde (MDA) and decreased reduced glutathione (GSH) caused by DOX. In in vitro studies, THSG 10−300 μmol/L ameliorated DOX-induced cardiomyocyte apoptosis in a concentration-dependent manner. Further studies showed that THSG inhibited reactive oxygen species (ROS) generation and prevented DOX-induced loss of mitochondrial membrane potential, caspase-3 activation and upregulation of Bax protein expression. We observed a protective response against damage after DOX treatment. The level of Bcl-2 protein was increased. Additionally, THSG inhibited a DOX-induced [Ca2+] increase.
These results showed that THSG protected against DOX-induced cardiotoxicity by decreasing ROS generation and intracellular [Ca2+] and by inhibiting apoptotic signaling pathways.
2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside; doxorubicin; apoptosis; reactive oxygen species
To evaluate the antifibrotic effect of telmisartan, an angiotensin II receptor blocker, in bile duct-ligated rats.
Adult Sprague-Dawley rats were allocated to 3 groups: sham-operated rats, model rats underwent common bile duct ligation (BDL), and BDL rats treated with telmisartan (8 mg/kg, po, for 4 weeks). The animals were sacrificed on d 29, and liver histology was examined, the Knodell and Ishak scores were assigned, and the expression of angiotensin-converting enzyme (ACE) and ACE2 was evaluated with immunohistochemical staining. The mRNAs and proteins associated with liver fibrosis were evaluated using RTQ-PCR and Western blot, respectively.
The mean fibrosis score of BDL rats treated with telmisartan was significantly lower than that of the model rats (1.66±0.87 vs 2.13±0.35, P=0.015). However, there was no significant difference in inflammation between the two groups, both of which showed moderate inflammation. Histologically, treatment with telmisartan significantly ameliorated BDL-caused the hepatic fibrosis. Treatment with telmisartan significantly upregulated the mRNA levels of ACE2 and MAS, and decreased the mRNA levels of ACE, angiotensin II type 1 receptor (AT1-R), collagen type III, and transforming growth factor β1 (TGF-β1). Moreover, treatment with telmisartan significantly increased the expression levels of ACE2 and MAS proteins, and inhibited the expression levels of ACE and AT1-R protein.
Telmisartan attenuates liver fibrosis in bile duct-ligated rats via increasing ACE2 expression level.
hepatic fibrosis; bile duct ligation; the Knodell and Ishak scoring system; angiotensin II; telmisartan
Doxorubicin (Dox) is one of the most effective chemotherapeutic agents; however, it causes dose-dependent cardiotoxicity. Evaluation of left ventricular function relies on measurements based on M-mode echocardiography. A new technique based on quantification of myocardial motion and deformation, strain echocardiography, has been showed promising profile for early detection of cardiac dysfunction. Different therapy strategies, such as flavonoid plant extracts and stem cells, have been investigated to improve heart function in toxic cardiomyopathy. This work aimed to assess early cardiac function improvement after treatments with either flavonoid extract from Camellia sinensis or mesenchymal stem cells in Dox cardiotoxicity using strain echocardiography. Twenty Wistar rats were randomly assigned to four groups. They received water (control, Dox, Dox + stem cells) or 100 mg/kg C. sinensis extract (Dox + C. sinensis) via gavage, daily, for four weeks. Animals also received saline (control) or 5 mg/kg doxorubicin (Dox, Dox + C. sinensis, Dox + stem cells) via intraperitoneal injection, weekly, for four weeks. Stem cells were injected (3 × 106 cells) through tail vein prior the beginning of the experiment (Dox + stem cells). Animals were evaluated by hematological, electrocardiography, echocardiography, and histopathological examinations. Dox cardiotoxicity was only diagnosed with strain echocardiography, detecting a decrease in ventricular function. C. sinensis extract did not prevent ventricular dysfunction induced by Dox. However, strain echocardiography examination revealed that Dox cardiotoxicity was significantly suppressed in rats treated with stem cells. In conclusion, strain echocardiography was able to detect precocity signs of heart failure and stem cell therapy showed cardioprotection effect against Dox cardiotoxicity.
Echocardiography; Cardiotoxicity; Stem cell therapy; Flavonoid
To investigate the effect of the aqueous extract of Phyllanthus niruri (Aq.E.PN) against doxorubicin (Dox)-induced myocardial toxicity in rats.
Materials and Methods:
Cardiotoxicity was produced by Dox administration (15 mg/kg for 2 weeks). Aq.E PN (200 mg/kg, orally) was administered as pretreatment for 2 weeks alternated with Dox for the next 2 weeks. The general observations, mortality, histopathology, biomarker enzymes like lactate dehydrogenase (LDH), creatinine phosphokinase (CPK) and alkaline phosphatase, diagnostic enzyme markers like aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and antioxidants such as glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were monitored after 3 weeks of the last dose.
Pretreatment with the Aq.E.PN significantly (P < 0.01) protected the myocardium from the toxic effects of Dox by reducing the elevated level of biomarker and diagnostic enzymes like LDH, CPK, AST and ALT to the normal levels. Aq.E PN increased the GSH, SOD and CAT levels and decreased the MDA levels in cardiac tissue. Administration of Dox caused cardiomyopathy associated with an antioxidant deficiency.
These results suggest a cardioprotective effect of P. niruri due to its antioxidant properties.
Phyllanthus niruri; antioxidant; cardiotoxicity; doxorubicin
We sought to investigate the effects of telmisartan on high-fat diet-induced hypertension and to explore the possible underlying mechanisms. Rats receiving high-fat diet were randomly divided into two groups, the telmisartan group (n = 9) and the high-fat diet group (n = 10). The control group consisted of age-matched rats on a regular diet (n = 10). At the end of the treatment, the body weight, blood pressure, insulin sensitivity and serum adiponectin levels of all rats were examined, and their visceral fat was extracted and weighed. Our results showed that telmisartan improved insulin resistance and dyslipidemia and increased serum adiponectin levels. Telmisartan also lowered both systolic blood pressure and diastolic blood pressure, and decreased the accumulation of perirenal fat associated with high-fat diet. Furthermore, telmisartan increased adiponectin mRNA expression in the perirenal fat. Correlation analysis showed that both systolic blood pressure and diastolic blood pressure were positively correlated with perirenal fat. These effects of telmisartan may be mediated through decreases in perirenal fat and contributed to the improvement of perirenal fat function. Our findings suggested a strong link between perirenal fat and high-fat diet-induced hypertension, and identified telmisartan as a potential drug for the treatment of obesity-related hypertension.
telmisartan; high-fat diet; hypertension; perirenal fat; adiponectin
To study the preventive role of curcumin against doxorubicin (Dox)-induced myocardial toxicity in rats.
Materials and Methods:
Cardiotoxicity was produced by cumulative administration of Dox (15 mg/kg for two weeks). Curcumin (200 mg/kg, po) was administered as pretreatment for two weeks and then for two alternate weeks with Dox. The general observations, mortality, histopathology, biomarker enzymes like lactate dehydrogenase (LDH) and creatine phosphokinase (CPK), biochemical parameters such as aspartate aminotransferase (AST) alanine aminotransferase (ALT) and alkaline phosphatase (ALP), antioxidant enzymes such as glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were monitored after three weeks of last dose.
The repeated administration of Dox induced cardiomyopathy associated with an antioxidant deficit and increased level biomarkers. Pretreatment with the curcumin significantly protected myocardium from the toxic effects of Dox by reducing the elevated level of biomarker enzymes like LDH and CPK and biochemical parameters such as AST, ALT and ALP back to normal. Curcumin increased the reduced level of GSH, SOD and CAT and decreased the elevated level of malondialdehyde (MDA) in cardiac tissue.
The biochemical and histopathology reports support the cardioprotective effect of curcumin which could be attributed to antioxidant.
Antioxidant; cardiotoxicity; curcumin; doxorubicin; free radicals
Clinical use of doxorubicin (DOX) is limited by its cardiotoxic side effects. Recent studies established that metformin (MET), an oral antidiabetic drug, possesses an antioxidant activity. However, whether it can protect against DOX-induced energy starvation and mitochondrial damage has not been reported. Our results, in a rat model of DOX-induced cardiotoxicity, show that DOX treatment significantly increased serum levels of LDH and CK-MB, indicators of cardiac injury, and induced expression of hypertrophic gene markers. DOX also caused marked decreases in the cardiac levels of glutathione, CoA-SH and ATP, and mRNA expression of catalase and NQO-1. These biochemical changes were associated with myocardial histopathological and ultrastructural deteriorations, as observed by light and electron microscopy, respectively. Cotreatment with MET (500 mg/kg) eliminated all DOX-induced biochemical, histopathological, and ultrastructural changes. These findings demonstrate that MET successfully prevents DOX-induced cardiotoxicity in vivo by inhibiting DOX-induced oxidative stress, energy starvation, and depletion of intramitochondrial CoA-SH.
We investigated the potential of telmisartan to improve microvascular dysfunction induced by myocardial ischemia/reperfusion (I/R) injury by activating the peroxisome proliferator-activated receptor gamma (PPARG) pathway.
Forty-eight male rabbits were randomly allocated into sham-operated, I/R, GW9662, telmisartan, telmisartan–GW9662, or candesartan groups. Rabbits were anesthetized, and the left anterior descending coronary artery (LAD) was ligated for 60 minutes. Following reperfusion for 6 hours, angiotensin II content of the heart was determined using radioimmunoassay. Myocardial neutrophil accumulation and microvessel cross-sectional area were examined histologically. Myocardial capillaries were examined with transmission electron microscopy. Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the myocardium were measured using enzyme-linked immunosorbent assay. Western blot was utilized for investigating the expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and PPARG.
Angiotensin II concentration was significantly increased in all treatment groups compared with the sham-operated group (P < 0.05, all). Accumulation of polymorphonuclear neutrophils was significantly lower, while microvessel cross-sectional area was significantly higher in the telmisartan, telmisartan-GW9662, and candesartan groups compared with the I/R group (P < 0.05). ICAM-1 and VCAM-1 levels were also significantly lower, and correlated with lower NF-κB expression in these groups. The effects were the most significant in the telmisartan group compared with the telmisartan–GW9662 and candesartan groups. Telmisartan significantly increased PPARG protein expression compared with all other groups (P < 0.05, all).
Except for the typical effects of angiotensin II-receptor blocker, telmisartan improved microvascular dysfunction during myocardial I/R injury via the PPARG pathway.
Ischemia/reperfusion; Microvascular dysfunction; Telmisartan; Peroxisome proliferator-activated receptor gamma
Doxorubicin is a widely used chemotherapy drug, but its application is associated with cardiotoxicity. Free radical generation and mitochondrial dysfunction are thought to contribute to doxorubicin-induced cardiac failure. Angiotensin-converting enzyme (ACE) inhibitors are commonly used as cardioprotective agents and have recently been shown in clinical studies to be efficacious in the prevention of anthracycline induced heart failure. Here we evaluated a mechanism for these protective effects by testing the ability of the ACE inhibitor enalapril to preserve mitochondrial function in a model of chronic doxorubicin treatment in rats.
Sprague Dawley rats were divided into three groups and followed for a total of 10 weeks: a) control-untreated, b) Doxorubicin treated (Dox), and c) Doxorubicin + Enalapril treated (DE). Doxorubicin was administered via intraperitoneal injection at weekly intervals from week 2 through week 7. Enalapril was administered in the drinking water of the DE group for the study duration.
Doxorubicin treatment produced a significant loss in left ventricular contractility (P< 0.05), decrease in mitochondrial function via impairment of state-3 respiration, decrease in the cytosolic fraction of ATP, and up-regulation of free radical production. Enalapril significantly attenuated the decrease in percent fractional shortening (P< 0.05) and prevented the doxorubicin-associated reduction in respiratory efficiency and cytosolic ATP content (P< 0.05). Importantly, enalapril also abolished the robust doxorubicin-induced increase in free radical formation.
Administration of enalapril attenuates doxorubicin-induced cardiac dysfunction via preservation of mitochondrial respiratory efficiency and reduction in doxorubicin-associated free radical generation.
doxorubicin; mitochondria; cardiotoxicity; ACE inhibitor; free radicals
Diabetic cardiovascular disease is associated with decreased adiponectin and increased oxidative stress. This study investigated the effect of telmisartan on the expression of adiponectin receptor 2 (adipoR2) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits in the heart and the expression of adiponectin receptor 1 (adipoR1) in aorta in type 2 diabetic rats.
Type 2 diabetes was induced by high-fat and high-sugar diet and intraperitoneal injection of a low dose of streptozotocin (STZ). Heart function, adipoR2, p22phox, NOX4, glucose transporter 4(GLUT4), monocyte chemoattractant protein-1(MCP-1) and connective tissue growth factor (CTGF)in the heart, and adipoR1, MCP-1 and nuclear factor kappa B (NF-κB) in aorta were analyzed in controls and diabetic rats treated with or without telmisartan (5mg/kg/d) by gavage for 12 weeks.
Heart function, plasma and myocardial adiponectin levels, the expression of myocardial adipoR2 and GLUT4 were significantly decreased in diabetic rats (P <0.05). The expression of myocardial p22phox, NOX4, MCP-1, and CTGF was significantly increased in diabetic rats (P <0.05). The expression of adipoR1 was decreased and the expression of MCP-1 and NF-κB was increased in the abdominal aorta in diabetic rats (P <0.05). Telmisartan treatment significantly attenuated these changes in diabetic rats (P <0.05).
Our results suggest that telmisartan upregulates the expression of myocardial adiponectin, its receptor 2 and GLUT4. Simultaneously, it downregulates the expression of myocardial p22phox, NOX4, MCP-1, and CTGF, contributing so to the improvement of heart function in diabetic rats. Telmisartan also induces a protective role on the vascular system by upregulating the expression of adipoR1 and downregulating the expression of MCP-1 and NF-κB in the abdominal aorta in diabetic rats.
Telmisartan; Adiponectin receptor; NADPH oxidase; Type 2 diabetic; Cardiac; Aorta
Aim and Objective:
The objective was to determine the activity of methanol extract of fruit of Trichosanthes cucumerina in doxorubicin-induced cardiotoxicity in rats.
Materials and Methods:
The methanol extract of fruit of T. cucumerina was prepared. Male Wistar rats were divided in four groups. Group I was vehicle control. Group II animals received doxorubicin 4 mg/kg i.p. on days 21, 28, 35, and 42. Group III and IV animals were treated with methanol extract of T. cucumerina (500 and 1000 mg/kg, respectively) for 49 days. Doxorubicin was administered on days 21, 28, 35, and 42 days. The parameters of study were body weight, serum biomarkers, ECG, blood pressure, and left ventricular function. At the end of the study, the histology of heart, liver, and kidney was carried out.
Cardiac toxicity by doxorubicin was manifested as body weight loss, elevated serum LDH and CK-MB, increased ST, QT and QRS complex, reduced blood pressure, and left ventricular function. The methanol extract of T. cucumerina significantly decreased LDH and CK-MB, reduced ST, QT interval and QRS complex, increased heart rate, restored blood pressure, and left ventricular function. Doxorubicin caused liver and kidney necrosis, cellular infiltration, and vascular changes that indicated injury.
T. cucumerina (1000 mg/kg) reduced the severity of doxorubicin-induced cardiac damage especially in heart. It is concluded that doxorubicin-induced cardiotoxicity is reduced by pretreatment with methanol extract of fruit of T. cucumerina.
Cardiotoxicity; doxorubicin; Trichosanthes cucumerina
Cardiac inflammation and generation of oxidative stress are known to contribute to trastuzumab (herceptin) induced cardiac toxicity. Toll-like receptors (TLRs) are a part of the innate immune system and are involved in cardiac stress reactions. Since TLR4 might play a relevant role in cardiac inflammatory signaling, we investigated whether or not TLR4 is involved in trastuzumab induced cardiotoxicity.
Seven days after a single injection of herceptin (2 mg/kg; i.p.), left ventricular pressure volume loops were measured in HeN compotent (TLR4+/+) and HeJ mutant (TLR4-/-) treated with trastuzumab and control mice. Immunofluorescent staining for monocyte infiltration and analyses of plasma by (ELISAs) for different chemokines including: MCP-1and tumor necrosis factor-α (TNF-α), Western immunoblotting assay for ICAM-1, and used troponin I for cardiac injury marker.
Trastuzumab injection resulted in an impairment of left ventricular function in TLR-4 competent (HeN), in contrast TLR4-/- trastuzumab mice showed improved left ventricular function EF%, CO; p < 0.05, attenuation of mononuclear cell infiltration in TLR4 -/-; p < 0.05 vs.TLR-4 competent (HeN), reduced level of cytokines TNF-α, MCP-1 and ICAM-1 expression in TLR4-/-, marked reduction of myocardial troponin-I levels in TLR4-deficient mice. Data are presented as means ± SE; n = 8 in each group p < 0.05 vs.TLR-4 competent (HeN).
Treatment with trastuzumab induces an inflammatory response that contributes to myocardial tissue TLR4 mediates chemokine expression (TNF-α, MCP-1and ICAM-1), so in experimental animals TLR4 deficiency improves left ventricular function and attenuates pathophysiological key mechanisms in trastuzumab induced cardiomyopathy.
Toll Like Receptor 4; cardiac-toxicity; Inflammation; trastuzumab
To determine whether angiotensin II receptor blockers (ARBs) could protect central neurons against nutrient deprivation-induced apoptosis in vitro and to elucidate the underlying mechanisms.
Primary rat cerebellar granule cells (CGCs) underwent B27 (a serum substitute) deprivation for 24 h to induce neurotoxicity, and cell viability was analyzed using LDH assay and WST-1 assay. DNA laddering assay and TUNEL assay were used to detect cell apoptosis. The expression of caspase-3 and Bcl-2, and the phosphorylation of Akt and GSK-3β were detected using Western blot analysis. AT1a mRNA expression was determined using RT-PCR analysis.
B27 deprivation significantly increased the apoptosis of CGCs, as demonstrated by LDH release, DNA laddering, caspase-3 activation and positive TUNEL staining. Pretreatment with 10 μmol/L ARBs (telmisartan, candesartan or losartan) partially blocked B27 deprivation-induced apoptosis of CGCs with telmisartan being the most effective one. B27 deprivation markedly increased the expression of AT1a receptor in CGCs, inhibited Akt and GSK-3β activation, decreased Bcl-2 level, and activated caspase-3, which were reversed by pretreatment with 1 μmol/L telmisartan. In addition, pretreatment with 10 μmol/L PPARγ agonist pioglitazone was more effective in protecting CGCs against B27 deprivation-induced apoptosis, whereas pretreatment with 20 μmol/L PPARγ antagonist GW9662 abolished all the effects of telmisartan in CGCs deprived of B27.
ARBs, in particular telmisartan, can protect the nutrient deprivation-induced apoptosis of CGCs in vitro through activation of PPARγ and the Akt/GSK-3β pathway.
cerebellar granule cell; nutrient deprivation; apoptosis; angiotensin II receptor blocker; telmisartan; AT1a receptor; Akt; GSK-3β; PPARγ; neurotoxicity
To mitigate the cardiotoxicity of anthracycline antibiotics without compromising their anticancer activities is still an issue to be solved. We previously demonstrated that schisandrin B (Sch B) could protect against doxorubicin (Dox)-induced acute cardiotoxicity via enhancing cardiomyocytic glutathione redox cycling that could attenuate oxidative stress generated from Dox. In this study, we attempted to prove if Sch B could also protect against Dox-induced chronic cardiotoxicity, a more clinically relevant issue, without compromising its anticancer activity.
Rat was given intragastrically either vehicle or Sch B (50 mg/kg) two hours prior to i.p. Dox (2.5 mg/kg) weekly over a 5-week period with a cumulative dose of Dox 12.5 mg/kg. At the 6th and 12th week after last dosing, rats were subjected to cardiac function measurement, and left ventricles were processed for histological and ultrastructural examination. Dox anticancer activity enhanced by Sch B was evaluated by growth inhibition of 4T1, a breast cancer cell line, and S180, a sarcoma cell line, in vitro and in vivo.
Pretreatment with Sch B significantly attenuated Dox-induced loss of cardiac function and damage of cardiomyocytic structure. Sch B substantially enhanced Dox cytotoxicities toward S180 in vitro and in vivo in mice, and increased Dox cytotoxcity against 4T1 in vitro. Although we did not observe this enhancement against the implanted 4T1 primary tumor, the spontaneous metastasis to lung was significantly reduced in combined treatment group than Dox alone group.
Sch B is capable of protecting Dox-induced chronic cardiotoxicity and enhancing its anticancer activity. To the best of our knowledge, Sch B is the only molecule ever proved to function as a cardioprotective agent as well as a chemotherapeutic sensitizer, which is potentially applicable for cancer treatment.