Nitric oxide and oxidative stress in brain and heart of normal rats treated with doxorubicin: Role of aminoguanidine

Biochemical and histological alterations of doxorubicin-induced neurotoxicity in rats: Protective role of luteolin

Doxorubicin (DOX) is a chemotherapeutic drug used in the treatment of various cancer types. DOX toxic side effects include neuronopathy and memory deficits. We investigated the effect of the antioxidant luteolin (LUT: 50 or 100 mg/kg; per os) on DOX (2 mg/kg; intraperitoneal)-induced oxidative stress (OS), inflammation, and apoptosis in the brain of Wistar rats for 14 days. We observed that LUT reduced DOX-mediated increase in OS biomarkers-catalase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase. LUT increased glutathione and total sulphydryl levels and alleviated DOX-induced increases in the levels of reactive oxygen and nitrogen species, lipid peroxidation, myeloperoxidase, nitric oxide, tumor necrosis factor-α, and interleukin-1β (IL-1β). Additionally, LUT suppressed caspase-3 activity, increased anti-inflammatory cytokine-IL-10 level, and reduced pathological lesions in the examined organs of rats cotreated with LUT and DOX. Collectively, cotreatment with LUT lessened DOX-induced neurotoxicity. Supplementation of LUT as a chemopreventive agent might be useful in patients undergoing DOX chemotherapy.

Aminoguanidine Prevents the Oxidative Stress, Inhibiting Elements of Inflammation, Endothelial Activation, Mesenchymal Markers, and Confers a Renoprotective Effect in Renal Ischemia and Reperfusion Injury

Oxidative stress produces macromolecules dysfunction and cellular damage. Renal ischemia-reperfusion injury (IRI) induces oxidative stress, inflammation, epithelium and endothelium damage, and cessation of renal function. The IRI is an inevitable process during kidney transplantation. Preliminary studies suggest that aminoguanidine (AG) is an antioxidant compound. In this study, we investigated the antioxidant effects of AG (50 mg/kg, intraperitoneal) and its association with molecular pathways activated by IRI (30 min/48 h) in the kidney. The antioxidant effect of AG was studied measuring GSSH/GSSG ratio, GST activity, lipoperoxidation, iNOS, and Hsp27 levels. In addition, we examined the effect of AG on elements associated with cell survival, inflammation, endothelium, and mesenchymal transition during IRI. AG prevented lipid peroxidation, increased GSH levels, and recovered the GST activity impaired by IRI. AG was associated with inhibition of iNOS, Hsp27, endothelial activation (VE-cadherin, PECAM), mesenchymal markers (vimentin, fascin, and HSP47), and inflammation (IL-1β, IL-6, Foxp3, and IL-10) upregulation. In addition, AG reduced kidney injury (NGAL, clusterin, Arg-2, and TFG-β1) and improved kidney function (glomerular filtration rate) during IRI. In conclusion, we found new evidence of the antioxidant properties of AG as a renoprotective compound during IRI. Therefore, AG is a promising compound to treat the deleterious effect of renal IRI.

Exercise Training for Cancer Survivors

OPINION STATEMENT

Cardiovascular diseases are a common cause of morbidity and mortality in cancer survivors. Furthermore, some cancer therapies are now being increasingly recognized to have negative cardiovascular effects, or cardiotoxicity. Exercise therapy has been found to improve cardiorespiratory fitness in patients with cancer as well as attenuate the cardiotoxic effects of cancer therapy. It is the centerpiece for cardiac and pulmonary rehabilitation programs. It is also an important component in cardio-oncology rehabilitation. Exercise is generally safe, and its benefit is observed when started as soon as the diagnosis of cancer and throughout cancer survivorship.

A Bibliometric Review of Publications on Oxidative Stress and Chemobrain: 1990-2019

Oxidative stress is considered one of the possible mechanisms behind chemobrain or the cognitive dysfunction persistent after chemotherapy treatment. Breast cancer patients have reported chemobrain symptoms since the 1990s. In this present bibliometric review, we employed the VOSviewer tool to describe the existing landscape on literature concerning oxidative stress, breast cancer chemotherapies, and chemobrain. As of 2019, 8799 papers were listed in the Web of Science database, with more than 900 papers published each year. As expected, terms relating to oxidative stress, mitochondria, breast cancer, and antioxidants have occurred very often in the literature throughout the years. In recent years, there has been an increase in the occurrence of terms related to nanomedicine. Only within the last decade do the keywords 'brain', 'blood-brain barrier', and 'central nervous system' appear, reflecting an increased interest in chemobrain. China has become the most prolific producer of oxidative stress and chemotherapy related papers in the last decade followed by the USA and India. In conclusion, the subject of oxidative stress as a mechanism behind chemotherapies' toxicities is an active area of research.

Assessing the Effects of Redox Modifier MnTnBuOE-2-PyP 5+ on Cognition and Hippocampal Physiology Following Doxorubicin, Cyclophosphamide, and Paclitaxel Treatment

Background: Chemotherapy treatment for breast cancer can induce cognitive impairments often involving oxidative stress. The brain, as a whole, is susceptible to oxidative stress due to its high-energy requirements, limited anaerobic respiration capacities, and limited antioxidant defenses. The goal of the current study was to determine if the manganese porphyrin superoxide dismutase mimetic MnTnBuOE-2-PyP (MnBuOE) could ameliorate the effects of doxorubicin, cyclophosphamide, and paclitaxel (AC-T) on mature dendrite morphology and cognitive function. Methods: Four-month-old female C57BL/6 mice received intraperitoneal injections of chemotherapy followed by subcutaneous injections of MnBuOE. Four weeks following chemotherapy treatment, mice were tested for hippocampus-dependent cognitive performance in the Morris water maze. After testing, brains were collected for Golgi staining and molecular analyses. Results: MnBuOE treatment preserved spatial memory during the Morris water-maze. MnBuOE/AC-T showed spatial memory retention during all probe trials. AC-T treatment significantly impaired spatial memory retention in the first and third probe trial (no platform). AC-T treatment decreased dendritic length in the Cornu Ammonis 1 (CA1) and dentate gyrus (DG) areas of the hippocampus while AC-T/MnBuOE maintained dendritic length. Comparative proteomic analysis revealed affected protein networks associated with cell morphology and behavior functions in both the AC-T and AC-T/MnBuOE treatment groups.

Mangiferin exert cardioprotective and anti-apoptotic effects in heart failure induced rats

Mangiferin is a well-known xanthone extracted from mango leaves (Mangifera indica Linn). Mangiferin is widely distributed in the bark, peel, leaf, seed, stalk, and kernel of mango and higher plants. The pharmacological properties of mangiferin, including its antioxidant, anticancer, antiaging, antiviral, hepatoprotective, analgesic, and immunomodulatory activities, have been described in several studies. We investigated the effect of mangiferin on isoproterenol-induced apoptosis. Experimental heart failure was induced in rats by intraperitoneal administration of isoproterenol (5 mg/kg) for 7 consecutive days. Rats were divided into five groups: group I (sham rats), group II (isoproterenol alone control), group III (isoproterenol + 25 mg/kg mangiferin), group IV (isoproterenol + 50 mg/kg mangiferin), and group V (isoproterenol + 0.0225 mg/kg digitalis as a positive control). Hemodynamic parameters and body weight, heart weight and liver weight, apoptosis induction, and caspase-3, Bax, and Bcl-2 protein levels were measured, and a histopathological analysis of cardiomyocytes was performed. In addition, apoptosis and protein expression of caspase-3, cleaved caspase-3, Bax, and Bcl-2 were measured in cardiac H9c2 cells. Mangiferin supplementation significantly increased heart rate and improved the maximum rate of decrease in left ventricular (LV) pressure, the maximum rate of increase in LV pressure, and LV systolic pressure. Mangiferin reduced inflammatory cell infiltration and the number of broken myocardial fibers, and decreased apoptosis in cardiomyocytes by reducing proteins levels of caspase-3 and Bax and increasing those of Bcl-2. Our findings suggest that mangiferin has a cardioprotective effect against isoproterenol-induced apoptosis in cardiomyocytes.

Morphometric analysis of structural renal alterations and beneficial effects of aminoguanidine in acute kidney injury induced by cisplatin in rats

Since cisplatin-induced nephrotoxicity has very important clinical consequences, the purpose of this study was to determine the potential protective effect of aminoguanidine on the acute kidney injury caused by cisplatin. Experiments were done on 40 Wistar rats divided into four groups. The CIS group received cisplatin in a single dose of 8 mg/kg, while the CISAG group received the same dose of cisplatin and aminoguanidine (100 mg/kg) by intraperitoneal injections. Animals in the AG group received only aminoguanidine (100 mg/kg) and those in the C group received saline. Quantitative evaluation of structural and functional alterations in the kidneys was performed by analysis of biochemical and parameters of oxidative stress and by histological and morphometric analysis of renal sections. Histological sections of kidney showed structural damage of proximal tubules and glomeruli that were induced by cisplatin. Morphometric analysis revealed statistically significant differences in the area of proximal tubules and the size and cellularity of glomeruli between the CIS and CISAG groups. Glomerular basement membrane thickness was increased in the CIS group, while aminoguanidine attenuated these changes in the CISAG group of rats. Our results suggest that aminoguanidine acts protectively and repairs structural and functional damage of kidney by engaging the existent antioxidative potential at the level of renal tissue.

Chemobrain in rats: Behavioral, morphological, oxidative and inflammatory effects of doxorubicin administration

Doxorubicin (DOX) is known to cause cognitive impairments in patients submitted to long-term chemotherapy (deficits also known as chemobrain). The present study investigated whether DOX administration could affect behavior and brain morphology, as well as oxidative and inflammatory status in rats. Male Wistar rats were injected with DOX (2.5 mg/kg/week, 4 weeks, i.p.) or saline. Behavioral analyses were performed. Brains were collected and analyzed by hematoxylin-eosin and luxol fast blue staining techniques and by immunohistochemistry (for glial fibrillary acidic protein expression in astrocytes; GFAP). Serum and brain levels of TNF-α, IL-1β, IL-6, IL-8, IL-10 and CXCL-1 were determined. Oxidative parameters, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), nitric oxide (NO•), brain iron and ferritin levels, as well as reduced and oxidized glutathione (GSH and GSSG, respectively) and thiobarbituric acid reactive substances (TBARS) were also assessed in brain. DOX-injected rats presented cognitive/memory impairments, increased GFAP expression, increased levels of TBARS, NO and GR, but decreased GSSG and ferritin levels in brain homogenate. In addition, increased serum and brain levels of IL-6, IL-8 and CXCL1 were noted in the DOX group, although IL-10 decreased. As DOX has a poor penetration across the blood-brain barrier (BBB), it is proposed that this drug elicits a systemic proinflammatory response with increase of proinflammatory cytokines which cross the BBB and can be involved in the induction of oxidative molecules and proinflammatory cytokines that altogether induce astrogliosis all over the brain. These events may be responsable for chemotherapy-induced cognitive/memory deficits.

Anthocyanin Attenuates Doxorubicin-Induced Cardiomyotoxicity via Estrogen Receptor-α/β and Stabilizes HSF1 to Inhibit the IGF-IIR Apoptotic Pathway

Doxorubicin (Dox) is extensively used for chemotherapy in different types of cancer, but its use is limited to because of its cardiotoxicity. Our previous studies found that doxorubicin-induced insulin-like growth factor II receptor (IGF-IIR) accumulation causes cardiomyocytes apoptosis via down-regulation of HSF1 pathway. In these studies, we demonstrated a new mechanism through which anthocyanin protects cardiomyoblast cells against doxorubicin-induced injury. We found that anthocyanin decreased IGF-IIR expression via estrogen receptors and stabilized heat shock factor 1 (HSF1) to inhibit caspase 3 activation and apoptosis of cardiomyocytes. Therefore, the phytoestrogen from plants has been considered as another potential treatment for heart failure. It has been reported that the natural compound anthocyanin (ACN) has the ability to reduce the risk of cardiovascular disease (CVD). Here, we demonstrated that anthocyanin acts as a cardioprotective drug against doxorubicin-induced heart failure by attenuating cardiac apoptosis via estrogen receptors to stabilize HSF1 expression and down-regulated IGF-IIR-induced cardiomyocyte apoptosis.

Effect of valsartan on cardiac senescence and apoptosis in a rat model of cardiotoxicity

The clinical application of doxorubicin is limited by its cardiotoxicity. The present study investigated the effect of valsartan on doxorubicin-induced cardiotoxicity in rats. Rats were divided into 6 groups: control, control + valsartan (10 mg/kg, for 14 days, orally), doxorubicin-treated (2.5 mg/kg, 3 times/week for 2 weeks, intraperitoneally), valsartan then doxorubicin, valsartan + doxorubicin, and doxorubicin then valsartan. ECG, isolated heart, lipid peroxidation (thiobaribituric acid reactive substances (TBARS)), total antioxidant capacity (TAC), and Bax, Bcl-2, and senescence marker protein 30 (SMP30) gene expression were measured in cardiac tissue. Blood samples were collected to measure lactate dehydrogenase (LDH) and creatine kinase MB (CK-MB). Doxorubicin significantly increased LDH, CK-MB, TBARS, heart rate (HR), Bax gene expression, and −dP/dtmax and decreased TAC, Bcl-2 and SMP30 gene expression, left ventricular developed pressure (LVDP), and +dP/dtmax. Also, doxorubicin lengthened ST, QT, and QTc intervals. Concurrent or post- but not pre-treatment of doxorubicin-treated rats with valsartan reduced LDH, CK-MB, TBARS, HR, Bax gene expression, −dP/dtmax, and ST, QT, and QTc intervals and increased TAC, Bcl-2 and SMP30 gene expression, LVDP, and +dP/dtmax. Therefore, we conclude that concurrent or post- but not pre-treatment of doxorubicin-induced rats with valsartan attenuated doxorubicin-induced cardiotoxicity through inhibiting oxidative stress, apoptosis, and senescence.

Chemotherapy-Induced Cardiotoxicity: Overview of the Roles of Oxidative Stress

Chemotherapy-induced cardiotoxicity is a serious complication that poses a serious threat to life and limits the clinical use of various chemotherapeutic agents, particularly the anthracyclines. Understanding molecular mechanisms of chemotherapy-induced cardiotoxicity is a key to effective preventive strategies and improved chemotherapy regimen. Although no reliable and effective preventive treatment has become available, numerous evidence demonstrates that chemotherapy-induced cardiotoxicity involves the generation of reactive oxygen species (ROS). This review provides an overview of the roles of oxidative stress in chemotherapy-induced cardiotoxicity using doxorubicin, which is one of the most effective chemotherapeutic agents against a wide range of cancers, as an example. Current understanding in the molecular mechanisms of ROS-mediated cardiotoxicity will be explored and discussed, with emphasis on cardiomyocyte apoptosis leading to cardiomyopathy. The review will conclude with perspectives on model development needed to facilitate further progress and understanding on chemotherapy-induced cardiotoxicity.

Physical exercise prior and during treatment reduces sub-chronic doxorubicin-induced mitochondrial toxicity and oxidative stress

Doxorubicin (DOX) is an anti-cancer agent whose clinical usage results in a cumulative and dose-dependent cardiotoxicity. We have previously shown that exercise performed prior to DOX treatment reduces the resulting cardiac(mito) toxicity. We sought to determine the effects on cardiac mitochondrial toxicity of two distinct chronic exercise models (endurance treadmill training-TM and voluntary free-wheel activity-FW) when used prior and during DOX treatment. Male-young Sprague-Dawley rats were divided into six groups (n=6 per group): SAL+SED (saline sedentary), SAL+TM (12-weeks TM), SAL+FW (12-weeks FW), DOX+SED (7-weeks of chronic DOX treatment 2mg/kg per week), DOX+TM and DOX+FW. DOX administration started 5weeks after the beginning of the exercise protocol. Heart mitochondrial ultrastructural alterations, mitochondrial function (oxygen consumption and membrane potential), semi-quantification of oxidative phosphorylation (OXPHOS) proteins and their in-gel activity, as well as proteins involved in mitochondrial oxidative stress (SIRT3, p66shc and UCP2), biogenesis (PGC1α and TFAM), acetylation and markers for oxidative damage (carbonyl groups, MDA,SH, aconitase, Mn-SOD activity) were evaluated. DOX treatment resulted in ultrastructural and functional alterations and decreased OXPHOS. Moreover, DOX decreased complex I activity and content, mitochondrial biogenesis (TFAM), increased acetylation and oxidative stress. TM and FW prevented DOX-induced alteration in OXPHOS, the increase in oxidative stress, the decrease in complex V activity and in complex I activity and content. DOX-induced decreases in TFAM and SIRT3 content were prevented by TM only. Both chronic models of physical exercise performed before and during the course of sub-chronic DOX treatment translated into an improved mitochondrial bioenergetic fitness, which may result in part from the prevention of mitochondrial oxidative stress and damage.

Liguzinediol improved the heart function and inhibited myocardial cell apoptosis in rats with heart failure

AIM

Liguzinediol is a novel derivative of ligustrazine isolated from the traditional Chinese medicine Chuanxiong (Ligusticum wallichii Franch), and produces significant positive inotropic effect in isolated rat hearts. In this study we investigated the effects of liguzinediol on a rat model of heart failure.

METHODS

To induce heart failure, male SD rats were injected with doxorubicin (DOX, 2 mg/kg, ip) once a week for 4 weeks. Then the rats were administered with liguzinediol (5, 10, 20 mg·kg(-1)·d(-1), po) for 2 weeks. Hemodynamic examination was conducted to evaluate heart function. Myocardial cell apoptosis was examined morphologically. The expression of related genes and proteins were analyzed using immunohistochemical staining and Western blot assays, respectively.

RESULTS

Oral administration of liguzinediol dose-dependently improved the heart function in DOX-treated rats. Electron microscopy revealed that liguzinediol (10 mg·kg(-1)·d(-1)) markedly attenuated DOX-induced injury of cardiomyocytes, and decreased the number of apoptotic bodies in cardiomyocytes. Furthermore, liguzinediol significantly decreased Bax protein level, and increased Bcl-2 protein level in cardiomyocytes of DOX-treated rats, led to an increase in the ratio of Bcl-2/Bax. Moreover, liguzinediol significantly decreased the expression of both cleaved caspase-3 and NF-κB in cardiomyocytes of DOX-treated rats. Administration of digitalis (0.0225 mg·kg(-1)·d(-1)) also markedly improved the heart function and the morphology of cardiomyocytes in DOX-treated rats.

CONCLUSION

Liguzinediol improves the heart function and inhibits myocardial cell apoptosis in the rat model of heart failure, which is associated with regulating Bcl-2, Bax, caspase-3 and NF-κB expression.

Analysis of the protective biochemical and pathologic effects of aminoguanidine on an experimental aspiration pneumonitis model induced by bile acids

BACKGROUND

Gastroesophageal reflux (GER) is a common clinical pathology detected in childhood. Bile acids (BAs) are present in reflux and cause various pathologies in the esophagus, the larynx, and the lungs.

OBJECTIVE

We aimed to show if aminoguanidine (AG) contributes to the biochemical and histopathologic treatment of experimental aspiration pneumonitis induced by BAs.

METHODS

Twenty-eight female Sprague Dawley rats were used. There were 4 groups in the study: (1) group aspirated with 0.9% saline (n = 7), (2) group aspirated with 0.9% saline and treated with AG (n = 7), (3) group aspirated with a solution of 10 mg/kg taurocholic acid and 5 mg/kg taurochenodeoxycholate (n = 7), and (4) group aspirated with BA and treated with AG (n = 7). The saline and BA solutions were administered as 1 mL/kg intratracheally. The AG was administered intraperitoneally twice a day at a 150 mg/kg dose for 7 days. The different histopathologic and biochemical parameters were analyzed.

RESULTS

Clara cell protein 16 and malondialdehyde levels were found to be significantly higher in the BA group than in the group where saline was administered; however, they were significantly lower in the BA + AG group than in the BA group. The total superoxide dismutase activity decreased significantly in the BA group compared with the group where saline was administered. A significant increase in superoxide dismutase activity was observed in the BA + AG group when compared with the group where only BA was administered. When the group where BA was administered solely was compared with the group where saline was administered, peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar histiocytes, interstitial fibrosis, and granuloma were significantly higher in the BA group than in the saline group. When the BA + AG group was compared with the BA group, peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar histiocytes, interstitial fibrosis, and granuloma were found to be significantly lower.

CONCLUSIONS

Oxidant stress increases and antioxidant capacity decreases in pneumonitis induced by BAs. AG administration as an antioxidant helps in recovery, both biochemically and histopathologically. Consequently, AG seems to be an alternative that should be considered in a conservative approach to treating aspiration pneumonitis.

Attenuation of insulin resistance, metabolic syndrome and hepatic oxidative stress by resveratrol in fructose-fed rats

Metabolic syndrome and oxidative stress are common complications of type 2 diabetes mellitus. The present study was designed to determine whether resveratrol, a widely used nutritional supplement, can improve insulin sensitivity, metabolic complication as well as hepatic oxidative stress in fructose-fed rats. Male Sprague Dawley rats (180-200 g) were divided into four groups with 8 animals each. Fructose-fed insulin resistant group (Dia) animals were fed 65% fructose (Research diet, USA) for a period of 8 weeks, whereas control group (Con) animals were fed 65% cornstarch (Research Diet, USA). Resveratrol, 10 mg/kg/day (Dia+Resv) or metformin 300 mg/kg/day (Dia+Met) were administered orally to the 65% fructose-fed rats for 8 weeks. At the end of the feeding schedule, Dia group had insulin resistance along with increased blood glucose, triglyceride, uric acid and nitric oxide (NO) levels. Significant (p<0.05) increase in hepatic TBARS and conjugated dienes, and significant (p<0.05) decrease in hepatic SOD and vitamin C was observed in Dia group compared to Con group. Administration of metformin or resveratrol significantly (p<0.05) normalized all the altered metabolic parameters. However, a marked insulin sensitizing action was only observed in the Dia+Resv group. Similarly, while metformin administration failed to normalize the increased TBARS levels and decreased SOD activity, resveratrol showed a more promising effect of all oxidative stress parameters measured in the present study. Attenuation of hepatic oxidative stress in fructose-fed rat liver after resveratrol administration was associated with significant (p<0.05) increase in nuclear level of NRF2 compared with other groups. The present study demonstrates that resveratrol is more effective than metformin in improving insulin sensitivity, and attenuating metabolic syndrome and hepatic oxidative stress in fructose-fed rats.

Chemotherapy-induced weakness and fatigue in skeletal muscle: the role of oxidative stress

SIGNIFICANCE

Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity.

RECENT ADVANCES

Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction.

CRITICAL ISSUES

These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress.

FUTURE DIRECTIONS

Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.

The relative efficacy of aminoguanidine and pentoxifylline in modulating endotoxin-induced cardiac stress

This study investigates the effect of aminoguanidine (AG), a selective inducible nitric oxide synthase (iNOS) inhibitor, and pentoxifylline (PTX), a tumour necrosis factor-alpha (TNF-α) inhibitor, on lipopolysaccharide (LPS)-induced cardiac stress. Rats were divided into four groups: group I served as a control, group II (LPS) received a single intraperitoneal injection of LPS (10 mg·kg(-1) ), group III (LPS+AG) and group IV (LPS+PTX) were injected with either AG (100 mg·kg(-1) ) or PTX (150 mg·kg(-1) ) intraperitoneally 10 days prior to LPS administration. Normalization of cardiac levels of nitrite/nitrate (NO(X) ), malondialdehyde (MDA), glutathione (GSH), heme oxygenase-1 (HO-1), glutathione peroxidase (GPx) and Na(+) , K(+) -ATPase activities was evident in the AG group. Both AG and PTX decreased the elevated serum TNF-α levels, the activities of lactate dehydrogenase (LDH), creatine kinase (CK) and cardiac myeloperoxidase (MPO). The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and phosphocreatine (PCr) were enhanced following AG and PTX pretreatments. Calcium (Ca(2+) ) levels were altered, and the histopathological observations supported the described results. Conclusively, the study highlights the cardioprotective potential of AG and PTX with superior results from AG. These findings reveal the relative contribution of nitric oxide and TNF-α to oxidative stress and energy failure during endotoxemia.

Protective effect of aminoguanidine against cyclophosphamide-induced oxidative stress and renal damage in rats

BACKGROUND

Cyclophosphamide (CP) is widely used in the treatment of tumors and B-cell malignant disease, such as lymphoma, myeloma, chronic lymphocytic leukemia, and Waldenstrom's macroglobulinemia. Renal damage is one of the dose-limiting side effects of CP. Oxidative stress is reported to play important roles in CP-induced renal damage.

AIM

To find out whether aminoguanidine (AG) protects against CP-induced oxidative stress and renal damage.

METHOD

Renal damage was induced in the rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 hour before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 hours after the administration of CP or saline. The kidneys were used for histological examination by light microscopy and biochemical assays--malondialdehyde, protein carbonyl content, reduced glutathione (GSH), and the activities of antioxidant enzymes including glutathione peroxidase (GPx), glutathione S transferase (GSTase), catalase, glutathione reductase, and myeloperoxidase (MPO), a marker of neutrophil infiltration.

RESULTS

Pretreatment with AG attenuated CP-induced renal damage histologically. Pretreatment with AG prevented CP-induced lipid peroxidation, protein oxidation, depletion of reduced GSH, and loss of activities of the antioxidant enzymes including GPx, catalase, and GSTase and also MPO activity.

CONCLUSION

The results of the present study reveal that AG can prevent CP-induced renal damage by inhibiting oxidative stress. Thus, AG may be useful for prevention of the nephrotoxicity of CP.

Nitric oxide synthase inhibition abrogates hydrogen sulfide-induced cardioprotection in mice

The cardioprotective property of hydrogen sulfide (H(2)S) is recently reported. However, cellular signaling cascades mediated by H(2)S are largely unclear. This study was undertaken to explore the molecular mechanism of H(2)S-induced cardioprotection in mouse heart by utilizing in vivo model of cardiac injury. We report here that intraperitoneal administration of sodium hydrogen sulfide (NaHS, 50 μmol kg(-1 )day(-1) for 2 days), a H(2)S donor, significantly (P ≤ 0.05) increased nitric oxide levels in serum as well as myocardium without any sign of myocardial injury. Typical characteristics of myocardial injury induced by isoproterenol (ISO) administration was significantly (P ≤ 0.05) abrogated by NaHS administration as evidenced from reduction in elevated thiobarbituric acid reactive substances (TBARS) and normalization of glutathione (GSH), glutathione peroxidase, superoxide dismutase (SOD), and catalase activity. Further, decrease in TNF-α expression and improvement in myocardial architecture was also observed. However, co-administration of N-nitro-L-arginine methyl ester, a nitric oxide synthase (NOS) inhibitor, and Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor along with NaHS and ISO abrogated the beneficial effect of H(2)S differentially. Inhibition of NOS significantly (P ≤ 0.05) increased serum creatine kinase, lactate dehydrogenase, serum glutamic oxaloacetic transaminase activity and myocardial TBARS, along with significant (P ≤ 0.05) reduction of myocardial GSH, SOD, and catalase. This was followed by increase in TNF-α expression and histopathological changes. Our results revealed that H(2)S provides myocardial protection through interaction with NOS and COX-2 pathway and inhibition of NOS completely abrogates the hydrogen sulfide-induced cardioprotection in mice.

Garlic improves insulin sensitivity and associated metabolic syndromes in fructose fed rats

BACKGROUND

Type 2 diabetes mellitus, characterized by peripheral insulin resistance, is a major lifestyle disorder of the 21st Century. Raw garlic homogenate has been reported to reduce plasma glucose levels in animal models of type 1 diabetes mellitus. However, no specific studies have been conducted to evaluate the effect of raw garlic on insulin resistance or type 2 diabetes mellitus. This study was designed to investigate the effect of raw garlic on fructose induced insulin resistance, associated metabolic syndrome and oxidative stress in diabetic rats.

METHODS

Male Sprague Dawley rats weighing 200-250 gm body weight were divided into 3 groups (n = 7 per group) and fed diet containing 65% cornstarch (Control group) and 65% fructose (Diabetic group) for 8 weeks. The third group (Dia+Garl group) was fed both 65% fructose and raw garlic homogenate (250 mg/kg/day) for 8 weeks. Whole garlic cloves were homogenized with water to make a fresh paste each day.

RESULTS

At the end of 8 weeks, serum glucose, insulin, triglyceride and uric acid levels, as well as insulin resistance, as measured by glucose tolerance test, were significantly (p < 0.01) increased in fructose fed rats (Diabetic group) when compared to the cornstarch fed (Control) rats. Administration of raw garlic to fructose fed rats (Dia+Garl group) significantly (p < 0.05) reduced serum glucose, insulin, triglyceride and uric acid levels, as well as insulin resistance when compared with fructose fed rats. Garlic also normalised the increased serum levels of nitric oxide (NO) and decreased levels of hydrogen sulphide (H2S) after fructose feeding. Although body weight gain and serum glycated haemoglobin levels of fructose fed rats (Diabetic group) were not significantly different from control rats, significant (p < 0.05) reduction of these parameters was observed in fructose fed rats after garlic administration (Dia+Garl group). Significant (p < 0.05) increase in TBARS and decrease in GSH was observed in diabetic liver. Catalase was not significantly affected in any of the groups. Administration of raw garlic homogenate normalised both hepatic TBARS and GSH levels.

CONCLUSIONS

Our study demonstrates that raw garlic homogenate is effective in improving insulin sensitivity while attenuating metabolic syndrome and oxidative stress in fructose-fed rats.

Alterations in brain antioxidant enzymes and redox proteomic identification of oxidized brain proteins induced by the anti-cancer drug adriamycin: implications for oxidative stress-mediated chemobrain

Adriamycin (ADR) is a chemotherapeutic for the treatment of solid tumors. This quinone-containing anthracycline is well known to produce large amounts of reactive oxygen species (ROS) in vivo. A common complaint of patients undergoing long-term treatment with ADR is somnolence, often referred to as "chemobrain." While ADR itself does not cross the blood brain barrier (BBB), we recently showed that ADR administration causes a peripheral increase in tumor necrosis factor alpha (TNF-alpha), which migrates across the BBB and leads to inflammation and oxidative stress in brain, most likely contributing to the observed decline in cognition. In the current study, we measured levels of the antioxidant glutathione (GSH) in brains of mice injected intraparitoneally (i.p.) with ADR, as well as the levels and activities of several enzymes involved in brain GSH metabolism. We observed significantly decreased GSH levels, as well as altered GSH/GSSG ratio in brains of ADR treated mice relative to saline-treated controls. Also observed in brains of ADR treated mice were increased levels of glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR). We also observed increased activity of GPx, but a significant reduction in GST and GR activity in mice brain, 72 h post i.p. injection of ADR (20 mg/kg body weight). Furthermore, we used redox proteomics to identify specific proteins that are oxidized and/or have differential levels in mice brains as a result of a single i.p. injection of ADR. Visinin like protein 1 (VLP1), peptidyl prolyl isomerase 1 (Pin1), and syntaxin 1 (SYNT1) showed differential levels in ADR treated mice relative to saline-treated controls. Triose phosphate isomerase (TPI), enolase, and peroxiredoxin 1 (PRX-1) showed significantly increased specific carbonylation in ADR treated mice brain. These results further support the notion ADR induces oxidative stress in brain despite not crossing the BBB, and that antioxidant intervention may prevent ADR-induced cognitive dysfunction.

Neuronal nitric oxide synthase is a key factor in doxorubicin-induced toxicity to rat-isolated cortical neurons

Doxorubicin (DOX) is neurotoxic to serum-free cultures of rat cortical neurons in a biphasic concentration manner. For concentrations up to 0.5 μM, cell death follows an apoptotic pattern, while for higher concentrations apoptosis is inhibited and necrosis becomes dominant. Considering the potential toxic effects of DOX resulting from its redox-cycling, in this study we investigated the generation of reactive species and subsequent oxidative stress effects, formation of quinoproteins, activation of NF-kB, depletion of energy levels and consequent cell death in cultures of primary rat cortical cells challenged with this antitumour drug. The influence of neuronal nitric oxide synthase (nNOS) on DOX-induced neuronal cell damage was subsequently evaluated. The exposure of rat cortical primary cell cultures to DOX resulted in a significant generation of ROS/RNS, activation of NF-kB, depletion of GSH levels, depletion of ATP, and cell death, in a concentration biphasic manner. Doxorubicin also significantly increased protein-bound quinone products in neurons in a concentration-dependent manner. Inhibition of nNOS decreased neuronal cell death induced by DOX in a significant way, at the first phase of the biphasic curve. In conclusion, this study shows, for the first time, a clear involvement of nNOS and subsequent ROS/RNS generation as crucial signalling mediators of DOX-induced neurotoxicity on isolated cortical neurons. Inhibition of ROS/RNS formation, modulation of NOS isoforms and modulation of NF-kB activation could be of beneficial in preventing damage in the CNS caused by DOX.

Aminoguanidine impedes human pancreatic tumor growth and metastasis development in nude mice

AIM: To study the action of aminoguanidine on pancreatic cancer xenografts in relation to cell proliferation, apoptosis, redox status and vascularization.

METHODS: Xenografts of PANC-1 cells were developed in nude mice. The animals were separated into two groups: control and aminoguanidine treated. Tumor growth, survival and appearance of metastases were determined in vivo in both groups. Tumors were excised and ex vivo histochemical studies were performed. Cell growth was assessed by Ki-67 expression. Apoptosis was studied by intratumoral expression of B cell lymphoma-2 protein (Bcl-2) family proteins and Terminal deoxynucleotidyl transferase biotin-dUTP Nick End Labeling (Tunel). Redox status was evaluated by the expression of endothelial nitric oxide synthase (eNOS), catalase, copper-zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD) and glutathione peroxidase (GPx). Finally, vascularization was determined by Massons trichromic staining, and by VEGF and CD34 expression.

RESULTS: Tumor volumes after 32 d of treatment by aminoguanidine (AG) were significantly lower than in control mice (P < 0.01). Median survival of AG mice was significantly greater than control animals (P < 0.01). The appearance of both homolateral and contralateral palpable metastases was significantly delayed in AG group. Apoptotic cells, intratumoral vascularization (trichromic stain) and the expression of Ki-67, Bax, eNOS, CD34, VEGF, catalase, CuZnSOD and MnSOD were diminished in AG treated mice (P < 0.01), while the expression of Bcl-2 and GPx did not change.

CONCLUSION: The antitumoral action of aminoguanidine is associated with decreased cell proliferation, reduced angiogenesis, and reduced expression of antioxidant enzymes.

Protection of multiple antioxidants Chinese herbal medicine on the oxidative stress induced by adriamycin chemotherapy

Adriamycin is an effective anthracycline anti-tumor antibiotic. However, the clinical use of adriamycin has been restricted by its serious side effects. Some reports indicated that the side effects of adriamycin could cause systemic injury, in which reactive oxygen species (ROS) play an important role. ROS are a large family of oxygen free radical and non-free radical active oxygen-containing molecules, including superoxide radical, hydrogen peroxide and hydroxyl radical, which contribute to oxidative stress. Although antioxidant treatment is a promising method to prevent the side effects, protection by a single antioxidant is limited. The Chinese herbal medicine ANTIOXIN is a multiple antioxidant that can effectively block oxidative stress. It was hypothesized that ANTIOXIN could effectively reduce the side effects of adriamycin. A rat tumor model with a transplanted tumor in the liver was treated with adriamycin and ANTIOXIN was used as a protection. Oxidative stress and antioxidant enzymes were evaluated. The results showed that adriamycin chemotherapy increased the level of malondialdehyde (MDA), nitrogen oxide (NO) and decreased the activities of total superoxide dismutase (T-SOD), manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione (GSH) and total antioxidant capacity (TAC). Adriamycin chemotherapy also decreased the expression of Bcl-2, increased the expression of iNOS and cell apoptosis in the liver and kidney. Multiple antioxidants ANTIOXIN had an antagonistic effect on these changes and significantly decreased the mortality of the experimental rats. These data demonstrated that adriamycin chemotherapy could cause oxidative stress to the whole body, on which multiple antioxidants based on the theory of 'multiple antioxidant chain' had effective protection.

Thrombopoietin protects against in vitro and in vivo cardiotoxicity induced by doxorubicin

BACKGROUND

Doxorubicin (DOX) is an important antineoplastic agent. However, the associated cardiotoxicity, possibly mediated by the production of reactive oxygen species, has remained a significant and dose-limiting clinical problem. Our hypothesis is that the hematopoietic/megakaryocytopoietic growth factor thrombopoietin (TPO) protects against DOX-induced cardiotoxicity and might involve antiapoptotic mechanism exerted on cardiomyocytes.

METHODS AND RESULTS

In vitro investigations on H9C2 cell line and spontaneously beating cells of primary, neonatal rat ventricle, as well as an in vivo study in a mouse model of DOX-induced acute cardiomyopathy, were performed. Our results showed that pretreatment with TPO significantly increased viability of DOX-injured H9C2 cells and beating rates of neonatal myocytes, with effects similar to those of dexrazoxane, a clinically approved cardiac protective agent. TPO ameliorated DOX-induced apoptosis of H9C2 cells as demonstrated by assays of annexin V, active caspase-3, and mitochondrial membrane potential. In the mouse model, administration of TPO (12.5 microg/kg IP for 3 alternate days) significantly reduced DOX-induced (20 mg/kg) cardiotoxicity, including low blood cell count, cardiomyocyte lesions (apoptosis, vacuolization, and myofibrillar loss), and animal mortality. Using Doppler echocardiography, we observed increased heart rate, fractional shortening, and cardiac output in animals pretreated with TPO compared with those receiving DOX alone.

CONCLUSIONS

These data have provided the first evidence that TPO is a protective agent against DOX-induced cardiac injury. We propose to further explore an integrated program, incorporating TPO with other protocols, for treatment of DOX-induced cardiotoxicity and other forms of cardiomyopathy.

Free radical mediated oxidative stress and toxic side effects in brain induced by the anti cancer drug adriamycin: insight into chemobrain

Adriamycin (ADR) is a chemotherapeutic agent useful in treating various cancers. ADR is a quinone-containing anthracycline chemotherapeutic and is known to produce reactive oxygen species (ROS) in heart. Application of this drug can have serious side effects in various tissues, including brain, apart from the known cardiotoxic side effects, which limit the successful use of this drug in treatment of cancer. Neurons treated with ADR demonstrate significant protein oxidation and lipid peroxidation. Patients under treatment with this drug often complain of forgetfulness, lack of concentration, dizziness (collectively called somnolence or sometimes called chemobrain). In this study, we tested the hypothesis that ADR induces oxidative stress in brain. Accordingly, we examined the in vivo levels of brain protein oxidation and lipid peroxidation induced by i.p. injection of ADR. We also measured levels of the multidrug resistance-associated protein (MRP1) in brain isolated from ADR- or saline-injected mice. MRP1 mediates ATP-dependent export of cytotoxic organic anions, glutathione S-conjugates and sulphates. The current results demonstrated a significant increase in levels of protein oxidation and lipid peroxidation and increased expression of MRP1 in brain isolated from mice, 72 h post i.p injection of ADR. These results are discussed with reference to potential use of this redox cycling chemotheraputic agent in the treatement of cancer and its chemobrain side effect in brain.

Neonatal alcohol exposure increases malondialdehyde (MDA) and glutathione (GSH) levels in the developing cerebellum

It has been suggested that developmental alcohol-induced brain damage is mediated through increases in oxidative stress. In this study, the concentrations of malondialdehyde (MDA) and reduced glutathione (GSH) were measured to indicate alcohol-mediated oxidative stress. In addition, the ability of two known antioxidants, melatonin (MEL) and lazaroid U-83836E (U), to attenuate alcohol-induced oxidative stress was investigated. Sprague-Dawley rat pups were randomly assigned to six artificially-reared groups, ALC (alcohol), MEL, MEL/ALC, U, U/ALC, and GC (gastrostomy control), and one normal suckle control (to control for artificial-rearing effects on the dependent variables). The daily dosages for ALC, MEL, and U were 6 g/kg, 20 mg/kg, and 20 mg/kg, respectively. Alcohol was administered in 2 consecutive feedings, and antioxidant (MEL or U) was administered for a total of 4 consecutive feedings (2 feedings prior to and 2 feedings concurrently with alcohol). The animals received treatment from postnatal days (PD) 4 through 9. Cerebellar, hippocampal, and cortical samples were collected on PD 9 and analyzed for MDA and GSH content. The results indicated that MDA concentrations in the cerebellum were significantly elevated in animals receiving alcohol; however, MDA levels in the hippocampus and cortex were not affected by alcohol treatment. Additionally, GSH levels in the cerebellum were significantly elevated in groups receiving alcohol, regardless of antioxidant treatment. Neither antioxidant was able to protect against alcohol-induced alterations of MDA or GSH. These findings suggest that alcohol might increase GSH levels indirectly as a compensatory mechanism designed to protect the brain from oxidative-stress-mediated insult.

Nitric oxide involvement in the delayed antiarrhythmic effect of treadmill exercise in dogs

We have shown previously that a single period of treadmill exercise in dogs protects the heart against the severe ventricular arrhythmias that arise when a major (anterior descending) branch of the left coronary artery is occluded following anaesthesia 24 h later. This protection is aminoguanidine sensitive, suggesting a role for nitric oxide (NO) in this exercise-induced delayed antiarrhythmic effect. The present study has further examined the possible role of NO as a mediator and/or as a trigger using the selective induced (iNOS) inhibitor S-(2-aminoethyl)-methyl-isothiourea (AEST) and the specific but not selective nitric oxide synthase inhibitor N(omega)-nitro-L-arginine-methyl-ester (L-NAME). Exercise markedly reduced the severity of ischaemia and reperfusion-induced ventricular arrhythmias 24 h later. Thus, only one of the dogs (8%) so exercised fibrillated on occlusion (contrast 46% in the control, non-exercised dogs; P<0.05) and the marked changes in the inhomogeneity of electrical activation that occur in the ischaemic region following occlusion were much reduced (P<0.05 compared to controls). This delayed exercise-induced cardioprotection was significantly attenuated by the nitric oxide synthase (NOS) inhibitors L-NAME, given prior to the exercise protocol and by AEST given prior to the coronary artery occlusion. For example, survival from the ischaemia-reperfusion insult was 54% in the exercise dogs, 0% in the controls and 14% in those dogs given a NOS inhibitor. We conclude that nitric oxide (NO) is both the trigger and the mediator of this delayed protection against ischaemia and reperfusion-induced arrhythmias.