Hyperlipidemic effects of adriamycin in rats

Zataria multiflora and its main ingredient, carvacrol, affect on the renal function, histopathological, biochemical and antioxidant parameters in adriamycin-induced nephrotic rats

Oxidative stress has a major role in the nephrosis. In the present study, the effects of hydroalcoholic extract of Zataria multiflora (ZM) and carvacrol (CAR) were evaluated on the renal damage induced by adriamycin (ADR). The animals accidentally divided into four groups including: Control, ADR, ZM + ADR and CAR + ADR. The renal tissue, urine, and blood samples subjected to biochemical markers and histopathological evaluation. ADR significantly decreased glomerular filtration rate (GFR) while escalated urine protein excretion as well as protein clearance (p < .01 to p < .001). Also, ADR significantly reduced the antioxidants and boosted the malondialdehyde (MDA) compared to the control (p < .05 to p < .01). In groups treated by ZM and CAR, GFR, and antioxidants significantly increased, whereas urine protein excretion and MDA decreased (p < .05 to p < .001). ZM and CAR induced an improvement in ADR-induced renal damage by improving renal function as well as antioxidant activity.

Edible leaf extract of Ipomoea aquatica Forssk. (Convolvulaceae) attenuates doxorubicin-induced liver injury via inhibiting oxidative impairment, MAPK activation and intrinsic pathway of apoptosis

Ipomoea aquatica Forssk. (Convolvulaceae) is an aquatic vegetable traditionally employed against toxic effects of xenobiotics. The present study has been designed to investigate the molecular mechanism underlying the beneficial role of the edible (aqueous) leaf extract of I. aquatica (AEIA) against doxorubicin (Dox)-induced liver injury. AEIA exhibited a dose-dependent (∼400 μg/ml) increase in cell viability against Dox (1 μM) in isolated rodent hepatocytes. AEIA (400 μg/ml) prevented the Dox-induced increase in ROS, redox imbalance, and activation of mitogen activated protein kinases (MAPK) and intrinsic pathway of apoptosis in hepatocytes. In the in vivo assay, administration of AEIA (100 mg/kg, p.o.) against Dox (3 mg/kg, i.p.) also reduced the oxidative impairment, DNA fragmentation, ATP formation, and up-regulated the mitochondrial co-enzymes Qs in the liver tissues of Wistar rats. Histological assessments were in agreement with the biochemical findings. Substantial quantities of phyto-antioxidants in AEIA may mediate its beneficial function against Dox-induced liver injury.

Development of doxorubicin-induced chronic cardiotoxicity in the B6C3F1 mouse model

Serum levels of cardiac troponins serve as biomarkers of myocardial injury. However, troponins are released into the serum only after damage to cardiac tissue has occurred. Here, we report development of a mouse model of doxorubicin (DOX)-induced chronic cardiotoxicity to aid in the identification of predictive biomarkers of early events of cardiac tissue injury. Male B6C3F(1) mice were administered intravenous DOX at 3mg/kg body weight, or an equivalent volume of saline, once a week for 4, 6, 8, 10, 12, and 14weeks, resulting in cumulative DOX doses of 12, 18, 24, 30, 36, and 42mg/kg, respectively. Mice were sacrificed a week following the last dose. A significant reduction in body weight gain was observed in mice following exposure to a weekly DOX dose for 1week and longer compared to saline-treated controls. DOX treatment also resulted in declines in red blood cell count, hemoglobin level, and hematocrit compared to saline-treated controls after the 2nd weekly dose until the 8th and 9th doses, followed by a modest recovery. All DOX-treated mice had significant elevations in cardiac troponin T concentrations in plasma compared to saline-treated controls, indicating cardiac tissue injury. Also, a dose-related increase in the severity of cardiac lesions was seen in mice exposed to 24mg/kg DOX and higher cumulative doses. Mice treated with cumulative DOX doses of 30mg/kg and higher showed a significant decline in heart rate, suggesting drug-induced cardiac dysfunction. Altogether, these findings demonstrate the development of DOX-induced chronic cardiotoxicity in B6C3F(1) mice.

The effect of doxorubicin on rats that received toxic and carcinogenic benzo(a)pyrene

Benzo(a)pyrene (B(a)P) is a polycyclic aromatic hydrocarbon with carcinogenic and toxic effects. Doxorubicin is a DNA-interacting drug widely used in chemotherapy. In the present study we investigated the effects of doxorubicin on rats that received benzo(a)pyrene. Sprague-Dawley male rats, 3-4 months old, were divided into 5 groups (n=9 per group). Group 1 (controls) received normal saline intraperitoneally (i.p.) and intragastrically (i.g.), Group 2 (controls) similarly received corn oil i.p. and i.g., Group 3 received corn oil soluble benzo(a)pyrene (10mg/kg b.wt every 10 days for 40 days), Group 4 received doxorubicin (4 mg i.p. on 3 consecutive days), Group 5 received doxorubicin for 3 days (as in group 4) followed by benzo(a)pyrene as in group 3. After twenty-four hours urine samples were collected, heart blood, liver and kidney tissue samples were obtained. Biochemical data were evaluated on urine and blood; liver and kidney tissue samples were investigated histologically. Uric acid, urine creatinine, creatine clearance, urea nitrogen, serum creatinine values, serum glutamic oxaloacetic transaminase (SGOT, AST), serum glutamic pyruvic transaminase (SGPT, ALT), alkaline phosphatase (ALP, AP), superoxide dismutase (SOD), catalase (CAT) activities and malondialdehyde (MDA) levels were significantly different in the 3rd group compared with control groups. Most of the parameters group 5 were statistically similar to control values. Histological appearance of the liver and the kidney tissue samples supported the improvement in the 5th group. The result of our study indicated that liver and kidney functions impaired with benzo(a)pyrene may be partially restored by doxorubicin.

[Oxidative stress and atherosclerosis]

Oxidative stress is a continuous level of oxidative damage in animal cells, which is caused by an overabundance of reactive oxygen species or a decline in antioxidant ability against them. Oxidative stress increases with individual risk factors of atherosclerosis such as obesity, hypertension, hyperlipidemia, diabetes and smoking. Thus, oxidative stress is considered to play a key role in the pathogenesis of atherosclerosis. This review discusses the relationship between oxidative stress and atherosclerosis based on findings from our research group. We have found that atherosclerotic lesions are formed in the aorta of mice fed a high-cholesterol and high-linoleic diet, in parallel with elevated serum lipid peroxide levels. This model is useful for primary screening of antiatherosclerotic agents with antioxidative activity. One notable factor in the development of atherosclerosis is oxidized low-density lipoprotein (OxLDL). In order to examine OxLDL levels in blood, we have developed anion-exchange HPLC methods using stepwise elution. Using these methods, we have found that OxLDL markedly increases in a rat model of metabolic syndrome, in animals exposed to cigarette smoke and in smokers in parallel with other oxidative stress markers. These oxidative stress markers have been attenuated by administration of several antioxidants. In addition, we have found that smoking accelerates atherogenesis in the aorta of apoE-deficient mice and this acceleration can be ameliorated by administration of vitamin E. These observations suggest that antioxidant supplementation may be an effective therapeutic strategy for metabolic syndrome and smoking-induced diseases in which elevated oxidative stress plays a pivotal role.

Adriamycin-induced heart failure: mechanism and modulation

Adriamycin (doxorubicin) is one of the most effective chemotherapeutic agents against a variety of cancers, but its usefulness is seriously curtailed by the risk of developing heart failure. Available laboratory evidence suggests that an increase in oxidative stress, brought about by increased free radical production and decreased myocardial endogenous antioxidants, plays an important role in the pathogenesis of heart failure. Adriamycin-induced apoptosis and hyperlipidemia may also be involved in the process. Probucol, a lipid-lowering drug and an antioxidant, completely prevents the occurrence of heart failure by reducing oxidative stress as well as by the modulation of apoptosis and high lipid concentrations. Thus, combined therapy with adriamycin and probucol has a high potential for optimizing the treatment of cancer patients.

Dietary cholesterol enhances impaired endothelium-dependent relaxations in aortas of salt-induced hypertensive Dahl rats

We investigated the effect of hypercholesterolemia on the vascular reactivity of thoracic aortas isolated from hypertensive Dahl salt-sensitive (DS) rats. DS rats were fed on a low-sodium diet (control group), a low-sodium plus high-cholesterol diet (CHOL group), a high-sodium diet (NaCl group) or a high-sodium plus high-cholesterol diet (NaCl + CHOL group) for 8 weeks. Hypercholesterolemia developed in the CHOL and NaCl + CHOL groups, while hypertension developed in the NaCl and NaCl + CHOL groups, with these changes being greatest in the NaCl + CHOL group. Aortic cholesteryl ester accumulation was attenuated in the aortic rings from the NaCl and NaCl + CHOL groups, compared to the control group. The degree of attenuation in the NaCl + CHOL group was significantly greater than that in the NaCl group. Endothelium-dependent relaxations induced by the calcium ionophore A23187 were attenuated only in the NaCl + CHOL group. Endothelium-independent relaxations in response to sodium nitroprusside were slightly but significantly attenuated in the NaCl + CHOL group. The relaxations in the CHOL group were comparable to those in the control group. These findings indicate that cholesterol feeding strikingly enhances the impaired endothelium-dependent relaxations and the slightly impaired endothelium-independent relaxations in the aorta of DS rats with salt-induced hypertension, parallel to the development of hypertension, hypercholesterolemia and cholesterol deposition.

Copper status and adriamycin treatment: effects on antioxidant status in mice

The biochemical response of Cu-sufficient and Cu-deficient mice to adriamycin (ADR) treatment was evaluated. Mice were injected intraperitoneally with ADR (17 mg/kg body wt.) or saline (0.9% w/v) and killed 4 d after injection. There was no effect of ADR on cardiac superoxide dismutase (SOD) activity in Cu-sufficient of Cu-deficient mice. ADR injection resulted in higher cardiac glutathione (GSH) concentrations in Cu-sufficient mice while it resulted in lower GSH concentrations in Cu-deficient mice relative to their saline-injected controls. The effects of ADR in Cu-deficient mice were tissue-specific as its administration resulted in lower hepatic SOD activity and higher hepatic GSH concentrations relative to saline-injected controls.

Effects of chronic administration of doxorubicin on myocardial creatine phosphokinase and antioxidant defenses and levels of lipid peroxidation in tissues and plasma of rats

Tissue and plasma levels of thiobarbituric acid reactive substances (TBARS) were measured in rats treated chronically with doxorubicin. In addition, heart creatine phosphokinase and antioxidant defenses were examined. Male rats received doxorubicin (DXR) 2 mg/kg or vehicle weekly subcutaneously for 13 weeks and were sacrificed at 14 and 19 weeks, 1 and 6 weeks after the last dose, respectively. Histological evaluation in DXR-treated rats at 14 and 19 weeks found significant and progressive cardiac and renal lesions as compared to controls. Heart TBARS were unchanged from controls. Plasma and kidney levels of TBARS were elevated above controls at both 14 and 19 weeks. Lung levels of TBARS were significantly elevated above controls at 14 weeks. Liver levels of TBARS were elevated at 19 weeks. Heart creatine phosphokinase activity was significantly depressed from controls at both 14 and 19 weeks. Heart glutathione peroxidase and superoxide dismutase activities were unchanged from controls. Heart glutathione, glutathione reductase, glucose-6-phosphate dehydrogenase, and catalase were elevated above controls at both 14 and 19 weeks. The lack of change in heart TBARS suggests that changes in TBARS in other organs may be secondary processes. The depression of creatine phosphokinase suggests that levels of adenosine triphosphate may be insufficient to sustain the myocardial function and this may partly be responsible for DXR-induced cardiac myopathy.

Suppression of adjuvant arthritis in rats by cholesterol

Dietary cholesterol suppressed adjuvant arthritis, a chronic inflammatory disease, in rats, but did not significantly affect carrageenin edema, an acute inflammation. When rats were fed a high-cholesterol diet beginning 10 days before injection of adjuvant, the development of the adjuvant-induced arthritis was greatly suppressed. Cholesterol feeding prevented hypertrophy of the adrenal gland in arthritic rats, but had little influence on the serum corticosterone level. A significant positive correlation was observed between the adrenal weight and the severity of the arthritis. These findings suggest that the effect of cholesterol feeding is not due to increased adrenal sterol synthesis. Dietary cholesterol also prevented hypertrophy of the spleen, but had no effect on atrophy of the thymus in adjuvant-treated rats. Cholesterol-fed rats showed a significant decrease in the serum lipid peroxide level and a significant increase in the serum copper level. Adjuvant treatment not only enhanced hypercholesterolemia produced by cholesterol feeding, but also the level of free cholesterol in serum. These results suggest that dietary cholesterol may exert some effect on the immune response through changes in spleen and liver functions.

Effects of chronic administration of doxorubicin on plasma levels of prostaglandins, thromboxane B2, and fatty acids in rats

The effects of multiple doses of doxorubicin (DXR) on hematocrit and plasma levels of prostaglandins (PG), thromboxane B2 (TxB2), total lipid, esterified and free fatty acids, and proteins were investigated in male rats. The rats received DXR (2 mg/kg) or vehicle weekly by the subcutaneous route for 2, 4, 8, and 13 weeks and were killed 1 week after their last dose. Another group of rats treated for 13 weeks was sacrificed at 19 weeks, 6 weeks after the last dose. No changes in hematocrit or plasma PG, TxB2, or total levels of fatty acids were noted between control and DXR-treated rats at either 3, 5, or 9 weeks. The hematocrit was slightly depressed from control levels at 14 and 19 weeks. Plasma PGE, PGF2 alpha, and TxB2 were elevated over control levels at 14 and 19 weeks. Plasma 6-keto-PGF1 alpha was increased over the control level only at 19 weeks. Total plasma lipid and esterified fatty acids were highly elevated over control levels at 14 and 19 weeks. Plasma free arachidonic acid was elevated over control levels at 14 and 19 weeks, while levels of other free fatty acids were unchanged. Plasma protein levels were slightly depressed from control levels at 3, 9, and 14 weeks. Elevations of plasma free arachidonic acid, PG, TxB2, esterified fatty acids, and total lipid might be involved in cardiotoxicity and nephrotoxicity found with chronic administration of DXR.

Lipid deposition in the aorta of adjuvant arthritic rats with hypercholesterolemia

This study offers findings which should aid in the development of a convenient animal model of atherosclerosis. Inbred Fisher strain rats were fed an atherogenic diet containing 1.5% cholesterol and 0.5% cholic acid and given a single subcutaneous injection of adjuvant (Mycobacterium butyricum) into the base of the tail. The animals were maintained for 8 weeks. Rats given the atherogenic diet showed markedly increased serum cholesterol levels, and all of those given the adjuvant injection developed severe polyarthritis. Cholesterol feeding tended to delay the onset of arthritis and remarkably suppressed the inflammatory response, particularly in the early stage of development. This may have been due to the lowered lipid peroxide levels in the serum of rats fed the atherogenic diet. Adjuvant arthritis together with cholesterol feeding markedly increased the cholesterol content of the aorta, whereas either treatment alone had little effect. The amounts of the connective tissue components and minerals in the aorta were not changed by both treatments. These results show that early atherosclerosis could be produced under the conditions used and that chronic inflammation and hypercholesterolemia are principal factors in the pathogenesis.