The effect of copper deficiency on adriamycin toxicity

Adriamycin-induced hepatic and myocardial lipid peroxidation and DNA damage, and enhanced excretion of urinary lipid metabolites in rats

Adriamycin produces clinically useful responses in a variety of human cancers including lymphomas, leukemias, and solid tumors. However, the toxicity of adriamycin has limited its usefulness. Iron-catalyzed free radical reactions as the peroxidation of membrane lipids, inactivation of critical enzymes, and the inhibition of DNA, RNA and protein synthesis in heart, liver and kidney have been implicated in the toxicity of adriamycin. In order to further assess the role of oxidative stress in the toxicity of adriamycin, the effects of adriamycin were examined on the urinary excretion of lipid metabolites at 0, 6, 12, 24, 48 and 72 h post-treatment, and on myocardial and hepatic lipid peroxidation and nuclear DNA single strand breaks at 24 h post-treatment following single oral and intravenous (i.v.) doses of 10 mg/kg adriamycin. Urinary malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) excretion was significantly increased at all time points examined. Following the oral administration of adriamycin, maximum excretion of MDA, FA, ACT and ACON of 6.2-, 2.7-, 3.7- and 2.2-fold relative to control values, respectively, occurred 24 h after treatment. However, following the i.v. administration of adriamycin, greatest increases in excretion of MDA, FA and ACT reaching 6.9-, 3.3- and 6.3-fold relative to control values, respectively, were observed 6 h after treatment, while the greatest increase in ACON excretion of 4.2-fold relative to control values occurred 12 h post-treatment. Following oral and i.v. administration of adriamycin, significant increases were observed in myocardial and hepatic lipid peroxidation in mitochondrial and microsomal membranes, and myocardial and hepatic nuclei DNA single strand breaks 24 h after treatment. The results indicate that adriamycin administration induces myocardial and hepatic lipid peroxidation which may be responsible for enhanced excretion of urinary lipid metabolites as a result of membrane damage, and also induces enhanced DNA damage. These effects may be due to adriamycin-induced production of reactive oxygen species.

Pharmacokinetics and pharmacodynamics in copper deficiency. I. Antiinflammatory activity of aspirin

The effect of nutritional copper (Cu) deficiency on the antiinflammatory activity and pharmacokinetics of aspirin (ASA) was investigated in rats. Male, weanling Sprague-Dawley rats were fed either a Cu-deficient (CuD) or Cu-sufficient (CuS) diet for 49-50 d. The antiinflammatory activity of ASA was studied using the carrageenan-induced paw edema (CPE) test. ANOVA analyses of edema volumes at 2, 3, 4, 5, and 21 h postcarrageenan indicated significant differences between groups. The percent inhibition of edema due to ASA treatment in CuS was lower than that in CuD rats at 5 h, AUC5h, and AUC21h. ASA was found to be significantly more effective in inhibiting the CPE in CuD rats when compared to the CuS rats. Thus, we hypothesized that the increase in ASA's antiinflammatory activity in CuD rats was a result of a decrement in its elimination during nutritional Cu deficiency. The elimination of ASA in CuD and CuS rats was studied using an iv dose of 200 mg/kg. Concentrations of ASA and salicylic acid (SA) were determined in blood; whereas the concentrations of SA, salicylic phenol-glucuronide (SPG), and salicyluric acid (SUA) were determined in urine by HPLC. The results of the pharmacokinetic analyses from blood and urinary data indicated no significant differences in the disposition of ASA between CuD and CuS rats. For instance, the total body clearance for ASA (mean +/- SD, mL/min/kg) was 37.9 +/- 9.4 and 38.5 +/- 13.9 (p > 0.05); and the volume of distribution (Vd) for ASA (mean +/- SD, mL/kg) was 385.5 +/- 110.3 and 397.1.1 +/- 137.9 (p > 0.05) for CuD and CuS groups, respectively. Thus, contrary to our hypothesis, the enhanced antiinflammatory activity of ASA in CuD rats does not appear to be mediated via a decrement in the elimination of the drug. In addition, plasma ASA-esterase activity was found to be independent of Cu nutritional status.

Copper deficient rat heart can compensate for doxorubicin-induced oxidant stress

The hypothesis that copper (Cu) alters drug metabolizing enzymes and functions as an antioxidant nutrient in doxorubicin cardiotoxicity was tested. Male Sprague-Dawley rats were fed Cu adequate (+Cu; 5 mg Cu/kg of diet), marginally Cu deficient (MCu; 1.2 mg Cu/kg of diet), or severely Cu deficient (-Cu; 0.5 mg Cu/kg of diet) diets for 6 wk. Doxorubicin (1, 2, or 4 mg/kg body wt) or saline were administered intraperitoneally 1 time/wk for 4 wk. Compared to control hearts, Cu,Zn superoxide dismutase activity was decreased by 9% in MCu rats and by 21-40% in -Cu rats. Glutathione peroxidase activity was elevated 5-15% in -Cu rats. Doxorubicin administration increased heart Cu,Zn superoxide dismutase activity in +Cu and -Cu rats 18 h after the last of 4 injections, but not 18 h after 1 injection. There was no synergism between doxorubicin and Cu deficiency on lipid peroxidation, plasma creatine phosphokinase, cardiac hypertrophy, electrocardiographic abnormalities, or morphological changes. Heart glutathione S-transferase activity was decreased by Cu deficiency, and like Cu,Zn superoxide dismutase activity, returned to normal in -Cu rats given doxorubicin. Thus, the Cu deficient rat heart may be able to compensate for doxorubicin-induced oxidant stress by increasing the activity of Cu,Zn superoxide dismutase and glutathione S-transferase.