Different effects of resveratrol on dose-related Doxorubicin-induced heart and liver toxicity.

The aim of the study was to evaluate the effect of resveratrol in doxorubicin-induced cardiac and hepatic toxicity. Doxorubicin was administered once a week throughout the period of 7 weeks with 1.0 or 2.0 mg/kg body weight or concomitantly with resveratrol (20 mg/kg of feed). Heart and liver toxicity was histologically and biochemically evaluated. Resveratrol protected from the heart lipid peroxidation caused by 1 mg doxorubicin and it sharply diminished superoxide dismutase activity. An insignificant effect of resveratrol on the lipid peroxidation level and the superoxide dismutase activity was observed in the hearts of rats administered a higher dose of doxorubicin. However, resveratrol attenuate necrosis and other cardiac histopathological changes were induced by a high dose of doxorubicin. Interestingly, it slightly intensified adverse cardiac histological changes in rats receiving a lower dose of doxorubicin. Resveratrol did not have any protective effect on the hepatic oxidative stress, while exerting a mild beneficial effect on the morphological changes caused by doxorubicin. All in all, this study has shown different effects of resveratrol on dose-related doxorubicin-induced heart and liver toxicity. Resveratrol may modulate the hepatic and cardiac effect of doxorubicin, depending on the drug dose.

Chronic Variable Stress Is Responsible for Lipid and DNA Oxidative Disorders and Activation of Oxidative Stress Response Genes in the Brain of Rats.

Chronic environmental stress is associated with reactive oxygen species (ROS) overproduction and the pathogenesis of depression. The purpose of this study was to evaluate biochemical and molecular changes associated with ROS generation in the brains of rats submitted to chronic variable stress. Male Wistar rats (50-55 days old, weighing 200-250 g) were divided in two groups (n = 10): control and stressed. Rats in the stressed group were exposed to stress conditions for 40 days. The animals were decapitated and the brain samples were collected. In prefrontal cortex, we measured the following biochemical parameters: lipid peroxidation and concentration of glutathione-GSH, GSSG, GSH/GSSG ratio, glutathione peroxidase, and glutathione reductase activities. In the hippocampus marker of DNA, oxidative damage and expression of DNA-repairing genes (Ogg1, MsrA) and gene-encoding antioxidative transcriptional factor (Nrf2) were determined. The results demonstrate indirect evidence of ROS overproduction and presence of oxidative stress. They also reveal disruption of oxidative defense systems (decreased GR activity, diminished GSH/GSSG ratio, and decreased Nrf2 expression) and activation of the oxidative DNA repair system (increased Ogg1 and MsrA expression). Together, the presented data suggest that independent activation of oxidative stress response genes occurs in chronic variable stress conditions.

Tirapazamine has no Effect on Hepatotoxicity of Cisplatin and 5-fluorouracil but Interacts with Doxorubicin Leading to Side Changes in Redox Equilibrium.

Tirapazamine is a hypoxia-activated prodrug which was shown to exhibit up to 300 times greater cytotoxicity under anoxic in comparison with aerobic conditions. Thus, the combined anticancer therapy of tirapazamine with a routinely used anticancer drug seems to be a promising solution. Because tirapazamine undergoes redox cycle transformation in this study, the effect of tirapazamine on redox hepatic equilibrium, lipid status and liver morphology was evaluated in rats exposed to cisplatin, doxorubicin and 5-fluorouracil. Rats were intraperitoneally injected with tirapazamine and a particular cytostatic. The animals were killed, and blood and liver were collected. Hepatic glucose, total cholesterol, triglycerides, NADH, NADPH glutathione and the activity of glucose-6-phosphate dehydrogenase were determined. Liver morphology and the immune expression of HMG-CoA-reductase were also assessed. Glucose, total cholesterol, triglycerides, bilirubin concentrations and the activity of aspartate and alanine aminotransferases were determined in the plasma. Tirapazamine displayed insignificant interactions with cisplatin and 5-fluorouracil referring to hepatic morphology and biochemical parameters. However, tirapazamine interacts with doxorubicin, thus leading to side changes in redox equilibrium and lipid peroxidation, but those effects are not severe enough to exclude that drug combination from further studies. Thus, tirapazamine seems to be a promising agent in successive studies on anticancer activity in similar schedules.

The differential effects of green tea on dose-dependent doxorubicin toxicity.

BACKGROUND: Doxorubicin (DOX) is an anticancer drug displaying cardiac and hepatic adverse effects mostly dependent on oxidative stress. Green tea (GT) has been reported to play a protective role in diseases resulting from oxidative stress. OBJECTIVE: The objective of this study was to evaluate if GT protects against DOX-induced oxidative stress, heart and liver morphological changes, and metabolic disorders. METHODS: Male Wistar rats received intraperitoneal injection of DOX (1.0 or 2.0 mg/kg b.w.) for 7 weeks or concomitantly GT extract soluble in drinking water. RESULTS: There were multidirectional effects of GT on blood metabolic parameters changed by DOX. Among all tested biochemical parameters, statistically significant protection of GT against DOX-induced changes was revealed in case of blood fatty acid-binding protein, brain natriuretic peptide, and superoxide dismutase. CONCLUSION: DOX caused oxidative stress in both organs. It was inhibited by GT in the heart but remained unchanged in the liver. DOX-induced general toxicity and histopathological changes in the heart and in the liver were mitigated by GT at a higher dose of DOX and augmented in rats treated with a lower dose of the drug.

Tirapazamine-doxorubicin interaction referring to heart oxidative stress and Ca²âº balance protein levels.

Doxorubicin (DOX) causes long-term cardiomyopathy that is dependent on oxidative stress and contractility disorders. Tirapazamine (TP), an experimental adjuvant drug, passes the same red-ox transformation as DOX. The aim of the study was to evaluate an effect of tirapazamine on oxidative stress, contractile protein level, and cardiomyocyte necrosis in rats administered doxorubicin. Rats were intraperitoneally injected six times once a week with tirapazamine in two doses, 5 (5TP) and 10 mg/kg (10TP), while doxorubicin was administered in dose 1.8 mg/kg (DOX). Subsequent two groups received both drugs simultaneously (5TP+DOX and 10TP+DOX). Tirapazamine reduced heart lipid peroxidation and normalised RyR2 protein level altered by doxorubicin. There were no significant changes in GSH/GSSG ratio, total glutathione, cTnI, AST, and SERCA2 level between DOX and TP+DOX groups. Cardiomyocyte necrosis was observed in groups 10TP and 10TP+DOX.

Intensification of doxorubicin-related oxidative stress in the heart by hypothyroidism is not related to the expression of cytochrome P450 NADPH-reductase and inducible nitric oxide synthase, as well as activity of xanthine oxidase.

Cytochrome P450 NADPH-reductase (P450R), inducible synthase (iNOS) and xanthine oxidase play an important role in the antracycline-related cardiotoxicity. The expression of P450R and iNOS is regulated by triiodothyronine. The aim of this study was to evaluate the effect of methimazole-induced hypothyreosis on oxidative stress secondary to doxorubicin administration. 48 hours after methimazole giving cessation, rats were exposed to doxorubicin (2.0, 5.0 and 15 mg/kg). Blood and heart were collected 4, 48 and 96 h after the drug administration. Animals exposed exclusively to doxorubicin or untreated ones were also assessed. The hypothyreosis (0.025% of methimazole) significantly increased the doxorubicin effect on the cardiac carbonyl group and they may increase the glutathione level. An insignificant effect of methimazole was noticed in case of the cardiac lipid peroxidation product, the amount of DNA oxidative damages, iNOS and xanthine oxidase-enzymes responsible for red-ox activation of doxorubicin. However, the concentration of P450R was affected by a lower dose of methimazole in rats administered with doxorubicin. Since in rats receiving doxorubicin changes in oxidative stress caused by methimazole were not accompanied by elevation of bioreductive enzymes, it may be concluded that these changes in the oxidative stress were not related to the tested enzymes.

Does administration of non-steroidal anti-inflammatory drug determine morphological changes in adrenal cortex: ultrastructural studies.

Rofecoxib (Vioxx© made by Merck Sharp & Dohme, the USA) is a non-steroidal anti-inflammatory drug which belongs to the group of selective inhibitors of cyclooxygenasis-2, i.e., coxibs. Rofecoxib was first registered in the USA, in May 1999. Since then the drug was received by millions of patients. Drugs of this group were expected to exhibit increased therapeutic action. Additionally, there were expectations concerning possibilities of their application, at least as auxiliary drugs, in neoplastic therapy due to intensifying of apoptosis. In connection with the withdrawal of Vioxx© (rofecoxib) from pharmaceutical market, attempts were made to conduct electron-microscopic evaluation of cortical part of the adrenal gland in preparations obtained from animals under influence of the drug. Every morning animals from the experimental group (15 rats) received rofecoxib (suspension in physiological saline)--non-steroidal anti-inflammatory drug (Vioxx©, Merck Sharp and Dohme, the USA), through an intragastric tube in the dose of 1.25 mg during 8 weeks. In the evaluated material, there was found a greater number of secretory vacuoles and large, containing cholesterol and other lipids as well as generated glucocorticoids, lipid drops in cytoplasm containing prominent endoplasmic reticulum. There were also found cells with cytoplasm of smaller density--especially in apical and basal parts of cells. Mitochondria occasionally demonstrated features of delicate swelling. The observed changes, which occurred on cellular level with application of large doses of the drug, result from mobilization of adaptation mechanisms of the organism.

High doses of medroxyprogesterone as the cause of disappearance of adherence of the zona pellucida to an oocyte.

The zona pellucida (ZP) is an external glycoprotein membrane of oocytes of mammals and embryos in the early stage of their development. ZP first appears in growing ovarian follicles as an extracellular substance between the oocyte and granular cells. The zona pellucid markedly affects the development and maturation of the oocyte. The morphology of the ZP-oocyte complex allows a more precise determination of the oocyte maturity. According to numerous experimental studies, ZP is essential for preimplantation embryonic development of humans and other mammals. It prevents dispersion of blastomeres and enhances their mutual interactions. ZP is a dynamic structure responsible for the provision of nutrients to early forms of oocytes in mammals. The aim of the present study was untrastructural evaluation of the ZP-oocyte contact during inhibited ovulation. Female white rats (Wistar strain) received a suspension of medroxyprogesterone acetate (MPA) in incremental intramuscular bolus doses of 3.7 mg (therapeutic dose), 7.4 mg and 11.1 mg. The animals were decapitated 5 days after the administration of MPA. Ovarian sections were evaluated under a transmission electron microscope (TEM) Zeiss EM 900. Morphometric analysis of ZP was conducted using the cell imaging system by Olympus. In females exposed to therapeutic doses of MPA, ZP showed the structure of granular-fibrous reticulum of a medium electron density with single cytoplasmic processes originating from the surrounding structures. The oocyte cell membrane generated single, delicate processes directed toward ZP. Microvilli of the oocyte were short and thin. In the group receiving 7.4 mg of MPA, ZP had the structure of a delicate, loose granular-fibrous reticulum, and the oocyte cell membrane generated single microvilli directed toward ZP. In both those groups, the close ZP-oocyte contact was observed. Otherwise, in the group exposed to the highest MPA doses (11.1 mg), thicker and more numerous oocyte microvilli were found, which did not penetrate ZP matrix. They were dense, irregularly separated contour, forming a barrier between ZP and oocyte. The present findings are likely to suggest that MPA has inhibiting effects on the synthesis of binding proteins and causes the loss of the oocyte contact with ZP.

Does ACE inhibitor modify the morphofunctional state of the nephron?

Captopril, the inhibitor of the angiotensin convertase (ACE) was administered to white rats in two doses: 0.23 mg/day/rat and 0.71 mg/day/rat. The preparation was being applied for the period of 3 weeks. Observations were carried out in a transmission electron microscope. In the kidneys of the animals subjected to the experiment, in the cells of the proximal canaliculi dilution of the cytoplasm, numerous vacuoles in the apical and basal part of the cell, dilation of the intercellular space as well as more numerous lysosomes were observed. The above-described changes were more distinctly marked in animals which were given a higher dose of the drug. The studies in the electron microscope revealed morphofunctional changes of the nephron related to the application of the Captopril. Application of the Captopril may temporarily modulate the morphofunctional status of certain structures of the nephron, which was demonstrated in the foregoing experiment.

High doses of atorvastatin (Sortis) modify the secretory process in the exocrine portion of the pancreas.

Changes were observed in the ultrastructure of the pancreatic acinar cells in rats after administration of atorvastatin (Sortis) in the therapeutic and ten times larger dose for the period of 6 weeks. It was found that atorvastatin given to rats in the therapeutic dose (80 mg/day) stimulated the secretion in pancreocytes, whereas the ten times higher dose of atorvastatin distorts the complicated process of the release of the secretion from the cell.

Ultrastructure of the hepatocytes after application of azithromycin (Sumamed).

Azithromycin (Sumamed, PLIVA Cracow) was administered intragastrically to rats in doses 10 times and 100 times bigger than the therapeutic dose (according to the indications for a 5-day treatment). Ultrastructural examinations of the liver were performed. Changes observed in the morphology of hepatocytes and Browicz-Kupffer cells (swelling of mitochondria, more numerous lysosomes, weaker RER content and granular material inside biliary canaliculi) may indicate temporary violation of the functional equilibrium in the liver due to the application of azithromycin.

The proximal convoluted tubule of rats' nephron after experimental administration of gentamicin.

The rats in this experiment received gentamicin in intraperitoneal injections in a dose ten times bigger than therapeutical. After ten days of drug administration, in the cells of proximal convoluted tubules of kidney there were observed the dilution of cytoplasm of various intensity, increases in amount and size of lysosomes, widening of endoplasmic reticulum tubules and swelling of mitochondria. The microscopic and ultrastructural pictures, after three weeks' break in gentamicin administration, showed fast regeneration of renal tubules. A large diversity of intensification of changes in particular individuals suggested individual reaction to gentamicin nephrotoxicity.

Morphological changes in adrenal cortex--the final effect of angiotensin II receptor antagonists.

The influence of losartan, angiotensin receptor on the histological image of the adrenal glomerular layer of white rats was revealed. The drug was administered in the therapeutic and ten times higher dose. It was manifested by the decrease of glandular cells and prevalence of blastic cells of the cortex. After a 2-month break in drug administration, the reconstruction of glandular cells was noticed, which could indicate that the observed changes are of transitory character.

Histological picture of intestinal mucosa of rats after simultaneous administration of atorvastatin and ethyl alcohol.

The rats received atorvastatin in the therapeutical dose and 10x higher, 20% solution of ethanol and ethanol with atorvastatin for 6 weeks. The microscopic investigations (H + E staining, Masson's method, PAS method by McManus) showed no changes in histological picture of intestinal mucosa after giving atorvastatin. The rats receiving alcohol and alcohol with atorvastatin showed similar changes, but different than the first groups. Under the epithelium of intestinal villi there were observed light, vesicle-like spaces, separation of epithelium from connective tissue stroma, also lack of the epithelium of the top of villi and hyperaemia of stroma of villi. The observed changes were stronger in rats receiving simultaneously alcohol and atorvastatin in the dose 10x higher than therapeutical. Hyperaemia of connective tissue of stroma of villi was still visible after month period of administration.