Elevated mitochondrial cisplatin-DNA adduct levels in rat tissues after transplacental cisplatin exposure

Although there is evidence that the toxic effects of cis- diamminedichloroplatinum(II) (cisplatin) include morphologically abnormal mitochondria, direct demonstrations of mitochondrial DNA damage by this chemotherapeutic agent have rarely been reported. Here we show that, in rats exposed to a single dose of cisplatin during gestation, cisplatin-DNA binding levels in both maternal and fetal liver and brain mitochondrial DNA are higher than those observed in genomic DNA. Pregnant F344/NCr rats were injected i.p. with either 5 or 15 mg cisplatin/kg body wt at 18 days of gestation and killed 24 h later. Cisplatin-DNA adducts were determined by dissociation-enhanced lanthanide fluoroimmunoassay using a cisplatin-DNA standard modified in the same range as the biological samples. Values for genomic cisplatin- DNA adducts in multiple maternal and fetal tissues have been presented elsewhere. Here, genomic DNA adduct levels for liver, brain, kidney and placenta are reported again for comparison with mitochondrial DNA adduct levels in the same tissues. In maternal and fetal brain, mitochondrial DNA adduct levels were approximately 7- to 50-fold higher than genomic DNA adduct levels, and in fetal liver they were approximately 2- to 16-fold higher than genomic DNA adduct levels. These studies demonstrate extensive cisplatin-DNA adduct formation in brain and liver mitochondria of fetal rats exposed transplacentally and suggest that mitochondrial DNA in some organs may be a particular target for cisplatin genotoxicity.      

Inhibition of ciprofibrate-induced hepatocarcinogenesis in the rat by dimethylthiourea, a scavenger of hydroxyl radical.

DNA damage caused by oxidative stress is considered to play an important role in peroxisome proliferator-induced hepatocarcinogenesis in rats and mice. In this study, we investigated the effect of dimethylthiourea (DMTU), a known hydroxyl radical scavenger, on ciprofibrate-induced hepatocarcinogenesis. Male F-344 rats were fed a diet containing 0.025% ciprofibrate and given daily intraperitoneal injections of DMTU (5 days a week) at a dose of 50 or 250 mg/kg body weight for 60 weeks at which time the study was terminated. Livers from all animals were analyzed grossly and microscopically for incidence, number and type of tumors. All rats given ciprofibrate alone developed altered areas, neoplastic nodules (NN) and hepatocellular carcinomas (HCC). Combined administration of ciprofibrate and DMTU resulted in inhibition of tumor development. In the group given higher doses of DMTU the incidence of NN was 100% and HCC 0%. The number of tumors per liver also significantly decreased (p<0.001). At lower dose levels DMTU caused significant reduction in the number of tumors per liver (p<0. 05) and a slight reduction (29%) in the incidence of HCC. The inhibitory effect of DMTU on ciprofibrate-induced hepatocarcinogenesis could be explained by hydroxyl radical scavenging properties of DMTU, resulting in decreased free radical induced DNA damage.     

Electron spin resonance studies on the mechanism of adriamycin-induced heart mitochondrial damages.

Rats were given i.p. injections of Adriamycin (4 mg/kg body weight) for 6 consecutive days. Electron spin resonance spectrometry with spin labeling and a trapping technique was applied to heart mitochondria obtained from treated and control animals, in order to examine the physical response of heart mitochondrial membrane affected by Adriamycin. The Adriamycin treatment resulted in a decrease of membrane fluidity (and an increase in order parameter S), with concomitant dysfunction of respiratory responses. The generation of hydroxyl radicals from mitochondria was enhanced in the Adriamycin-treated group. In addition, superoxide dismutase activity in the mitochondrial matrix was found to decrease. The heart mitochondria of Adriamycin-treated animals contained a large amount of lipid peroxide. These results suggest that the enhancement of hydroxyl radical formation in mitochondria affected by Adriamycin is one of the factors involved in Adriamycin-induced cardiotoxicity.     

(-)-Epigallocatechin gallate can prevent cisplatin-induced lung tumorigenesis in A/J mice

Risks of secondary lung cancer in patients with non-small cell lung cancer and small cell lung cancer are estimated to be 1-2% and 2-10% per patient per year, respectively. Cisplatin is widely used in the treatment of lung cancer and is also known as a carcinogen in experimental animals. In this study, the effect of (-)-epigallocatechin gallate (EGCG) on cisplatin-induced lung tumors in A/J mice was investigated. Female A/J mice (4 weeks old) were divided into four groups: group 1, control without treatment; group 2, EGCG treatment (1 mg/ml in tap water); group 3, weekly cisplatin treatment (1.62 mg/kg body wt, i.p.) for 10 weeks; group 4, cisplatin plus EGCG treatment (EGCG was started 2 weeks before cisplatin treatment). Four groups of mice were killed at week 30 after treatment. Tumor incidence was 26.3% (5/19) in group 1, 30% (6/20) in group 2, 100% (19/19) in group 3 and 94.4% (17/18) in group 4. Tumor multiplicity (the number of tumors per mouse, mean +/- SD) was 0.4 +/- 0.8 in group 1, 0.4 +/- 0.8 in group 2, 5.1 +/- 2.1 in group 3 and 2.8 +/- 2.3 in group 4. Tumor multiplicity was significantly reduced by adding EGCG to cisplatin-treated mice (P < 0.01). Furthermore, EGCG significantly reduced cisplatin-induced weight loss from 24.7-26.3% (cisplatin treatment) to 10.8-11.6% (cisplatin plus EGCG treatment) (P < 0.01). These findings suggest that EGCG can inhibit cisplatin-induced weight loss and lung tumorigenesis in A/J mice.     

Amifostine as a protector against cisplatin-induced toxicity in nude mice

The mechanisms mediating the protective effects of amifostine on cisplatin-induced toxicity were investigated in tumor-bearing nude mice by quantitative immunohistochemistry for analysis of cisplatin-DNA adduct levels in tumors and kidneys. The mice were treated with cisplatin 5 or 10 mg/kg i.p. with or without amifostine 200 mg/kg 30 min prior to cisplatin. Toxicity was noted in terms of mortality and changes in body weight. Mortality was similar in the four treatment groups, regardless of cisplatin dose or whether amifostine was added or not. At a cisplatin dose of 5 mg/kg, amifostine did not affect the moderate decrease in body weight. Cisplatin 10 mg/kg alone gave a significant loss of body weight, with the nadir on day 7. By adding amifostine to 10 mg/kg cisplatin the weight loss was much less pronounced. Tumor growth was significantly more retarded among animals treated with 10 mg/kg cisplatin alone compared with amifostine+cisplatin 10 mg/kg. There was no difference in tumor growth retardation between cisplatin 5 mg/kg alone or in combination with amifostine. The most likely explanation was that the pronounced tumor growth retardation with 10 mg/kg cisplatin alone was due to the decline in the general condition of the animals rather than increased antitumoral activity per se. Analysis of cisplatin-DNA adducts in tumors showed no difference whether cisplatin 10 mg/kg was combined with amifostine or not. In kidneys there were significantly fewer tubular cells with very high adduct levels in animals pretreated with amifostine.     

Sunitinib improves chemotherapeutic efficacy and ameliorates cisplatin-induced nephrotoxicity in experimental animals

Purpose

Therapeutic inhibition of angiogenesis has a benefit in the treatment of neoplastic diseases. Cisplatin is a widely used anti-cancer agent; however, it has serious side effects on non-tumor cells and causes nephrotoxicity due to its reactive oxygen species?Cmediated effect. Thus, a combination between cisplatin and angiogenesis inhibitors may be useful in cancer treatment. In the present study, the effect of sunitinib, a multi-targeted receptor tyrosine kinase inhibitor, on the antitumor activity as well as the nephrotoxic side effect of cisplatin was examined.

Methods

The antitumor activity was evaluated both in vitro using cultured Ehrlich ascites carcinoma (EAC) cells and in vivo using a mouse model of solid tumor. In addition, the effect of cisplatin and/or sunitinib on the angiogenic marker, VEGF, was examined. Nephrotoxicity was induced in rats by single i.p. injection of cisplatin (6?mg/kg).

Results

Sunitinib significantly potentiated the cytotoxic effect of cisplatin in vitro and in vivo. The nephrotoxicity of cisplatin was evidenced by decrease in the body weight, increase in kidney/body weight ratio and decrease in the percent survival of rats. The toxicity was also confirmed biochemically by measuring some kidney function parameters and oxidative stress markers. Sunitinib significantly decreased cisplatin-induced changes in serum creatinine, blood urea nitrogen, creatinine clearance and micro total protein in urine, renal malondialdehyde levels and reduced glutathione contents. In addition, sunitinib effectively blunted cisplatin-induced proximal and distal tubules necrosis.

Conclusion

The potential for sunitinib to ameliorate the cisplatin-evoked toxicity as well as to improve the chemotherapeutic effect could have beneficial implications for patients undergoing chemotherapy with cisplatin.     

Modulation of Cisplatin toxicity by glutathione

Organ toxicity is the major limiting factor associated with chemotherapeutic treatment of malignancy. By raising the toxicity threshold of the organ to the detrimental effects of chemotherapeutic agents, larger and possibly curative doses may be administered without unacceptable side effects. Glutathione (GSH), a major nonprotein cellular thiol, participates in numerous cellular functions, including detoxification of chemotherapeutic agents. Previously, GSH was shown to protect against cisplatin-induced lethal toxicity. We find that in non-tumor bearing animals GSH injections (500 mg/kg body weight) prior to and after a single cisplatin injection (16 mg/kg) provided significant protection against the lethal effects of this drug (90% survival for GSH+cisplatin versus 35% for cisplatin alone). In addition, when GSH was given concurrently with the cisplatin, renal toxicity was markedly reduced as assessed by renal tubular dilation, tubular sloughing, and lumenal casts. When GSH was given with cisplatin no significant differences in the number of tumor cures was observed over cisplatin treatment alone; however, a small but statistically significant increase in tumor size was observed for cisplatin+GSH treated animals. Our results suggest that GSH may protect normal as well as malignant tissue and that further studies should be designed to determine a GSH dose and schedule regimen to be used with higher cisplatin dose schedules.     

灯盏花素对顺铂肾损害的防治及抗氧化的实验

目的观察灯盏花素对小鼠顺铂（cisplatin,DDP）肾损害的防治及抗氧化作用,探究其可能的作用机制。方法以 DDP 8 mg/kg单次腹腔注射制备小鼠肾脏损害模型,再以不同剂量的灯盏花素灌胃,1次/天,连续给药7 d后采样,观察肾脏结构变化,检测血清中肌酐（Scr）、尿素氮（BUN）、丙二醛（MDA）含量及超氧化物歧化酶（SOD）活性,肾皮质 SOD 及 MDA 的变化。 结果灯盏花素可明显改善顺铂肾损害的小鼠肾脏结构,降低血清Scr、BUN及肾皮质 MDA含量（P<0.05,P<0.01）,而 SOD 活性明显升高（P<0.05）。 结论灯盏花素可明显减轻顺铂引起的肾毒性,其机制可能与抑制顺铂肾损害所致血液和肾皮质脂质过氧化反应增强有关。     

Magnesium depletion enhances cisplatin-induced nephrotoxicity.

Purpose: Nephrotoxicity and magnesium (Mg)-depletion are well-known side effects to cisplatin (CP) treatment. The purpose of this present study was to investigate the role of Mg on CP induced changes in renal function. CP induced renal dysfunction was achieved by treatment with CP or vehicle (2.5 mg/kg) once weekly for 3 weeks. Since the CP-induced renal damage, including tubular reabsorption defects, is most prominent within the outer medulla (OM), changes in the expression pattern of OM aquaporins and sodium transporters including the Na,K-ATPase (-subunit), type III Na,H-exchanger (NHE3), aquaporin 1 (AQP1) and 2 (AQP2) and the Na,K,2Cl-cotransporter (NKCC2) were investigated by semi-quantitative Western blotting. Experimental design: Rats had access to either a diet with standard Mg or to a Mg-depleted diet. Cisplatin was administered to female Wistar rats once a week for 3 weeks according to four regimens: (1) Cisplatin 2.5 mg/kg body weight i.p., to rats on a diet with standard Mg, (2) Cisplatin 2.5 mg/kg body weight i.p., to rats on a diet with low Mg, (3) Isotonic NaCl 2.5 ml/kg body weight i.p., to rats on a diet with standard Mg, (4) Isotonic NaCl 2.5 ml/kg body weight i.p., to rats on a diet with low Mg. Results: CP had no effect on plasma creatinine or urea in rats with standard Mg intake, but the expression of all five transporters was significantly reduced when compared to vehicle treated rats on standard Mg-intake. Vehicle treated rats on low Mg-intake had a significant reduction in the expression of Na,K-ATPase, NHE3 and NKCC2, but unchanged expression levels of AQP1 or AQP2 when compared to standard treated controls. Forty percent of the CP-treated rats on low Mg-intake died during the experiment and the remaining animals had marked increased plasma creatinine and urea. Furthermore, the Western blot analysis revealed an almost complete disappearance of all four transporters, suggesting a dramatic synergistic effect of CP and Mg-depletion on renal function including the expression pattern of outer medullary sodium transporters and aquaporins. Conclusions: This study indicates a substantial additive effect of Mg-depletion on cisplatin induced renal toxicity as evidenced by significant changes in plasma creatinine and urea, renal failure induced mortality and loss of renal transporters. This should give cause for concern since the nephrotoxicity observed during cisplatin treatment might be substantiated by the known Mg-loss associated with cisplatin treatment especially in patients suffering from intense gastro-intestinal side effects.     

The effect of sodium thiosulfate on subcellular localization of platinum in rat kidney after treatment with cisplatin

Female Sprague-Dawley rats were given 10 mg/kg of i.v. cis-diammine-dichloroplatinum(II) (cisplatin) simultaneously with i.v. sodium thiosulfate (STS) at a 200-fold molar excess to cisplatin, then subcellular (nuclei, mitochondria, microsomes, cytosol) distribution of platinum within rat kidney cells was determined 15 min, 1 h, 8 h and 24 h after cisplatin injection. Blood urea nitrogen levels were measured in rats treated in the same manner described above. STS was found to block cisplatin-induced nephrotoxicity. However, differences in platinum concentrations in total homogenate or each subcellular fraction between STS-treated rats and controls were not significant enough to fully account for the drastic protective effect of STS against cisplatin nephrotoxicity.     

American ginseng berry extract and ginsenoside Re attenuate cisplatin-induced kaolin intake in rats

Purpose Cisplatin, a chemotherapeutic agent, causes significant nausea and vomiting. It is postulated that cisplatin-induced oxidant stress may be responsible for these symptoms. We tested whether pretreatment with American ginseng berry extract (AGBE), an herb with potent antioxidant capacity, and one of its active antioxidant constituents, ginsenoside Re, could counter cisplatin-induced emesis using a rat pica model.Methods In rats, exposure to emetic stimuli such as cisplatin causes significant kaolin intake, a phenomenon called pica. We therefore measured cisplatin-induced kaolin intake as an indicator of the emetic response. Rats were pretreated with vehicle, AGBE (dose range 50–150 mg/kg, IP) or ginsenoside Re (2 and 5 mg/kg, IP). Rats were treated with cisplatin (3 mg/kg, IP) 30 min later. Kaolin intake, food intake, and body weight were measured every 24 h for 120 h. Additionally, the free radical scavenging activity of AGBE was measured in vitro using ESR spectroscopy.Results A significant dose-response relationship was observed between increasing doses of pretreatment with AGBE and reduction in cisplatin-induced pica. Kaolin intake was maximally attenuated by AGBE at a dose of 100 mg/kg. Food intake also improved significantly at this dose (P<0.05). Pretreatment with ginsenoside Re (5 mg/kg) also decreased kaolin intake (P<0.05). In vitro studies demonstrated a concentration-response relationship between AGBE and its ability to scavenge superoxide and hydroxyl radicals.Conclusion Pretreatment with AGBE and its major constituent, Re, attenuated cisplatin-induced pica, and demonstrated potential for the treatment of chemotherapy-induced nausea and vomiting. Significant recovery of food intake further strengthens the conclusion that AGBE may exert an antinausea/antiemetic effect.     

Pu-erh Tea Powder Preventive Effects on Cisplatin-Induced Liver Oxidative Damage in Wistar Rats

Background: Chemotherapy is one of the major means for control of malignancies, with cisplatin (CDDP) as one of the main agents, widely used for the treatment of various malignant solid tumors. However, prevention of hepatotoxicity from cisplatin is one of the urgent issues in cancer chemotherapy. In this study, we aimed to investigate the effects of pu-erh tea on hepatotoxicity through body weight and tissue antioxidant parameters like, liver coefficient, serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), malondialdehyde(MDA) and glutathione (GSH) levels, and light microscopic evaluation by histological findings. Materials and Methods: The rats were randomly divided into five groups: Control (n=10), cisplatin (3 mg/kg p.i., n=10), cisplatin+pu-erh (0.32 g/kg/day i.g., n=10), cisplatin+pu-erh (0.8 g/kg/day i.g., n=10) and cisplatin+pu-erh (1.6 g/kg/day i.g., n=10). Pu-erh tea powderwas administrated for 31 consecutive days. The rats were sacrificed at the end on the second day after a single dose of cisplatin treatment for measuring indices. Results: Pu-erh tea powder exhibited a protective effect by decreasing MDA and GSH and increasing the SOD and GSH-PX levels and GSH-PX/MDA ratio in camparison with the control group. Besides, pu-erh tea was also able to alleviate the pathological damage to some extent. Conclusion: Pu-erh tea powder is protective against cisplatin-induced liver oxidative damages, especially at themedium dosage (0.8 g/kg/d).     

Garcinol sensitizes human head and neck carcinoma to cisplatin in a xenograft mouse model despite downregulation of proliferative biomarkers

Platinum compounds such as cisplatin and carboplatin are frequently used as the first-line chemotherapy for the treatment of the head and neck squamous cell carcinoma (HNSCC). In the present study, we investigated whether garcinol, a polyisoprenylated benzophenone can chemosensitize HNSCC to cisplatin. We found that garcinol inhibited the viability of a panel of diverse HNSCC cell lines, enhanced the apoptotic effect of cisplatin, suppressed constitutive as well as cisplatin-induced NF-κB activation, and downregulated the expression of various oncogenic gene products (cyclin D1, Bcl-2, survivin and VEGF). In vivo study showed that administration of garcinol alone (0.5 mg/kg body weight, i.p. five times/week) significantly suppressed the growth of the tumor, and this effect was further increased by cisplatin. Both the markers of proliferation index (Ki-67) and microvessel density (CD31) were downregulated in tumor tissues by the combination of cisplatin and garcinol. The pharmacokinetic results of garcinol indicated that good systemic exposure was achievable after i.p. administration of garcinol at 0.5 mg/kg and 2 mg/kg with mean peak concentration (Cmax) of 1825.4 and 6635.7 nM in the mouse serum, respectively. Overall, our results suggest that garcinol can indeed potentiate the effects of cisplatin by negative regulation of various inflammatory and proliferative biomarkers.     

Ototoxicity,nephrotoxicity and pharmacokinetics of cisplatin and its monohydrated complex in the guinea pig

PURPOSE: To evaluate and compare the ototoxicity and nephrotoxicity of cisplatin and cis-diammineaquachloroplatinum(II) ion (monohydrated complex of cisplatin, MHC, formed in vivo by hydrolysis of cisplatin) after their separate administration to guinea pigs. METHODS: A dose of 4 mg/kg body weight of MHC was deemed suitable for the toxicity evaluation after dose titration. Electrophysiological hearing thresholds (auditory brainstem response, ABR), plasma creatinine and weight were measured in three groups of animals before and after receiving MHC 4 mg/kg (0.0141 mmol/kg), cisplatin 4.24 mg/kg (0.0141 mmol/kg, i.e. equimolar dose) or cisplatin 8 mg/kg (0.0267 mmol/kg) as an i.v. bolus injection. Cisplatin and MHC were analysed using liquid chromatography with post-column derivatization. RESULTS: Administration of MHC 4 mg/kg caused a moderate ABR threshold shift, a significant increase in creatinine and a significant weight loss, changes similar to those seen after administration of cisplatin 8 mg/kg. Animals given cisplatin 4.24 mg/kg had a slight increase in creatinine, but had no ABR threshold shift and gained weight during the experiment. The pharmacokinetic parameters of cisplatin and MHC were estimated after administration of cisplatin 4.24 mg/kg and MHC 4 mg/kg. The area under the blood-ultrafiltrate concentration versus time curve (AUC) for cisplatin after administration of MHC 4 mg/kg was 23% (56+/-5.0 micro g.min.ml(-1)) (means+/-SD) of that after administration of cisplatin 4.24 mg/kg (240+/-25 micro g.min.ml(-1)). The AUC for MHC after administration of cisplatin 4.24 mg/kg was 20% (30+/-4.9 micro g.min.ml(-1)) of that after administration of MHC 4 mg/kg (149+/-26 micro g.min.ml(-1)). CONCLUSIONS: MHC 4 mg/kg causes ototoxicity, nephrotoxicity and weight loss when administered to guinea pigs. The toxic effects were similar to those seen after administration of cisplatin 8 mg/kg and higher than those seen after administration of cisplatin 4.24 mg/kg.     

Protection by αG-Rutin, a Water-soluble Antioxidant Flavonoid, against Renal Damage in Mice Treated with Ferric Nitrilotriacetate

The protective effect of aG-Rutin against ferric nitrilotriacetate (Fe-NTA)-induced renal damage was studied in male ICR mice. Fe-NTA induces renal lipid peroxidation, leading to a high incidence of renal cell carcinoma in rodents. Administration of αG-Rutin (50 μmol as rut in/leg) by gastric intubation 30 min after i.p. injection of Fe-NTA (7 mg Fe/kg) most effectively suppressed renal lipid peroxidation. Repeated i.p. injection of Fe-NTA (2 mg FeAg/day for the first 3 days and 3 mg Fe/ kg/day for 12 days, 5 days a week) causes subacute nephrotoxicity as revealed by induction of karyomegalic cells in renal proximal tubules. A protective effect was observed in mice given αG-Rutin 30 min after each Fe-NTA treatment. To elucidate the mechanism of protection by αG-Rutin, the pharmacokinetics and hydroxyl radical-scavenging effect of αG-Rutin were investigated by HPLC analysis and by electron spin resonance (ESR) spin trapping with 5,5-dimethyl-l-pyrroline-N-oxide (DMPO), respectively. When mice were given αG-Rutin (50 μmol as rutin Ag) by gastric intubation, rapid absorption into the circulation was observed. The plasma concentration of äG-Rutin reached the highest level 30 min after oral administration and then decreased to the control level within 60 min. äG-Rutin inhibited the formation of DMPO-OH in a concentration-dependent manner. Further, chelating activity of äG-Rutin to ferric ions was shown by spectrophotometric analysis. These results suggest that absorbed äG-Rutin works as an antioxidant in vivo either by scavenging reactive oxygen species or by chelating ferric ions and this serves to prevent oxidative renal damage in mice treated with Fe-NTA.     

Reduction in mitochondrial oxidative stress mediates hypoxia-induced resistance to cisplatin in human transitional cell carcinoma cells

Tumor hypoxia is known to promote the acquisition of more aggressive phenotypes in human transitional cell carcinoma (TCC), including drug resistance. Accumulating evidence suggests that mitochondria play a central role in the chemoresistance of TCC. However, the role of mitochondria in the hypoxia-induced drug resistance in TCC remains elusive. The present study investigated the function of mitochondria in the drug resistance using a TCC cell line under hypoxic conditions. In vitro hypoxia (0.1% O₂, 48 h) was achieved by incubating TCC cells in air chamber. Mitochondrial events involving hypoxia-induced drug resistance were assessed. Hypoxia significantly reduced the cisplatin-induced apoptosis of TCC cells. Additionally, hypoxia substantially decreased the level of mitochondrial reactive oxygen species (ROS) generated by cisplatin treatment. Analogously, elimination of mitochondrial ROS significantly rescued cells from cisplatin-induced apoptosis. Hypoxia enhanced mitochondrial hyperpolarization, which was not related to ATP production or the reversal of ATP synthase activity. The mitochondrial DNA (mtDNA) amplification efficiency data illustrated that hypoxia significantly prevented oxidative damage to the mitogenome. Moreover, transmission electron microscopy revealed that cisplatin-induced disruption of the mitochondrial ultrastructure was abated under hypoxic conditions. Notably, depletion of mtDNA by ethidium bromide abrogated hypoxia-induced resistance to cisplatin. Taken together, the present study demonstrated that TCC cells exposed to hypoxic conditions rendered mitochondria less sensitive to oxidative stress induced by cisplatin treatment, leading to enhanced drug resistance.     

Induction of free radicals and tumors in the kidneys of Wistar rats by ferric ethylenediamine-N,N'-diacetate

An iron chelate, ferric ethylenediamine-N,N’-diacetate[Fe(III)-EDDA], was found to produce hydroxyl radicals withhydrogen peroxide, as determined by both a deoxyribose degradationtest and electron spin resonance. Hydroxyl radical productionwas inhibited not only by adding hydroxyl radical scavengersand catalase, but also by adding superoxide dismutase to thereaction mixture, suggesting that superoxide anion may be involvedin the hydroxyl radical production. A single injection of Fe(III)-EDDA(10 mg Fe/kg body wt) to Wistar rats induced thiobarbituricacid reactivity in the kidneys and liver. Repeated Injectionsof Fe(III)-EDDA (10 mg Fe/kg body wt, twice weekly for 3 months)induced a 40% incidence of renal tumors, including renal adenocarcinomaand renal adenoma, 1 year later. These results suggest thatFe(III)-EDDA is an effective free radical producer in vitroand in vivo and that it may be useful in preparing animal modelsrelated to iron-dependent free radical damage. The results supportour hypothesis that endogenous or exogenous iron, complexedwith certain kinds of chelators, promotes free radical-dependenttissue damage and ultimately leads to carcinogenesis in theaffected tissue.     

Reduction of cisplatin toxicity by fosfomycin in animal models

The protective effect of fosfomycin against cisplatin-induced toxicities was studied in rats. A total of 64 Fischer rats were injected intravenously with daily doses of 1, 2, 5 and 10 mg/kg of cisplatin with or without 300 mg/kg of fosfomycin for a period varying from 1 to 10 days. The same total dose of 10 mg/kg of cisplatin was given to all animals. Cisplatin-induced toxic side-effects of body weight loss, nephrotoxicity and ototoxicity were significantly reduced functionally or histopathologically by the combined administration of cisplatin and fosfomycin. A comparison of different dosage schedules with a total dose of 10 mg/kg of cisplatin showed that a higher daily dose for a shorter time period produced more marked toxicities.     

Methimazole as a protectant against cisplatin-induced nephrotoxicity using the dog as a model

The protective effect of methimazole, a commonly used antithyroid drug, on cisplatin-induced nephrotoxicity was studied. Eight dogs received 80 mg/m² cisplatin i.v. without saline prehydration. Dogs were randomized into two groups of four dogs each: one group received 40 mg/kg methimazole i.p. at 30 min prior to and 4 h after cisplatin delivery, and the other group received saline placebo i.p. Methimazole protected dogs against the in vivo nephrotoxicity elicited by cisplatin as evidenced by clinicopathologic and histopathologic indices. Protection was not complete, as methimazole-treated animals developed mild histopathologic renal changes. Measures of renal oxidative stress did not differ between the two groups at day 5 following cisplating treatment. No difference was noted for serum thyroxine concentrations before or after therapy in either group; however, serum levels of 3,5,3-triiodothyronine were significantly higher on day 5 in both groups of dogs receiving cisplatin, regardless of whether they received methimazole or not. Methimazole as used in this study was found to be well tolerated in dogs over the short term, with no significant clinical or clinicopathologic toxicity being observed. The results of this study support the additional evaluation of methimazole as a protectant against cisplatin-induced nephrotoxicity using the dog as a model.This work was supported in part by Bristol-Myers Squibb Co. (Evansville, Ind.)     

氨磷汀对顺铂肾毒性损伤的保护作用及其机制的研究

目的 观察顺铂的肾毒性损伤部位、形式与肾功能检查结果的相关性,以了解细胞凋亡的发生机制和氨磷汀的保护机制是否与肾组织Fas和FasL表达改变有关。方法 随机将大鼠分成3组,即对照组（生理盐水）、顺铂组（6mg／kg）和氨磷汀组（顺铂6mg／kg＋氨磷汀200mg／kg）,取其血清标本和肾组织,分别做血清BUN、Cr检测和肾组织病理学检查,并用原位缺口末端标记法（TUNEL）做肾组织凋亡细胞检测、Fas和FasL免疫组化染色,再用图像分析软件对其做阳性细胞计数和染色总灰度值测定。结果 顺铂组动物血清BUN、Cr值均明显高于对照组和氨磷汀保护组,3d时,差异已有统计学意义（P〈0．05）;5d时,两者差异分别为P〈0．01和P〈0．05;10d时,恢复正常。顺铂组肾小管上皮细胞坏死和凋亡均很严重,其凋亡细胞计数明显高于对照组和氨磷汀组（P值均〈0．01）,肾组织Fas和FasL表达的总灰度值,明显高于对照组和氨磷汀组（P值均〈0．01）。结论 氨磷汀对顺铂的肾毒性损伤有保护作用,其机制可能与抑制肾组织Fas和FasL的表达有关。