protection by ozone

Background : Acute renal failure is a dose-limitingfactor of cisplatin chemotherapy. Here, we show theprotective effect of ozone oxidative preconditioningagainst cisplatin-induced renal dysfunction in rats.Ozone oxidative preconditioning is a prophylacticapproach, which favors the antioxidant�/pro-oxidantbalance for preservation of the cell redox state byincreasing antioxidant endogenous systems in var-ious in vivo and in vitro experimental models.Aims : To analyze the protective role of ozone oxida-tive preconditioning against cisplatin-induced ne-phrotoxicity.Methods : Male Sprague�/Dawley rats were pretreatedwith 15 intrarectal applications of ozone/oxygenmixture at 0.36, 0.72, 1.1, 1.8 and 2.5 mg/kg beforecisplatin intraperitoneal injection (6 mg/kg). Serumand kidneys were extracted and analyzed 5 days aftercisplatin treatment for determinations of the renalcontent of glutathione, thiobarbituric acid-reactivesubstances, renal concentration and enzymatic activ-ities of catalase, superoxide dismutase and glu-tathione peroxidase.Results : Ozone pretreatment prevented the increasein serum creatinine levels, the glutathione depletionand the inhibition of superoxide dismutase, catalaseand glutathione peroxidase activities induced bycisplatin in the rat kidney. Also, the renal contentof thiobarbituric acid-reactive substances was de-creased by ozone therapy. These protective effectsof ozone were dose dependent.Conclusions : Intrarectal ozone therapy preventedeffectively the renal antioxidant unbalance inducedby cisplatin treatment.

Key words: Ozone oxidative preconditioning, Cisplatin-induced nephrotoxicity, Antioxidant defenses, Lipid perox-idation

Mediators of Inflammation, 13(1), 13�/19 (February 2004)

Protection by ozonepreconditioning is mediated bythe antioxidant system incisplatin-induced nephrotoxicityin rats

Aluet Borrego1,CA, Zullyt B. Zamora1,

Ricardo Gonzalez1, Cheyla Romay1,

Silvia Menendez1, Frank Hernandez1,

Teresita Montero2 and Enys Rojas1

1Department of Biomedicine, Ozone Research Center,National Center for Scientific Research, BiomedicineDepartment, P.O. Box 6414, Havana City, Cuba; 2‘Dr.Luis Dıaz Soto’ Surgical and Clinical Hospital, HavanaCity, Cuba

CACorresponding authorTel: �/537 271 23 24E-mail: [email protected]

Introduction

Cisplatin (CDDP) is an effective chemotherapeuticagent commonly used in the treatment of a variety ofsolid-organs cancers, including those of the head,neck, testis, ovary and breast.1 Unfortunately,28�/36% of patients receiving a dose of CDDPdevelop acute renal failure.1 Therefore, its pathogen-esis has been the focus of many investigations, whichhave shown that acute renal failure induced by CDDPis accompanied by the reduced renal blood flowassociated with increased renal vascular resistanceand histological damage to the proximal tubularcells.2,3

Additionally, evidence is available that the cellularevents in CDDP-mediated nephrotoxicity, includingapoptosis induction, decreased protein synthesis,membrane peroxidation, mitochondrial dysfunctionand DNA injury, are a consequence of reactiveoxygen species (ROS) generation, which produces

oxidative renal damage.4�9 Thus, administration ofCDDP causes depletion of renal reduced glutathione(GSH) and an increase of lipid peroxidation accom-panied with a decrease in the activity of enzymes thatprotect against lipid peroxidation in the kidney, suchas superoxide dismutase (SOD), catalase (CAT) andglutathione peroxidase (GSH-Px).4�9

In agreement with this, administration of knownantioxidant molecules like vitamin E, ascorbic acid,ebselen, lipoic acid, GSH and its esters, CAT and theSOD mimetic orgotein, among others, have shownnephroprotective effects in CDDP-treated rats.10�16

Recently it was reported that oxidative precondi-tioning with ozone prevents renal damage in ratssubmitted to warm ischemia,17 suggesting that oxida-tive preconditioning with ozone may provide aprophylactic approach for minimizing renal damagebefore transplantation, which is also mediated byROS production. Taking into account these findings,we decided to evaluate the role of ozone oxidative

Research Communication

ISSN 0962-9351 print/ISSN 1466-1861 online/04/10013-07 – 2004 Taylor & Francis LtdDOI: 10.1080/09629350410001664806

13

preconditioning in CDDP-induced acute renal da-mage in rats and to determine its potential protectiveeffects on some important constituents of the anti-oxidant system in the kidney.

Materials and methods

Chemicals

Serum creatinine (Cr) was measured spectrophoto-metrically with the Cr assay kits purchased fromBiological Products Enterprise ‘Carlos J Finlay’(Havana, Cuba). All reagents used in determinationsof GSH, SOD, CAT, GSH-Px, thiobarbituric acid-reactive substances (TBARS) and cisplatin werepurchased from Sigma Chemicals (St Louis, MO,USA). Other reagents of analytical grade were ob-tained from normal commercial sources.

Animals

Male Sprague�/Dawley rats (200�/250 g) were ob-tained from the National Center for LaboratoryAnimal Production (CENPALAB, Havana Cuba). Theanimals were housed under a 12 h light�/dark cyclewith room temperature maintained at 258C, humidityat 60% and food and water available ad libitum . Theexperiments were conducted in accordance with theethical guidelines for investigations in laboratoryanimals and were approved by the Ethical Committeefor Animal Experimentation of the National Center forScientific Research, Havana, Cuba.

Experimental design

Ozone (O3) was generated by an OZOMED 01equipment manufactured by the Ozone ResearchCenter (Cuba). O3 obtained from medical-gradeoxygen (O2) was used immediately. The O3 concen-tration was measured using an ultraviolet spectro-photometer at 254 nm. An O3/O2 mixture wasadministered by rectal insufflations (i.r.) at doses of0.36, 0.72, 1.1, 1.8 and 2.5 mg/kg. The volume ofinsufflated mixture was approximately 9 ml. Oxida-tive preconditioning was performed with 15 applica-tions (one daily) of the O3/O2 mixture. CDDPwas applied 1 day after the 15 applications of theO3/O2 mixture by an intraperitoneal injection (6 mg/kg). Five days after CDDP injection, animals weresacrificed by asphyxia in ether.

The animals were divided into 10 groups of sevenrats each: (1) non-treated control rats, (2) rats treatedwith O2, (3) rats treated with O3/O2 mixture (1.1 mg/kg), (4) rats treated with O2�/CDDP, (5) rats treatedonly with CDDP, (6) rats treated with O3/O2 mixture(10 mg of ozone/ml of mixture at a dose of 0.36 mg/kg)�/CDDP, (7) rats treated with O3/O2 mixture

(20 mg of ozone/ml of mixture at a dose of 0.72mg/kg)�/CDDP, (8) rats treated with O3/O2 mixture(30 mg of ozone/ml of mixture at a dose of 1.1 mg/kg)�/CDDP, (9) rats treated with O3/O2 mixture(50 mg of ozone/ml of mixture at a dose of 1.8 mg/kg)�/CDDP, and (10) rats treated with O3 O2 mixture(70 mg of ozone/ml of mixture at a dose of 2.5 mg/kg)�/CDDP. Rats were killed 5 days after CDDPinjection by an overdose of ether. The blood wascollected and serum was separated by centrifugationfor Cr analysis. The kidneys were dissected andimmediately frozen at �/208C until analysis could becompleted.

Kidney homogenates were obtained using a tissuehomogenator (Ultraturrax T-25 Polytron) at 48C. Thehomogenates were prepared by using a 100 mM KClbuffer (pH 7) containing 0.3 mM ethylenediaminetetraacetic acid (1:10 w/v) for GSH, TBARS, GSH-Pxand SOD determinations (Buffer 1). The homoge-nates were spun down with a centrifuge at 600�/gfor 60 min at 48C. The supernatants were taken forbiochemical determinations.

Kidney homogenates for CAT enzymatic assaywere carried out using 50 mM phosphate buffer(pH 7) containing 1% Triton X-100 (1:9 w/v) (Buffer2). The homogenates were centrifuged at 600�/g for60 min at 48C and the supernatants were used for theCAT assay.

Determination of GSH

GSH was determined by a slightly modified versionof the method of Beutler et al. ,18 using a spectro-photometer. One milliliter of the kidney homogenate,as described earlier, was mixed with 1.5 ml of 5%metaphosphoric acid and centrifuged at 3000�/g for10 min at room temperature. Fifty hundred micro-liters of this acidic supernatant was mixed with 2 mlof 0.2 M phosphate buffer and 0.25 ml of 0.04% 5,5?-dithio-bis(-2-nitrobenzoic acid). Absorbance of theyellow solution was measured at 412 nm within 10min. A molar extinction coefficient of 13.6 M/cm thatdescribes the formation of the thiolate anion by thereaction of sulfhydryl groups with 5,5?-dithio-bis-2-nitrobenzoic acid at 412 nm was used to quantifyGSH.

Determination of SOD activity

Enzymatic activity of SOD was determined by amodified version of the method of Minami andYoshikawa.19 Fifty microliters of the kidney homo-genate was mixed with 450 ml of cold deionizedwater, 125 ml of chloroform and 250 ml of ethanol.The mixture was centrifuged at 8000�/g for 2 min at48C. Fifty hundred microliters of the extract wasadded to the reaction mixture containing 500 ml of72.4 mM Tris cacodylate buffer with 3.5 mM diethy-

A. Borrego et al

14 Mediators of Inflammation � Vol 13 � 2004

lene pentaacetic acid (pH 8.2), 100 ml of 16% Triton-X100 and 250 ml of 0.9 mM nitro blue tetrazolium. Thereaction mixture was incubated for 5 min at 378Cbefore adding 10 ml of 9 mM pyrogallol (dissolved in10 mM hydrochloric acid), and then it was incubatedfor exactly 5 min at 378C. The reaction was stoppedwith the addition of 300 ml of 2 M formic buffer(pH 3.5) containing 16% Triton-X 100. The absor-bance was measured at 540 nm in the spectro-photometer. One unit of SOD enzymatic activity isequal to the amount of enzyme that diminishes theinitial absorbance of nitro blue tetrazolium by 50%.

Determination of CAT activity

CAT was determined according to the method ofEvans and Diplock.20 Kidney homogenate was di-luted with Buffer 2, as already described, to obtain anadequate dilution of the enzyme. Then, 2 ml of theenzyme dilution were added to the cuvette andmixed with 1 ml of 30 mM H2O2, and then theabsorbance was measured at 240 nm, for 30 sec, inthe spectrophotometer. Initial absorbance of thereaction mixture must be around 0.5. The enzymeactivity is expressed as the first-order constantthat describes the decomposition of H2O2 at roomtemperature.

Determination of GSH-Px activity

Enzymatic activity of GSH-Px was measured using amodified version of the method of Thonson et al .21

All reaction mixtures were dissolved in 20 mMsodium phosphate buffer containing 6 mM ethylene-diamine tetraacetic acid (pH 7.0). The reactionmixture consisted of 98.8 ml of phosphate buffer,700 ml of 2.86 mM GSH, 100 ml of 1 mM sodium azide,100 ml of 1 mM NADPH and 4.2 ml of GSH reductase(0.5 u). Then, 10 ml of the tissue homogenate super-natant were added to the reaction mixture andincubated at room temperature for 10�/15 min.Afterward, 10 ml of 30 mM t -butyl hydroperoxide(dissolved in bidistilled water) was added to thereaction mixture and measured at 340 nm for 7 min inthe spectrophotometer. A molar extinction coefficientof 6.22�/103 M/cm was used to determine theactivity of GSH-Px. The enzyme activity is expressedas international units of enzymatic activity per milli-gram of protein. International units are expressed asmicromoles of hydroperoxides transformed per min-ute per milliliter of enzyme.

Lipid peroxidation assay

This assay was used to estimate TBARS levels asdescribed by Ohkawa et al .22 Two hundred millilitersof tissue homogenate supernatant were added to 100ml of sodium dodecyl sulfate, 750 ml of 20% acetic acid

(pH 3.5), 750 ml of 0.6% thiobarbituric acid and 300 mlof distilled water, and were incubated at 958C for 60min. The samples were allowed to cool at roomtemperature. Then 2.5 ml of butanol:pyridine (15:1)and 500 ml of distilled water were added, vortexed,and centrifuged at 2000�/g for 15 min. The absor-bance of three ml of the colored layer was measuredat 532 nm spectrophotometrically using 1,1,3,3-tetraethoxypropane as standard.

Protein assay

Protein concentrations were determined by themethod of Lowry23 using bovine serum albumin asstandard.

Histopathological assessment of renal damage

The left kidneys were quickly removed and fixed in10% formaldehyde. Tissues were embedded in par-affin, sectioned at 3 mm, stained with hematoxylinand eosin (H/E) and evaluated by light microscopy.

Statistical analysis

Data are expressed as means9/standard error of themean and analyzed statistically using one-way ana-lysis of variance followed by the Duncan multiplerange test for serum Cr determinations, whereas theKruskall�/Wallis test followed by the Mann�/Whitneytest was applied for the rest of the markers. The 0.05level of probability was used as statistical signifi-cance.

Results

Loss of body weight in all animals was observed 5days after CDDP injection. The mean reduction inbody weight was approximately 16 g, which repre-sents 8% of the initial body weight. This effect onbody weight was not reversed in animal groupsunder O3 therapy with mixtures of O3/O2 adminis-tered by rectal insufflation.

The levels of Cr in the blood serum of control andexperimental rats are presented in Table 1. AfterCDDP injection, Cr levels increased about four-fold atday 5 with respect to non-treated controls. However,there were no significant differences in the concen-trations of Cr in rat serum between the non-treatedcontrols and those only treated with O2. No signifi-cant differences in Cr levels were found between thegroup treated with CDDP alone and the other onewith CDDP�/O2. In contrast, oxidative precondition-ing with O3/O2 mixture during 15 days at doses of0.72 and 1.1 mg/kg but not 0.36 mg/kg induced aremarkable decrease in Cr levels in serum with

Ozone preconditioning in nephrotoxicity

Mediators of Inflammation � Vol 13 � 2004 15

respect to the higher values in CDDP group. Greaterdoses of 1.8 and 2.5 mg/kg did not significantlydecrease Cr (Table 1).

The concentration of renal reduced GSH wassignificantly decreased (58% of non-treated control)in CDDP-treated rats. Ozone therapy (0.72, 1.1, 1.8and 2.5 mg/kg i.r.) prevented renal GSH depletioninduced by CDDP. This effect was greater at doses of0.72 and 1.1 mg/kg (pB/0.01). The lowest dose of O3

(0.36 mg/kg) was not effective in the prevention ofGSH depletion.(Table 1).

The kidney TBARS content used as a measure oflipid peroxidation was significantly increased in ratstreated with CDDP alone, as compared with non-treated controls. Oxidative preconditioning withO3/O2 mixture during 15 days induced significantdecrease in TBARS content at O3 doses of 0.72 mg/kg(pB/0.05), 1.1 mg/kg (pB/0.001), 1.8 mg/kg(pB/0.001) and 2.5 mg/kg (pB/0.01) as comparedwith CDDP alone. The lower O3 dose (0.36 mg/kg)did not induce any significant change on renal TBARScontent. The data indicate that the induction of lipidperoxidation made by CDDP in the kidney isattenuated by O3 therapy in a dose-dependentmanner (Table 1).

SOD activity in the kidney was significantly de-creased (71% of non-treated control) in CDDP-treatedrats (Table 1). Pretreatment with O3/O2 mixtures(0.72 and 1.1 mg/kg) significantly increased(pB/0.01) SOD activity in CDDP-treated animals,which was close to values of non-treated control.However, the lower O3 dose (0.36 mg/kg) and thegreater ones (1.8 and 2.5 mg/kg) did not avoid thedecreasing in SOD activity. On the contrary, thegreatest O3 tested dose (2.5 mg/kg) induced aremarkable and significant decrease (pB/0.01) ofSOD activity (3.059/0.48) versus (6.29/0.9) in theCDDP-treated control, which provides evidence of itsdeleterious effect on this antioxidant enzyme.

CAT activity in the rat kidney was significantlydecreased (63% of non-treated control) in CDDP-treated rats. Pretreatment with O3 (0.72, 1.1,1.8 and2.5 mg/kg, but not 0.36 mg/kg) significantly pre-vented (pB/0.05) the inhibitory effect of CDDP onCAT activity (Table 1).

GSH-Px activity in the kidney was significantlydecreased (82% of non-treated control) in CDDP-treated rats. O3 pretreatment (0.72 and 1.1 mg/kg)significantly increased, almost twice (pB/0.01), theGSH-Px activity with respect to both CDDP-treatedcontrol rats and non-treated rats. The greater O3

doses (1.8 and 2.5 mg/kg) induced a minor increaseon the enzyme activity (Table 1).

The histopathological changes in the kidney tissueare reported in Fig. 1. Non-treated rats exhibitedcellular tumefaction, probably due to the type ofeuthanasia (asphyxia by ether) (Fig. 1A). Rats treatedwith CDDP alone revealed intense tubular necrosis,desquamation of renal tubular cells, and castformation in the lumen, as reported in previousworks (Fig. 1B). O3-treated rats with 1.1 mg/kgshowed a moderate cellular tumefaction, revealingno significant differences between them and non-treated rats. At greater doses of 1.8 and 2.5 mg/kgdoses, histopathological changes in renal tissue werequite similar to those present in CDDP-treated rats.O3 oxidative preconditioning provided significantprotection against CDDP-induced nephrotoxicity,and the majority of the treated animals showed nosignificant histopathological alterations (Fig. 1C).

Discussion

The aim of this work was to determine the effect ofO3 oxidative preconditioning on the severity ofCDDP-induced nephrotoxicity. In the present study,CDDP-induced acute kidney damage was character-

Table 1. Biochemical determinations in experimental groups

Experimental groups Serum Crlevels (mM)

GSH (nmol/mgof protein)

TBARS (nmol/mg of protein)

SOD (SOD units/mg of protein)

CAT (k15/g ofwet tissue)

GSH-Px (IU/mgof protein)

Non-treated control 67.99/11.73* 9.39/0.90* 0.259/0.014* 8.79/1.15* 6.89/0.39 * 6.09/0.25*Oxygen-treated control 70.69/6.61* 8.99/0.96 * 0.269/0.012* 8.89/1.26* 6.79/0.63* 6.19/0.14*Ozone-treated control 69.29/7.61* 8.59/0.47* 0.319/0.034* 8.69/1.72* 6.79/1.56* 6.19/0.14*CDDP control 280.69/45.05 5.49/0.76 0.639/0.12 6.29/0.9 4.39/0.74 5.39/0.69O2�/CDDP control 288.49/44.03 4.99/0.81 0.559/0.029 6.69/0.94 4.39/0.49 5.59/0.55O3 (0.36 mg/kg)�/CDDP 294.99/47.70 6.69/1.34 0.549/0.077 6.89/1.23 5.29/0.79 5.99/0.98O3 (0.72 mg/kg)�/CDDP 106.09/29.78* 12.39/1.17* 0.489/0.049 9.19/0.81* 5.59/0.67* 10.59/1.03*O3 (1.1 mg/kg)�/CDDP 130.49/30.41* 13.49/2.7* 0.299/0.062* 9.19/1.01* 6.09/0.54* 7.99/1.32*O3 (1.8 mg/kg)�/CDDP 288.49/47.81 10.99/1.57* 0.229/0.03* 6.19/0.9 5.99/0.57* 5.89/0.89 *O3 (2.5 mg/kg)�/CDDP 392.99/47.56 10.69/1.76 * 0.289/0.033* 3.09/0.48* 6.19/64* 5.79/0.62 *

Data presented as (mean9/standard error of the mean. Serum Cr was measured with the Cr assay kits (Biological Products Enterprise ‘Carlos JFinlay’, Havana, Cuba). GSH was determined by the method of Beutler et al.18 Enzymatic activity of SOD was determined by a version of themethod of Minami and Yoshikawa19 (one unit of SOD enzymatic activity is equal to the amount of enzyme that diminishes the initial absorbanceof nitro blue tetrazolium by 50%). CAT was determined according to the method of Evans and Diplock20 (the enzyme activity is expressed as thefirst-order constant that describes the decomposition of hydrogen peroxide at room temperature). Enzymatic activity of GSH-Px was measuredusing a modified version of the method of Thonson et al.21 (the enzyme activity is expressed as international units of enzymatic activity permilligram of protein). TBARS levels were estimated by Ohkawa et al.22 Protein concentrations were determined by the method of Lowry.23 *Significant differences with CDDP-treated control groups (pB/0.05).

A. Borrego et al


ized by a significant increase in serum Cr, decreasesin the kidney GSH content and GSH-Px, SOD andCAT activities, and an increase in TBARS productionin comparison with the non-treated controls. Histo-pathological examination of the kidneys of CDDP-treated rats revealed marked tubular necrosis anddesquamation of renal tubular cells. These results arein accordance with previous reports.4�16

The mechanisms underlying CDDP-induced ne-phrotoxicity have not been fully elucidated. Severalinvestigators have shown that ROS are closely relatedto the nephrotoxicity induced by CDDP.5�7,14 It hasalso been reported that the inordinate generation ofROS contributes to the initiation and/or maintenanceof acute tubular necrosis.5�7,14 Indeed, several anti-oxidants such as SOD, ebselen, vitamin E and vitaminC are reported to attenuate cisplatin-induced renaltoxicity.10�16 Several reports demonstrate differentmechanisms involved in the CDDP-induced nephro-toxicity including protein kinase C activation,24

elevation of caspase-3 activity resulting in renal cellapoptosis,8 enhancement of intrarenal synthesis ofthromboxane A2

25 and dyslipidemia.26

Oxidative preconditioning is analogous to otherphenomena such as ischemic preconditioning,27

thermal preconditioning28 and chemical precondi-

tioning.29 All of these processes have in common that

a repeated and controlled stress is able to protect

against a prolonged and severe stress.Intrarectal O3 therapy has conferred protection

against hepatic ischemia/reperfusion injury by the

adenosine accumulation and by blocking the

xanthine/xanthine oxidase pathway, decreasing

ROS generation after reperfusion.30�32 Recently, it

was demonstrated that intrarectal application of an

O3/O2 mixture reduced ROS by stimulation and/or

preservation of the endogenous antioxidant systems

in experimental models of liver and renal ischemia-

reperfusion, respectively.30�32 Also, there is evidence

of an increase in the activity of antioxidant enzymes

such as SOD and GSH-Px and a decrease of

malondialdehyde after O3 preconditioning in patients

with cardiopathy and in rats suffering ischemia/

reperfusion damage.17,33

Our experimental results clearly demonstrate that

oxidative preconditioning with O3 exerts protective

effects in CDDP-induced acute nephrotoxicity in rats.

Furthermore, the data provide strong evidence that

i.r. O3 therapy effectively prevented a decrease in the

renal antioxidant defense system and certainly

avoided the deleterious effect of CDDP on it.

FIG. 1. Histopathological changes in rat kidneys after CDDP administration (6 mg/kg) and under i.r. O3 therapy. (A) Lightmicrograph of rat kidneys from the control group. Slight cellular tumefaction ascribed to the type of euthanasia (asphyxia byether). H/E stain,�/100. (B) Light micrograph from a CDDP-treated rat. Note the widespread tubular necrosis and castformation in the tubular lumen. H/E stain,�/100. (C) Light micrograph of a rat kidney, which received 15 applications of O3 (1.1mg/kg) by rectal insufflation before CDDP injection. Moderate cellular tumefaction was observed. H/E stain,�/100.



Thus, the pretreatment with O3/O2 mixture pre-vented GSH depletion and the decrease of SOD, CATand GSH-Px activities induced by CDDP in ratkidney. Also, renal TBARS content was diminishedby O3 therapy. These protective effects of O3 weredose dependent. The lowest dose of 0.36 mg/kg didnot induce any significant change in the formerantioxidant markers. In contrast, the doses of 0.72and 1.1 mg/kg significantly reduced serum Cr andTBARS levels and preserved some constituents of theantioxidant defense, such as GSH content, SOD, CATand GSH-PX activities, which were levels close to oreven greater than those of non treated controls(Table 1).

Furthermore, the preservation of renal SOD, CATand GSH-PX activities by O3 pretreatment at lowerdoses (0.72 and 1.1 mg/kg) shows that this agent canprotect these enzymes even 5 days after CDDPadministration. Neither significant change of GSHand TBARS renal content nor statistic differences inCAT activity were found at the greater ozone doses of1.8 and 2.5 mg/kg as compared with that of 1.1 mg/kg, which indicates that the ‘plateau effect’ in thedose�/response curves was reached.

Induction of CAT, SOD, and GSH-Px by O3 therapyis probably due to hydrogen peroxide produced asresult of O3 decomposition. Hydrogen peroxide hasbeen shown to be one of the major intermediates ofO3 decomposition along with oxygen radicals (OH+

and O2+).

In contrast, the greatest O3 dose (2.5 mg/kg)induced a marked and significant decrease of SODactivity (3.059/0.48 u/mg of protein) as comparedwith non-treated controls (8.729/1.15 u/mg of pro-tein), which reveals deleterious effects of ozonetreatment on this enzyme, which is probably due toSOD inactivation by H2O2 at greater concentrationsas it has been demonstrated by Marklund.34 Thisauthor suggested that inactivation of Cu Zn SOD byH2O2 appears to be due to a Fenton-type reaction ofH2O2 with Cu, forming a reactive intermediate thatdestroys an essential liganding histidine residue ofthe enzyme. Whiteside and Hassan also demon-strated induction and inactivation of CAT and SODby ozone in cultures of Escherichia coli.35

Furthermore, they showed that an increase in theactivities of CAT and SOD by O3 was due to inductionof the novo enzyme synthesis rather than activationof pre-existing apoproteins. Thus, the observedinduction of SOD, CAT and GSH-Px in response toO3 pretreatment provides further evidence that thereis a correlation between antioxidant enzyme bio-synthesis and O3 exposure.

Additionally, these authors also showed that theantioxidant enzymes are subjected in vivo to thedamaging effects of O3 at relatively high doses.Therefore, in concordance with our results thisobservation provides evidence that O3, besides

inducing the biosynthesis of these enzymes, couldalso cause inactivation of them by the mechanismpreviously explained.

In addition, O3 oxidative preconditioning mightprevent CDDP-induced acute renal failure throughattenuation of renal tubular damage and enhance-ment of the regenerative response of the damagedtubular cells. As shown in Fig. 1, animals treated withi.r. O3 therapy before CDDP recovered the normalstructure of its kidneys 5 days after CDDP adminis-tration, showing a moderate cellular tumefaction, incontrast with CDDP-treated rats, which showedsevere acute tubular necrosis.

In conclusion, a single dose of CDDP leads to theinhibition of renal antioxidant enzyme activity,depletion of renal GSH levels, increased serum Crand enhanced renal lipid peroxidation, which causenephrotoxicity. Our results support the evidence thatpart of the mechanism of nephrotoxicity in CDDP-treated rats is related to depletion and inhibition ofthe antioxidant system. Therefore, the prevention ofthis inhibition in rats protected by i.r. O3 therapysupport the potential use of it at low doses toameliorate CDDP-induced renal injury.

References

1. Lebwohl D, Canetta R. Clinical development of platinum complexes incancer therapy: an historical perspective and an update. Eur J Cancer1998; 34: 1522�/1534.

2. Winston JA, Safirstein R. Reduced renal blood flow in early cisplatin-induced acute renal failure in the rat. Am J Physiol 1985; 249: F490�/

F496.3. Dobyan DC, Levi J, Jacobs C. Mechanism of cis-platinum nephrotoxicity

II. Morphological observations. J Pharmacol Exp Ther 1980; 213: 551�/

556.4. Brady HR, Kone BC, Stromski ME. Mitochondrial injury: an early event in

cisplatin toxicity to renal proximal tubules. Am J Physiol 1990; 258:F1181�/F1187.

5. Baliga R, Ueda N, Walker PD. Oxidant mechanisms in toxic acute renalfailure. Am J Kidney Dis 1997; 29: 465�/477.

6. Matsushima H, Yonemura K, Ohishi K, Hishida A. The role of oxygenfree radicals in cisplatin-induced acute renal failure in rats. J Lab ClinMed 1998; 131: 518�/526.

7. Nath KA, Norby SM. Reactive oxygen species and acute renal failure. AmJ Med 2000; 109: 665�/678.

8. Lau AH. Apoptosis induced by cisplatin nephrotoxic injury. Kidney Int1999; 56: 1295�/1298.

9. Zhang JG, Lindup WE. Cisplatin nephrotoxicity: decreases in mitochon-drial protein sulphydryl concentration and calcium uptake by mitochon-dria from rat renal cortical slices. Biochem Pharmacol 1994; 47: 1127�/

1135.10. Hussain KC, Morris C, Whitworth GL. Protection by ebselen against

cisplatin-induced nephrotoxicity: antioxidant system. Mol Cell Biochem1998; 178: 127�/133.

11. Appenroth D, Frob S, Kersten L, Splinter FK, Winnefeld K. Protectiveeffect of vitamin E and C on cisplatin nephrotoxicity in developing rats.Arch Toxicol 1997; 71: 677 �/683.

12. Somani SM, Husain K, Whitworth C, Rybak LP. Dose-dependentprotection by lipoic acid against cisplatin-induced nephrotoxicity inrats: antioxidant defense system. Pharmacol Toxicol 2000; 86: 234�/240.

13. Babu E, Gopal Krishman V, Sriganth IN. Cisplatin induced nephrotoxi-city and the modulating effect of glutathione esters. Mol Cell Biochem1995; 144: 7�/11.

14. Tsutsumishita Y, Onda T, O Kada K. Involvement of H2O2 production incispaltin-induced nephrotoxicity. Biochem Biophys Res Commun 1998;242: 310�/312.

15. Davis CA, Nick HS, Agarwal A. Manganese superoxide dismutaseattenuates cisplatin-induced renal injury: importance of superoxide.J Am Soc Nephrol 2001; 12: 2683�/2690.

A. Borrego et al


16. Sheikh-Hamad D, Timmins K, Jalali Z. Cisplatin-induced renal toxicity:possible reversal by N-acetylcysteine treatment. J Am Soc Nephrol 1997;8: 1640�/1644.

17. Barber E, Menendez S, Leon OS, et al . Prevention of renal injury afterinduction of ozone tolerance in rats submitted to warm ischemia. MediatInflamm 1999; 8: 37�/41.

18. Beutler F, Duron O, Mikus B. Improved method for the determination ofblood glutathione. J Lab Clin Med 1963; 16: 882�/889.

19. Minami M, Yoshikawa H. A simplified assay method of superoxidedismutase activity for clinical use. Clin Chim Acta 1979; 92: 337�/372.

20. Rice Evans C, Diplock AT. Laboratory techniques in biochemistry andmolecular biology. In: Burtin RH, Knippenberg PH, eds. Techniques inFree Radical Research , Amsterdam: Elsevier, 1991: 199�/201.

21. Faraji B, Kang HK, Valentine JL. Methods for determining Glutathioneperoxidase activity in blood. Clin Chem 1987; 33: 539 �/543.

22. Ohkawa H, Orishi N, Yagi K. Assay for lipid peroxidation in animals andtissues by thiobarbituric acid reaction. Anal Biochem 1979; 95: 351 �/

358.23. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement

with the Folin phenol reagent. J Biol Chem 1951; 193: 165�/175.24. Ikeda S, Fukuzaki A, Kaneto H, Ishidoya S, Orikasa S. Role of protein

kinase C in cisplatin nephrotoxicity. Int J Urol 1999; 6: 245�/250.25. Blochl-Daum B, Pehamberger H, Kurz C, et al . Effects of cisplatin on

urinary thromboxane B2 excretion. Clin Pharmacol Ther 1995; 58:418 �/424.

26. Abdel-Gayoum AA, El-Jenjan KB, Ghwarsha KA. Hyperlipidemia incisplatin-induced nephrotoxic rats. Hum Exp Toxicol 1999; 18: 454 �/

459.27. Murry CE, Richard VJ, Reimer KA, Jennings RB. Ischemic precondition-

ing slows energy metabolism and delays ultrastructural damage during asustained ischemic episode. Circ Res 1990; 66: 913�/931.

28. Neschis DG, Safford SD, Raghunath PN, et al . Thermal preconditioningbefore rat arterial balloon injury: limitation of injury and sustainedreduction of intimal thickening. Thromb Vasc Biol 1998; 18: 120�/126.

29. Riepe MW, Ludolph AC. Chemical preconditioning: a cytoprotectivestrategy. Mol Cell Biochem 1997; 174: 249�/254.

30. Leon OS, Menendez S, Merino N, et al . Ozone oxidative precondition-ing: a protection against cellular damage by free radicals. MediatInflamm 1998; 7: 289�/294.

31. Peralta C, Leon OS, Xaus C, et al . Protective effect of ozone treatment onthe injury associated with hepatic ischemia-reperfusion: antioxidant-prooxidant balance. Free Radic Res 1999; 31: 191�/196.

32. Peralta C, Xaus C, Bartrons R, Leon OS, Gelpı E, Rosello-Catafau J. Effectof ozone treatment on reactive oxygen species and adenosine produc-tion during hepatic ischemia-reperfusion. Free Radic Res 2000; 33: 595�/

605.33. Hernandez F, Menendez S, Wong R. Decrease of blood cholesterol and

stimulation of antioxidative response in cardiopathy patients treatedwith endovenous ozone therapy. Free Radic Biol Med 1995; 19: 115�/

119.34. Marklund SL. Properties of extracellular superoxide dismutase from

human lung. Biochem J 1984; 220: 269�/272.35. Whiteside C, Hassan HM. Induction and inactivation of catalase and

superoxide dismutase of Escherichia coli by ozone. Arch BiochemBiophys 1987; 257: 464�/471.

Received 6 October 2003Accepted 30 October 2003



Submit your manuscripts athttp://www.hindawi.com

Stem CellsInternational

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Immunology ResearchHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinson’s Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttp://www.hindawi.com

protection by ozone

Documents