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The effects of PPAR-g agonist pioglitazone on renalischemia/reperfusion injury in rats

Buket Reel, PhD,a Mehmet Guzeloglu, MD,b,* Alper Bagriyanik,c Soner Atmaca, MD,c

Koray Aykut, MD,b Gokhan Albayrak, MD,b and Eyup Hazanb

a Faculty of Pharmacy, Department of Pharmacology, Ege University, Izmir, Turkeyb Faculty of Medicine, Department of Cardiovascular Surgery, Izmir University, Izmir, Turkeyc Faculty of Medicine, Department of Histology and Embryology, Dokuz Eylul University, Izmir, Turkey

a r t i c l e i n f o

Article history:

Received 28 May 2012

Received in revised form

20 July 2012

Accepted 9 August 2012

Available online 25 August 2012

Keywords:

Renal ischemia/reperfusion

PPAR-g agonist

MMP

Oxidative stress

Inflammation

* Corresponding author. Department of CardTel.: þ90 532 472 0220; fax: þ90 232 483 5476

E-mail address: mehmetguzeloglu@hotm0022-4804/$ e see front matter ª 2013 Elsevhttp://dx.doi.org/10.1016/j.jss.2012.08.020

a b s t r a c t

Background: Acute renal failure due to renal ischemia/reperfusion (IR) injury is a significant

clinical problem in cardiovascular surgery. Reactive oxygen species and inflammation play

essential roles in the pathophysiology of IR injury. Matrix metalloproteinases (MMPs) are

enzymes that play important roles in inflammation and mediate extracellular matrix

degradation. It is known that peroxisome proliferatoreactivated receptor-g agonists have

antiinflammatory and antioxidant effects. In the present study, we aimed to investigate the

effects of pioglitazone, a synthetic peroxisome proliferatoreactivated receptor-g agonist,

on MMPs and oxidative stress in a renal IR injury model in rats.

Materials and methods: Male Wistar albino rats were divided into three groups: control

(n ¼ 7), placebo (n ¼ 7; saline/p.o.), and pioglitazone (n ¼ 7; 5 mg/kg/day/p.o.). In the control

group, a right nephrectomy was conducted without left renal IR injury. In the placebo and

pioglitazone groups, pretreatments were started 3 d before operation. In both groups, left

renal pedicles were clamped for 60 min and then reperfused for 60 min. Paraffinized renal

sections were evaluated histopathologically. Furthermore, expressions of MMP-2, MMP-9,

tissue inhibitor of metalloproteinase (TIMP)-2, superoxide dismutase 1 (SOD1), and

p47-phox/p67-phox subunits of NADPH oxidase were determined by immunostaining and

scoring.

Results: In the placebo group, renal IR injury induced diffuse tubular necrosis and intense

acute inflammation, but pioglitazone inhibited these effects. MMP-2, MMP-9, and TIMP-2

expression increased in the placebo group. However, while MMP-2 and -9 expression

decreased, TIMP-2 expression did not change in the pioglitazone group. p47-phox/p67-

phox expression increased in the placebo group, but SOD1 expression did not change.

Pioglitazone diminished p47-phox/p67-phox expression, whereas it enhanced SOD1

expression.

Conclusion: Our results suggest that pioglitazone might be helpful to reduce renal IR injury

because of its antiinflammatory and antioxidant effects.

ª 2013 Elsevier Inc. All rights reserved.

iovascular Surgery, Izmir University Medical School, Karsiyaka, Izmir, Turkey..ail.com (M. Guzeloglu).ier Inc. All rights reserved.

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4 177

1. Introduction its reduction in oxidative stress and inhibition of proin-

Renal ischemia/reperfusion injury (IRI) induced by cardio-

vascular surgical procedures, such as thoracoabdominal

aortic aneurysm repair or heart transplantation, is the major

cause of acute renal failure, and also may lead to the devel-

opment or progression of some forms of chronic kidney

disease [1,2]. Development of renal IRI induces the generation

of reactive oxygen species (ROS) and the decline of antioxidant

protection [3,4]. Besides, ischemic damage to the renal

vasculature results in a breakdown of barrier function and

increased adhesiveness to inflammatory cells, both of which

are likely to contribute to the loss of function following

ischemic injury [5e7].

Matrix metalloproteinases (MMPs) are a family of at least

23 structurally and functionally related zinc-dependent

endopeptidases, which regulate fundamental cellular activi-

ties such as cell proliferation, migration, and differentiation

by degrading extracellular matrix [8,9]. Many pathologic

processes, including inflammation and oxidative and nitro-

sative stress, are involved in the increase of MMP expression

and activity. Accordingly, MMPs play an important role in

disease progression after IRI [10,11]. Activities of proin-

flammatory MMPs are controlled by endogenous MMP inhib-

itors, including tissue inhibitors of metalloproteinases

(TIMPs-1e4) [10]. The accumulation of inflammatory cells

during IRI leads to an increase in ROS, reactive nitrogen

species, and proinflammatory cytokines in the ischemic

tissues. All these stimuli can induce strong transcriptional

expression and/or posttranslational activation of MMPs after

an ischemic injury [11].

Peroxisome proliferatoreactivated receptor-g (PPAR-g) is

a ligand-activated transcription factor belonging to the

nuclear hormone receptor superfamily. PPAR-gmodulates the

function of many target genes and participates in the regula-

tion of vital processes such as inflammation, proliferation,

migration, matrix remodeling, and differentiation [12,13].

Thiazolidinediones, which are widely used in the treat-

ment of type II diabetics as insulin sensitizers, are selective

activators of PPAR-g [14]. PPAR-g agonists are likely to exert

their antiinflammatory effects by negatively regulating the

expression of proinflammatory genes that are induced during

macrophage differentiation and activation [12,15,16]. Besides,

PPAR-g agonists have been reported to have a potent antiox-

idant effect and ameliorate oxidative injury [17,18].

In relation to these data, recent evidence demonstrated

that PPAR-g agonists reduce the injury caused by ischemia

and reperfusion of kidney [19,20]. In particular, pioglitazone,

which is a synthetic PPAR-g agonist, was reported to inhibit

inflammation and oxidative stress induced by some IRI

models independently from its insulin-sensitizing effect

[21e24].

Although antiinflammatory and antioxidant protective

effects of pioglitazone in atherosclerosis and IRI in some

organs are known, its effects on intracellular and molecular

mechanisms involved in renal IRI have not been fully clari-

fied yet.

In light of the data collected, we proposed that PPAR-g

agonist pioglitazonemay show renoprotective effects through

flammatory MMPs in an experimental renal IRI model in rats.

2. Materials and methods

This study was approved by the Local Ethics Committee of

DokuzEylulUniversity, SchoolofMedicine.All animals received

care in compliance with the “Principles of Laboratory Animal

Care” formulated by the National Society for Medical Research

and the Guide for the Care and Use of Laboratory Animals.

Animalswere kept in a light- and temperature-controlled room.

They were fed regular rat chow and had free access to water.

2.1. Experimental groups

Male Wistar albino rats, (250e300 g, n ¼ 21) were randomly

divided into three groups, each consisting of seven animals, as

control, placebo, and pioglitazone group. The rats in the

placebo and pioglitazone groups were administered vehicle

(saline) or pioglitazone (5 mg/kg/d) through an orogastric tube

for 3 d before the surgery. Thereafter, the rats were anes-

thetized with an intraperitoneal injection of ketamine (75 mg/

kg) and xylazine (8 mg/kg), an upper abdominal midline inci-

sion was made, and renal blood vessels were isolated bilat-

erally with minimal dissection. A right nephrectomy was

performed in the control group. In the placebo and pioglita-

zone groups, a right nephrectomy followed by occlusion of the

left renal pedicle for 60 min and reperfusion for 60 min was

performed. At the end of the experimental procedure, the rats

underwent a left nephrectomy under anesthesia. Then the left

kidneys of the animals were cut into two halves and imme-

diately fixed in 10% neutral buffered formalin solution for

24e48 h for histologic evaluation, or stored at �80�C for

subsequent biochemical analyses.

2.2. Histologic evaluation of renal injury

The fixed kidney samples were dehydrated through graded

ethanol series. Samples were embedded in paraffin by the

standardmethod and 5-mm-thick sectionsweremounted onto

glass slides. Then, sections were stained with hematoxylin-

eosin or periodic acideSchiff, according to standard proto-

cols. Sections were examined under a light microscope (Leica

DM6000; Leica Microsystems, Wetzlar, Germany), which is

connected to an image capture system, and images takenwith

the digital video camera (Leica DC280; Leica Microsystems)

were transferred to the computer.

Histologic analyses of equally distributed cross-sections

were performed by two masked histologists. One hundred

tubules, 25 fromeachof the fourdifferent areasof kidney (outer

cortex, inner cortex, outer stripe of the outer medulla, and

medullary rays), were randomly evaluated. One hundred

tubules were scored for each section. Themean score for each

of the four regions was calculated. An overall renal tubular

score that included all four regionswas also calculated for each

rat. Tubular atrophywasevaluatedby scoringas follows: 0¼no

atrophy; 1 ¼ <25%; 2 ¼ between 25% and 50%; and 3 ¼ >50%.

Similarly, acute inflammationwasgradedbyscoringas follows;

Table 1 e Histopathologic scores for acute inflammationand tubular necrosis in the renal tissues of rats in thecontrol, placebo, and pioglitazone groups.

Histopathologic scores 0 1 2 3

Acute inflammation

Control (n ¼ 7) 7 0 0 0

Placebo* (n ¼ 7) 0 0 7 0

Pioglitazoney (n ¼ 7) 1 4 2 0

Necrosis

Control (n ¼ 7) 7 0 0 0

Placebo* (n ¼ 7) 0 0 0 7

Pioglitazonez (n ¼ 7) 0 2 5 0

Histopathologic scores were accepted as 0, negative; 1, weak; 2,

moderate; 3, strong.

* P < 0.001, c2 test, control versus placebo group.yP < 0.05, c2 test, placebo group versus pioglitazone group.zP < 0.01, c2 test, placebo group versus pioglitazone group.

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4178

0 ¼ no detectable inflammation; 1 ¼ minimal focal inflamma-

tion; 2 ¼ multifocal polymorphonuclear leukocytes; and

3 ¼ moderate patchy-form polymorphonuclear leukocytes.

2.3. Immunohistochemistry

Five-micrometer sample sections from paraffin-embedded

tissues were incubated at 60�C overnight, then deparaffi-

nized in xylene for 30 min. After the sections were rehydrated

through a decreasing series of ethanol, they were washed in

Fig. 1 e Representative photomicrographs of paraffin transverse

stained with hematoxylin-eosin or periodic acideSchiff. Asteris

indicate hemorrhagia and the arrows show congestion. (Color v

distilled water for 10 min. Then in order to unmask antigens,

they were heated with 10 mM citrate buffer (Cat. #AP-9003-

125, Labvision, Thermo Scientific, Cheshire, UK) for 5 min.

After washing in deionized water three times, each for 2 min,

sections were delineated using a Dako pen (Dako, Glostrup,

Denmark), In order to inhibit endogenous peroxidase activity,

samples were incubated in 3% H2O2 for 5 min. After blocking

with a serum solution for 30 min, the sections were incubated

with primary antibody in a humid chamber for 18 h at þ4�C.Anti-MMP-2 (Cat. #MAB 3308; Millipore, MA), anti-MMP-9 (Cat.

#MAB 3309; Millipore, MA), anti-TIMP-2 (Cat. #MAB 13446;

Chemicon, MA), anti-p47-phox (Cat. #07-001; Upstate, MA),

p67-phox (Cat. #07-002; Upstate, MA), and Cu-Znesuperoxide

dismutase (SOD) (Cat. #07-403; Upstate, MA) primary anti-

bodies were used. Samples were then incubated with bio-

tinylated anti-mouse secondary antibodies and with

streptavidin conjugated to horseradish peroxidase for 30 min,

each prepared according to kit instructions (Cat #85-9043,

Histostain-Plus Bulk Kit Broad Spectrum; Invitrogen, Cama-

rillo, CA). They were finally incubated with 3,30 dia-

minobenzidine hydrochloride (Cat #1718096; Roche, Penzberg,

Germany), and nuclei were counterstained with Mayer’s

hematoxylin. All dilutions and washing steps were performed

with phosphate-buffered saline, pH 7.4. Sections were dehy-

drated through a graded ethanol series, cleared in xylene, and

mounted in Entellan (Cat #107961; Merck, Darmstadt,

Germany). Then, images of the sections were evaluated by an

image analysis system consisting of a light microscope (Leica

DM6000; Leica Microsystems), digital video camera (Leica

sections of left renal cortical and medullary tissues of rats

ks point out the inflammatory cells. Heads of arrows

ersion of Figure is available online.)

Table 2 e Immunoscores for MMP-2, MMP-9, and TIMP-2in the renal tissues from rats in the control, placebo, andpioglitazone groups.

Immunoscores 0 1 2 3

MMP-2

Control (n ¼ 7) 6 1 0 0

Placebo* (n ¼ 7) 0 1 4 2

Pioglitazoney (n ¼ 7) 1 6 0 0

MMP-9

Control (n ¼ 7) 5 2 0 0

Placebo* (n ¼ 7) 0 0 4 3

Pioglitazoney (n ¼ 7) 1 4 2 0

TIMP-2

Control (n ¼ 7) 3 4 0 0

Placeboz (n ¼ 7) 0 4 3 0

Pioglitazone (n ¼ 7) 0 6 1 0

Immunoscores were accepted as 0, negative; 1, weak; 2, moderate;

3, strong.

* P < 0.01, c2test, control versus placebo group.y P < 0.05 c2 test, placebo group versus pioglitazone group.z P < 0.05, c2 test, control versus placebo group.

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4 179

DC280; Leica Microsystems), and an image capture system,

which is connected to the light microscope. Appropriate

positive controls were also stained.

2.4. Biochemical examinations

Renal samples, which were stored at �80�C previously, were

homogenized in 50 mmol L�1 phosphate buffer (pH ¼ 7.4) by

sonication on ice and then extraction was performed. Total

oxidant status (TOS) and total antioxidant status (TAS) were

determined with commercial spectrophotometric kits (RL0024

and RL0017, respectively; Rel Assay Diagnostics, Gaziantep,

Turkey) as previously described [25e27].

Fig. 2 e Representative photomicrographs of paraffin transverse

Immunohistochemical analysis with MMP-2, MMP-9, and TIMP

immunopositive areas. (Color version of Figure is available onli

2.5. Statistical analysis

Statistical analysis was performed using SPSS version 15.0

for Windows (SPSS Inc, Chicago, IL). A c2 test was used to

evaluate the difference of histologic and immunohisto-

chemical data between control, placebo, and pioglitazone

groups. An unpaired Student t-test was used to compare the

biochemical data. P < 0.05 was considered statistically

significant.

3. Results

3.1. Histology

Renal sections were examined histologically and acute

inflammation and tubular necrosis were evaluated by

scoring.

Histologic examination of renal tissues of the control group

showed normal renal morphology (Table 1, Fig. 1).

Renal tubular injury and acute inflammation scores of the

placebo group were significantly higher compared with those

of the control group (P < 0.001) (Table 1, Fig. 1). Diffuse tubular

necrosis, intracytoplasmic vacuolization, hemorrhage,

congestion, and mononuclear cell infiltration were observed

in the cortical and medullary tissue sections of the placebo

group (Table 1, Fig. 1).

Following pretreatment with pioglitazone, both acute

inflammation and tubular injury scores of the pioglitazone

group were significantly lower compared with those of the

placebo group (P < 0.05 and P < 0.01, respectively) (Table 1,

Fig. 1). Minimal congestion and tubular necrosis, and a slight

mononuclear cell infiltration, were observed in the cortical

and medullary tissue sections of the pioglitazone group

(Table 1, Fig. 1).

sections of left renal cortical tissues of rats.

-2 antibodies. Dark brownestained areas show

ne.)

Fig. 3 e Representative photomicrographs of paraffin transverse sections of left renal medullary tissues of rats.

Immunohistochemical analysis with MMP-2, MMP-9, and TIMP-2 antibodies. Dark brownestained areas show

immunopositive areas. (Color version of Figure is available online.)

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4180

3.2. Immunohistochemistry

Immunopositivity for MMP-2, MMP-9, and TIMP-2 was signif-

icantly increased in the placebo group compared with that of

the control group (P < 0.01, P < 0.01, and P < 0.05, respectively)

(Table 2, Figs. 2 and 3). Pioglitazone pretreatment significantly

reduced expression of bothMMPs (P< 0.05) but did not change

TIMP-2 expression (Table 2, Figs. 2 and 3).

Immunoscoring for p47-phox, p67-phox, and SOD1 anti-

bodies demonstrated that immunopositivity for both phox

Table 3 e Immunoscores for p47-phox, p67-phox, andSOD in the renal tissues of rats in the control, placebo,and pioglitazone groups.

Immunoscores 0 1 2 3

p47-phox

Control (n ¼ 7) 7 0 0 0

Placebo* (n ¼ 7) 0 0 1 6

Pioglitazoney (n ¼ 7) 0 5 2 0

p67-phox

Control (n ¼ 7) 6 1 0 0

Placeboz (n ¼ 7) 0 0 4 3

Pioglitazonex (n ¼ 7) 0 4 3 0

SOD1

Control (n ¼ 7) 0 5 2 0

Placebo (n ¼ 7) 1 5 1 0

Pioglitazonex (n ¼ 7) 0 0 5 2

Immunoscores were accepted as 0, negative; 1, weak; 2, moderate;

3, strong.

* P < 0.001, c2 test, control versus placebo group.yP < 0.01, c2 test, placebo group versus pioglitazone group.zP < 0.01, c2 test, control versus placebo group.xP < 0.05, c2 test, placebo group versus pioglitazone group.

antibodies was significantly increased (P < 0.001, P < 0.01,

respectively) (Table 3, Figs. 4 and 5), but SOD immunoposi-

tivity was not affected by renal IRI in the placebo group. Pio-

glitazone treatment significantly decreased both p47-phox

and p67-phox immunopositivity (P < 0.01, P < 0.05, respec-

tively) but increased SOD immunopositivity (P< 0.05) (Table 3,

Figs. 4 and 5).

3.3. Biochemical examinations

Statistical analysis of spectrophotometric data for TOS and

TAS showed that TOS levels were significantly increased but

TAS levels did not change in the placebo group as compared

with those of the control group (P < 0.05) (Fig. 6). In addition,

TAS levels in the pioglitazone group were significantly higher

than those of the placebo group (P < 0.05) (Fig. 6). However,

TOS levelswere similar in the pioglitazone and placebo groups

(Fig. 6).

4. Discussion

Acute renal insufficiency due to ischemia/reperfusion injury

is one of themost common and important complications seen

after cardiovascular procedures that require clamping of the

aorta above the renal arteries, such as repair of coarctation of

the aorta, thoracoabdominal aortic aneurysm repair, and

aortic dissection [28]. Currently, there is no effective agent to

prevent or treat this complication, thus increasing its

morbidity and mortality. Various agents, including PPAR

agonists, are being evaluated in experimental and clinical

studies. PPAR agonists acting via PPAR activation through

different mechanisms have been shown to have preventive

and therapeutic effects on IRI [29e33].

Fig. 4 e Representative photomicrographs of paraffin transverse sections of left renal cortical tissues of rats.

Immunohistochemical analysis with p47-phox, p67-phox, and SOD1 antibodies. Dark brownestained areas show

immunopositive areas. (Color version of Figure is available online.)

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4 181

PPARs are ligand-activated nuclear transcription factors

belonging to the nuclear receptor superfamily. So far three

PPAR isoforms, designated as a, d, and g, have been identi-

fied. These three receptor subtypes are expressed in many

tissues in the human body. Improving insulin sensitivity

in diabetes, cellular differentiation and apoptosis, and anti-

inflammatory effects are the main effects of PPAR-g agonists

[14,34].

It has been demonstrated that PPAR-g agonists suppress

the production of inflammatory cytokines interleukin 1b,

Fig. 5 e Representative photomicrographs of paraffin transverse

Immunohistochemical analysis with p47-phox, p67-phox, and

immunopositive areas. (Color version of Figure is available onli

interleukin 6, and tumor necrosis factor a in stimulated

human peripheral blood monocytes [35]. They exert their

antiinflammatory effects through the negative regulation of

proinflammatory gene expression, which occurs in response

to monocyte/macrophage differentiation or activation [15].

PPAR-g agonists also lead to apoptosis in macrophages stim-

ulated by tumor necrosis factor a / interferon g due to the

inhibition of antiapoptotic nuclear factor-kB signaling

pathway [36]. In addition, it has been shown that these

agonists inhibit MMP and enhance PPAR-g expression [37].

sections of left renal medullary tissues of rats.

SOD1 antibodies. Dark brownestained areas show

ne.)

Fig. 6 e TOS (A) and TAS (B) levels in renal tissues of rats.

Values are represented asmean ± SEM. *P< 0.05, unpaired

Student t-test between control (n [ 5) and placebo (n [ 7)

groups. DP < 0.05, unpaired Student t-test between

placebo (n [ 7) and pioglitazone (Pio) (n [ 6) groups.

j o u r n a l o f s u r g i c a l r e s e a r c h 1 8 2 ( 2 0 1 3 ) 1 7 6e1 8 4182

Previous studies reported that pioglitazone, a PPAR-g

agonist, improves ischemia/reperfusion injury, which causes

intestinal damage [38], gastric mucosal damage [39], and

pulmonary damage [40] and also reduces myocardial infarc-

tion area [41], when pretreatment was performed before

ischemia. Rosiglitazone, another PPAR-g agonist, was shown

to improve renal function after IRI [42]. Hu et al. [43], in their

study on the protective effects of pioglitazone on IRI in mice,

observed that blood urea nitrogen and creatinine levels and

histopathologic scores were lower in animals pretreated with

pioglitazone. They concluded that PPAR activation by piogli-

tazone exerts protective effects on renal IRI in mice by

inhibiting renal cell apoptosis. In the present study, we also

detected significant inflammation and tubular necrosis in the

renal tissue after IRI in the placebo-treated rats. However, the

inflammation and necrosis scores were significantly lower in

the rats pretreated with pioglitazone.

It has been demonstrated that MMP-2 and MMP-9 are

enhanced in postischemic renal tissue and are localized in the

renal tubules, interstitial cells, and tubulointerstitial space

[44]. Moreover, experimental studies revealed that inhibition

of MMP-2 and MMP-9 is associated with a decrease in the IRI

level [45,46]. The present study revealed increased MMP-2,

MMP-9, and TIMP-2 levels after renal IRI. Furthermore,

although no significant difference was observed in TIMP-2

expression, MMP-2 and MMP-9 levels in rats that were pre-

treated with pioglitazone were significantly lower than those

of the placebo group.

The NOX family of NADPH oxidases consists of enzymes

that play a role in various physiological and pathologic

processes, and lead to ROS production. During these processes,

p47-phox and p67-phox, which are the cytosolic subunits of

NADPHoxidase, playorganizerandactivator roles, respectively

[47]. As they are likely to be involved in various disease

processes, NOX enzymes are established drug targets as well

[47,48]. We found that p47-phox and p67-phox expression was

significantly enhanced in the ischemia/reperfusion-induced

rats and was significantly reduced in those pretreated with

pioglitazone.

Schneider et al. [49] reported no difference between the

renal IRI and the control group in terms of the expression of

SOD1, which is the cytoplasmic form of SOD. Similarly, we

also found that there is no difference in SOD1 levels between

IRI-induced and control rats.

It has been reported that PPAR-g activation encodes target

genes, including genes that encode antioxidative enzymes,

such as SOD1, catalase, and thioredoxin [50]. Consistent with

this evidence, the present study demonstrated higher SOD1

levels in rats pretreated with pioglitazone as compared with

those of the placebo group. It has been suggested that renal IRI

is more severe in the event of SOD1 deficiency. Moreover, it

has been stated that SOD1 production is not essential for renal

function under normal conditions, but the antioxidant effect

of SOD1 is beneficial in the case of IRI due to increased ROS

production [51]. From this point of view, it can be suggested

that increased SOD1 levels in the rats preatreated with pio-

glitazone might contribute to the improvement of IRI.

It is known that inhibition of ROS production and removal

of ROS after IRI ameliorates renal injury [52]. In the present

study, IRI-induced rats showed increased TOS levels but

showed no significant difference in TAS levels compared with

those of the controls. TAS level was found to be increased in

those pretreated with pioglitazone.

In conclusion, the present study demonstrated that pio-

glitazone has antioxidant effects due to its regulation of SOD1

and TAS levels and inhibitory effects on proinflammatory

MMPs in a renal IRI model in rats. Our results suggest that

pretreatment with pioglitazone may reduce IRI during renal

transplantation and cardiovascular surgical procedures.

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