EFFECTS OF ENDURANCE TRAINING ON ANTIOXIDANT DEFENSE MECHANISMS AND LIPID PEROXIDATION IN TESTIS OF RATS

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EFFECTS OF ENDURANCE TRAINING ONANTIOXIDANT DEFENSE MECHANISMS AND LIPIDPEROXIDATION IN TESTIS OF RATSY. Aksoy a; T. Yapanoğlu a; H. Aksoy b; B. Demircan b; N. Öztaşan c; E. Çanakçid; İ. Malkoç ea Department of Urology, School of Medicine, Ataturk University, Erzurum, Turkeyb Department of Biochemistry, School of Medicine, Ataturk University, Erzurum,Turkeyc Department of Physiology, School of Medicine, Ataturk University, Erzurum, Turkeyd Department of Anesthesiology and Reanimation, School of Medicine, AtaturkUniversity, Erzurum, Turkey

e Department of Anatomy, School of Medicine, Ataturk University, Erzurum, Turkey

Online Publication Date: 01 August 2006

To cite this Article: Aksoy, Y., Yapanoğlu, T., Aksoy, H., Demircan, B., Öztaşan, N., Çanakçi, E. and Malkoç, İ.(2006) 'EFFECTS OF ENDURANCE TRAINING ON ANTIOXIDANT DEFENSE MECHANISMS AND LIPIDPEROXIDATION IN TESTIS OF RATS', Systems Biology in Reproductive Medicine, 52:4, 319 — 323

To link to this article: DOI: 10.1080/01485010500503587URL: http://dx.doi.org/10.1080/01485010500503587

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EFFECTS OF ENDURANCE TRAINING ON ANTIOXIDANT DEFENSEMECHANISMS AND LIPID PEROXIDATION IN TESTIS OF RATS

Y. Aksoy and T. Yapanoglu & Department of Urology, School of Medicine,Ataturk University, Erzurum, Turkey

H. Aksoy and B. Demircan & Department of Biochemistry, School of Medicine,Ataturk University, Erzurum, Turkey

N. Oztasan & Department of Physiology, School of Medicine, Ataturk University,Erzurum, Turkey

E. Canakci & Department of Anesthesiology and Reanimation, School of Medicine,Ataturk University, Erzurum, Turkey

I. Malkoc & Department of Anatomy, School of Medicine, Ataturk University,Erzurum, Turkey

& Male rats were equally divided into trained rest (TR), trained exhaustive exercise (TE),untrained rest (UR), and untrained exhaustive exercise (UE). Endurance training consisted oftreadmill running for 1.5 h=d, 5 days a week for 8 weeks reaching the speed of 2.1 km=h at the forti-eth week. For acute exhaustive exercise, graded treadmill running was conducted reaching the speedof 2.1 km=h at 95th min, 10% uphill, continued until exhaustion. Testicular tissue malondialde-hyde (MDA), antioxidant potential (AOP) levels, superoxide dismutase (SOD), glutathione peroxi-dase (GSH-Px), glutathione-S-transferase (GST), glutathione reductase (GR) and catalase (CAT)activities were determined. There was a slight decrease, but not significant, in the SOD activity inUE group compared to TE and TR groups. Activity of GSH-Px decreased in the UE group comparedto UR, TR and TE groups. Acute exhaustive exercise did not affect testicular tissue GSH-Px activityin trained rats. Testicular tissue GST activity of the UE group was similar to TE group, but lowerthan UR and TR groups. In UE group, testicular tissue AOP values were lower than UR, TRand TE groups. The oxidative effects of acute exhaustive exercise on the rat testis decreased withendurance training. Endurance training prevents oxidative injuries by eliminating oxygen radi-cals and inhibiting lipid peroxidation via preventing decreases in antioxidant enzyme activities.

Keywords endurance training, antioxidant enzymes, oxidative stress, testis

This research was supported by The Research Foundation of the Ataturk University (2001=53),Erzurum, Turkey. The authors thank Dr. Mustafa Gul and Dr. Fatih Akcay for their invaluable and help-ful suggestions.

Address correspondence to Yılmaz Aksoy, Department of Urology, Medical School, Ataturk Univer-sity, 25240 Erzurum, Turkey. E-mail: [email protected]

Archives of Andrology, 52:319–323, 2006Copyright # Taylor & Francis Group, LLCISSN: 0148-5016 print/1521-0375 onlineDOI: 10.1080/01485010500503587

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INTRODUCTION

Regular exercise provides various beneficial health effects such asreduced risk of cardiovascular diseases, osteoporosis and obesity. Exerciseincreases oxygen consumption as compared with basal levels, particularlyin skeletal and heart muscles. This situation increases production of reactiveoxygen species (ROS), such as superoxide (O2

�� ), hydrogen peroxide(H2O2) and hydroxyl radical (�OH) [6]. Exhausting exercise caused anapproximately threefold increase in ROS concentration in the venous circu-lation of humans [3]. Although there is conflicting evidence whether acuteexercise increases antioxidant levels, it is well established that endurancetraining generally increases levels of several enzymatic and non-enzymaticantioxidants [2]. The process of lipid peroxidation is one of oxidative con-version of polyunsaturated fatty acids (PUFA), which are abundant in testes,and the products malondialdehyde (MDA), which is usually measured asthiobarbituric acid reactive substances (TBARS) or lipid peroxides [13].

While oxidative stress could cause a primary decrease in antioxidants,mobilization from secondary sources elsewhere in the body might increase[6, 9]. The testes contain a low amount of antioxidant enzymes comparedto other tissues, such as liver and kidney [11]. Oxidative damage to thesperm membrane is an important pathophysiological mechanism in maleinfertility [16].

The present study was undertaken to investigate whether endurancetraining reduces acute exhaustive exercise-induced oxidative stress in therat testis.

MATERIALS AND METHODS

Fifty-six male Sprague-Dawley rats (12 wks old), fed with standard lab-oratory chow and water, were used in the study. Animal experimentationswere approved by the Ethical Committee of the Ataturk University andcarried out in an ethically proper way by following the guidelines provided.

Training and Acute Exhaustive Exercise

Rats were equally divided into trained [trained rest (TR) and trainedexhaustive exercise (TE)] and untrained groups [untrained rest (UR) anduntrained exhaustive exercise (UE)] at random. Training continued1.5 h=d, 5 days a week for 8 weeks. During the eighth week of the training pro-gram, the UE group was also accustomed to treadmill running 1.0–1.2 km=h,15 min=day, for 5 days before sample collection. In acute exhaustive exercise,running speed was 1.2 km=h (10% uphill gradient) for the first 10 min. Afterthat, the speed was increased gradually to 2.1 km=h at 95th min, and keptconstant until the rats were exhausted.

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Preparation of Supernatants

Testis were removed, decapsulated and homogenized and the homoge-nates were centrifuged at 10 000 g for 15 min at 4�C and supernatants werestored at�80�C in aliquots until biochemical measurements. Cu-Zn super-oxide dismutase (SOD) activity was estimated by the nitroblue tetrazolium(NBT) reduction by O2

�� generated by the xanthine=xanthine oxidase sys-tem [17]. Glutathione peroxidase (GSH-Px) activity was measured [14].The glutathione-S-transferase (GST) activity was assayed using chlorodinitro-benzene as a substrate [10]. Glutathione reductase (GR) activity was assayedusing oxide glutathione as substrate [15]. Catalase (CAT) activity wasdetermined, the rate of decay of H2O2 absorbance at 240 nm [1]. Testiculartissue antioxidant potential (AOP) value was measured [7].

MDA method was based on the spectrophotometric absorbancemeasurement of the pink colored product of the TBARS [12]. Total TBARSwere expressed as MDA, using a molar extinction coefficient for MDA of1.56� 105 cm�1 M�1. Protein levels of the homogenates were determined[5], with bovine albumin as standard.

RESULTS

Body weights were increased during the 8 weeks of study period of bothtrained (218� 30 vs. 267� 37 g before and after 8-week training, respect-ively) and untrained groups (192� 34 vs. 236� 45 g before and after 8-week training, respectively). There was a slight decrease regarding toSOD activity in UE group when compared with TE and TR groups, but thisdecrease did not reached statistical significance. The activity of GSH-Px wasfound to decrease in the UE group when compared to the UR, TR and TEgroups.

Testicular tissue GST activity of the UE group was lower than those ofthe UR and TR groups (p < 0.05) and similar to that of the TE group.There was no significant difference between TE group and UR or TRgroups regarding to testicular tissue GST activity.

Mean testicular tissue GR activity of the UR group was similar to thoseof other groups. Endurance training significantly decreased testicular tissueCAT activity when compared to the UR group. In TE group, CAT activity wasnot different from UR or UE groups. In UE group, testicular tissue AOPvalues were lower than those of UR, TR and TE groups, and differenceswere statistically significant. There were not any significant differences interms of AOP values among the other groups. Testicular tissue MDAconcentration significantly increased in the UE group as compared toUR, TR and TE groups. There was no significant difference in terms of

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testicular MDA concentration between TE group and UR control group. Inthe TR group, MDA concentration was similar to UR group and lower thanthat of UE group.

DISCUSSION

Acute exhaustive exercise adversely affects testis antioxidant-oxidantsystem in the sedentary group, but not in the trained group. There are con-troversial results regarding the effects of training on the testis oxidativestress. In a previous study, a significant elevation was found in MDA levelsof testis by treadmill swimming at 3 h=day, 5 days=week, for 4 weeks [13].Exercise training for 15 min during the first week and for 30 min the secondthrough to 6.5 weeks significantly decreased the testicular MDA concen-tration [11], in our study, while endurance training did not alter testiculartissue MDA concentration with or without acute exhaustive exercise, acuteexhaustive exercise increased testicular tissue MDA concentration inuntrained rats. Treadmill run (35 m=min., 15% uphill, 1 h=day, 5 days=week,for 18 weeks) prevented the acute exercise-induced increase in MDA levelsin liver and white skeletal muscle in rats [2].This may result from differenttraining protocols in those studies. We applied an 8-week training program,which is longer than those of above studies. Additionally, our daily trainingduration was longer than that of Husain et al. [11], but shorter than ofManna et al.’s [13]. Of the antioxidant enzymes, GSH-Px shows an adaptiveresponse to exercise. In a study, exercise elevated testis GSH-Px activity, butthe increase was insignificant [11]. There was significant reduction intesticular GSH-Px activity after 4 weeks of intensive swimming exercise[13], while acute exhaustive exercise resulted in a decrease in GSH-Pxactivity of untrained rats, but not in trained rats, in line with the findingin erythrocyte trained athletes after exercise [8].

GSH-Px and GR are the most important enzymes in the reduced glu-tathione-oxidized glutathione (GSH-GSSG) cycle [18]. In tissue, formedH2O2 is reduced by GSH-Px, which concomitantly produces GSSG. Theback reduction of GSSG is done by GR GST and GSH are important regu-lators for proliferation and differentiation of germ cells, and they protectthe germ cells against the harmful effects of free radicals [13]. Acuteexhaustive exercise decreased testicular GST activity in sedentary rats, butnot in trained group. In contrast to this finding, unaffected erythrocyteGST activity has been found in rats after 40 min of exercise [4]. In ourstudy, testicular GST activity was not altered by training. This finding agreeswith the results of Husain et al. [11]. Adversely, swimming caused decreasesin testicular GST activity [13].

Testicular GR and SOD activities were unaffected by exercise in bothsedentary and trained groups in our study. Unaffected erythrocyte GR

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and SOD activities have been reported in rats after 40 min exercise at 60%of their peak oxygen consumption [4]. Exercise training significantlydecreased SOD activity, but not GR activity in rat testis [11]. Manna et al.[13] noted a significant reduction in testicular SOD activity after 4 weeksof intensive swimming exercise. Training decreased testicular CAT activityin the present study. A decrease in CAT activity has been found in rats after4 weeks of intensive swimming exercise [13], indicating that H2O2 gener-ated during the exercise is not efficiently scavenged by CAT. However,increased testicular CAT activity is found in trained rats [11].

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