1 ÖNSÖZ
Testis torsiyonu 25 yaşın altında 1/4000 sıklıkla gözlenen acil bir durumdur. Bu durum infertilite sonuçlanabilen testikuler hasara neden olmasından dolayı acil teşhis edilip tedavi edilmesi gerekmektedir. Testikuler hasarın patolojik mekanizması
kısmen anlaşılmış olup, reaktif oksijen moneküllerin fazla üretilmesi hücre içi ve doku hasarında ana etken olduğu gösterilmiştir. Alpha-lipoic acid, quercetineve melatonin gibi antioksidan moneküller iskemi-reperfüzyon hasarına karşı koruyucu olduğu gösterilmesine rağmen toksik yan etkileri nedeniyle klinik kullanımda olan monekül yoktur.Mannitol Üroloji’de(parsiyelnefrektomi) ve Nöroşiruji’de(intracranial
hemorajide) klinik kullanımı olan aynı zaman antioksidan özelliği bilinen moneküldür.
Biz Namık Kemal Üniversite Bilimsel Araştırma Proje birimi tarafından destek alarak, sıçanlarda deneysel olarak oluşturulan testis torsiyonu modelinde mannitolun
koruyucu etkisini araştıran projeyi sonuçlandırdık.
2 İÇİNDEKİLER
1. Önsöz 1
2. İçindekiler 2
3. Tablolar ve Figürler 3
4. Özet 4
5. Abstract 5
6. Introduction 6
7. Material and Methods 6
8. Experimental Design 6
9. Statistical Analysis 8
10. Results 8
11. Comment 13
12. Conclusions 15
13. References 15
3 Tablolar ve Figürler
Table 1- Experimental groups in study.
Table 2- Histopathologicalevaluation of studygroups
Figure 1.Light microscopy of testicular tissue in different groups.H&E
Figure 2.Light microscopy of testicular tissue in different groups. PCNA
Figure 3-Biochemicalevaluation of anti-oxidantenzymes in studygroups
4
MANNITOLUN TESTİS TORSİYONU ÜZERİNE KORUYUCU ETKİSİ. BİR DENEYSEL ÇALIŞMA
Giriş: Testikuler torsiyon testis hasarına sebep olan acil bir durumdur. Testis
torsiyonunun zarar verici etkisini azaltan herhangi tedavi seçeneği hastanın geleçek hayatı için önemlidir. Bu deneysel çalışmada biz sıçan testis torsiyon modelindeki iskemi-reperfüzyon hasarına mannitolun koruyucu etkisini araştırmayı planladık.
Materyal, Metod:Toplam 32 erkek Spraguee-Dawley sıçan çalışmaya alındı. Her grupta 8 sıçan olmak üzere 4 grup oluşturuldu.Grup A, sağ testis scrotal insizyonla dışarı çıkarılıp torsiyon oluşturulmadan tekrar scrotuma yerleştirilen sham grubuydu.
Grup B, sağ testis 720⁰ saat yönünde döndürülerek torsiyon oluşturulan ve tedavi almayan gruptu. Grup C, benzer şekilde torsiyon oluşturulup torsiyon sonrası saline tedavisi verilen gruptur. Grup D ise torsiyon sonrası mannitol tedavisi verilen
gruptur.Testisler 3 saat sonar detorsiyone edildikten sonra2 saat sonar orşiektomi edildi.
Sonuçlar:Testis yapısı mannitol tedavisi almayan torsiyon gruplarında ciddi şekilde zarar gördü. Öbür yandan, testis dokusunun yapısı koruyucu etki gösteren mannitol tedavisinde belirgin olarak daha iyiydi. Proliferating cell nuclear antigen(PCNA) index ve antioxidant aktivite benzer şekilde mannitol grubunda tedavi almayanve saline grubuna gore yüksekti(p<0.01). Apoptotic index mannitol grubunda tedavi almamış ve saline grubuna gore belirgin şekilde düşüktü(p<0.01).
Tartışma: Mannitol tedavisi almamış testis torsiyonunda seminifer tubul yapısı ciddi şekildebozulmasına ragmen mannitol grubunda yapısal bozukluk belirgin olarak azdı.
Mannitol tedavisinin reaktif oksijen seviyesinide belirgin şekilde azalması apoptozisinde azalmasını sağlayabildi.Bu sonuçlar, diğer organ modellerinde gösterildiği gibi iskemi-reperfüzyon hasarına mannitol tedavisinin koruyucu etkisini gösteren çalışmalarla benzerdir.
Sonuç:Mannitol infüzyonunun, sıçanlarda testis torsiyonu sonrası iskemi reperfüzyon hasarına karşı koruyucu etkisi vardır. Bu deneysel çalışmanın sonuçları insanlarda testis torsiyonunda mannitolun etkinliğini araştırmayı düşünen klinikçilere yol gösterebilir.
Keywords:Testiculartorsion, Mannitol, IschemiaReperfusionInjury, Treatment, Rat Model.
Anaktar Kelimeler: Testis torsiyonu, Mannitol, İskemi-reperfüzyon hasarı, Tedavi, Sıçan modeli
5
MANNITOL HAS PROTECTIVE EFFECT ON TESTICULAR TORSION. AN EXPERIMENTAL RAT MODEL
Introduction: Testicular torsion is an emergency condition that causes testicular injury. Any treatment opportunity reducing the destructive effect of testicular torsion is important for future life of patients. In this experimental study, we aimed to investigate the protective effect of mannitol on I/R injury in rat testes torsion model.
Material, Methods: A total of 32, male SpragueeDawley rats were included to survey. Four experimental groups were formed of each including 8 rats. Group A was a sham group in which the right testis was brought out through a scrotal incision and then replaced to the scrotum without torsion. In Group B, right testis was torsioned by rotating 720⁰ clock-wise and fixed to scrotum without any treatment. In Group C, same testicular torsion process was performed with saline infusion just after testicular torsion. In group D, mannitol infusion was used just after testicular torsion. Testicles were detorsioned after 3 hours and left inside for more 2 hours before orchiectomy.
Histopathological, immunohistochemical and biochemical analysis were performed.
Results: Testicular architecture was significantly disturbed in torsion groups without mannitol infusion. On the other hand, testicular tissue structure was significantly better in mannitol treated group, which demonstrated a protective effect. Similar findings were also shown for proliferating cell nuclear antigen(PCNA) index and antioxidant activity which were higher in mannitol group compared to no treatment and saline groups.(p<0.01) Apoptotic index was also significantly decreased in mannitol treated group compared to no treatment and saline groups.(p<0.01)
Discussion: The seminiferous tubule structure in testicular torsion without mannitol treatment was significantly disturbed whereas the structural disruption was considerable less in mannitol group. Mannitol treatment had also significantly decreased reactive oxygen radical levels and was able to decrease apoptosis. The results were consistent with other organ model studies that evaluated the protective effect of mannitol treatment in ischemia-reperfusion injury.
Conclusion: Mannitol infusion had protective effect against ischemia reperfusion injury in testicular torsion at rats. This experimental study results may guide the clinicians to evaluate the effectiveness of mannitol in human testicular torsion.
Keywords:Testiculartorsion, Mannitol, IschemiaReperfusionInjury, Treatment, Rat Model.
6 Introduction
Testicular torsion is an emergency condition with an incidence of 1/4000 in males under 25 years of age.[1Williamson, 1976] It causes testicular injury, leading to potential of infertility and subfertility; thus, immediate diagnosis and intervention is mandatory.[2 Çay, 2006] Although the main pathological mechanisms of testicular injury in torsion has partially been understood, overproduction of reactive oxygen species(ROS) was implicated as one of the main factors in cellular and tissue damage.[3Dokmeci, 2006] Several antioxidant molecules like alpha-lipoic acid, quercetine and melatonin were found to be effective against ischemia- reperfusion(I/R) injury, but these molecules were unfavourably used in clinical practice because of their toxic side effects.[4-6Aktoz,2010; Kanter, 2010; Ozbal S, 2012]
Mannitol has traditionally been administered before partial nephrectomy to reduce ischemic renal damage as an intravascular volume expander with a function of free radical scavenging, as well as being an osmotic diuretic.[7Zager, 1985] It reduces oxidant-derived injury in kidneys, heart and lungs.[8-10England, 1986;Haraldsson, 1995;Weinbroum, 1999] In this experimental study, we hypothesized that mannitol may have antioxidant protective effect on ischemia and reperfusion injury in testicular torsion and aimed to investigate this protective effect with histopathological and biochemical outcomes in rat testes.
MaterialandMethods
With the approval of local animal care and use committee, a total of 32, 6-months mature male SpragueeDawley rats, weighting between 240 to 280gr. were included to study. We randomly formed four experimental groups, of each including 8 rats(Table-1). All animals were housed at a temperature and light controlled room, with ad libitum access to water and rat chow. All animals received human care according to the criteria outlined in the ‘‘Guide for the Care and Use of Laboratory Animals’’.
Experimental Design
Surgical procedures were performed under ketamine(50mg/kg,i.p.) and xylazine(10mg/kg,i.p.) anaesthesia with sterile conditions. A scrotal midline incision was made and torsion was induced by rotating the right testis 720⁰ clock-wise and maintained by fixing the testis. Same surgical procedure was performed in sham group except testicular torsion. Saline(NaCl at 0.09%,10 mL/kg/min) was administered during the procedure to all groups for hydration. After 3 hours torsion period, the suture was removed with de-torsion procedure. Testis was replaced into the scrotum for an extra 2 hours period. At the end of study, the rats were decapitated and right orchiectomy was performed for biochemical and histopathological examinations.(Table 1)
7 Sham group (Group A): A sham procedure was performed to determine the biochemical and histopathologic basal values. The right testis was brought out through the incision and then replaced to the scrotum without torsion. A 4/0 silk suture was used to fix the testis into the scrotum. After 2 hours period, right testis was removed for evaluation.
Ischemia-reperfusion (I-R)/untreated group (Group B): After 3 hours of unilateral testicular torsion, de-torsion was performed and testis was replaced to scrotum and fixed. The rats in that group only received saline solution (NaCl at 0.02%, 10 mL/kg/min) during the procedure and did not receive any treatment after detorsion process. After 2 hours of detorsion period, right testis was removed for evaluation.
Ischemia-reperfusion (I-R)/saline bolus treated group (Group C): The same surgical procedure (torsion and detorsion) as in group 2 was performed. The rats were given a bolus of saline solution (1 mg/kg;i.v.) immediate after the detorsion. The bolus injection was given intravenously in 2 minutes period and the testis was removed 2 hours after detorsion.
Ischemia-reperfusion (I-R)/mannitol bolus treated group (Group D):The same surgical procedure (torsion and detorsion) as in other groups was performed. The rats were treated with a bolus of mannitol (1 mg/kg;i.v.) immediate after the detorsion. The bolus injection was given intravenously in 2 minutes period that started immediately after reperfusion and the testis was removed 2 hours after the de-torsion.
Table 1- Experimental groups in study.
Testicular specimens were individually immersed in Bouin’s fixative, dehydrated in alcohol and embedded in paraffin. Sections of 5µm were obtained, de-paraffinized, and stained with hematoxylin and eosin(H&E) for evaluation by a histologist in a random order under blindfold conditions with standard light microscopy by the same pathologist. Three slides, prepared from the upper, lower and mid-portions of the testes. Mean seminiferous tubule diameter(MSTD) was measured in micrometers.
Spermatogenesis was assessed histopathologically using Johnsen’s mean testicular biopsy score(MTBS) criteria.[3,4Dokmeci, 2006; Aktoz,2010] A score of 0–10 was given to each tubule according to epithelial maturation. Preparations were evaluated with a bright field microscope(Olympus CX41-Japan) and photographed. We determined testicular tissue antioxidant enzyme activities including catalase(CAT), superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px). Testicular tissue levels of lipid peroxidation products; malondialdehyde(MDA) and xanthine oxidase(XO) activity were also determined.
8 Immunohistochemical reactions were performed according to the avidin biotin complex technique described by Hsu et al. [11Hsu, 1981]. The sections were incubated with specific monoclonal anti PCNA antibody (Cat. #MS-106-B, Thermo LabVision, USA).To quantify the incidence of PCNA, ten seminiferous tubules were counted in each slide. Both stained and non-stained germ cells were counted, and the ratio of stained cells to the total number of germ cells, “PCNA index,” was calculated for each seminiferous tubule.
Germ cell apoptosis was evaluated by the terminal dUTP nick end-labeling (TUNEL) assay. The TUNEL method, which detects fragmentation of DNA in the nucleus during apoptotic cell death in situ, was employed using an apoptosis detection kit (TdT-FragelTM DNA Fragmentation Detection Kit, Cat. No. QIA33, Calbiochem, USA). Quantitative analysis of testicular apoptosis was estimated. The incidence of apoptosis was evaluated in 100 tubules of each testis. These seminiferous tubules containing three or more apoptotic cells by TUNEL stain were calculated. The apoptosis percentage was calculated by the ratio of the positive seminiferous tubules of apoptosis to the total number of seminiferous tubules in a cross-section.
Frozen testis tissue was homogenized. The homogenates were filtered and centrifuged using a refrigerated centrifuge at 4 ⁰C and supernatant were frozen at -20
⁰C in aliquots until used for biochemical assays. The protein content of the supernatant was determined using the Lowry method[12]Catalase, SOD, GSH-Px and MDA level were determined by usingRat ELISA Kit(SRB/Shanghai).
Measurement of serum XO activity was measured spectrophotometrically by the formation of uric acid from xanthine through an increase in absorbance at 293 nm.[13] The results were expressed in units per liter of plasma(U/L).
Statistical Analysis
All data were analyzed with the Statistical Package for the Social Sciences for Windows software(Version 17.0 SPSS, Chicago, IL). Data were presented as mean and standard deviation or percentage. Data in independent groups were analyzed for normalcy with Kolmogorov–Smirnov test and further evaluated with independent t- test or Mann–Whitney U test. Data in dependent groups were analyzed with paired t- test or Wilcoxon signed test after evaluation of normalcy with Kolmogorov–Smirnov test.
RESULTS
The mean MSTD and Johnsen’s MTBS values in each group are shown in table 2.
Mean MSTD and MTBS of the Group B(I/R) and Group C(I/R+saline) were significantly lower than Group D(I/R + mannitol) and sham group(p< 0.01).
9 Histopathological Evaluation
Apoptotic Index PCNA Index MTBS MSTD
Group A 3,88±0,83b 36,47±1,36b 9,23±0,17b 273,25±5,14b Group B 25,88±2,91a,b 22,22±2,34a,b 4,57±0,22a,b 209±6,11a,b Group C 25,52±2,87a,b 22,51±2,99a,b 4,76±0,14a,b 210,63±5,09a,b Group D 15,25±1,48a 29,28±1,66a 6,72±0,25a 229,63±6,18a
Table 2 - Histopathological evaluation of study groups
MSTD; Mean seminiferous tubular diameter, MTBS; Mean testicular biopsy score,
PCNA; Proliferating cell nuclear antigen, I/R; Ischemia- reperfusion,
Group A; Sham operation group, Group B (I/R); Three hours ischemia and two hours reperfusion, Group C (I/R+Saline); Three hours ischemia and two hours reperfusion and saline bolus treated group, Group D (I/R+Mannitol); Three hours ischemia and two hours reperfusion and mannitol bolus treated group.
a P < 0.01 compared to group A b P < 0.01 compared to group D
Testicular architecture was normal in Sham group. Seminiferous tubular morphology was regular with normal spermatogenesis(Fig. 1a). Microscopic findings of testicular tissue were similar in group B(I/R) and group C(I/R+Saline). These findings were a marked decrease in the seminiferous tubular diameter, with severe distortion, extensive disorganization, sloughing, and a loss of maturation of germ cells(Fig. 1b).
The tissue appearance was significantly better in Mannitol group with improved histological findings compared to Group B and Group C(Fig. 1c).
10 Figure 1.Light microscopy of testicular tissue in different groups. H&E: (a)In sham group, normal testicular architecture was seen; (b)After I/R, severe testicular damage was noted; (c)Mannitol treatment prevented testicular damage. (H&E, scale bar, 50 µm).
Under light microscopy, I/R and I/R+Saline groups had similar immunohistochemical findings. There were significant number of PCNA positive cells in sham group(Fig.
2a). The number of PCNA positive germinal cells was lower in the I/R and I/R+Salinegroups(Fig. 2b). PCNA positive germinal cells were also lower in mannitol treated group, compared to sham group(Fig. 2c), but the mean PCNA index of this group was significantly higher than Group B and Group C(p < 0.01)
The amount of germ cell apoptosis was higher in I/R and I/R+Salinegroups(Fig. 2e) compared to sham group(Fig. 2d). Mannitol infusion markedly reduced the numberof germ cell apoptosis.(Fig. 2f)The apoptotic index significantly decreased in mannitol treated I/R group, compared to I/R and I/R+Saline groups.(p < 0.01)
Oxidant(MDA, XO) and antioxidant(GPx, CAT and SOD) levels of the experimental groups are shown in Fig 3. The SOD, CAT and GPx activities in I/R+Mannitol group were significantly higher than those in the I/R group(p<0.01). Malondialdehyde levels in testes were significantly higher in I/R group compared to the sham and the I/R+Mannitol group.(p < 0.01) Xantine Oxidase activity in I/R+Mannitol group were significantly lower than those in the I/R group, but was higher than control group.( p <
0.01)
11 Figure 2.Light microscopy of testicular tissue in different groups. PCNA: (a)In sham group, PCNA positive cells were strongly detected in spermatogonia and early-stage spermatocytes. (b) After I/R, the number of PCNA positive germinal cells were significantly lower in I/R group than sham group.(c) Treatment of mannitol markedly increased the number of PCNA positive germinal cells(Arrowhead: Spermatogonia, Arrow: Germinal cells). TUNEL: (a)In sham group, a few TUNEL positive germ cells are observed in the seminiferous epithelium; (b)Positive cells of TUNEL staining were increased in I/R rats. (c)Treatment with mannitol markedly reduced the number of germ cell apoptosis in the seminiferous epithelium (Arrow:TUNEL-positive germ cells), (Immunoperoxidase, haematoxylin counterstain and TUNEL, scale bar, 50 µm).
Figure 2
PCNA TUNEL
12 Figure 3-Biochemical evaluation of anti-oxidantenzymes in study groups
MDA;Malondialdehyde, GPx;Glutathione peroxidase,SOD; Superoxide dismutase, CAT; Catalase, XO; Xanthine oxidase, I/R. (Values were expressed as mean ± SD, n = 8 for each group.)
Group A;Sham operation group, Group B (I/R); Three hours ischemia and two hours reperfusion, Group C (I/R+Saline); Three hours ischemia and two hours reperfusion and saline bolus treated group, Group D (I/R+Mannitol); Three hours ischemia and two hours reperfusion and mannitol bolus treated group.
a P < 0.01 comparedtogroup A
b P < 0.01 comparedtogroup D.
c P < 0.05 comparedtogroup A
d P < 0.05 comparedtogroup D
MDA GPx SOD XO CAT
Group A 2,72±0,65 35,35±6,57 4,77±0,35 0,21±0,02 27,84±2,81 Group B 8,49±0,85a,b 22,30±5,27a,b 1,85±0,28a,b 0,32±0,03a,b 17,22±3,52a,b Group C 8,22±0,71a,b 21,69±4,16a,b 1,88±0,31a,d 0,31±0,03a,b 17,01±2,04a,b Group D 3,37±0,82 29,84±1,34 2,38±0,28c 0,25±0,02a 22,56±2,43a
13 Comment
Pathogenic mechanism of I/R injury is mostly attributed to overproduction of ROS in various organ models.[2-6 Çay, 2006;Dokmeci, 2006;Aktoz, 2010;Kanter2010;
Ozbal, 2012] During ischemic phase of I/R process, hypoxic condition develops due to the disruption of blood flow. Hypoxic conditions leads to conversion of hypoxanthine deoxygenase to XO, which is a superoxide enzyme generator.[2,14Çay, 2006;Adivarekar, 2005] With restoration of oxygen supply to tissues, mitochondrial respiratory system causes an overproduction of free radicals.
Enzymatic antioxidant defence system, which includes SOD, CAT and GSH-Px, reacts to scavenge the free radicals to protect tissues from I/R injury.[2,3 Çay, 2006;Dokmeci, 2006] Ischemia stimulates chemotactic factors and leads to migration of polymorphonuclear leukocytes to ischemic region, which also generates ROS.[14Adivarekar, 2005] Excessive amounts of ROS react with membrane lipids and results in lipid peroxidation and loss of cellular components.[15 Barlas, 2002]
This lipid peroxidation reaction can indirectly be shown by MDA, which indicates to cellular damage due to ROS affect.[3,6Dokmeci, 2006; Ozbal, 2012]
Changes in tissue antioxidant enzyme activities(CAT, SOD and GSH-Px) and changes in the tissue levels of MDA and XO in the I/R group demonstrated a significant I/R injury in testicular torsion. The most important indicator of tissue injury due to I/R effect was MDA level.[3,6Dokmeci, 2006; Ozbal, 2012] Malondialdehyde was significantly higher in group B(I/R) and Group C(I/R+Saline) compared to Sham group, but was not significantly different in group D(I/R+mannitol). This finding might be related with the ability of mannitol to act as a scavenger of hydroxyl radical, which decreased the devastating affects of I/R reaction. The tissue levels of XO are also an indicator of I/R reaction, which increase rapidly after ischemia. This is probably due to the degradation of xanthine dehydrogenase to XO by the effect of ischemia[16Bulkley, 1987]. During this degradation, highly toxic oxygen free radicals such as superoxide anions and hydrogen peroxide are generated. Compared to Sham group, XO levels were significantly higher in group B and C. On the other hand, XO levels in mannitol group were comparative with Sham group. Similar to our findings, XO levels were significantly increased after reperfusion in double organ models, but the rise of XO levels had been limited by mannitol.[17Weinbroum, 2009]
Mannitol usage was able to decrease unfavourable effects of I/R reaction in testicular torsion.
Reactive oxygen species, such as superoxide anion, hydrogen peroxide, and hydroxyl radicals were generated from oxygen species by the partial de- oxygenation.[18Ray, 2012] Enzymatic antioxidant defence systems, such as SOD, catalase and GSH-Px protect tissues from ROS. Superoxide dismutase is a strong antioxidant that can selectively and rapidly reduces superoxide anion radical to hydrogen peroxide. It can be used for measuring oxidative stress. Glutathione peroxidase is also very effective against cellular damage caused by H2O2. It constitutes the first step in antioxidant defence system against I/R damage.[19Filho, 2004] Catalase is another enzyme that protects tissue from I/R damage. We demonstrated a significant decrease of these antioxidant enzymes in Group B and C compared to Sham group. Infusion of mannitol had protective effect against tissue damage and the decrease of antioxidant enzyme levels were lower in mannitol group compared to Group B and C.
14 Previous studies showed that MSTD and MTBS were good markers for evaluation of tissue damage in early periods of testicular de-torsion.[3-6Dokmeci, 2006; Aktoz, 2010; Kanter 2010; Ozbal, 2012] We also used those findings to investigate the preservative effect of mannitol administration on testicular torsion. The seminiferous tubule structure in testicular torsion without mannitol treatment was significantly disturbed whereas the structural disruption was considerable less in mannitol group.
The MTBS and MSTD values were lowest in non-mannitol torsion group. The difference between non-mannitol and mannitol treated groups were significantly different in terms of MTBS and MSTD values. These differences predicted the preservative function of mannitol in testicular torsion model at rats. Turner et al demonstrated an increase in testicular ROS levels after the repair of torsion and suggested that ROS were responsible for the germ cell apoptosis after detorsion.[20Turner, 1997] With this proposal, antioxidant treatments had been applied to decrease ROS levels and were able to decrease apoptosis in testicular torsion models[4,5,6,20Aktoz, 2010; Kanter 2010; Ozbal, 2012;Turner, 1997]. The number and signal density of TUNEL-positive germ cells were also significantly high in the non-mannitol torsion group. Mannitol treatment reduced the reactivity and the number of apoptotic germ cells. Another predictive factor determining the germ cell damage is PCNA in testicular germ cells, which indicates the reduction of cellular proliferative activity and spermatogenesis. We were able to detect PCNA-positive cells in spermatogonia and early-stage spermatocytes at control rats. However, the signal density of positive cells was significantly lower in non-mannitol treated group.
The rate of PCNA expression in mannitol treated group was also lower than control group, but it was significantly higher than non-mannitol treated group. This finding was comparative to Kanter et al study[5Kanter, 2010].
Beside the free radical scavenger effect of mannitol, its osmotic property had also protective effect against I/R injury. Because of the hyperosmolar property of mannitol, it doesn’t penetrate to cellular membranes which causes hemodilution and dehydration of tissue.[21Rudehill, 1993] Mannitol was shown to decrease blood viscosity and systemic vascular resistance.[22Burke, 1981] In rabbit model, mannitol was able to restore cardiac microcirculatory flow and decreased myocardial damage and edema[23Magovern, 1984]. We also observed a marked decrease of testicular edema with mannitol infusion. Protective effect of mannitol for I/R injury might also be related with restoring the microvascular circulation in the early phase of I/R period and decrease the possible damage of this situation to testicular tissue. On the other hand, it was documented that hypo-osmolarmannitol solution was also effective against organ damage in pancreatic ischemia model, which proposes that not only the osmolality property of mannitol has protective effect against I/R injury.[17Weinbroum, 2009] Even only the antioxidant property of mannitol was able to decrease tissue damage in I/R injury models.
There are also some studies documenting the ineffectivity of mannitol on I/R injury.
Although mannitol was reported to be effective in I/R injury at renal transplantation, it did not show any difference in renal functions at partial nephrectomy models.[24,25Porra, 1992; Omae 2014] Mannitol was also shown to decrease muscular edema in low flow ischemia model, but it caused no difference in no-flow ischemia of gracilis muscle in dog model [26,27Shah 1981,Faust 1988]. The variability between models and treatment dosages could be an explanation for those different results. In a study that was designed by Weinbroum et al, mannitol was
15 found to be effective at a specific dosage and any increase or decrease of that dosage decreased the antioxidant activity of the regimen.[17Weinbroum, 2009] In order to eliminate this possible bias, we used the dosage that had been shown to have antioxidant activity in I/R injury models and we were able to observe a protective effect of mannitol infusion on testicular torsion in rats. Evaluating proper dosage of mannitol for testicular torsion may be meaningfull idea for future researches. Mannitol infusion might also be givenprior to detortion, which might give an idea for its clinical use. Most of the patients with testicular torsion apply to emergency units and there is a time delay between the diagnosis and treatment.
Mannitol infusion during this period may also have protective effect on testicular structure. As we did not have any group demonstrating this data, it is impossible to make a conclusion related with the protective effect of mannitol infusion prior to detortion. This subject will be a suitable new era for future researches.
Conclusions
As a conclusion, mannitol infusion had protective effect against I/R injury in testicular torsion at rats. Unlike the other antioxidant molecules that have toxic side effects, mannitol usage can be a solution to decrease I/R injury in testicular torsion.
This experimental study results may lead to human studies, which will guide the clinicians for the affectivity of mannitol as an antioxidant and tissue preservative treatment for human testicular torsion.
Acknowledgment
The authors do not have any conflict of interests and no competing financial interests exist. This study was financed by scientific research project of Namik Kemal University, Tekirdag, Turkey.
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