Neutrophil Oxidative Stress Research Articles

Myeloperoxidase ablation ameliorates behavioral and inflammatory-related features in the 5XFAD mouse model of alzheimer's disease (AD)

Background & Aim Myeloperoxidase (MPO) is a potent enzyme expressed mostly by neutrophils, that catalyzes the formation of reactive oxygen species (ROS), mainly hypochlorous acid. MPO is a primary mediator of neutrophils oxidative stress response and was shown to be essential for the formation of neutrophils extracellular traps (NETs). Upon secretion, MPO was also shown to attach to blood endothelial cells and promote their degradation, making it a therapeutic target in multiple clinical incidences, including neurodegenerative disorders. Here, we aimed to assess the role of neutrophil-derived MPO in 5XFAD model of AD. Methods, Results & Conclusion For that purpose, we subjected 5XFAD mice to myeloablative irradiation and bone marrow-repopulation from MPO Knock-out (KO) mice to form 'MPO KO-5XFAD' mice. MPO KO-5XFAD mice exhibited improvement in their risk assessment behavior, as measured by the 'Elevated plus maze/ test and the 'Open field' test, when compared to 5XFAD mice transplanted with WT cells (termed 'WT-5XFAD'). Remarkably, MPO KO-5XFAD mice also showed improved spatial recognition and learning, as was evident in the 'Y-maze' test, the 'Morris water maze' test and by 'Contextual fear conditioning' test. Hippocampal RNA expression analysis by QPCR indicated decreased expression of proinflammatory cytokines in MPO KO-5XFAD mice, along with decreased blood brain barrier damage and reduced expression of murine APOE. Together, these results indicate a substantial involvement of blood-derived oxidative damage in mouse model of AD, and assign MPO as a potential therapeutic target in AD.

Neutrophil gelatinase-associated lipocalin and oxidative stress markers based -scores to improve the diagnostic accuracy of chronic kidney diseases

Neutrophil gelatinase-associated lipocalin and oxidative stress markers based -scores to improve the diagnostic accuracy of chronic kidney diseases

Isoflavone Ameliorated Oxidative Stress and Vascular Damages in Nicotine-Administrated Mice

Nicotine has been linked to the development of abdominal aortic aneurysms. Isoflavones, a group of polyphenolic compounds, reportedly exhibit antioxidant and anti-inflammatory properties and facilitate cardiovascular protection. However, the effects of isoflavone on nicotine-induced abdominal aortic aneurysms have not yet been elucidated. The objective of the current study was to evaluate the inhibitory effect of isoflavone on nicotine-induced weakening of the aortic wall in mouse models. Nicotine reportedly increases the occurrence of abdominal aortic aneurysms by activating endothelin-1 (ET-1), angiotensinogen and the angiotensin II type 1 (AT1) receptor, leading to an increase in neutrophil elastase, oxidative stress, and matrix metalloproteinase (MMP)-2 expression, which causes vascular wall weakness and damage. Immunohistological analyses have indicated that isoflavone significantly inhibits the activation of ET-1, angiotensinogen and the AT1 receptor in nicotine-administered mice. Additionally, isoflavone suppressed elastic fiber destruction and decreased areas positive for MMP-2, neutrophil elastase, and malondialdehyde in the vascular wall of nicotine-administered mice. Considered together, these findings suggest that isoflavone shows potential for preventing vascular wall injury induced by nicotine administration, and that food containing isoflavone may protect against abdominal aortic aneurysms.

Propofol inhibits endogenous formyl peptide-induced neutrophil activation and alleviates lung injury

Critically ill patients have a high risk of sepsis. Various studies have demonstrated that propofol has anti-inflammatory effects that may benefit critically ill patients who require anesthesia. However, the mechanism and therapeutic effect remain incompletely understood. Our previous data suggest that propofol can act as a formyl peptide receptor 1 (FPR1) antagonist. Here, we hypothesize that propofol mitigates sepsis-induced acute lung injury (ALI) by inhibiting mitochondria-derived N-formyl peptide-mediated neutrophil activation. Oxidative stress caused by activated neutrophils is involved in the pathogenesis of ALI. In human neutrophils, propofol competitively reduced the release of superoxide and associated reactive oxygen species induced by fMMYALF, a human mitochondria-derived N-formyl peptide, suggesting that propofol effectively suppresses neutrophilic oxidative stress. In addition, propofol significantly inhibited fMMYALF-induced elastase release, chemotaxis, calcium mobilization, and phosphorylation of protein kinase B and mitogen-activated protein kinases. These results indicate that propofol suppresses neutrophil activation by blocking the interaction between endogenous N-formyl peptide and its receptor, FPR1, thus inhibiting downstream signaling. Furthermore, propofol alleviated alveolar wall disruption, edematous changes, and neutrophil infiltration in lipopolysaccharide-induced ALI in mice. Noticeably, propofol improved the survival of sepsis mice. This study indicates that the anti-neutrophil effects of propofol may benefit critically ill septic patients.

Chrysin attenuates carrageenan-induced pleurisy and lung injury via activation of SIRT1/NRF2 pathway in rats

Chrysin, a natural polyphenol plentifully contained in honey, propolis, vegetables and fruits, it has been reported to exert a variety of pharmacological activities. In the present study, we mainly investigated the protective effects and underlying molecular mechanisms of chrysin on carrageenan-induced lung injury in rats. The results showed that chrysin inhibited the neutrophils infiltration, attenuated histological injury of lung tissues, decreased PMNs markers level and oxidative stress markers levels of lungs in rats. Further studies showed chrysin can inhibit the NF-кB activation in neutrophils cells, activate SIRT1/NRF2 pathway and reduce the expression of adhesion molecule in lung tissues. Taken together, these results suggested that chrysin can attenuate carrageenan-induced lung injury via inhibition of neutrophils activation and oxidative stress response, and that this attenuation is, at least partially, related to up-regulation of SIRT1/NRF2 signaling pathway. This study also validates SIRT1/NRF2 is an effective pharmacological target to protect against carrageenan-induced lung injury.

Photobiomodulation reduces neutrophil migration and oxidative stress in mice with carrageenan-induced peritonitis.

The purpose of the study is to investigate the effects of two doses of photobiomodulation (PBM) on inflammatory parameters including cell migration and oxidative stress in carrageenan-induced peritonitis models. Twenty-eight mice were divided into four groups: saline; untreated carrageenan (Cg; inflammation induced); and PMB treatment groups L1 and L5 (inflammation induced with carrageenan followed by laser irradiation at 1 and 5J/cm2, respectively). After 30min of inducing inflammation, laser irradiation was administered every hour, for 4h. Peritoneal fluid was collected for analyses. The total leukocyte number in the peritoneal fluid in L1 (4.33 ± 2.34) and L5 (4.95 ± 2.86) after PBM was lower than that in Cg (10.93 ± 5.15cells/ml). The average differential count of neutrophils in the Cg was 9.46 ± 4.31cells/ml, which was higher than that in L1 (3.7 ± 2.08) and L5 (4.94 ± 2.57). Myeloperoxidase activity was also lower in L1 (1.89 ± 0.43) and L5 (4.84 ± 2.62) than in Cg (22.92 ± 4.52UMPO/ml). Malondialdehyde content was lower in L1 (137.5 ± 12.33) and L5 (169.6 ± 22.77) than in Cg (345.7 ± 65.67nmol/ml). Glutathione peroxidase concentration was significantly higher in L1 (155.2 ± 12.43) and L5 (145.9 ± 9.585) than in Cg (79.75 ± 9.567μ/ml). Nitrite concentration was lower in L1 (0.3317μM ± 0.0669) and L5 (0.2429μM ± 0.0232) than in Cg (0.8380μM ± 0.01615). Laser irradiation at 1 and 5J/cm2 reversed the inflammation (as indicated by neutrophil infiltration and oxidative stress).

Luteolin attenuates neutrophilic oxidative stress and inflammatory arthritis by inhibiting Raf1 activity

Neutrophils play a significant role in inflammatory tissue injury. Activated neutrophils produce reactive oxygen species (ROS), release proteases, and form neutrophil extracellular traps (NETs), significantly affecting the pathogenesis of inflammatory arthritis. We examined the therapeutic effects of luteolin, a flavone found in many plants, in neutrophilic inflammation and on acute inflammatory arthritis. Luteolin significantly inhibited superoxide anion generation, ROS production, and NET formation in human neutrophils. The increase in elastase release, CD11b expression, and chemotaxis was also inhibited by luteolin. Luteolin significantly suppressed phosphorylation of extracellular signal-regulated kinase (Erk) and mitogen-activated protein kinase kinase-1 (MEK-1), but not c-Jun N-terminal kinase (JNK) and p38 mitogen–activated protein kinase (MAPK). Analysis of the molecular mechanism further revealed that luteolin acts as a Raf-1 inhibitor. In mice with complete Freund’s adjuvant-induced arthritis, luteolin ameliorated neutrophil infiltration as well as the thickness of paw edema and ROS production. In conclusion, in addition to its known ROS scavenging effect, this study is the first to provide evidence that luteolin diminishes human neutrophil inflammatory responses by inhibiting Raf1-MEK-1-Erk. Our results focused on the importance of neutrophil activation in inflammatory tissue injury and offer opportunities for the development of luteolin’s therapeutic potential to attenuate neutrophilic inflammatory diseases.

Polynuclear neutrophil variation and oxidative stress in Type 2 Diabetics

Polynuclear neutrophil variation and oxidative stress in Type 2 Diabetics

A novel NOX2 inhibitor CYR5099 attenuates neutrophilic oxidative stress and inflammatory paw injury in mice

A novel NOX2 inhibitor CYR5099 attenuates neutrophilic oxidative stress and inflammatory paw injury in mice

Heme Drives Oxidative Stress-Associated Cell Death in Human Neutrophils Infected with Leishmania infantum.

Free heme is an inflammatory molecule capable of inducing migration and activation of neutrophils. Here, we examine the heme-driven oxidative stress-associated cell death mechanisms in human neutrophils infected with Leishmania infantum, an etiologic agent of visceral leishmaniasis (VL). We first performed exploratory analyses in a population of well characterized treatment-naïve VL patients as well as uninfected controls, who were part of previously reported studies. We noted a positive correlation between serum concentrations of heme with heme oxygenase-1 (HO-1) and lactate deydrogenase, as well as, a negative correlation between heme values and peripheral blood neutrophils counts. Moreover, in vitro infection with L. infantum in the presence of heme enhanced parasite burden in neutrophils, while increasing the production of reactive oxygen species and release of neutrophilic enzymes. Additional experiments demonstrated that treatment of infected neutrophils with ferrous iron (Fe+2), a key component of the heme molecule, resulted in increased parasite survival without affecting neutrophil activation status. Furthermore, stimulation of infected neutrophils with heme triggered substantial increases in HO-1 mRNA expression as well as in superoxide dismutase-1 enzymatic activity. Heme, but not Fe+2, induced oxidative stress-associated cell death. These findings indicate that heme promotes intracellular L. infantum survival via activation of neutrophil function and oxidative stress. This study opens new perspectives for the understanding of immunopathogenic mechanisms involving neutrophils in VL.

Inhibition of leukotriene B4 synthesis protects against early brain injury possibly via reducing the neutrophil-generated inflammatory response and oxidative stress after subarachnoid hemorrhage in rats

Leukotriene B4 (LTB4) is a highly potent neutrophil chemoattractant and neutrophils induces inflammatory response and oxidative stress when they recruit to and infiltrate in the injuried/inflamed site, such as the brain parenchyma after aneurysmal subarachnoid hemorrhage (SAH). This study is to investigate the potential effects of inhibition of LTB4 synthesis on neutrophil recruitment, inflammatory response and oxidative stress, as well as early brain injury (EBI) in rats after SAH. A pre-chiasmatic cistern SAH model of rats was used in this experiment. SC 57461A was used to inhibit LTB4 synthesis via intracerebroventricular injection. The brain tissues of temporal lobe after SAH were analyzed. Neuronal injury, brain edema and neurological function were evaluated to investigate the development of EBI. We found that inhibition of LTB4 synthesis after SAH could reduce the level of myeloperoxidase, alleviate the inflammatory response and oxidative stress, and reduce neuronal death in the brain parenchyma, and ameliorate brain edema and neurological behavior impairment at 24h after SAH. These results suggest that inhibition of LTB4 synthesis might alleviate EBI after SAH possibly via reducing the neutrophil-generated inflammatory response and oxidative stress.

225 - Pre-fibrotic Status in the Lung of a Mouse Model of Metabolic Syndrome: Implication of Oxidative Stress and Inflammation

Obesity is a low-grade chronic inflammatory disease resulting from adipose tissue inflammation. Metabolic syndrome (MS) is the most serious consequence of obesity. Although many organs are affected in the MS, its impact on lung biochemistry is less known. Herein we aimed at determining the impact of MS on redox/inflammatory status and potential consequences in the lung using a previously developed mouse model of MS. To achieve this goal, 6 week-old male C57BL / 6J mice were fed for 16 weeks with a low fat- (LFD) or a high fat-diet (HFD, chicken fat) and water supplemented with 10% fructose (F). Thus, the experimental design included 2 groups: LFD (control) HFD+F (MS). Compared to control, the lung parenchyma of MS mice showed increased neutrophils content, MPO activity, oxidative stress (NOX-2, carbonyls, TBARS and nitrotyrosine) and inflammation markers (iNOS, ICAM-1, TNF-α and IL-6). In addition and compared to LFD, the lung parenchyma of HFD+F mice had a lower total antioxidant capacity, GSH/GSSG ratio; and activity of catalase, superoxide dismutase and glutathione peroxidase. Interestingly and compared to LFD, the lung parenchyma of HFD+F mice had an increased pro-fibrotic status as assessed by trichromic stain and TGF-β expression. In this study, we report a mouse model of MS showing lung oxidative stress/inflammation and a profibrotic status.

Microparticles Triggered by CO 2 Induce Colonic Lymphocyte Activation

Background Elevations of CO2 on the order of 0.4%, as occur in poorly ventilated buildings and people with obstructive sleep apnea, stimulate neutrophil oxidative stress triggering generation of microparticles (MPs) that cause vascular injuries in colon and elsewhere (FRBM 106:406, 2017 and J Appl Physiol 123:297, 2017). We hypothesized that the MPs will alter colonic T-lymphocyte mitotic responses and CO2 and/or MPs may alter colonic microbiota. Methods Control mice and those exposed to air+0.4% CO2 for 4 days were euthanized, lamina propria CD4+ T cell isolated from distal colon to assess proliferative responses to protein from autologous fecal extracts, and for microbiome analyses after fecal DNA and RNA extractions. T-cell mitotic responses were assessed as (H3) thymidine incorporation and results normalized to responses from control cells incubated in RPMI buffer. Results CD4 cells from CO2 mice exhibited 1.60 + 0.07 (n=15 all groups, SE, p + 0.07 and 1.64 + 0.07 fold . Control CD4 cells did not respond to control fecal protein challenge (1.04 + 0.03) but did to CO2 fecal challenge (1.40 + 0.06, p . 001). Interventions that eliminated blood-borne neutrophil-derived MPs including injection with neutrophil-Ly6G specific F(ab)2 fragments and polyethylene glycol telomere B surfactant abrogated CO2 mouse CD4 cell mitotic responses: respectively, 1.08 + 0.01 and 1.02 + 0.03 fold (NS). A single injection with 500 mg/kg ascorbic acid also abrogated response, 1.02 + 0.01 fold. Fecal microbiota species identified by DNA profiling and metatranscriptome sequence abundance analysis demonstrated nominal differences due to CO2 exposures. Conclusion Colonic CD4+ T-cells are activated by circulating MPs and when MPs elevations are inhibited, colonic vascular integrity and T-cell changes do not occur. Response to ascobic acid suggests that oxidants on or derived from MPs may contribute to T-cell activation.

Opioid-mediated Neutrophil Microparticle Production and NLRP3 Inflammasome Activation Cause Vascular Damage

Background Opioid-receptors are found on leukocytes within and outside the central nervous system. Inflammation and interleukin (IL)-1β, in particular, play major roles in addiction. Because IL-1β must be packaged within extracellular vesicles for transport, we hypothesized that opioids stimulate production of microparticles (MPs). Methods Human and murine neutrophil MPs production were assessed by flow cytometry in response to morphine and hydromorphone ex vivo , and mice were injected with drugs to assess in vivo responses. Results Human and murine neutrophils generate MPs high in IL-1β by a complex oxidative stress response involving mitochondria, NADPH oxidase and nitric oxide synthase-2, similar to that seen with other stimuli (FRBM 106:406, 2017). After 1 hour incubation of 550 murine neutrophils, 0, 0.1, 1, 5 and 10 µM morphine triggered generation of, respectively (mean + SE, n=3, *p + 5, 296 + 34, 1351 + 179*, 2560 + 413* and 3113 + 982* MPs. IL-1β content of MPs was similarly increased such that control MPs had 1.6 + 0.6 pg/million MPs whereas those generated due to 10 µM morphine had 92.8 + 8.1 (p . 01) pg/million MPs. Morphine responses were inhibited by 1 µM naloxone (opioid-receptor antagonist). When injected into mice, morphine and hydromorphone increase blood-borne MPs with surface proteins indicative of production by neutrophils (Ly6G+), microglia (P2Y12 and CD45+) and endothelium (CD31+/CD41-dim). Time-course and dose-responses demonstrated diffuse capillary leak similar to that seen with other stimuli (J Appl Physiol 123:297, 2017) likely due to neutrophil MPs, spinal microglia activation assessed as CD68 expression by immunohistochemistry, and progressive elevations of circulating microglia MPs with repetitive dosing. Conclusion Opioid-receptor stimulation triggers neutrophil oxidative stress, MPs production and NLRP3 inflammasome activation. Circulating MPs cause vascular injuries and may play a critical role in opioid addiction.

Spectroscopic studies and thermal analysis of mononuclear metal complexes with moxifloxacin and 2,2′-bipyridine and their effects on acute lung injury induced by hydrochloric acid in rats

The article describes the interaction of Y(III), Zr(IV), La(III), Ce(IV) and U(VI) with moxifloxacin hydrochloride and 2,2′-bipyridine. Characterization of complexes was made by elemental analyses, molar conductivity, magnetic moment measurements and spectral measurements e.g. IR, UV–Vis., 1H NMR and mass as well as thermal analyses (TG and DTG). The molar conductivity shows that the complexes are electrolytes nature. Spectroscopic investigation of the solid complexes studied here indicate that moxifloxacin hydrochloride and 2,2′-bipyridine are coordinated to the metal ions in a neutral bidentate manner. After complete characterization, the chemical formulae of the complexes were established. The calculated bond length and force constant, F(UO), in the uranyl complex are 1.756 Å and 637.90 Nm−1, respectively. Kinetic and thermodynamic parameters were determined using Coats–Redfern and Horowitz–Metzger equations. Establishment of hydrochloric acid that induce acute lung injury (ALI) in rats by intratracheal administration through damaging the alveolar epithelium and activation of the neutrophil and subsequent oxidative stress by increasing malondialdehyde (MDA), tumor necrosis factor (TNF-α) and neutrophil, which were confirmed by histopathological investigation while decreasing in antioxidant enzymes and lymphocytes. Whereas treatment with mixed-ligand metal complexes significantly decrease MDA, TNF-α and neutrophils and increase antioxidant and lymphocytes.

The Role of NrF2 in the Regulation of Periodontal Health and Disease

Immune-related disease tolerance is an important defense strategy that facilitates the maintenance of health in organs and tissues that are commonly colonized by bacteria. Immune tolerance to dysbiotic, tooth-borne biofilms is a poorly understood yet clinically relevant concept in the immunopathological mechanisms that are involved in the pathogenesis of periodontitis, particularly those related to neutrophil and macrophage responses. In periodontal health, neutrophils and macrophages respond to the formation of pathogenic bacterial biofilms by the production of bactericidal reactive oxygen species (ROS). However, when released in excess, ROS cause tissue damage and exacerbate inflammation. To counter these destructive responses, many cell types, including neutrophils and macrophages, launch a dedicated antioxidant system that limits the cell and tissue-damaging effects of ROS. The expression of antioxidants is primarily regulated by genetic response elements in their promoters. Here we consider the roles of nuclear factor erythroid 2-related factor (NrF2), a transcription factor, and other key regulators of antioxidants. The concept of disease tolerance, neutrophil and macrophage-generated oxidative stress, and their relationship to the pathogenesis of periodontitis is reviewed. We focus on the regulation of NrF2 and recent evidence suggesting that NrF2 plays a central role in host protection against tissue destruction in periodontitis.

Anti-inflammatory effect of the monoterpene myrtenol is dependent on the direct modulation of neutrophil migration and oxidative stress

Myrtenol is a bicyclic monoterpene with anti-inflammatory properties. However, the mechanisms involved are partially unknown. Here, we investigated the effect of myrtenol during experimental chronic arthritis and the possible modulating activity of oxidative stress and neutrophil migration. Complete Freund's Adjuvant (CFA)-sensitized rats were treated with vehicle (1 mL/kg, po), myrtenol (12.5, 25 or 50 mg/kg, po), indomethacin (10 mg/kg, po) or dexamethasone (0.4 mg/kg) followed by intra-articular injection of CFA (0.5 mg/mL, 50 μL per joint). Then, paw edema and articular incapacitation (paw elevation time) were evaluated for 14 days. On the last day, a blood concentration superoxide dismutase (SOD) and nitrite was determined. In another experimental setting, human neutrophils were incubated with vehicle (sterile saline, 1 mL) or myrtenol (10–100 ng/mL) and the in vitro chemotaxis to N-formylmethionine-leucyl-phenylalanine (fMLP) (10−7 M/well) was evaluated. In addition, antiinflammatory effect of myrtenol was investigated in carrageenan-induced peritonitis. We found that CFA induced a prominent paw swelling and incapacitation of the joint, which were significantly prevented by myrtenol (P < 0.05). In addition, blood accumulation nitrite was attenuated by myrtenol when compared with vehicle-treated CFA group (P < 0.05). Furthermore, plasma levels of SOD were significantly increased by myrtenol versus vehicle-treated CFA group (P < 0.05). Moreover, fMLP-triggered neutrophil chemotaxis and carrageenan-induced peritonitis were markedly prevented by myrtenol (P < 0.05). Therefore, myrtenol showed anti-inflammatory and antinociceptive effects on experimental chronic arthritis, which seems to be related to the direct modulation of neutrophil migration and antioxidant activity.

Evaluation of Total, Active, and Specific Myeloperoxidase Levels in Women with and without Endometriosis

Myeloperoxidase (MPO) is a proinflammatory enzyme and a marker for neutrophil activation and oxidative stress. Since oxidative stress and inflammation are linked to the pathogenesis of endometriosis, we hypothesized that the total, active, and specific (active/total) MPO levels were significantly different in plasma of women with and without endometriosis. Samples were selected from our biobank from women with endometriosis (n = 212) and controls without endometriosis (n = 121) across the menstrual cycle. Total MPO plasma levels were measured by immunoassay and MPO activity by enzymatic assay. Total and active MPO levels did not differ significantly among endometriosis cases and controls, whereas the specific MPO activity was significantly lower in women with endometriosis than that in controls (p = 0.0159). After the subdivision of control patients into women with a normal pelvis and women with other benign gynecological disorders, a significant difference was observed only between women with endometriosis and women with other benign gynecological disorders (p = 0.0266). In conclusion, systemic MPO levels may not be suited as a single biomarker for endometriosis. Our data support the involvement of MPO in other gynecological disorders but do not provide any evidence for an association with endometriosis.

Protective and therapeutic effects of Danhong injection on acute pancreatitis‑associated lung injury.

Lung functional impairment caused by acute pancreatitis (AP) is the primary contributor to AP‑associated mortality. Previous studies have reported that AP‑associated lung injury is associated with systemic inflammatory response syndrome and oxidative stress. In the present study, the protective effects of Danhong injection (DHI), a widely used Chinese Traditional Medicine preparation, on AP‑associated lung injury in rats was examined. The myeloperoxidase activity, malondiadelhyde level and superoxide dismutase activity determination demonstrated the anti‑inflammatory and anti‑oxidative properties of DHI. The results of western blotting and reverse‑transcription‑semi‑quantitative polymerase chain reaction indicated that DHI could protect rats against AP‑associated lung injury, and the protective effect was associated with the suppression of nuclear factor‑κB activation and cell adhesion molecule expression, and the reduction of neutrophil infiltration and oxidative stress levels. As demonstrated by HE staining, DHI inhibited the pancreas and lung tissue injury. Therefore, DHI could be a potential candidate for the treatment of patients with AP‑associated lung injury.

Effects of platelet-rich plasma against experimental ischemia/reperfusion injury in rat testis

Testicular torsion is a common problem and, to date, there is no agent to preserve testicular function following detorsion. Platelet-rich plasma (PRP), with its rich growth factor composition, has proven beneficial in regenerative therapy. It is believed that PRP has not been studied in testis for ischemia/reperfusion (I/R) injury. This study investigated the effect of PRP in an I/R rat model 1 month after detorsion. Of 24 adult male Sprague-Dawley rats, 18 were randomly assigned into three groups, with six in each: control, I/R and I/R+PRP. The PRP was prepared from the remaining six. Each group underwent right orchiectomy. Ischemia was performed by rotating the left testis 720° and fixing with a nylon suture for 4h. Reperfusion occurred 4h later by removing the suture, and PRP was administered at a dose of 10μl (2000×109/l) into the left testis via the intraparenchymal route. Animals were sacrificed at the fourth week, and testes were taken for malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), myeloperoxidase (MPO), transforming growth factor β (TGF-β), and caspase-3 measurements. Ischemia/reperfusion caused a significant increase in MDA, MPO and caspase-3 activity, and significant decrease in GSH levels and SOD activity. The PRP treatment helped correct the alterations in SOD, caspase-3, and MPO activities and MDA levels. However, the mean MDA level and MPO activity were not totally restored compared with the controls. Serum testosterone levels of the I/R group were significantly lower compared with the control and I/R+PRP groups. TGF-β and caspase-3 protein expressions were significantly higher in the I/R group compared with the control group and were low with PRP administration compared with I/R groups (summary Table). The findings of the present study suggest that PRP, by inhibiting neutrophil infiltration and oxidative stress and increasing antioxidant defense, exerts protective effects on testicular tissues against I/R. This study had some limitations: a scoring system was not used in the assessment of spermatogenesis in the histopathological findings and specific testis cell types were not histologically assessed. In light of the biochemical, histological and, especially, hormonal findings, intraparenchymal PRP injection may have a protective effect in testicular tissue against I/R injury.