Ischemia-reperfusion Injury In Rat Kidney Research Articles

The Effect of Fingolimod on Renal Ischemia/Reperfusion Injury in a Rat Model.

Ischemia/reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI) that induces inflammation and oxidative stress. The main goal of the current study was to assess the impact of fingolimod on kidney IRI in rats. For this purpose, 18 male Wistar rats (220-250g) were divided into three groups including (i) Sham, (ii) I/R, and (iii) fingolimod+I/R. The last group was pretreated with a single dose of fingolimod (1mg/kg) (intraperitoneal injection) before induction of the I/R injury. Kidney function, oxidative stress marker (malondialdehyde), and antioxidant markers (catalase, superoxide dismutase, glutathione, glutathione peroxidase, and total antioxidant capacity) were determined in the kidney tissue of the rats. Moreover, kidney samples were taken for histological analysis. Fingolimod pre-treatment could significantly improve the glutathione peroxidase (p<0.01) and glutathione (p<0.001) activities along with the total antioxidant capacity levels (p<0.001) when compared to the I/R group. Moreover, significant recovery of kidney function and histology was seen in the fingolimod+ I/R group compared to the I/R group (p<0.01). Fingolimod pretreatment could improve renal function, antioxidant capacity, and histological alterations after I/R injury. Hence, it might protect the kidney against IRI-related kidney damage including AKI and transplantation.

Angiotensin II Type 2 Receptor (AT2R) Modulates CD4+ T Cells into Regulatory T Cells (Tregs) in Kidney Ischemia-Reperfusion Injury in Rats: Role of PP2A

Angiotensin II Type 2 Receptor (AT2R) Modulates CD4+ T Cells into Regulatory T Cells (Tregs) in Kidney Ischemia-Reperfusion Injury in Rats: Role of PP2A

Does Ambroxol alleviate kidney ischemia-reperfusion injury in rats?

Objective(s):Ischemia-reperfusion injury is a life-threatening clinical problem that can occur after transplantation or a number of clinical procedures. The purpose of the study was to investigate the effects of Ambroxol on kidney damage caused by experimentally induced ischemia-reperfusion injury in rats. Materials and Methods:Wistar albino rats were divided into 3 groups: Control (CTR, n=6), Kidney ischemia-reperfusion (K-IR, n=6), And kidney ischemia reperfusion+Ambroxol (K-IR+AMB, n=6). In K-IR+AMB group, Ambroxol (30 mg/kg) was administered orally 30 min before the ischemia period. K-IR and K-IR+AMB groups underwent 45 min of kidney ischemia followed by a 6-hour reperfusion period. At the end of the reperfusion period, blood and kidney tissue samples were collected after euthanasia. From the blood samples, BUN and creatinine levels were determined to assess kidney function, and TNF-α and IL-1β concentrations were evaluated to determine inflammatory response. Results:While serum BUN, creatinine activities, and TNF-α and IL-1β concentrations were higher in both IR groups compared with the CTR group, these values were found to be lower in the K-IR+AMB group compared with the K-IR group. Histopathological examination revealed that interstitial edema and desquamation of tubular cells in the K-IR group were more severe than in the K-IR+AMB group. Conclusion:Ambroxol treatment alleviated the production of pro-inflammatory cytokines and the harmful cellular effects in the tubular cells.

Assessment of the Nephroprotective Properties of the Erythropoietin Mimetic Peptide and Infliximab in Kidney Ischemia-Reperfusion Injury in Rats.

Chronic kidney disease (CKD) or acute kidney injury (AKI) causes impaired kidney function, leading to cognitive impairment, neuropathy, and cerebrovascular disease. Due to kidney damage, toxinsstay in thebloodrather thanleavingthebodythrough the urine, and brain function is affected by kidney-brain interaction. The present study aimed to investigate the protective effects of erythropoietin mimetic peptide (pHBSP) and infliximab on ischemic renal reperfusion injury. The experiment was performed on 70 white male Wistar laboratory rats which received recombinant erythropoietin, pHBSP, and infliximab. Under anesthesia, traumatic vascular clamps were applied to the left renal pedicle for 40 min, and nephrectomy was performed on the right. Functional tests and laboratory tests were performed 5 min and 24 h after the reperfusion. Thereafter, 24 h after the surgery, the plasma creatinine and urea levels in the sham-operated animals were obtained at 45.9±0.8 mmol/L and 6.7±0.2 mmol/L, respectively. Plasma creatinine and urea levels in the control group animals were 102.63±3.6 mmol/L and 21.80±1.29 mmol/L, respectively. The administration of pHBSP and infliximab to the animals with ischemia-reperfusion kidney injury has a pronounced nephroprotective effect, as compared to erythropoietin. There was a significant decrease in blood levels of creatinine and urea, improvement of microcirculation in the kidney, normalization of glomerular filtration rate, and fractional sodium excretion. The results of the study demonstrated pointed to the prospects of pHBSP and infliximab administration in ischemia-reperfusion kidney injury and justified the feasibility of further research in this field.

Restoration of afferent arteriolar autoregulatory behavior in ischemia-reperfusion injury in rat kidneys.

Renal autoregulation is critical in maintaining stable renal blood flow (RBF) and glomerular filtration rate (GFR). Renal ischemia-reperfusion (IR)-induced kidney injury is characterized by reduced RBF and GFR. The mechanisms contributing to renal microvascular dysfunction in IR have not been fully determined. We hypothesized that increased reactive oxygen species (ROS) contributed to impaired renal autoregulatory capability in IR rats. Afferent arteriolar autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. IR was induced by 60 min of bilateral renal artery occlusion followed by 24 h of reperfusion. Afferent arterioles from sham rats exhibited normal autoregulatory behavior. Stepwise increases in perfusion pressure caused pressure-dependent vasoconstriction to 65 ± 3% of baseline diameter (13.2 ± 0.4 μm) at 170 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in IR rats. Baseline diameter averaged 11.7 ± 0.5 µm and remained between 90% and 101% of baseline over 65-170 mmHg, indicating impaired autoregulatory function. Acute antioxidant administration (tempol or apocynin) to IR kidneys for 20 min increased baseline diameter and improved autoregulatory capability, such that the pressure-diameter profiles were indistinguishable from those of sham kidneys. Furthermore, the addition of polyethylene glycol superoxide dismutase or polyethylene glycol-catalase to the perfusate blood also restored afferent arteriolar autoregulatory responsiveness in IR rats, indicating the involvement of superoxide and/or hydrogen peroxide. IR elevated mRNA expression of NADPH oxidase subunits and monocyte chemoattractant protein-1 in renal tissue homogenates, and this was prevented by tempol pretreatment. These results suggest that ROS accumulation, likely involving superoxide and/or hydrogen peroxide, impairs renal autoregulation in IR rats in a reversible fashion.NEW & NOTEWORTHY Renal ischemia-reperfusion (IR) leads to renal microvascular dysfunction manifested by impaired afferent arteriolar autoregulatory efficiency. Acute administration of scavengers of reactive oxygen species, polyethylene glycol-superoxide dismutase, or polyethylene glycol-catalase following renal IR restored afferent arteriolar autoregulatory capability in IR rats, indicating that renal IR led to reversible impairment of afferent arteriolar autoregulatory capability. Intervention with antioxidant treatment following IR may improve outcomes in patients by preserving renovascular autoregulatory function and potentially preventing the progression to chronic kidney disease after acute kidney injury.

Effect of oleuropein on oxidative stress, inflammation and apoptosis induced by ischemia-reperfusion injury in rat kidney

AimsThis study aimed to evaluate the effect of oleuropein (OLE), the main phenolic compound present in olive leaves, on kidney ischemia-reperfusion injury (IRI) and to explore the underlying protective mechanism. Main methodsRat kidneys were subjected to 60 min of bilateral warm ischemia followed by 120 min of reperfusion. OLE was administered orally 48 h, 24 h and 30 min prior to ischemia at doses of 10, 50 and 100 mg/kg body weight. The creatinine, urea, uric acid concentrations and lactate dehydrogenase (LDH) activity in plasma were evaluated. Oxidative stress and inflammation parameters were also assessed. Renal expression of AMP-activated protein kinase (p-AMPK), endothelial nitric oxide synthase (eNOS), mitogen-activated protein kinases (MAPK), inflammatory proteins and apoptotic proteins were evaluated using Western blot. Key findingsOur results showed that OLE at 50 mg/kg reduced kidney IRI as revealed by a significant decrease of plasmatic creatinine, urea, uric acid concentrations and LDH activity. In parallel, OLE up-regulated antioxidant capacities. Moreover, OLE diminished the level of CRP and the expression of cyclooxygenase 2 (COX-2). Finally, OLE enhanced AMPK phosphorylation as well as eNOS expression whereas MAPK, and cleaved caspase-3 implicated in cellular apoptosis were attenuated in the ischemic kidneys. SignificanceIn conclusion, this study shows that OLE could be used as therapeutic agent to reduce IRI through its anti-oxidative, anti-inflammatory and anti-apoptotic properties.

Protective mechanisms of piperine against renal ischemia–reperfusion injury in rats

Background: Renal ischemia–reperfusion injury (IRI) is a major clinical problem associated with kidney transplantation, leading to high mortality and morbidity. IRI involves activation of oxidative stress and inflammatory pathways, eventually leading to cell death and organ failure. Piperine is a phenolic active ingredient of black pepper, which showed promising antioxidant and anti-inflammatory potential. Objectives: We hypothesized that piperine would protect against renal IRI in rats via inhibition of oxidative stress and inflammation. Materials and Methods: Male Sprague Dawley rats were subdivided into four groups; sham, IR, IR + piperine, and sham + piperine. All animals have been treated for 4 days with either vehicle or piperine (100 mg/kg/day). One hour after the last piperine or vehicle administration, animals were subjected to bilateral renal ischemia for 45 min by clamping both renal pedicles, followed by reperfusion for 24 h. At the end of the experiments, kidneys were harvested for the determination of lipid peroxidation (malondialdehyde [MDA]), reduced glutathione (GSH), inflammatory and apoptotic markers, and histopathology. Serum levels of creatinine and urea have been determined. Results: Induction of renal IR increased renal oxidative stress (increased MDA and decreased GSH) and the expression levels of inflammatory and proapoptotic genes (nuclear factor-kappa B, inducible nitric oxide synthase, cyclooxygenase-2, and caspase-3). Moreover, serum levels of creatinine and urea were significantly elevated. Alternatively, pretreatment of the animals with piperine resulted in normalization of these parameters. Conclusion: The results showed that piperine pretreatment protects against IRI in rat kidneys via mechanisms involving amelioration of oxidative stress along with inflammatory and apoptotic pathways.

Effect of dexmedetomidine on ischemia-reperfusion injury of liver and kidney tissues in experimental diabetes and hepatic ischemia-reperfusion injury induced rats

Background: Reperfusion following ischemia can lead to more injuries than ischemia itself especially in diabetic patients. The aim of this study was to evaluate the effect of dexmedetomidine on ischemia-reperfusion injury (IRI) in rats with have hepatic IRI and diabetes mellitus.

Effects of cyclosporine on ischemia-reperfusion injuries in rat kidneys. An experimental model.

PurposeTo assess Cyclosporine A (CsA) therapy at an intraperitoneal dose of 15 mg.kg -1 in a rodent model of non-septic renal ischemia.MethodsTwenty male Wistar rats were randomized to receive CsA therapy or none therapy before undergoing 30 minutes of renal ischemia followed by reperfusion. Additionally, 10 rats were randomized to undergo the same surgical procedure of the aforementioned animals with neither ischemia nor CsA therapy. Twelve hours after kidney ischemia, the left kidneys were evaluated for histological injury according to Park’s criteria. Serum creatinine (Cr), urea nitrogen (Ur) and sodium levels were obtained at different times of the experimental protocol.ResultsRodents in the CsA group showed negative results (p<0.05) in serum variables (Cr: 0.41±0.05mg/dL vs . 4.17±1.25mg/dL; Ur: 40.90±3.98mg/dL vs . 187.70±22.93mg/dL) even the non CsA or control group (Cr: 0.35±0.07mg/dL vs . 3.80±1.20mg/dL; Ur: 40.10±4.70mg/dL vs . 184.50±49.80mg/dL). The negative results were also verified in histological evaluation, CsA group had 50% in the very severe grade of lesion, 10% in the severe and 40% in the moderate to severe whereas the control group had 90% in the very severe grade.ConclusionCsA was incapable of preventing the deleterious effects of ischemia-reperfusion injury in rat kidneys.

Human extracellular microvesicles from renal tubules reverse kidney ischemia-reperfusion injury in rats.

Hypoxic acute kidney injury, a major unresolved problem, initiates, or aggravates, renal functional and structural decline. There is no treatment for hypoxic acute renal injury and its sequelae. We tested the hypothesis that human kidney tubular cells, or their extracellular vesicles (exosomes), prevent renal injury when infused intravenously 24 hours after 50 minutes of bilateral renal ischemia in Nude rats. Cells and their exosomes were from harvested human kidneys declined for transplantation. Injections of either cells or exosomes, given after 24 and 48 hours of reperfusion, preserved renal function and structure in both treatment groups. However, exosomes were superior to cells; and maintained renal vascular and epithelial networks, prevented renal oxidant stress, and apoptosis; and restrained activation of pro-inflammatory and pro-fibrogenic pathways. Exosomes worked in 24 hours, consistent with functional rather than regenerative activity. Comprehensive proteomic analysis identified 6152 renal proteins from all cellular compartments; and 628 were altered by ischemia at all cell levels, while 377 were significantly improved by exosome infusions. We conclude that renal damage from severe ischemia was broad, and human renal exosomes prevented most protein alterations. Thus, exosomes seem to acutely correct a critical and consequential abnormality during reperfusion. In their absence, renal structure and cells transition to a chronic state of fibrosis and extensive renal cell loss.

Resveratrol Alleviates Inflammatory Responses and Oxidative Stress in Rat Kidney Ischemia-Reperfusion Injury and H2O2-Induced NRK-52E Cells via the Nrf2/TLR4/NF-κB Pathway

Background: Ischemia-reperfusion injury (IRI) is one of the major causes of postoperative renal allograft dysfunction, which is mainly the result of proinflammatory reactions including inflammatory responses, oxidative stress, and metabolic disorders. Resveratrol (RSV) plays an important role in protecting various organs in IRI because it reduces oxidative stress, lessens the inflammatory response, and exerts anti-apoptotic effects. The aim of this study was to demonstrate the renoprotective effect of RSV in inhibiting inflammatory responses, reducing oxidative stress, and decreasing cell apoptosis in vivo and in vitro. Methods: RSV was administered before renal ischemia and H₂O₂ induction. Serum and kidneys were harvested 24 h after reperfusion and NRK-52E cells were collected 4 h after H₂O₂ stimulation. Serum creatinine and blood urea nitrogen were used to assess renal function. Hematoxylin and eosin staining was performed to assess histological injury. Quantitative real-time PCR and enzyme-linked immunosorbent assay were used to assess proinflammatory cytokine expression. Oxidative stress–related proteins, such as Nrf2 and TLR4, were evaluated by western blot. Terminal deoxynucleotidyl transferase–mediated dUTP-biotin nick end labeling assay was used to detect apoptotic cells in tissues, and western blot was used to evaluate the expression of caspase-3, -8, and -9 in this study. Results: RSV inhibited inflammatory responses and improved renal function after renal IRI. Additionally, RSV decreased oxidative stress and reduced cell apoptosis by upregulating Nrf2 expression, downregulating the TLR4/NF-κB signaling pathway, and by decreasing caspase-3 activity and caspase cascades. Conclusion: Our study demonstrated the mechanisms underlying RSV renoprotection. We found that RSV exerts its greatest effects by blocking inflammatory responses, lowering oxidative stress, and reducing apoptosis via the Nrf2/TLR4/NF-κB pathway.

Ang-1 promotes homing of endothelial progenitor cells on renal ischemia and reperfusion injury in male rats

Objective To assess whether angiopoietin-1 (Ang-1) promoted the homing of endothelial progenitor cells (EPCs) to protect kidneys from ischemia/reperfusion injury (IRI) in male rats. Methods Recombinant adenovirus encoding Ang-1 gene (Ad- Ang-1) was used to infect EPCs, and the transfection efficiency was identified. Male Sprague-Dawley rats were injected EPCs suspension liquid which was transfected by Ad-Ang-1 from the femoral vein of rats after the operation method of IRI-operated group. At 24 h and 72 h after reperfusion, serum samples were respectively collected for renal function. Besides, kidney tissues were harvested to observe renal morphology changes. Subsequently, vascular endothelial growth factor (VEGF), Ang-1 and angiopoietin-2 (Ang-2) expression levels in the kidneys were measured with quantitative real-time PCR and Western Blot at the indicated time points after reperfusion. Results The renal function was significantly improved, after EPCs transplantation with Ad- Ang-1. At 72 hours after reperfusion, expression levels of VEGF, Ang-1 and Ang-2 in the kidneys of EPCs-treated rats were significantly increased. Conclusions EPCs transplantation with Ad- Ang-1 in the treatment of kidney IRI in rats is effective. In addition, Ang-1 would play important roles in the protective effect of homing of EPCs on renal acute IRI, and further promote renal angiogenesis. Key words: Reperfusion Injury; Kidney; Transfection; Stem Cells

Hydrodynamic Isotonic Fluid Delivery Ameliorates Moderate-to-Severe Ischemia-Reperfusion Injury in Rat Kidneys.

Highly aerobic organs like the kidney are innately susceptible to ischemia-reperfusion (I/R) injury, which can originate from sources including myocardial infarction, renal trauma, and transplant. Therapy is mainly supportive and depends on the cause(s) of damage. In the absence of hypervolemia, intravenous fluid delivery is frequently the first course of treatment but does not reverse established AKI. Evidence suggests that disrupting leukocyte adhesion may prevent the impairment of renal microvascular perfusion and the heightened inflammatory response that exacerbate ischemic renal injury. We investigated the therapeutic potential of hydrodynamic isotonic fluid delivery (HIFD) to the left renal vein 24 hours after inducing moderate-to-severe unilateral IRI in rats. HIFD significantly increased hydrostatic pressure within the renal vein. When conducted after established AKI, 24 hours after I/R injury, HIFD produced substantial and statistically significant decreases in serum creatinine levels compared with levels in animals given an equivalent volume of saline via peripheral infusion (P<0.05). Intravital confocal microscopy performed immediately after HIFD showed improved microvascular perfusion. Notably, HIFD also resulted in immediate enhancement of parenchymal labeling with the fluorescent dye Hoechst 33342. HIFD also associated with a significant reduction in the accumulation of renal leukocytes, including proinflammatory T cells. Additionally, HIFD significantly reduced peritubular capillary erythrocyte congestion and improved histologic scores of tubular injury 4 days after IRI. Taken together, these results indicate that HIFD performed after establishment of AKI rapidly restores microvascular perfusion and small molecule accessibility, with improvement in overall renal function.

Changes of miRNA-17-5p, miRNA-21 and miRNA-106a level during rat kidney ischemia-reperfusion injury

Ischemia-reperfusion (I/R) is a main cause of acute kidney injury (AKI). The renal expression profiles of microRNA (miRNA) and time course of their changes after renal I/R were explored to screen acute AKI prognostic-related microRNAs and biomarkers. The expression profile of miRNA was analyzed for detecting miRNAs in kidney after renal I/R injury. Real-time polymerase chain reaction (PCR) was performed to validate the results of microarray. And the relationship was examined between kidney injury and time course of changes in selected miRNAs. Twenty-one miRNAs were differentially expressed in kidney of rats with renal I/R injury. And 5 miRNAs had prominent differences. miR-17-5p, miR-21 and miR-106a were selected for further confirmation by quantitative real-time-PCR. And the results were consistent with those of microarry. During early stage (4 h) after I/R, the expression level of miR-17-5p significantly increased (P < 0.05). And it occurred earlier than those of BUN level and plasma concentration of neutrophil gelatinase-associated lipocalin (NGAL). Renal expressions of miR-21 and miR-106a were significantly elevated in ischemia 20 min and 30 min groups at 12 h and 24 h post-reperfusion (P < 0.01). And the trend was in accordance with those of BUN and NGAL. miR-21, miR-17-5p and miR-106a are differentially expressed during different phases of renal I/R injury. And miR-17-5p is more sensitive than BUN and NGAL so that it is a more ideal biomarker for AKI.

Genome-wide gene expression profiling of ischemia-reperfusion injury in rat kidney, intestine and skeletal muscle implicate a common involvement of MAPK signaling pathway

The mechanisms of ischemia‑reperfusion (I/R) injury have not been fully elucidated to date. In order to determine the genetic involvement across different organs during I/R injury, a DNA microarray approach was used to analyze the gene expression profiles of the kidney, intestine, and skeletal muscle in a rat model of I/R injury. Fifteen male Lewis rats were divided randomly into three different organ groups; a sham operation (control group), 60‑min‑ischemia (Is group) only, and 60‑min‑ischemia plus 60‑min‑reperfusion (I/R group), respectively. The target genes were identified by DNA microarray and studied by quantitative polymerase chain reaction (qPCR). By comparing the I/R group with the control group, a 2‑fold upregulation of 467, 172, and 3932 and a 2‑fold downregulation of 437, 416, and 4203 genes were identified in the kidney, small intestine, and skeletal muscle, respectively. Several commonly upregulated genes associated with mitogen‑activated protein kinase (MAPK) pathways, including Jun, Atf3, junB, Fos, Adm and Dusp 1, were differentially expressed in the I/R group. The mRNA expression levels of the target genes were confirmed by qPCR. The present study hypothesized that the MAPK pathway may function in a common pathway of I/R injury and regulate the pathogenesis through activator protein 1. The findings of the present study contributed to the understanding of the molecular pathways associated with I/R injury.

Continuous Infusion of Dexmedetomidine Improves Renal Ischemia-reperfusion Injury in Rat Kidney

Dexmedetomidine has shown beneficial effects in several inflammatory models, including ischemia-reperfusion injury (IRI). This study investigated whether the continuous infusion of dexmedetomidine could improve renal IRI in rats. Rats were subjected to either a sham operation and given pentobarbital (10 mg/kg/h; n=6) or were subjected to 45 minutes of renal ischemia and anesthetized with pentobarbital (10 mg/kg/h; n=6), dexmedetomidine (10 or 20 μg/kg/h; both n=6), or both pentobarbital (10 mg/kg/h) and dexmedetomidine (1.0 μg/kg/h; n=6) for 6 hours of reperfusion. Blood urea nitrogen and serum creatinine were measured 6 hours after reperfusion. Gene expression mediated by inflammatory systems in the kidney was measured with the real-time reverse-transcriptase polymerase chain reaction. Treatment with 10 or 20 μg/kg/h of dexmedetomidine reduced renal dysfunction. The increases in the messenger RNA expression of interleukin-6, intercellular adhesion molecule 1, and inducible nitric oxide synthase caused by renal IRI were suppressed. Under In rats under pentobarbital anesthesia, 1.0 μg/kg/h of dexmedetomidine also improved renal dysfunction after renal IRI. The present study demonstrates that continuous infusion of dexmedetomidine improves renal IRI. Moreover, with pentobarbital anesthesia, a dose of dexmedetomidine lower than the sedative dose also improves renal IRI.

Protective Effects of Phosphodiesterase-4-specific Inhibitor Rolipram on Acute Ischemia-reperfusion Injury in Rat Kidney

To investigate the effect of Rolipram, a phosphodiesterase-4-inhibitor, on renal ischemia-reperfusion injury (IRI) in rats. Thirty rats were divided into 5 different groups of 6 rats. Nothing was done to the control group. In the second group, the renal pedicle was clamped for 30 minutes. In the third group, 1 mg/kg of Rolipram was given by intraperitoneal injection 30 minutes before clamping. The fourth group received the same injection when the clamp was placed, as did the fifth group 30 minutes after the clamp was opened. Clamping time was set at 30 minutes. Twenty-four hours later, nephrectomy was performed in all the groups. Half of each kidney was examined histopathologically. Levels of biochemical agents, such as malondialdehyde, superoxide dismutase, and catalase, were measured in the other half. The malondialdehyde (MDA) levels significantly decreased and reached control levels in the group in which Rolipram was administered 30 minutes after reperfusion (P = .07). The catalase and superoxide dismutase activities obtained from renal homogentisates of the ischemia groups were evaluated; there were striking increases in tissue levels of these 2 enzymes in the groups in which Rolipram was administered during ischemia and 30 minutes after ischemia (P < .001). Histopathologically, there was no significant difference in inflammation between the Rolipram-administrated groups compared with group 1 (control) and group 2 (IRI). Tubular necrosis and apoptosis was significantly lower in group 5 than the other groups, except group 1 (P < .001). We suggest that in surgical procedures that can lead to renal IRI, the administration of Rolipram can decrease oxidative renal tissue damage and the severe deterioration of renal function.

Protective effects of astilbin on renal ischemia-reperfusion injury in rats

To investigate the protective effects of astilbin on renal ischemia-reperfusion (IR) injury in rats. Twenty-four male SD rats, two months old, were randomly allocated into three groups: sham-operated group (n=8), untreated group (n=8) and astilbin group (n=8). Rats in the untreated group and the astilbin group underwent temporary renal artery occlusion to induce IR injury. The rats in the astilbin group were intraperitoneally injected with 12 mg/mL astilbin at a dose of 30 mg/kg from 3 day before IR injury until to be sacrificed once per day, and rats in the untreated group were injected with equal volume of normal saline at the same time. After 6-hour reperfusion, blood urea nitrogen (BUN) and serum creatinine (SCr) and histological changes of the renal tissues were detected to evaluate renal injury. Expressions of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein in the renal tissues and the serum contents of interleukin-6 (IL-6) and IL-1beta were also measured with semi-quantitative reverse transcription-polymerase chain reaction, Western blotting or enzyme-linked immunosorbent assay. Compared with the untreated group, BUN and SCr levels were significantly decreased in the astilbin group after 6-hour reperfusion (P<0.01), and similar results were also found in histological examination. The expressions of MCP-1 mRNA and protein in renal tissues in the astilbin group were lower than those in the untreated group. The serum contents of IL-6 and IL-1beta were decreased in the astilbin group as compared with the untreated group (P<0.01). Astilbin can ameliorate kidney IR injury in rats by inhibiting the production of chemokine MCP-1 and cytokines IL-6 and IL-1beta.

Expression of the RNA-stabilizing protein HuR in ischemia-reperfusion injury of rat kidney

The RNA-binding protein human antigen R (HuR) participates in the posttranscriptional regulation of mRNAs bearing 3' AU-rich and U-rich elements, which HuR can stabilize under conditions of cellular stress. Using the LLC-PK(1) proximal tubule cell line model, we recently suggested a role for HuR in protecting kidney epithelia from injury during ischemic stress (Jeyaraj S, Dakhlallah D, Hill SR, Lee BS. J Biol Chem 280: 37957-37964, 2005; Jeyaraj SC, Dakhlallah D, Hill SR, Lee BS. Am J Physiol Renal Physiol 291: F1255-F1263, 2006). Here, we have extended this work to show that small interfering RNA-mediated suppression of HuR in LLC-PK(1) cells increased apoptosis during energy depletion, while overexpression of HuR diminished apoptosis. Suppression of HuR also resulted in diminished levels of key cell survival proteins such as Bcl-2 and Hsp70. Furthermore, rat kidneys were subjected in vivo to transient ischemia followed by varying periods of reperfusion. Ischemia and reperfusion (I/R) affected intensity and distribution of HuR in a nephron segment-specific manner. Cells of the proximal tubule, which are most sensitive to I/R injury, demonstrated a transient shift of HuR to the cytoplasm immediately following ischemia. Over a 14-day period following the onset of reperfusion, nuclear and total HuR protein gradually increased in cortical and medullary proximal tubules, but not in non-proximal tubule cells. HuR mRNA was expressed in two forms with alternate transcriptional start sites that increased over a 14-day I/R period, and in vitro studies suggest selective translatability of these two mRNAs. Baseline and I/R-stimulated levels of HuR mRNA did not parallel those of HuR protein, suggesting translational control of HuR expression, particularly in medullary proximal tubules. These findings suggest that alterations in distribution and expression of the antiaptotic protein HuR specifically in cells of the proximal tubule effect a protective mechanism during and following I/R injury in kidney.

Change of Melanocortin Receptor Expression in Rat Kidney Ischemia–Reperfusion Injury

Objectives α-Melanocyte stimulating hormone (α-MSH) may ameliorate renal ischemia–reperfusion (I/R) injury. Recent data suggest that melanocortin receptors may be related to the anti-inflammatory and immunomodulating action for α-MSH. We designed this experiment to determine the renal distribution of α-MSH receptors; melanocortin-1 receptor (MC-1R) and melanocortin-3 receptor (MC-3R). Methods Sprague-Dawley male rats ( n = 24) were randomly divided into 2 groups: the sham ( n = 2) and the operation groups with warm ischemia ( n = 12). Animals in the operation group were subjected to 40 minutes of warm renal ischemia. Western blotting analyses and immunohistochemistry were employed to determine expression of MC-1R and MC-3R. Results Expression of MC-1R and MC-3R was decreased on 1 day after reperfusion. Immunohistochemical study confirmed the findings of Western blot analysis. Conclusions The present study demonstrated novel renal expression of MC-1R and MC-3R, especially in the outer medulla, representative of the renal I/R injury. Our current study suggested that the mechanisms of action of α-MSH may significantly attenuate the renal I/R injury by specific kidney-targeted effects via MC-Receptors as well as by systemic cytokine effects.