Antioxidant and antiapoptotic effects of darbepoetin-α against traumatic brain injury in rats

Introduction

In this study, we tried to determine whether darbepoetin-α would protect the brain from oxidative stress and apoptosis in a rat traumatic brain injury model.

Material and methods

The animals were randomized into four groups; group 1 (sham), group 2 (trauma), group 3 (darbepoetin α), group 4 (methylprednisolone). In the sham group only the skin incision was performed. In all the other groups, a moderate traumatic brain injury modelwas applied.

Results

Following trauma both glutathione peroxidase, superoxide dismutase levels decreased (p < 0.001 for both); darbepoetin-α increased the activity of both antioxidant enzymes (p = 0.001 and p < 0.001 respectively). Trauma caused significant elevation in the nitric oxide synthetase and xanthine oxidase levels (p < 0.001 for both). Administration of darbepoetin-α significantly decreased the levels of nitric oxide synthetase and xanthine oxidase (p < 0.001 for both). Also, trauma caused significant elevation in the nitric oxide levels (p < 0.001); darbepoetin-α administration caused statistically significant reduction in the nitric oxide levels (p < 0.001). On the other hand, malondialdehyde levels were increased following trauma (p < 0.001), and darbepoetin α significantly reduced the malondialdehyde levels (p < 0.001). Due to the elevated apoptotic activity following the injury, caspase-3 activity increased significantly. Darbepoetin-α treatment significantly inhibited apoptosis by lowering the caspase-3 activity (p < 0.001). In the darbepoetin group, histopathological score was lower than the trauma group (p = 0.016).

Conclusions

In this study, darbepoetin-α was shown to be at least as effective as methylprednisolone in protecting brain from oxidative stress, lipid peroxidation and apoptosis.     

Time-dependent expression of endothelin-1 in lungs and the effects of TNF-α blocking peptide on acute lung injury in an endotoxemic rat model

Endothelin (ET)-1 is a potent vasoconstrictor that has been implicated in the pathogenesis of a number of diseases, and some studies suggest that circulating ET-1 is elevated in sepsis. The present study investigated whether ET plays a role in sepsis-mediated acute lung injury and whether its expression could be down regulated by blockade of TNF-α in septic lung. Male Wistar rats at 8 weeks of age were administered with either saline or lipopolysaccharide (LPS) at different time points (1, 3, 6 and 10 h) and various tests were then performed. The features of acute lung injury were observed at 1 h after LPS administration, which gradually became severe with time. Systolic and diastolic pressures were reduced just about one hour after LPS administration, whereas pulmonary TNF-α levels were significantly increased at various time points after LPS administration. LPS induced a time-dependent expression of ET-1 and ET(A) receptor in the lungs compared to control, peaking and increasing by 3 fold at 6 h after induction of endotoxemia, whereas levels of ET(B) receptor, which has vasodilating effects, were remarkably down regulated time-dependently. We conclude that time-dependent increase of ET-1 and ET(A) receptor with the down regulation of ET(B) receptor may play a role in the pathogenesis of acute lung injury in endotoxemia. Finally, treatment of LPS-administered rats with TNF-α blocking peptide for three hours significantly suppressed levels of pulmonary ET-1. These data taken together, led us to conclude that differential alteration in ET expression and its receptors may be mediated by TNF-α and may, in part, account for the pathogenesis of acute lung injury in endotoxemia.     

Identification of genes involved in gentamicin-induced nephrotoxicity in rats – A toxicogenomic investigation

For the application of microarray technology as an additional endpoint in toxicological studies, there is a need to understand associations between pathological processes and gene expression alterations. In the current study, we investigated gentamicin as a nephrotoxic model compound. Gene expression changes of the kidney in response to a dose of 80 mg/kg gentamicin were analyzed by using DNA microarray technology and alterations in gene expression were associated with results from conventional histopathological investigations and with the described pathomechanisms of gentamicin. Under the conditions of our experiment, the mRNA level of 211 genes were found to be deregulated by gentamicin. The gentamicin-induced affection of proximal convoluted tubules was associated with a strong up-regulation of mRNAs encoding for proteins which are used as nephrotoxicity markers in urine and plasma such as Kim-1, Osteopontin and TIMP1. Candidate marker genes for nephrotoxicity such as GATM were deregulated. Gentamicin-induced lysosomal phospholipidosis was indicated by deregulation of lysosomal located gene products such as ATP6V1D, a subunit of the lysosomal H+ transporting ATPase. Effects on glucose transport and metabolism were indicated by the down-regulation on SGLT-2 and glucose-6-phoshatase. Renal cell apoptosis was indicated by up-regulated genes as TP53 and BAX. The role of oxidative stress in gentamicin toxicity was reflected by deregulation of transferrin receptor and heme oxygenase. The results of the study show the potential of microarray technology to study a complex mechanism of toxicity in a single study.     

Temporal–spatial expression of ENOLASE after acute spinal cord injury in adult rats

ENOLASE enzymes are abundantly expressed, cytosolic carbon–oxygen lyases known for their role in glucose metabolism. Recent accumulation of evidence revealed that, in addition to its glycolytic function, enolase is also associated with ischemia, hypoxia and to be a neurotrophic factor. To analysis the certain expression and biological function in central nervous system, we performed an acute spinal cord contusion injury model in adult rats. Western blot analysis indicated a marked upregulation of ENOLASE after spinal cord injury (SCI). Immunohistochemistry revealed wide distribution of enolase in spinal cord, including neurons and glial cells. Double immunofluorescent staining for proliferating cell nuclear antigen and phenotype-specific markers showed increases of enolase expression in proliferating microglia and astrocytes. Our data suggest that enolase may be implicated in the proliferation of microglia and astrocytes after SCI.     

Influences of HIF-lα on Bax/Bcl-2 and VEGF expressions in rats with spinal cord injury

Hypoxia-inducible factor 1-alpha (HIF-1α) is a subunit of HIF-l and thought to be able to protect hypoxic cells from apoptosis or necrosis under ischemic and anoxic conditions. This study aimed to investigated whether recombinant adenovirus vector over-expressing HIF-lα could affect apoptosis-related proteins (Bcl-2 and Bax) and vascular endothelial growth factor (VEGF) in a rat spinal cord injury (SCI) model. A total of 60 male SD rats were divided into 4 groups: Sham, Control, Ad-Blank and Ad-HIF-1α groups. 1, 3, 7, 14, 28 days after surgery, the behavioral recovery was evaluated with BBB scales. Then, rats were sacrificed and the spinal cord was collected for detection of Bcl-2, Bax and VEGF expressions by immunohistochemistry. Results showed the Bcl-2, Bax, VEGF and HIF-lα expressions increased in animals with SCI, but the increase in Bcl-2, VEGF and HIF-lα expressions were higher in Ad-HIF-1α group when compared with other groups, but Bax expression decreased significantly. In addition, administration of Ad-HIF-1α significantly reduced apoptotic cells and promoted the recovery of neurological function. In conclusion, administration of Ad-HIF-1α after SCI could ameliorate neuronal apoptosis and promote angiogenesis in rats. Our study provides a basis for further exploration of the relationship between HIF1α and SCI.     

Influence of L-arginine on expression of HSP70 and p-53 proteins – early biomarkers of cellular danger in renal tubular cells. Immunohistochemical assessment

Introduction

The aim of the present study was to investigate expression of HSP70 and p-53 proteins as mechanisms of protection of the renal tubular epithelial cells from l-arginine that induces cellular stress.

Material and methods

The study material consisted of 16 white Wistar female rats. The rats were divided into 2 equal groups. The rats in the experimental group received L-arginine 40 mg/kg body weight per capita every other day for 2 weeks and were decapitated after 3 weeks of the experiment. After decapitation, specimens from the kidney were collected, fixed in 10% formalin, and then embedded in paraffin blocks. Proteins HSP70 and p-53 on slides were detected using the standard three-step immunohistochemical method.

Results

The quantitative evaluation of HSP70 and p-53 expression showed that the area occupied with positive HSP70 and p-53 reaction in the rat renal tubular cells of the experimental group (p-53: 2835.44 ±254.72 µm²; HSP70: 24111.42 ±4290.88 µm²) was more statistically significant than the control group (p-53: 1882.05 ±466.43 µm²; HSP70: 11388.63 ±1455.24 µm²). In the present study, the dose of L-arginine was similar to the one that was used in the gestosis treatment of pregnant women.

Conclusions

The renal epithelial cells responded to L-arginine therapy, increasing expression of HSP70 and p-53 proteins. The study showed that L-arginine as a donor of exogenous nitric oxide has a disruptive effect on the renal tubular cells of rat kidneys. Thus it is going to be a subject of the author''s future investigations.     

Immunohistochemical detection of estrogen receptor �� in alveolar bone cells of estradiol-treated female rats: possible direct action of estrogen on osteoclast life span

The role of estrogen in bone resorption has been specifically related to the effect of estrogen on the signalling pathway that inhibits the formation of osteoclasts. However, osteoclast apoptosis and a significant reduction in the number of these cells have been observed in the alveolar bone of female rats treated with estradiol. In the present study, the expression of estrogen receptor β (ERβ) in the cells of alveolar bone was evaluated in estradiol‐treated and ‐untreated female rats. In order to test the possible direct action of estrogen on osteoclasts, the relationship between apoptosis and ERβ expression in these cells was also analysed. The animals received estradiol for 14 days and the alveolar bone fragments were embedded in paraffin for the quantification of tartrate‐resistant acid phosphatase‐positive osteoclasts. The expression of ERβ and apoptosis in the osteoclasts were evaluated by ERβ immunohistochemistry and Terminal deoxynucleotidyl transferase‐mediated dUTP Nick‐End Labelling (TUNEL) methods, respectively. To confirm osteoclast death by apoptosis, these cells were analysed under transmission electron microscopy. Some osteoclasts from estradiol‐treated animals were found to be undergoing apoptosis and the number of tartrate‐resistant acid phosphatase‐positive osteoclasts was significantly reduced. ERβ immunolabelling was observed in the cytoplasm and nuclei of active osteoblasts, osteocytes and osteoclasts in both groups, suggesting a direct participation of estrogen on alveolar bone cells. However, following estradiol treatment, a strong ERβ immunolabelling was often observed in the TUNEL‐positive osteoclasts. Therefore, these results indicate that, in addition to the other signalling pathway, the reduction of alveolar bone resorption is also related to a direct action of estrogen on osteoclasts, promoting apoptosis in these cells, via ERβ.     

A modified “double-hit” induced acute lung injury model in rats and protective effects of tetramethylpyrazine on the injury via Rho/ROCK pathway

We focused on the production and evaluation of a modified “double-hit” induced acute lung injury (ALI) model, which closely mimics the clinical situation. Further, tetramethylpyrazine (TMP), an alkaloid contained in ligustrazine was evaluated for its potent anti-inflammatory effects in this model. Rats were randomized into 4 groups: G1 (NS control group), G2 (“double-hit” group), G3 (low dosage TMP group) and G4 (high dosage TMP group). The rats in G2, G3 and G4 were intraperitoneally injected with a low dose of LPS followed by intratracheal injection with median dose of LPS to establish the “double-hit” model. The rats in G3, G4 were intraperitoneally injected with low (G3), high (G4) dosage TMP for the protection against ALI. Upon termination of the experiment, TMP attenuated the harmful changes in animal model reaction, breathing frequency, histological examination, lung W/D-weight ratio, BAL fluid PMNs percentage, MPO activity and ROCK2 mRNA expression. We found inhibiting RhoA/ROCK pathway might attribute to TMP-induced protection against ALI.     

The effect of erythropoietin on endometrial edema during ischemia–reperfusion injury in rats

This experimental study examined the effect of erythropoietin (Epo) in a rat model and particularly in an ischemia–reperfusion protocol. The potential beneficial effect of Epo was studied pathologically using endometrial edema (EE) lesions. Endometrial edema was evaluated 60 min after reperfusion (Groups A and C) and 120 min after reperfusion (Groups B and D) in rats. Epo was administered only in Groups C and D. Epo administration non-significantly increased the EE scores by 0.05 (p = 0.9315). Reperfusion non-significantly increased the EE scores by 0.15 (p = 0.6508). Epo administration and reperfusion together non-significantly increased the EE scores by 0.027 (p = 0.8898). Epo administration, reperfusion, and their interaction reduced the EE scores from significant to non-significant levels. Perhaps a study time longer than 2 h or a higher Epo dose could result in complete resolution of the endometrial edema formed as a result of the ischemia–reperfusion injury in this rat model.     

Toxicity study of separase inhibitor–Sepin-1 in Sprague-Dawley rats

Sepin-1 is a small compound that inhibits enzymatic activity of Separase and growth of cancer cells. As part of the IND-enabling studies to develop Sepin-1 as a chemotherapeutic agent, herein we have profiled the toxicity of Sepin-1 in Sprague-Dawley rats in a good laboratory practice (GLP) setting. The maximum tolerated dose (MTD) of Sepin-1 in rats is 40 mg/kg in single dose study and 20 mg/kg in the study dosed for 7 consecutive days. The toxicity study consists of two parts–Main Study and Recovery Study. Sepin-1 with 0 (control), 5 (low dose), 10 (median dose), and 20 (high dose) mg/kg was administered by bolus intravenous injection to rats once daily for 28 consecutive days. The animals in the Main Study were euthanized on Day 29, whereas animals in the Recovery Study were allowed to recover for 28 days following the 28-day Sepin-1 dose before they were euthanized on Day 29 of the off-dose period. Although the effects of Sepin-1 at low and median doses are minimal, hematological analysis shows that high-dose Sepin-1 is associated with decrease of red blood cells and hemoglobin, and increase in the number of reticulocytes and platelets as well as mean corpuscular volume. Clinical chemistry indicates that Sepin-1 causes increase of total bilirubin and decrease of creatine kinase. Histopathology analysis indicates Sepin-1 results in minimal bone marrow erythroid hyperplasia, minimal to moderate splenic extramedullary hematopoiesis, minimal splenic lymphoid depletion, minimal to mild thymic lymphoid depletion, and minimal to mild mandibular lymph node lymphoid hyperplasia in male and female rats in the Main Study. Those abnormal changes are Sepin-1 dose-dependent and mostly reversible after a 28-day recovery period in animals from the Recovery Study. Based on our results, we conclude that Sepin-1 at pharmacologic doses (5−10 mg/kg) is well tolerable, with no significant rates of mortality or morbidity, and can further be developed as a potential new drug to treat Separase-overexpressed tumors.     

Transplantation of stromal-derived factor 1α and basic fibroblast growth factor primed insulin-producing cells reverses hyperglycaemia in diabetic rats

The defective insulin production is associated with severely reduced islet cell mass leading to diabetes. Growth factors preconditioned stem cells have arisen as an effective therapy to treat many diseases including diabetes. The current study was designed to assess the effect of pretreatment of ASCs derived IPCs with combination of stromal cell derived factor 1 alpha (SDF1α) and basic fibroblast growth factor (bFGF) in improving glucose tolerance in streptozotocin induced diabetic rats. The results showed maximally significant reduction in hyperglycaemia and fibrosis, while up-regulation of survival and pancreas-specific genes, insulin levels and homing of transplanted cells in SDF-1α?+?bFGF IPCs transplanted rats as compared with other groups. Moreover, increased expression of insulin, glucagon and Glut-2 in pancreas of the SDF-1α?+?bFGF IPCs transplanted group indicated more regeneration of pancreas. Hence, the use of IPCs preconditioned with SDF-1α?+?bFGF would be more effective for treating diabetes.     

The effect of TNFα on food intake and central insulin sensitivity in rats

Circulating and tissue levels of the proinflammatory cytokine tumor necrosis factor α (TNFα) are elevated in obesity. TNFα interferes with insulin signaling in many tissues and also plays a causal role in the anorexia that accompanies severe challenges to the immune system. The interactions between TNFα and insulin in the control of eating are less well known. The present study evaluated the role of TNFα in the central nervous system control of food intake by insulin in adult male Long Evans rats. We first determined the ability of several doses of TNFα injected into the 3rd cerebral ventricle (i3vt) to reduce food intake in male rats. Subsequently, we assessed the ability of a subthreshold dose of TNFα to modulate the effect of i3vt insulin on food intake in male rats fed a low-fat chow or a high-fat (HF) diet. TNFα administered i3vt dose-dependently reduced food intake in rats fed a standard low-fat chow diet. Moreover, a low, sub-threshold dose of TNFα diminished the reduction in food intake by insulin in rats maintained on a chow diet, but enhanced insulin action in rats maintained on a HF diet. These data suggest that the interaction of TNFα with central insulin varies with nutritional and/or dietary conditions.     

Interleukin-1β of Red nucleus involved in the development of allodynia in spared nerve injury rats

Previous studies have indicated that interleukin-1β (IL-1β) is involved not only in immune modulation, but also in the modulation of pain in both the peripheral and central nervous systems. The current study investigated the expression of IL-1β in the brain of rats with spared nerve injury (SNI), using immunohistochemical technique. The results showed that immunoreactive-like IL-1β protein was significantly elevated in the Red nucleus (RN) 2 weeks after SNI. To further study the function of IL-1β in RN, different doses of IL-1β neutralizing antibody (10, 1.0 and 0.1 ng) were microinjected into the RN contralateral to the nerve injury side of neuropathic rats. The results indicated that the higher doses of anti-IL-1β antibody (10 and 1.0 ng) significantly attenuated the mechanical allodynia of neuropathic rats. However, administration of 0.1 ng anti-IL-1β antibody did not show anti-allodynia effect. These results suggest that IL-1β of RN is involved in the development of neuropathic pain in SNI rats.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.     

Role of angiotensin Ⅱ and JAK2 signal pathway in transdifferentation of renal tubular cells in mice after acute ischemic followed by reperfusion

Objective To investigate the effect of angiotensin (Ang) Ⅱ and its Janns-activated kinase-2 (JAK2) signal pathway in transdifferentiation of renal tubular cells under the challenge of acute ischemic reperfusion injury.Methods Models of acute ischemic reperfusion injury were established and the level of local Ang Ⅱ ,a key element of renin-angiotensin system (RAS),in kidney was measured using radioimmunity technique.The expression of α-smooth muscle actin (α-SMA),a phenotype of mesenchymal cells,was detected by RT-PCR and inununohistochemistry methods.Renal tubule cells ( NRK-52E) were cultured with various concentration of Ang Ⅱ ,followed by blocking of PD123319,Ang U receptor 2 antagonist,and AG490,an inhibitor of JAK2 signal pathway.Results Ang 0 of kidney tissue increased immediately after acute ischemic-reperfusion injury,in time dependent fashion.Expression of α-SMA in renal tubule cells was found at 48 hours after ischemic-reperfusion injury and in NRK-52E cells treated by high concentration of Ang Ⅱ and was dose and time dependent.The peak of α-SMA expression was seen after 30 minute treatment at the dose of 10-9'mol/L,which was interrupted by both of PD123319 and AG490.Conclusions Transdifferentiarion of renal tubular epithelial cells occurs under acute ischemic- reperfusion injury.Local renin-angiotensin system may play a role in the transdifferentiation of TEC through AT2 receptor and its JAK2 signal pathway.