ABSTRACT
Hypoxia-induced erythropoietin signaling plays an important role in tumor growth and invasion. In the present study, we investigated the contribution of erythropoietin signaling pathway to castration-resistant prostate cancer and the development of a neuroendocrine phenotype. Immunohistochemical staining showed that the erythropoietin and erythropoietin receptor scores in castration-resistant prostate cancer and androgen-dependent prostate cancer were 7.55 versus 4.5 and 7.45 versus 5.9,respectively (P < 0.001). Furthermore, a cell proliferation assay was conducted, and the differential expression of erythropoietin and erythropoietin receptor in LNCaP cells and hypoxia-induced LNCaP cells was evaluated using western blot and quantitative real-time PCR. The proliferation capacity of hypoxia-induced LNCaP cells was similar in cultures of both fetal bovine serum and charcoal-stripped fetal bovine serum, suggesting that LNCaP cells acquired hypoxia-induced androgen-independent growth. After 2 weeks of hypoxic culture, LNCaP cells showed a neuroendocrine cell change and increased expression of neuron-specific enolase, erythropoietin, and erythropoietin receptor; knockdown of erythropoietin receptor reversed the hypoxia-induced upregulation of neuron-specific enolase in the LNCaP cells. In conclusion, the concurrent upregulation of erythropoietin and erythropoietin receptor in castration-resistant prostate cancer suggests that the erythropoietin/erythropoietin receptor autocrine loop plays an important role in the progression of castration resistance and is responsible for the development of a neuroendocrine phenotype.
ABSTRACT
Background & objectives: Chronic kidney disease (CKD) patients on dialysis regularly receive erythropoiesis stimulating agent (ESA) for treating renal anaemia during their dialysis unlike those who are not on dialysis. In such patients, the longer acting ESA can be helpful in reducing their frequent visits to the health care facilities and improving their compliance. This study was aimed to examine the efficacy and safety of continuous erythropoietin receptor activator (CERA), a long acting ESA in treating renal anaemia in patients with diabetic CKD not on dialysis. Methods: In this prospective, open-labelled, pilot clinical study, 35 adult type 2 diabetes patients with nephropathy and renal anaemia, who were not on dialysis nor receiving treatment with ESA were administered CERA subcutaneously once in two weeks for a period of 24 weeks. The primary efficacy end point was to evaluate the Hb response (Hb rise of ≥1 g/dl above the baseline or Hb level ≥11 g/dl) during the study period. Results: All patients showed Hb rise ≥1 g/dl during the study period and 80 per cent patients could achieve Hb value ≥11 g/dl. The maximum median Hb rise of 1.2 g/dl occurred in the initial 6 weeks after starting the treatment. The mean creatinine clearance (CrCl) improved by 2.8 ml/min, with mean Hb rise of 2.6 g/dl from the baseline after administration of CERA. Worsening of blood pressure (BP) control (42.9%) was the most common adverse event. Interpretation & conclusions: CERA once in two weeks was found to be efficacious in correcting anaemia in the ESA-naïve patients with diabetic nephropathy who are not on dialysis. However, regular monitoring of blood pressure is required while on treatment with CERA.
ABSTRACT
Continuous erythropoietin receptor activator (CERA) is an erythropoietin with a long-half life. This study investigated the efficacy of CERA for correcting anemia in Korean patients on dialysis. Patients (> or =18 yr) who were not receiving any ESAs for more than 8 weeks were randomly assigned to either intravenous CERA once every 2 weeks (n=39) or epoetin beta thrice-weekly (n=41) during a 24-week correction phase. Hemoglobin (Hb) response was defined as increase of Hb by at least 1 g/dL and Hb> or =11 g/dL without red blood cell (RBC) transfusion. Median dialysis duration was 1.7 (0.3-20.8) and 1.6 (0.4-13.8) yr in CERA and epoetin beta group, respectively. Hemoglobin response rate of CERA was 79.5% (95% confidence interval [CI], 63.5-90.7). As the lower limit of 95% CI was higher than pre-specified 60% response rate, it can be concluded that CERA corrected anemia (P<0.05). Hb response rate of epoetin beta was 87.8% (95% CI, 73.8-95.9) (P=0.37). Median time to response was 12 weeks in CERA and 10.3 weeks in epoetin beta (P=0.03). It is suggested that once every 2 weeks administration of CERA is effective for correcting anemia in Korean patients on long-term hemodialysis with longer time-to-response than thrice weekly epoetin beta. (ClinicalTrials.gov registry No. NCT00546481)
Subject(s)
Female , Humans , Male , Middle Aged , Anemia/drug therapy , Erythropoietin/therapeutic use , Hemoglobins/analysis , Polyethylene Glycols/therapeutic use , Quality of Life , Recombinant Proteins/therapeutic use , Renal Dialysis , Renal Insufficiency, Chronic/drug therapy , Republic of KoreaABSTRACT
Objective To explore the influence of erythropoietin (EPO) on infection induced neonatal rat brain injury at different starting time and its related mechanism.Methods Postnatal day 2 (P2) newborn SD rats were randomly divided into 4 groups:control group (group A),lipopolysaccharide (LPS) group (group B),the early EPO group(group C)and the later EPO group(group D).Pups in group A,B and C were injected different drugs intraperitoneally(group A for saline,group B for 0.6 mg/kg of LPS,and group C for 0.6 mg/kg of LPS and 5 000 U/kg of EPO) once a day for consecutive 5 days(P2-P6).LPS in group D were injected 0.6 mg/kg of LPS intraperitoneally once a day for consecutive 5 days(P2 P6),and with 5 000 U/kg of EPO once a day for consecutive 5 days(P7-P1 1).Rats in each group were given different drugs starting at corresponding time by intraperitoneal injection for 5 consecutive days.Every 10 newborn rats in group A and B were selected randomly on P2(6 h after intraperitoneal injection of drugs for the first time),P7 and P12,the brains were divided into the left and the right hemispheres marked by sagittal suture,using enzyme-linked immunosorbent assay method to evaluate the erythropoietin receptor(EPOR) protein level with the right cerebral hemisphere and reverse transcription-polymerase chain reaction (RT-PCR) method was used to investigate EPOR mRNA level of the left cerebral hemisphere.Immunohistochemical method was adopted to evaluate the expression of myelin basic protein(MBP),glial fibrillary acidic protein(GFAP) and EPOR at specified time point,and HE dyeing for the pathological changes of brain damage in different groups.Results HE staining of the group A presented the normal structure in the neonatal rat brain.Reduced numbers of hippocampal pyramidal cells,expansion of the lateral ventricles and periventricular leukomalacia were found in group B.No leukomalacia or lateral ventricles's expansion in EPO administrated groups and it was more obvious in group C.The EPOR protein and mRNA of group B was increased compared with the group A.The EPOR protein and mRNA levels had a tendency to decline with the increase of age.The MBP expression of group B(107.46 ±3.65)was significantly reduced compared with the group A(146.78 ± 3.13) (P ＜ 0.05),and the expression of EPO groups increased in contrast to the group B,moreover,the group C (126.25 ± 4.42) increased more obviously than that of group D(117.35 ± 3.42) (P ＜ 0.05).The GFAP expression of group B(141.46 ± 11.92 at P7 and 149.48 ± 13.59 at P12) increased significantly than group A(120.63 ± 13.32 at P7 and 119.74 ± 12.48 at P12) (P ＜0.05),the EPO group expressed lower than group B at the P12,and the group C (134.59 ± 12.19) decreased than the group D(137.27 ± 13.87) (P ＞ 0.05).Conclusions EPO shows a protective effect on the cerebral white matter injury caused by postpartum infection,it is superior to administer EPO at early time than later time.The mechanism of the protective effect may be connected with the fact that the infection can induce the expression of brain EPOR and the EPOR expression level has a tendency to decline with the increase of age.
ABSTRACT
ObjectiveTo observe the influence of polyethylene glycol-conjugated hemoglobin (PEG-Hb) solution combined with cisplatin on the expression of erythropoietin/erythropoietin receptor (EPO/EPOR) and tumor angiogenesis in cancer treatment.MethodsHeLa cells were injected subcutaneously into the right oxter of 3-4 weeks old BALB/c nude mice to establish cervical tumor xenograft model.Then animals were randomly assigned to 4 groups (n=10) and treated respectively:group 1(control); group 2,cisplatin (5 mg/kg); group 3,PEG-Hb (0.6 g/kg); group 4 cisplatin (5 mg/kg) plus PEG-Hb (0.6 g/kg).The volume oftumors in each groups were measured in 4 weeks treatment period.Efficacy was measured as percent tumor growth inhibition (TGI) relative to salinetreated group.CD31 was detected by immunohistochemistry and its expression was identified as microvascular density (MVD).Expressions of hypoxia inducible factor-1α(HIF-1α) and EPO/EPOR in tumor tissues were analyzed by irnmunohistochemistry.EPOR protein level was tested by western blot.ELISA method was used in measuring EPO concentration in serum.ResultsTumor volume was significantly decreased in group 4 compared with other groups.Immunoreactivity data demonstrated lower expression of CD31,HIF-1α and EPO/EPOR in group 4.The expression of EPOR in the endothelial cells was also significantly decreased in group 4.Western-blot data indicated lower EPOR protein level in group 4.Serum level of EPO was also decreased in group 4.ConclusionPEG-Hb plus cisplatin is benefit to tumor tissue oxygenation,therefore it can inhibit the tumor angiogenesis and down regulate the erythropoietin/erythropoietin receptor system.The result can provide more evidence for the enhanced sensitivity effect of the artificial oxygen carrier in cancer therapy.
ABSTRACT
Objective To evaluate the efficacy,safety and tolerance of continuous erythropoietin receptor activator (CERA) once every 2 weeks intravenous injection on anemia correction in dialysis patients compared to Epoetin-3 (EPO-β) administration.Methods An open-label,randomized,parallel,active-control and multi-center clinical trial was performed.All the hemodialysis or peritoneal dialysis patients with chronic renal anemia who had not been treated with erythropoiesis-stimulating agents (ESAs)for at least 8 weeks before entering the treatment phase were randomized (1∶1) to receive either CERA once every 2 weeks intravenous administration (CERA group,n=132) or intravenous EPO-β three times weekly (EPO group,n=133) for 24 weeks including 16-week correction period and 8-week efficacy evaluation period.At week 25,the patients who reached the target Hb (defined as Hb≥ 110 g/L and increase in Hb≥10 g/L from baseline without red blood cell transfusion during the 24 weeks after the first dose) were kept on CERA or EPO-β treatment regimen for the subsequent 28 weeks to evaluate the long-term safety and tolerability.The starting dose of CERA was 0.4 μg/kg.Two primary endpoints were (1) the Hb response rate during the first 24 weeks; and (2)the mean change in Hb between the baseline and the evaluation periods (week 17 to week 24).Results Totally 232 patients (87.5％) completed the first 24-week treatment and 198 patients (74.7％) completed the whole study treatment (52 weeks).The response rate in CERA group during the first 24 weeks was 87.12％[95％ CI(80.2％ to 92.3％)].Since the lower limit of the 95％CI was greater than 60％ (P ＜ 0.01),CERA once every 2 weeks intravenous administration was considered as effective in correction of renal anemia.The difference between CERA group and EPO group in mean change of Hb from evaluation periods to baseline in the per-protocol (PP) population was-4.7 g/L [95％CI (-7.38 g/L to-1.92 g/L)].Since the lower limit of 95％CI was greater than the pre-defined noninferiority margin-7.5 g/L (P=0.0205),CERA was considered as non-inferior to EPO in the maintenance of Hb after anemia correction.The Hb level remained stable during the subsequent 28-week extension period in both CERA and EPO groups.During the whole study period,the overall safety findings were similar in CERA and EPO groups,50.0％ and 54.6％ of patients experienced at least one adverse event (AE) respectively.The findings from AEs were in accordance with the characteristics of the studied population.Conclusions Intravenous CERA once every 2 weeks is safe and effective for correcting anemia in dialysis patients.Treatment with CERA once every 2 weeks is also non-inferior to 3 times weekly EPO in maintaining the Hb level after the correction.In general,long-term intravenous administration of CERA is well tolerated by dialysis patients with chronic renal anemia.
ABSTRACT
Objective To evaluate the efficacy and safety of continuous erythropoietin receptor activator (C.E.R.A.) once every 4 weeks by subcutaneous administration on hemoglobin (Hb)maintenance in dialytic patients with chronic renal anemia who had been treated with stable dose of erythropoietin (EPO).Methods This was an open,randomized,controlled,multi-center trial.All the hemodialysis or peritoneal dialytic patients in EPO maintenance treatment received subcutaneous EPO-β during the 6-week pre-treatment period to maintain Hb level between 100 g/L and 120 g/L.Eligible patients were randomized (2∶1 ) to accept either C.E.R.A.once every 4 weeks by subcutaneous administration ( C.E.R.A.group,n =187 ) or subcutaneous EPO-β 1-3 times weekly ( EPO group,n =94) for 28 weeks (including 20-week dose titration period and 8-week efficacy evaluation period ). The starting dose of C.E.R.A.was converted according to the dose of EPO-β administered in the week preceding the first study drug administration.The primary outcome was the change of Hb level between the baseline and that in the efficacy evaluation period.Results Totally 253 patients completed the whole 28-week treatment.The change of baseline-adjusted mean Hb was +2.57 g/L for C.E.R.A.group and + 1.23 g/L for EPO group,resulting in a treatment difference of 1.34 g/L (95％ CI - 1.11-3.78 g/L).Since the lower limit of 95％ CI was greater than the pre-defined non-inferiority margin -7.5 g/L( P ＜ 0.0001 ),C.E.R.A.once every 4 weeks by subcutaneous administration was clinically non-inferior to EPO regarding the maintenance of stable Hb level.The proportion of patients maintaining Hb level within the range of 100-120 g/L through efficacy evaluation period was similar between the two groups ( 69.0％ for C.E.R.A.group vs 68.9％ for EPO group,P ＞0.05 ).The overall incidence of adverse events was similar between the C.E.R.A.(41.7％)and EPO (46.2％ ) groups ( P ＞ 0.05 ).The safety findings were in accordance with the patients' primary diseases rather than the administration.Conclusions Conversion from EPO to C.E.R.A.once every 4 weeks by subcutaneous injection could maintain the Hb in target level in dialytic patients with renal anemia,and it was non-inferior to EPO.In general,subcutaneous administration of C.E.R.A.is well tolerated in dialytic patients with chronic renal anemia.
ABSTRACT
Background: Tissue hypoxia is a characteristic patho-physiologic property of colorectal cancer. This process may also add to a therapeutic problem of solid tumor resistance to chemo- and radiation therapy. Erythropoietin (Epo) expression is induced by tissue hypoxia. Acting via its receptor (EpoR), Epo inhibits apoptosis of erythroid cells and has been shown to rescue neurons from hypoxic damage. Increased Epo and EpoR expression has been recently described in human breast, renal and cervical carcinoma. Given the characteristic tumor diathesis present in majority of colorectal cancers, we examined whether Epo signaling may play a role in colonic neoplastic progression. Materials and Methods: Expression of Epo and EpoR was examined using immunohistochemistry in 24 cases of primary colorectal and metastatic adenocarcinomas versus adenomas and normal colonic mucosa. Immunohistochemical stains were evaluated semiquantitatively based on a four-tiered scale. Based on the combination of extent and intensity of immunoreactivity, an immunostaining score (0-300) was determined for each sample. Expression of Epo and EpoR protein and mRNA was examined using Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively, in both normal colonic tissue and carcinoma specimens in five cases. Results: Epo expression was sequentially increased in normal colonic mucosa (8.3 ± 5.6, mean ± SEM), adenoma (26.4 ± 9.1), primary carcinoma (96.1 ± 12.8) and metastatic carcinoma (122 ± 51.3). EpoR expression was also sequentially increased in normal colonic mucosa (22.3 ± 11.8), adenoma (108.7 ± 24.2), primary carcinoma (178.7 ± 16.6) and metastatic carcinoma (220 ± 58.3) (P< 0.05 for all results). Epo and EpoR showed enhanced expression in the areas adjacent to ischemia/necrosis. Western blot and RT-PCR analysis revealed increased EpoR protein and mRNA levels in carcinoma compared to normal mucosal colon specimens. Focal stromal Epo and EpoR immunoreactivity was present in 10 and 12 cases, respectively. Conclusions: The uniform increase in the expression of Epo and EpoR along the colonic neoplastic sequence and further increase in ischemic/necrotic areas indicates that the Epo signaling pathway is an important component in colon carcinogenesis including possible epithelial-stromal interactions.
Subject(s)
Adenocarcinoma/pathology , Adenocarcinoma/secondary , Adenoma/pathology , Hypoxia , Blotting, Western , Colonic Neoplasms/pathology , Colonic Neoplasms/secondary , Erythropoietin/biosynthesis , Gene Expression , Humans , Immunohistochemistry , Microscopy , Receptors, Erythropoietin/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Signal TransductionABSTRACT
Erythropoietin(EPO) has an anti-apoptotic effect,and promotes the proliferation and differentiation of erythroid progenitor cells. Several studies have indicated that EPO can protect photoreceptor cells from the lightinduced retinal degeneration ;protect retinal neurons from ischemia-reperfusion injury and retinal ganglion cells after acute and chronic ocular hypertension; promote ganglion cell survival and axonal regeneration after optic nerve transaction; attenuate inflammation in multiple sclerosis optic neuritis; reduce the permeability of the retinal barrier and protect retinal neurons in diabetic retinopathy; enhance the stability of hypoxic retinal vessels in retinopathy of prematurity. Herein,we review the distribution of EPO and its receptor in retina,their expression in animal model of retinal diseases,and their effects and mechanisms in protection of retinal neurons and optic nerve.
ABSTRACT
Objective Although vascular endothelial growth factor(VEGF)is a primary mediaor in diabetic retinopathy(DR).VEGF inhibition alone is insufficient for preventing retinal neovascularization.Some studies showed that erythropoietin(EPO)is a potent retinal angiogenic factor of independent of VEGF in DR.The present study is to investigate the effect of high glucose on the expression of mRNA and protein of the erythropoietin receptor(EPOR)in cultured human umbilical vein endothelial cells(UVECs)in vitro.MethodsHuman UVECs from the cell center of the hospital were cultured in vitro and passaged in DMEM containing 10% neonatal bovine serum with 22mmol/L of glucose for 12,24,48 and 72 hours in the experimental group.Cells cultured in 5.5mmol/L glucose were used as control group Ⅰ and mannitol + 22mmol/L of glucose(isotope)as control group Ⅱ.The expression of EPOR mRNA in Human UVECs were detected by semi-quantitative reverse transcriptase(RT)-polymerase chain reaction(PCR)and detected at A_(260mm)/A_(280mm).The PCR product was calculated as the A value of EPOR mRNA amplification/the A value of GAPDH mRNA amplification.The expression of EPOR protein in Human UVECs was detected by immunocytochemistry.ResultsThe A_(260mm)/A_(280mm) value of EPOR mRNA receptor expression was 0.32±0.02 in the 5.5mmol/L glucose group,and 0.34±0.02 in the mannitol+22mmol/L glucose group(P>0.05).In 12 hours,24 hours and 72 hours after the experiment,the A260mm/A280mm value of EPOR mRNA was 0.82±0.01,0.96±0.02 and 1.02±0.01,respectively,indicating a significant increase in comparison with the 5.5mmol/L glucose group.The expression of Human UVECs protein was gradually increased with passage in the experimental group.Expression of Human UVECs protein was stronger in various time points in the 22mmol/L glucose group than in the 5.5mmol/L glucose group.ConclusionHigh glucose elevates the expression of EPOR mRNA and protein in Human UVECs in a time-dependent manner.The effect of high glucose(22mmol/L glucose)on the expression of EPOR mRNA and protein in Human UVECs is not related to osmotic pressure.
ABSTRACT
Background and purpose:It was reported that erythropoietin may directly or indirectly induce the tumor cells to proliferate and result in diseases progression when recombinant human erythropoictin is used clinically in cancer-related anemia.Recently,the expression of erythropoietin-receptor(Epo-R)was detected in breast cancer.This study was done to detect the expression of Epo-R,estrogen receptor(ER),progesterone receptor(PR)and human epidermal growth factor receptor 2(Her-2)in breast cancer,and to investigate the relationships between these indexes and the clinical significance.Methods:Sixty breast cancer patients were analyzed,the expression of Epo-R and microvascular density(MVD)were detected by immunohistochernistry,in order to clarify the relationships between the expression level of Epo-R,MVD and ER,PR,Her-2.Results:The rate of Epo-R expression was 78.3%,the mean number of positive tumor cells was 39±24,while the tissue MVD was 25±9.The expression level of Epo-R was positively correlated with the MVD.Also,the level of MVD was higher in the group of Epo-R positive than the negative,which has significant difference(t=3.4252,P＜0.001).The expression level of ER,PR has no definite relationships with Epo-R,MVD.The expression level of Her-2 was both closely associated with Epo-R,MVD.The expression level of Epo-R has an obvious relationship with clinical stage,lymph node status and the size(P＜0.001).The value of MVD was positively correlated with lymph node status,while not with clinical stage and the size.Conclusion:The expression level of Epo-R was markedly higher in breast cancer,and has a positive correlation with the tissue MVD.The expression level of Epo-R and MVD were significantly associated with Her-2,but not with ER and PR.It may contribute to clarifying the clinicopathological characteristics and prognosis of breast cancer by detecting both the expression level of Epo-R and MVD.
ABSTRACT
Objective To detect the expression of EPOR in ovarian epithelial tumor. Study the biologic effect of rHuEPO to ovarian epithelial tumor cell H08910. Methods RT-PCR analyses were used to detect the expression of EPOR in ovarian epithelial tumor cell, FCM assay was used to detect rHuEPOs effect to ovarian epithelial tumor cell proliferation and inhibition ratio. Results There is EPOR expressions in ovarian epithelial tumor cell. rHuEPO could reduce ovarian epithelial tumor cell expressions (P <0.01). Conclusion The lower expression of EPOR was observed in ovarian epithelial tumor cell. Use rHuEPO couldn't promote the cancer's progression and bring negative effect in clinical practice. Further clinical research is required to prove it.
ABSTRACT
BACKGROUND AND OBJECTIVES: Erythropoietin (EPO) is produced in the kidney and locally in the CNS and acts through binding to erythropoietin receptor (EPO-R). Apart from playing an essential role in erythropoiesis, recent research has shown that EPO has neurotrophic and neuroprotective functions in the CNS and found EPO and EPO-R in the inner ear. The aim of this study is to investigate distribution and expression of EPO and EPO-R in the inner ear after noise exposure. MATERIALS AND METHOD: Normal guinea pigs were exposed to noise. Ten of them were sacrificed at 1 hour of the noise exposure (group B) and another 10 animals were sacrificed at day 7 (group C). Four were normal controls that were not exposed to noise (Group A). Auditory function was evaluated by ABR for 7 days. Noise-induced morphological changes of cochlea were studied by phalloidin stain. The expression of EPO and EPO-R was examined by immunofluorescence. RESULTS: The hearing threshold shift reached a level of 40 dB SPL at 8 kHz at day 1 after noise exposure and underwent a partial recovery at day 7. Increased expression of EPO and EPO-R were observed at the level of spiral ganglion cells in the noise-exposed animals. CONCLUSION: It is suggested that noise exposure affects the distribution and expression of EPO and EPO-R in the inner ear.
Subject(s)
Animals , Cochlea , Ear, Inner , Erythropoiesis , Erythropoietin , Guinea , Guinea Pigs , Hearing , Kidney , Noise , Phalloidine , Receptors, Erythropoietin , Spiral GanglionABSTRACT
In order to explore the expression of erythropoietin receptor (EPOR) in pancreatic cell ine NIT-1 and its effect on cell apoptosis after binding with erythropoietin (EPO), NIT-1 cells were cultured and expanded. The expression of EPOR was detected using electrophoresis. NIT-1 apoptosis was induced by cytokines and their effects on cell apoptosis and cell insulin secretion were assayed after binding of EPO to EPOR. The results showed that EPOR was expressed in NIT-1 cells. Recom- binant human EPO (rHuEPO) had no effect on cell apoptosis but significantly inhibited apoptosis in- duced by cytokines, rHuEPO had no effect on cell insulin secretion but significantly improved insulin secretion inhibited by cytokines. From these findings, it was concluded that EPOR was expressed in NIT-1 cells and EPO could protect N1T-1 cells from apoptosis induced by cytokines.
ABSTRACT
Objective To investigate the expressions of erythropoietin(EPO)and its receptor(EPO-R)in the spinal cord after acute traumatic injury in adult rats.Methods Sixty-nine Wistar rats were randomly divided into three groups:normal control group(n=5),spinal cord injury group(n=32),and sham operation group(n= 32).The injury group and sham operation group were further randomly divided into eight subgroups respectively (n=4)(1h,6h,12h,24h,3d,7d,14d,28 dafter operation).The expressions of EPO and EPO-R at different time points were detected by RT-PCR,Western blot and immunohistochemical staining.Results EPO was nut detected at any time point in the normal control grnup,spinal cord injury group or sham operation group.The EPO-R expression was not found in the normal control group or sham operation group.RT-PCR and Western blot analyses revealed EPO-R mRNA and protein expressions in the injury group as early as 6 h after injury.The EPO-R mRNA and protein expressions sharply increased at 12 h,peaked at 24 h to 7 d,and gradually declined after 7 d. They were still higher than those in the control rats 28 d after injury.The EPO-R immunoreactivity was chiefly found in neurons,oligodendrocytes,vascular endothelial and ependymal cells.Conclusion The EPO-R expression can be up-regulated obviously in the injured spinal cord,which provides a molecular basis for the nerooprotection of exogenous EPO.