Awake rabbit model of ischemic spinal cord injury with delayed paraplegia:The role of ambient temperature

Background:Paraplegia after spinal cord ischemia is a devastating condition in the clinic.Here,we develop an awake rabbit model of spinal cord ischemia with delayed paraplegia and explore the influence of ambient temperature on the outcomes after injury.Methods:A total of 47 male rabbits were involved in the present study.Transient spinal cord ischemia was induced by occluding the infrarenal abdominal aorta of awake rabbits at different ambient temperatures.To find the optimal conditions for developing delayed paraplegia,hindlimb motor function after ischemia was evaluated between experiments.Results:The onset and magnitude of ischemic injury varied with the ambient temperature maintained during the peri-i schemia period.More serious spinal cord injury occurred when ischemia was induced at higher temperatures.At 18°C,25-minute ischemia resulted in 74%of rabbits developing delayed paraplegia.At a temperature of 28°C or higher,most of the animals developed acute paraplegia immediately.While at 13°C,rabbits usually regained normal motor function without paraplegia.Conclusion:This awake rabbit model is highly reproducible and will be helpful in future studies of delayed paraplegia after spinal cord ischemia.The ambient temperature must be considered while using this model during investigation of therapeutic interventions.

A new peptide,VD11,promotes structural and functional recovery after spinal cord injury

The regenerative capacity of the central nervous system is very limited and few effective treatments are currently available for spinal cord injury.It is therefore a priority to develop new drugs that can promote structural and functional recovery after spinal cord injury.Previous studies have shown that peptides can promote substantial repair and regeneration of injured tissue.While amphibians have a pronounced ability to regenerate the spinal cord,few studies have investigated the effect of amphibian spinal cord-derived peptides on spinal cord injury.Here we report for the first time the successful identification and isolation of a new polypeptide,VD11(amino acid sequence:VDELWPPWLPC),from the spinal cord of an endemic Chinese amphibian(Odorrana schmackeri).In vitro experiments showed that VD11 promoted the secretion of nerve growth factor and brain-derived neurotrophic factor in BV2 cells stimulated with lipopolysaccharide,as well as the proliferation and synaptic elongation of PC12 cells subjected to hypoxia.In vivo experiments showed that intravertebral injection of VD11 markedly promoted recovery of motor function in rats with spinal cord injury,alleviated pathological damage,and promoted axonal regeneration.Furthermore,RNA sequencing and western blotting showed that VD11 may affect spinal cord injury through activation of the AMPK and AKT signaling pathways.In summary,we discovered a novel amphibian-derived peptide that promotes structural and functional recovery after spinal cord injury.

Effects of Methylprednisolone on the Expression and Activity of Calpain Following Ischemia-Reperfusion Spinal Cord Injury in Rats

The present study was undertaken to examine the effects of methylprednisolone on the expression and activity of calpain in spinal cord tissue following spinal cord ischemia-reperfusion injury in rats. Adult male Sprague-Dawley rats were subjected to sham operations, ischemia-reperfusion and vehicle treated, or ischemia-reperfusion with methylprednisolone administration after injury. The expression of calpain I in the injured segments of the spinal cord as well as the degradation of the 68 kD neurofilament protein (NFP), a calpain-specific substrate, was determined at 3 h, 24 h, 72 h and 7 days after reperfusion using immunohistochemical labeling and western blot analysis, respectively. Three hours after spinal cord reperfusion, calpain I-positive cells and NFP degradation products were evident. The number of positive cells and immunoreactivity increased with time and peaked at 72 h after reperfusion. In addition, the number of calpain I-positive cells and the abundance of NFP degradation products were significantly lower in the methylprednisolone group, compared with vehicle treated animals following ischemia-reperfusion injury. The results of this study suggest that methylprednisolone can inhibit the expression and degradation activity of calpain following ischemia-reperfusion injury, providing further insight into the therapeutic benefits of methylprednisolone treatment for spinal cord injury.

Pathophysiological mechanisms of chronic compressive spinal cord injury due to vascular events

Cervical spondylotic myelopathy is the main cause of non-traumatic spinal cord injury,with chronic static and/or dynamic compressive spinal cord injury as the unique pathogenesis.In the progression of this condition,the microvascular network is compressed and destroyed,resulting in ischemia and hypoxia.The main pathological changes are inflammation,damage to the blood spinal cord barriers,and cell apoptosis at the site of compression.Studies have confirmed that vascular regeneration and remodeling contribute to neural repair by promoting blood flow and the reconstruction of effective circulation to meet the nutrient and oxygen requirements for nerve repair.Surgical decompression is the most effective clinical treatment for this condition;however,in some patients,residual neurological dysfunction remains after decompression.Facilitating revascularization during compression and after decompression is therefore complementary to surgical treatment.In this review,we summarize the progress in research on chronic compressive spinal cord injury,covering both physiological and pathological changes after compression and decompression,and the regulatory mechanisms of vascular injury and repair.

Changes of blood flow in spinal cord following ischemia and reperfusion and its relation with pathological damages in rabbits

objective: To investigate the changes of spinal cord blood flow (SCBF) after the ischemia and reperfusion injury of the spinal cord and its relation with pathological damages. Methods: Twenty adult Japanese big-ear white rabbits equally randomized into the control group, 30-min-ischemic group, 60-min-is chemic group and 90-min-ischemic group. All the rabbits in the latter 3 groups were inflicted with the is chemia and reperfusion injury of the spinal cord through selective occlusion of the lumbar artery. SCBF was measured with the hydrogen clearance method and the pathological changes of the injured spinal cord were observed with Nissl’s staining. Results: SCBF during ischemia was 0 ml/100 g/min. During reperfusion, it was recovered to different levels. However, it was still decreased as compared with that before ischemia and that in the control group. The pathological changes of the gray matter were the most significant. The severi ty of the pathological changes decreased in the order from 90-min-ischemic group, 6O-min-ischemic group to 30-min ischemic group. Conclusion: Reversible injury occurs in rabbits after ischemia for 30 min, irreversible injury in those after ischemia for 90 min and partially reversible injury in those after ischemia for 60 min.

Inhibition of LncRNA Vof-16 expression promotes nerve regeneration and functional recovery after spinal cord injury

Our previous RNA sequencing study showed that the long non-coding RNA ischemia-related factor Vof-16(lncRNA Vof-16)was upregulated after spinal cord injury,but its precise role in spinal cord injury remains unclear.Bioinformatics predictions have indicated that lncRNA Vof-16 may participate in the pathophysiological processes of inflammation and apoptosis.PC12 cells were transfected with a pHBLV-U6-MCS-CMV-ZsGreen-PGK-PURO vector to express an lncRNA Vof-16 knockdown lentivirus and a pHLV-CMVIE-ZsGree-Puro vector to express an lncRNA Vof-16 overexpression lentivirus.The overexpression of lncRNA Vof-16 inhibited PC12 cell survival,proliferation,migration,and neurite extension,whereas lncRNA Vof-16 knockdown lentiviral vector resulted in the opposite effects in PC12 cells.Western blot assay results showed that the overexpression of lncRNA Vof-16 increased the protein expression levels of interleukin 6,tumor necrosis factor-α,and Caspase-3 and decreased Bcl-2 expression levels in PC12 cells.Furthermore,we established rat models of spinal cord injury using the complete transection at T10.Spinal cord injury model rats were injected with the lncRNA Vof-16 knockdown or overexpression lentiviral vectors immediately after injury.At 7 days after spinal cord injury,rats treated with lncRNA Vof-16 knockdown displayed increased neuronal survival and enhanced axonal extension.At 8 weeks after spinal cord injury,rats treated with the lncRNA Vof-16 knockdown lentiviral vector displayed improved neurological function in the hind limb.Notably,lncRNA Vof-16 knockdown injection increased Bcl-2 expression and decreased tumor necrosis factor-αand Caspase-3 expression in treated animals.Rats treated with the lncRNA Vof-16 overexpression lentiviral vector displayed opposite trends.These findings suggested that lncRNA Vof-16 is associated with the regulation of inflammation and apoptosis.The inhibition of lncRNA Vof-16 may be useful for promoting nerve regeneration and functional recovery after spinal cord injury.The experiments were approved by the Institutional Animal Care and Use Committee of Guangdong Medical University,China.

Protective effect of propofol preconditioning and postconditioning against ischemic spinal cord injury

Propofol preconditioning has been shown to provide neuroprotection against spinal ischemia/reperfusion injury. In this study, spinal cord ischemia/repeffusion injury was induced by blocking the abdominal aorta in rabbits for 40 minutes. Results showed that the co-application of propofol preconditioning and postconditioning regimen ameliorated pathological injury of the ischemic spinal cord and suppressed the elevation of malondialdehyde levels and increased superoxide dismutase activities in the spinal cord tissues. Co-application of propofol preconditioning and postconditioning resulted in potent protective effects against spinal cord ischemia/reperfusion injury and prolonged the spinal cord＇s tolerance to ischemia. This protection was associated with the anti-lipid peroxidation capacity of the spinal cord tissues.

Expression of long non-coding RNAs in complete transection spinal cord injury: a transcriptomic analysis

Long non-coding RNAs(lncRNAs)are abundantly expressed in the central nervous system and exert a critical role in gene regulation via multiple biological processes.To uncover the functional significance and molecular mechanisms of lncRNAs in spinal cord injury(SCI),the expression signatures of lncRNAs were profiled using RNA sequencing(RNA-seq)technology in a Sprague-Dawley rat model of the 10th thoracic vertebra complete transection SCI.Results showed that 116 of 14,802 detected lncRNAs were differentially expressed,among which 16—including eight up-regulated(H19,Vof16,Hmox2-ps1,LOC100910973,Ybx1-ps3,Nnat,Gcgr,LOC680254)and eight down-regulated(Rmrp,Terc,Ngrn,Ppp2r2b,Cox6a2,Rpl37a-ps1,LOC360231,Rpph1)—demonstrated fold changes>2 in response to transection SCI.A subset of these RNA-seq results was validated by quantitative real-time PCR.The levels of 821 mRNAs were also significantly altered post-SCI;592 mRNAs were up-regulated and 229 mRNAs were down-regulated by more than 2-fold.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analyses showed that differentially expressed mRNAs were related to GO biological processes and molecular functions such as injury and inflammation response,wound repair,and apoptosis,and were significantly enriched in 15 KEGG pathways,including cell phagocytosis,tumor necrosis factor alpha pathway,and leukocyte migration.Our results reveal the expression profiles of lncRNAs and mRNAs in the rat spinal cord of a complete transection model,and these differentially expressed lncRNAs and mRNAs represent potential novel targets for SCI treatment.We suggest that lncRNAs may play an important role in the early immuno-inflammatory response after spinal cord injury.This study was approved by the Administration Committee of Experimental Animals,Guangdong Province,China.

Delayed xenon post-conditioning mitigates spinal cord ischemia/reperfusion injury in rabbits by regulating microglial activation and inflammatory factors

The neuroprotective effect against spinal cord ischemia/reperfusion injury in rats exerted by delayed xenon post-conditioning is stronger than that produced by immediate xenon post-conditioning. However, the mechanisms underlying this process remain unclear. Activated microglia are the main inflammatory cell type in the nervous system. The release of pro-inflammatory factors following microglial activation can lead to spinal cord damage, and inhibition of microglial activation can relieve spinal cord ischemia/reperfusion injury. To investigate how xenon regulates microglial activation and the release of inflammatory factors, a rabbit model of spinal cord ischemia/reperfusion injury was induced by balloon occlusion of the infrarenal aorta. After establishment of the model, two interventions were given： （1） immediate xenon post-conditioning—after reperfusion, inhalation of 50% xenon for 1 hour, 50% N2/50%O2 for 2 hours; （2） delayed xenon post-conditioning—after reperfusion, inhalation of 50% N2/50%O2 for 2 hours, 50% xenon for 1 hour. At 4, 8, 24, 48 and 72 hours after reperfusion, hindlimb locomotor function was scored using the Jacobs locomotor scale. At 72 hours after reperfusion, interleukin 6 and interleukin 10 levels in the spinal cord of each group were measured using western blot assays. Iba1 levels were determined using immunohistochemistry and a western blot assay. The number of normal neurons at the injury site was quantified using hematoxylin-eosin staining. At 72 hours after reperfusion, delayed xenon post-conditioning remarkably enhanced hindlimb motor function, increased the number of normal neurons at the injury site, decreased Iba1 levels, and inhibited interleukin-6 and interleukin-10 levels in the spinal cord.Immediate xenon post-conditioning did not noticeably affect the above-mentioned indexes. These findings indicate that delayed xenon post-conditioning after spinal cord injury improves the recovery of neurological function by reducing microglial activation and the release of interleukin-6 and interleukin-10.

Eph receptor A4 regulates motor neuron ferroptosis in spinal cord ischemia/reperfusion injury in rats

Previous studies have shown that the receptor tyrosine kinase Eph receptor A4(EphA4) is abundantly expressed in the nervous system. The EphA4 signaling pathway plays an important role in regulating motor neuron ferroptosis in motor neuron disease. To investigate whether EphA4 signaling is involved in ferroptosis in spinal cord ischemia/reperfusion injury, in this study we established a rat model of spinal cord ischemia/reperfusion injury by clamping the left carotid artery and the left subclavian artery. We found that spinal cord ischemia/reperfusion injury increased EphA4 expression in the neurons of anterior horn, markedly worsened ferroptosis-related indicators, substantially increased the number of mitochondria exhibiting features consistent with ferroptosis, promoted deterioration of motor nerve function, increased the permeability of the blood-spinal cord barrier, and increased the rate of motor neuron death. Inhibition of EphA4 largely rescued these effects. However, intrathecal administration of the ferroptosis inducer Erastin counteracted the beneficial effects conferred by treatment with the EphA4 inhibitor. Mass spectrometry and a PubMed search were performed to identify proteins that interact with EphA4, with the most notable being Beclin1 and Erk1/2. Our results showed that inhibition of EphA4 expression reduced binding to Beclin1, markedly reduced p-Beclin1, and reduced Beclin1-XCT complex formation. Inhibition of EphA4 also reduced binding to p-Erk1/2 and markedly decreased the expression of c-Myc, transferrin receptor 1, and p-Erk1/2. Additionally, we observed co-localization of EphA4 and p-Beclin1 and of EphA4 and p-ERK1/2 in neurons in the anterior horn. In conclusion, EphA4 participates in regulating ferroptosis of spinal motor neurons in the anterior horn in spinal cord ischemia/reperfusion injury by promoting formation of the Beclin1-XCT complex and activating the Erk1/2/c-Myc/transferrin receptor 1 axis.

Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

It remains unclear whether spinal cord ischemia-reperfusion injury caused by ischemia and other non-mechanical factors can be monitored by somatosensory evoked potentials. Therefore, we monitored spinal cord ischemia-reperfusion injury in rabbits using somatosensory evoked potential detection technology. The results showed that the somatosensory evoked potential latency was significantly prolonged and the amplitude significantly reduced until it disappeared during the period of spinal cord ischemia. After reperfusion for 30-180 minutes, the amplitude and latency began to gradually recover; at 360 minutes of reperfusion, the latency showed no significant difference compared with the pre-ischemic value, while the somatosensory evoked potential amplitude in- creased, and severe hindlimb motor dysfunctions were detected. Experimental findings suggest that changes in somatosensory evoked potentia~ ~atency can reflect the degree of spinat cord ischemic injury, while the amplitude variations are indicators of the late spinal cord reperfusion injury, which provide evidence for the assessment of limb motor function and avoid iatrogenic spinal cord injury.

Functional recovery of the spinal cord following ischemia and reperfusion injury

Objective: To study the changes of excitatory amino acids (EAAs) and intracellular calcium ([Ca 2+ ]i), and the protective effect of EAAs receptor antagonists in the tissues of rabbit lumbar spinal cord after 40 minues ischemia and 4 hours reperfusion. Methods: Thirty healthy rabbits were divided into six groups: sham operation, 40 minues ischemia,4 hour reperfusion, ketamine and MgSO 4 treatment, ketamine treatment, and saline treatment groups. The contents of EAAs (glutamate and aspartate) and [Ca 2+ ] i were measured. Results: The contents of glutamate and aspartate were decreased to 15.18 μmol/g± 2.33 μmol/g and 9.99 μmol/g ± 0.69 μmol/g, respectively; 13.75 μmol/g± 2.58 μmol/g and 6.49 μmol/g± 1.39 umol/g after reperfusion. In the ischemia group, the [Ca 2+ ]i was elevated to 221.2 μg/g ± 4.27 μg/g, and elevated further to 298.3 μg/g± 9.26 μg/g after reperfusion, being significantly higher than that of ischemia and control groups. Ketamine could obviously increase the level of glutamate and aspartate and decrease the level of [Ca 2+ ]i during the ischemia and reperfusion injury. Conclusions: The excitotoxicity of EAAs and the overload of calcium induced by EAAs play a harmful role in ischemia and reperfusion injury. Ketamine has an effective inhibitory effect.

Neuroprotection of Erythropoietin and Methylprednisolone against Spinal Cord Ischemia-Reperfusion Injury

Recent research based on various animal models has shown the neuroprotective effects of erythropoietin （EPO）. However, few studies have examined such effects of EPO in the clinic. In this study we enrolled patients with spinal cord ischemia-reperfusion （I-R） injury to investigate the clinical application of EPO and methylprednisolone （MP） for the neuroprotection against spinal cord I-R injury. Retrospective analysis of 63 cases of spinal cord I-R injury was performed. The Frankel neurological performance scale was used to evaluate the neurological function after spinal cord injury （SCI）, including 12 cases of scale B, 30 cases of scale C, and 21 cases of scale D. These cases were divided into 2 groups： group A （27 cases） got treatment with both EPO and MP; group B （36 cases） got treatment with MP only. The neurological function of patients after treatment was evaluated by American Spinal Cord Injury Association （ASIA） index score, and activity of daily living （ADL） of the patients was also recorded. All patients got follow-up and the follow-up period ranged from 24 to 39 months （mean 26 months）. There was no significance difference in neurological function between groups A and B before the treatment （P〉0.05）. However, the neurological function and ADL scores were significantly improved 1 week, 1 year or 2 years after the treatment compared to those before the treatment （P〈0.05）, and the improvement was more significant in group A than in group B （P〈0.05）. It is suggested that the clinical application of EPO and MP provides the neuroprotection against spinal cord I-R injury.

Ginsenoside Rd inhibits apoptosis following spinal cord ischemia/reperfusion injury

Ginsenoside Rd has a clear neuroprotective effect against ischemic stroke. We aimed to verify the neuroprotective effect of ginsenoside Rd in spinal cord ischemia/reperfusion injury and explore its anti-apoptotic mechanisms. We established a spinal cord ischemia/reperfusion injury model in rats through the occlusion of the abdominal aorta below the level of the renal artery for 1 hour. Successfully established models were injected intraperitoneally with 6.25, 12.5, 25 or 50 mg/kg per day ginsenoside Rd. Spinal cord morphology was observed at 1, 3, 5 and 7 days after spinal cord ischemia/reperfusion injury. Intraperitoneal injection of ginsenoside Rd in ischemia/reperfusion injury rats not only improved hindlimb motor function and the morphology of motor neurons in the anterior horn of the spinal cord, but it also reduced neuronal apoptosis. The optimal dose of ginsenoside Rd was 25 mg/kg per day and the optimal time point was 5 days after ischemia/ reperfusion. Immunohistochemistry and western blot analysis showed ginsenoside Rd dose-de- pendently inhibited expression of pro-apoptotic Caspase 3 and down-regulated the expression of the apoptotic proteins ASK1 and JNK in the spinal cord of rats with spinal cord ischemia/reper- fusion injury. These findings indicate that ginsenoside Rd exerts neuroprotective effects against spinal cord ischemia/reperfusion injury and the underlying mechanisms are achieved through the inhibition of ASK1-JNK pathway and the down-regulation of Caspase 3 expression.

Key genes expressed in different stages of spinal cord ischemia/reperfusion injury ischemia/reperfusion injury

The temporal expression of microRNA after spinal cord ischemia/reperfusion injury is not yet fully understood. In the present study, we established a model of spinal cord ischemia in Sprague-Dawley rats by clamping the abdominal aorta for 90 minutes, before allowing reperfusion for 24 or 48 hours. A sham-operated group underwent surgery but the aorta was not clamped. The damaged spinal cord was removed for hematoxylin-eosin staining and RNA extraction. Neuronal degeneration and tissue edema were the most severe in the 24- hour reperfusion group, and milder in the 48-hour reperfusion group. RNA amplification, labeling, and hybridization were used to obtain the microRNA expression profiles of each group. Bioinformatics analysis confirmed tour differentially expressed microRNAs （miR-22-3p, miR-743b-3p, miR-201-5p and miR-144-5p） and their common target genes （Tmem69 and Cxcll0）. Compared with the sham group, miR- 22-3p was continuously upregulated in all three ischemia groups but was highest in the group with 11o reperfusion, whereas miR-743b-3p, miR-201-5p and miR-144-5p were downregulated in the three ischemia groups. We have successfully identified the key genes expressed at different stages of spinal cord ischemia/reperfusion injury, which provide a reference for future investigations into the mechanism of spinal cord injury.

Differential protein expression in spinal cord tissue of a rabbit model of spinal cordischemia/reperfusion injury

New Zealand rabbits were randomly divided into an ischemia group （occlusion of the abdominal aorta for 60 minutes）, an ischemia-reperfusion group （occlusion of the abdominal aorta for 60 minutes followed by 48 hours of reperfusion） and a sham-surgery group. Two-dimensional gel electrophoresis detected 49 differentially expressed proteins in spinal cord tissue from the ischemia and ischemia/ reperfusion groups and 23 of them were identified by mass spectrometry. In the ischemia group, the expression of eight proteins was up regulated, and that of the remaining four proteins was down regulated. In the ischemia/reperfusion group, the expression of four proteins was up regulated, and that of two proteins was down regulated. In the sham-surgery group, only one protein was detected. In the ischemia and ischemia/reperfusion groups, four proteins overlapped between groups with the same differential expression, including three that were up regulated and one down regulated. These proteins were related to energy metabolism, cell defense, inflammatory mechanism and cell signaling.

Propofol regulates Ca～(2+),Mg～(2+),Cu～(2+) and Zn～(2+) balance in the spinal cord after ischemia/reperfusion injury

This study assessed concentrations of Ca2＋, Mg2＋, Cu2＋ and Zn2＋ in blood serum and spinal cord tissues, as well as the possible mechanisms by which propofol may protect spinal cord tissues during ischemia/reperfusion injury. With prolonged duration of ischemia/reperfusion injury, serum Ca2＋ and Cu2＋ concentrations gradually increased, but Mg 2＋ and Zn2＋ concentrations gradually decreased. Seven days after spinal cord injury, changes in Ca2＋, Mg2＋, Cu2＋ and Zn2＋ concentrations were significant. After 7 days of reperfusion, changes in the concentrations of Ca2＋, Mg2＋, Cu2＋ and Zn2＋ in spinal cord homogenates were consistent with those in the serum. After propofol treatment, no significant changes in Ca2＋, Mg2＋, Cu2~ and Zn2＋ concentrations in serum and spinal cord homogenates were noted during ischemia/reperfusion injury. These findings suggest that propofol exerts protective effects against spinal cord injury by stabilizing or recovering metal ion balance in ischemic regions.

Characteristics of mRNA dynamic expression related to spinal cord ischemia/reperfusion injury:a transcriptomics study

Following spinal cord ischemia/reperfusion injury,an endogenous damage system is immediately activated and participates in a cascade reaction.It is difficult to interpret dynamic changes in these pathways,but the examination of the transcriptome may provide some information.The transcriptome reflects highly dynamic genomic and genetic information and can be seen as a precursor for the proteome.We used DNA microarrays to measure the expression levels of dynamic evolution-related m RNA after spinal cord ischemia/reperfusion injury in rats.The abdominal aorta was blocked with a vascular clamp for 90 minutes and underwent reperfusion for 24 and 48 hours.The simple ischemia group and sham group served as controls.After rats had regained consciousness,hindlimbs showed varying degrees of functional impairment,and gradually improved with prolonged reperfusion in spinal cord ischemia/reperfusion injury groups.Hematoxylin-eosin staining demonstrated that neuronal injury and tissue edema were most severe in the 24-hour reperfusion group,and mitigated in the 48-hour reperfusion group.There were 8,242 differentially expressed m RNAs obtained by Multi-Class Dif in the simple ischemia group,24-hour and 48-hour reperfusion groups.Sixteen m RNA dynamic expression patterns were obtained by Serial Test Cluster.Of them,five patterns were significant.In the No.28 pattern,all differential genes were detected in the 24-hour reperfusion group,and their expressions showed a trend in up-regulation.No.11 pattern showed a decreasing trend in m RNA whereas No.40 pattern showed an increasing trend in m RNA from ischemia to 48 hours of reperfusion,and peaked at 48 hours.In the No.25 and No.27 patterns,differential expression appeared only in the 24-hour and 48-hour reperfusion groups.Among the five m RNA dynamic expression patterns,No.11 and No.40 patterns could distinguish normal spinal cord from pathological tissue.No.25 and No.27 patterns could distinguish simple ischemia from ischemia/reperfusion.No.28 pattern could analyze the need for inducing reperfusion injury.The study of specific pathways and functions for different dynamic patterns can provide a theoretical basis for clinical differential diagnosis and treatment of spinal cord ischemia/reperfusion injury.

Protective effects of prostaglandin E1 perfusion againstspinal cord ischemia-reperfusion injury in a rabbit model

BACKGROUND： Prostaglandin E1 （PGE1） is known to be protective in ischemia-reperfusion of heart, lung,renal, and liver tissue. It still remains to be determined whether PGE1 exhibits similar protection against spinal cord ischemia-reperfusion injury in a rabbit model. OBJECTIVE： To observe the large, ventral horn, motor neurons of the spinal cord, as well as limb function, and to investigate whether perfusion of PGE1 exhibits protective effects against spinal cord ischemia-reperfusion injury in a rabbit model. DESIGN, TIME AND SETTING： Controlled observation. The experiment was performed at the Department of Orthopedics, First Affiliated Hospital of Liaoning Medical University between June and October 2007. MATERIALS： Twenty male, New Zealand white rabbits, weighing 2.0 kg and of mixed gender, were used in the present study. The following chemicals and compounds were used： prostaglandin E1 injectable powder,as well as malondialdehyde and ATPase kits. Animal intervention was in accordance with animal ethical standards. METHODS： We separated rabbits into control and experimental groups randomly, with 10 rabbits in each group. Rabbits were used as spinal cord ischemia models by segmentally cross-clamping the infrarenal aorta. The control group was subsequently perfused for five minutes with blood and saline solution, and the experimental group was perfused for 5 minutes with blood and saline solution containing PGE1 （100 ng/kg/min）. MAIN OUTCOME MEASURES： The neurological function of the hind limbs was assessed 12, 24, and 48 hours after model establishment. All animals were sacrificed and spinal cords were harvested for histological analyses. The large motor neurons in the ventral horn of L1-7 were observed by inverted microscope. RESULTS： All 20 rabbits were included in the final analysis, without any loss. In the ventral horn of the L5-7 segments, there were more large motor neurons that appeared viable in the experimental group than the control group （P 〈 0.05）. The scores of hind limb functions were greater in the experimental group after 12, 24, and 48 hours （P 〈 0.01）. CONCLUSION： Perfusion of PGE1 reduced the amount of neuronal damage in the spinal cord ischemia-reperfusion injury rabbit model. These results correlated with increased numbers large motor neurons in the ventral horn of the spinal cord, as well as improved hind limb function.

Oxidative phosphorylated neurofilament protein M protects spinal cord against ischemia/reperfusion injury

Previous studies have shown that neurofilament protein M expression is upregulated in the early stage of spinal cord ischemia/reperfusion injury, indicating that this protein may play a role in the injury process. In the present study, we compared protein expression in spinal cord tissue of rabbits after 25 minutes of ischemia followed by 0, 12, 24, or 48 hours of reperfusion with that of sham operated rabbits, using proteomic two-dimensional gel electrophoresis and mass spec- trometry. In addition, the nerve repair-related neurofilament protein M with the unregulated expression was detected with immunohistochemistry and western blot analysis. Two-dimen- sional gel electrophoresis and mass spectrometry showed that, compared with the sham group, upregulation of protein expression was most significant in the spinal cords of rabbits that had undergone ischemia and 24 hours of reperfusion. Immunohistochemical analysis revealed that neurofilament protein M was located in the membrane and cytoplasm of neuronal soma and axons at each time point after injury. Western blot analysis showed that neurofilament protein M expression increased with reperfusion time until it peaked at 24 hours and returned to baseline level after 48 hours. Furthermore, neurofilament protein M is phosphorylated under oxidative stress, and expression changes were parallel for the phosphorylated and non-phosphorylated forms. Neurofilament protein M plays an important role in spinal cord ischemia/reperfusion injury, and its functions are achieved through oxidative phosphorylation.