Inhibiting SHP2 reduces glycolysis, promotes microglial M1 polarization, and alleviates secondary inflammation following spinal cord injury in a mouse model

Reducing the secondary inflammatory response, which is partly mediated by microglia, is a key focus in the treatment of spinal cord injury. Src homology 2-containing protein tyrosine phosphatase 2(SHP2), encoded by PTPN11, is widely expressed in the human body and plays a role in inflammation through various mechanisms. Therefore, SHP2 is considered a potential target for the treatment of inflammation-related diseases. However, its role in secondary inflammation after spinal cord injury remains unclear. In this study, SHP2 was found to be abundantly expressed in microglia at the site of spinal cord injury. Inhibition of SHP2 expression using siRNA and SHP2 inhibitors attenuated the microglial inflammatory response in an in vitro lipopolysaccharide-induced model of inflammation. Notably, after treatment with SHP2 inhibitors, mice with spinal cord injury exhibited significantly improved hind limb locomotor function and reduced residual urine volume in the bladder. Subsequent in vitro experiments showed that, in microglia stimulated with lipopolysaccharide, inhibiting SHP2 expression promoted M2 polarization and inhibited M1 polarization. Finally, a co-culture experiment was conducted to assess the effect of microglia treated with SHP2 inhibitors on neuronal cells. The results demonstrated that inflammatory factors produced by microglia promoted neuronal apoptosis, while inhibiting SHP2 expression mitigated these effects. Collectively, our findings suggest that SHP2 enhances secondary inflammation and neuronal damage subsequent to spinal cord injury by modulating microglial phenotype. Therefore, inhibiting SHP2 alleviates the inflammatory response in mice with spinal cord injury and promotes functional recovery postinjury.

C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 pathway as a therapeutic target and regulatory mechanism for spinal cord injury

Spinal cord injury involves non-reversible damage to the central nervous system that is characterized by limited regenerative capacity and secondary inflammatory damage.The expression of the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis exhibits significant differences before and after injury.Recent studies have revealed that the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis is closely associated with secondary inflammatory responses and the recruitment of immune cells following spinal cord injury,suggesting that this axis is a novel target and regulatory control point for treatment.This review comprehensively examines the therapeutic strategies targeting the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis,along with the regenerative and repair mechanisms linking the axis to spinal cord injury.Additionally,we summarize the upstream and downstream inflammatory signaling pathways associated with spinal cord injury and the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis.This review primarily elaborates on therapeutic strategies that target the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis and the latest progress of research on antagonistic drugs,along with the approaches used to exploit new therapeutic targets within the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis and the development of targeted drugs.Nevertheless,there are presently no clinical studies relating to spinal cord injury that are focusing on the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis.This review aims to provide new ideas and therapeutic strategies for the future treatment of spinal cord injury.

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

Previous studies have shown that Biochanin A,a flavonoid compound with estrogenic effects,can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury;howeve r,its effect on spinal cord injury is still unclea r. In this study,a rat model of spinal cord injury was established using the heavy o bject impact method,and the rats were then treated with Biochanin A(40 mg/kg) via intrape ritoneal injection for 14 consecutive days.The res ults showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal co rd tissue injury,reduced inflammation and oxidative stress in spinal cord neuro ns,and reduced apoptosis and pyroptosis.In addition,Biochanin A inhibited the expression of inflammasome-related proteins(ASC,NLRP3,and GSDMD)and the Toll-like receptor 4/nuclear factor-κB pathway,activated the Nrf2/heme oxygenase 1 signaling pathway,and increased the expression of the autophagy markers LC3 Ⅱ,Beclin-1,and P62.Moreove r,the therapeutic effects of Biochanin A on early post-s pinal cord injury were similar to those of methylprednisolone.These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways.These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

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.

Baicalin attenuates blood-spinal cord barrier disruption and apoptosis through PI3K/Akt signaling pathway after spinal cord injury

Baicalin is a natural active ingredient isolated from Scutellariae Radix that can cross the blood-brain barrier and exhibits neuroprotective effects on multiple central nervous system diseases.However,the mechanism behind the neuroprotective effects remains unclear.In this study,rat models of spinal cord injury were established using a modified Allen's impact method and then treated with intraperitoneal injection of Baicalin.The results revealed that Baicalin greatly increased the Basso,Beattie,Bresnahan Locomotor Rating Scale score,reduced blood-spinal cord barrier permeability,decreased the expression of Bax,Caspase-3,and nuclear factorκB,increased the expression of Bcl-2,and reduced neuronal apoptosis and pathological spinal cord injury.SH-SY5 Y cell models of excitotoxicity were established by application of 10 m M glutamate for 12 hours and then treated with 40μM Baicalin for 48 hours to investigate the mechanism of action of Baicalin.The results showed that Baicalin reversed tight junction protein expression tendencies(occludin and ZO-1)and apoptosis-related protein expression(Bax,Bcl-2,Caspase-3,and nuclear factor-κB),and also led to up-regulation of PI3 K and Akt phosphorylation.These effects on Bax,Bcl-2,and Caspase-3 were blocked by pretreatment with the PI3 K inhibitor LY294002.These findings suggest that Baicalin can inhibit bloodspinal cord barrier permeability after spinal cord injury and reduce neuronal apoptosis,possibly by activating the PI3 K/Akt signaling pathway.This study was approved by Animal Ethics Committee of Xi'an Jiaotong University on March 6,2014.

Aldehyde dehydrogenase 2 overexpression inhibits neuronal apoptosis after spinal cord ischemia/reperfusion injury

Aldehyde dehydrogenase 2（ALDH2）is an important factor in inhibiting oxidative stress and has been shown to protect against renal ischemia/reperfusion injury.Therefore,we hypothesized that ALDH_2 could reduce spinal cord ischemia/reperfusion injury.Spinal cord ischemia/reperfusion injury was induced in rats using the modified Zivin＇s method of clamping the abdominal aorta.After successful model establishment,the agonist group was administered a daily consumption of 2.5%alcohol.At 7 days post-surgery,the Basso,Beattie,and Bresnahan score significantly increased in the agonist group compared with the spinal cord ischemia/reperfusion injury group.ALDH_2expression also significantly increased and the number of apoptotic cells significantly decreased in the agonist group than in the spinal cord ischemia/reperfusion injury group.Correlation analysis revealed that ALDH_2 expression negatively correlated with the percentage of TUNEL-positive cells（r=-0.485,P〈0.01）.In summary,increased ALDH_2 expression protected the rat spinal cord against ischemia/reperfusion injury by inhibiting apoptosis.

Neuroprotective effects of the immunodepressant FTY720 on caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury

BACKGROUND：Studies on the immunodepressant FTY720 have primarily focused on organ transplantation and autoimmune disease therapy.However,the effects on caspase-3 expression and neural apoptosis following acute spinal cord injury remain uncertain.OBJECTIVE：To elucidate the underlying mechanism of the immunodepressant FTY720 to alleviate spinal cord injury by inhibiting expression of caspase-3 and neural apoptosis.DESIGN,TIME AND SETTING：A randomized,controlled,animal experiment was performed at Central Laboratory of the Second Affiliated Hospital of Dalian Medical University from April to July 2009.MATERIALS：FTY720 was provided by Wuhan Yuancheng Technology Developing,China.METHODS：A total of 120 Sprague Dawley rats were randomly assigned to sham-surgery,model,and FTY720 groups.Spinal cord injury at the T9-10 segment was induced in model groups using the free-fall method.Following establishment of spinal cord injury at the T9-10 segment in the FTY720 group,rats were treated with an intragastric injection of 0.3 mL saline-diluted FTY720 （3 mg/kg）.MAIN OUTCOME MEASURES：At 6,12,24,48,and 72 hours following spinal cord injury,caspase-3 expression was detected using streptavidin-peroxidase immunohistochemistry,and neural apoptosis was detected using the TUNEL method.RESULTS：Positive caspase-3 expression and neural apoptosis was not observed in the sham-surgery group at the various time points.The number of apoptotic cells increased with time after acute spinal cord injury,peaked at 24 hours following injury,and then gradually reduced.However,neural apoptosis remained at a high level.Caspase-3 expression positively correlated with neural apoptosis （r= 0.864,P〈 0.05）.Caspase-3 expression and neural apoptosis significantly decreased following FTY720 therapy （P〈 0.05）.CONCLUSION：FTY720 significantly reduced caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury.

Mitomycin C induces apoptosis in human epidural scar fibroblasts after surgical decompression for spinal cord injury

Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C （1, 5, 10, 20, 40 μg/mL） for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 （Z-IETD-FMK and Z-LEHD-FMK, respectively） did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein （CHOP） and caspase 4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.

Neurocyte Apoptosis and Expressions of Caspase-3 and Fas after Spinal Cord Injury and Their Implication in Rats

To study the expression of neurocyte apoptosis and the changes of caspase-3 and Fas after spinal cord injury （SCI） in rats, improved Allen＇s method was used to make model of acute SCI at the level of T9 and T10. The animals were divided into six groups： a control group and 5 injury groups. The segments of injured spinal cords were taken 6, 24, 48 h and 7, 15 days after injury for morphological studies, including HE staining, Hoechst33258 staining and TUNEL labeling. The expression of caspase-3 was detected by immunohistochemical staining and RT-PCR. TUNEL-positive cells began to appear in the compression region 6 h after the injury, mostly located in the gray matter. TUNEL-positive cells were found in both gray and white matter, reaching a peak at the 3rd day. They began to decrease at the 7th day, distributed mostly in the white matter. Fas increased at the 6th h and peaked at the 3th day. Caspase-3 mRNA increased at the 6th h, peaking 48 h after the trauma, and decreased after 7 days. The protein expression of caspase-3, as revealed by immunohistochemical staining, was similar to TUNEL in time. It is concluded that apoptosis takes place after spinal cord injury, and caspase-3 mRNA and protein expressions were enhanced in the apoptosis. The expression of caspase-3 has a positive correlation with Fas expression.

Total flavonoids of hawthorn leaves promote motor function recovery via inhibition of apoptosis after spinal cord injury

Flavonoids have been reported to have therapeutic potential for spinal cord injury.Hawthorn leaves have abundant content and species of total flavonoids,and studies of the effects of the total flavonoids of hawthorn leaves on spinal cord injury have not been published in or outside China.Therefore,Sprague-Dawley rats were used to establish a spinal cord injury model by Allen's method.Rats were intraperitoneally injected with 0.2 m L of different concentrations of total flavonoids of hawthorn leaves(5,10,and 20 mg/kg)after spinal cord injury.Injections were administered once every 6 hours,three times a day,for 14 days.After treatment with various concentrations of total flavonoids of hawthorn leaves,the Basso,Beattie,and Bresnahan scores and histological staining indicated decreases in the lesion cavity and number of apoptotic cells of the injured spinal cord tissue;the morphological arrangement of the myelin sheath and nerve cells tended to be regular;and the Nissl bodies in neurons increased.The Basso,Beattie,and Bresnahan scores of treated spinal cord injury rats were increased.Western blot assays showed that the expression levels of pro-apoptotic Bax and cleaved caspase-3 were decreased,but the expression level of the anti-apoptotic Bcl-2 protein was increased.The improvement of the above physiological indicators showed a dose-dependent relationship with the concentration of total flavonoids of hawthorn leaves.The above findings confirm that total flavonoids of hawthorn leaves can reduce apoptosis and exert neuroprotective effects to promote the recovery of the motor function of rats with spinal cord injury.This study was approved by the Ethics Committee of the Guangxi Medical University of China(approval No.201810042)in October 2018.

Serine-threonine protein kinase activation may be an effective target for reducing neuronal apoptosis after spinal cord injury

The signaling mechanisms underlying ischemia-induced nerve cell apoptosis are poorly understood. We investigated the effects of apoptosis-related signal transduction pathways following ischemic spinal cord injury, including extracellular signal-regulated kinase（ERK）, serine-threonine protein kinase（Akt） and c-Jun N-terminal kinase（JNK） signaling pathways. We established a rat model of acute spinal cord injury by inserting a catheter balloon in the left subclavian artery for 25 minutes. Rat models exhibited notable hindlimb dysfunction. Apoptotic cells were abundant in the anterior horn and central canal of the spinal cord. The number of apoptotic neurons was highest 48 hours post injury. The expression of phosphorylated Akt（pAkt） and phosphorylated ERK（p-ERK） increased immediately after reperfusion, peaked at 4 hours（p-Akt） or 2 hours（p-ERK）, decreased at 12 hours, and then increased at 24 hours. Phosphorylated JNK expression reduced after reperfusion, increased at 12 hours to near normal levels, and then showed a downward trend at 24 hours. Pearson linear correlation analysis also demonstrated that the number of apoptotic cells negatively correlated with p-Akt expression. These findings suggest that activation of Akt may be a key contributing factor in the delay of neuronal apoptosis after spinal cord ischemia, particularly at the stage of reperfusion, and thus may be a target for neuronal protection and reduction of neuronal apoptosis after spinal cord injury.

The Effect of Electroacupuncture on Neuronal Apoptosis and Related Functions in Rats with Acute Spinal Cord Injury

Objective: To investigate the effect and significance of electroacupuncture (EA) on neuronal apoptosis and hindlimb motor and bladder functional improvement in rats with acute spinal cord injury (SCI). Methods: Sixty healthy Sprague Dawley rats were randomly assigned to sham, model, EA, and EA control groups (n = 15 each). EA group rats received EA treatment at Zhibian and Shuidao acupoints seven times daily, whereas EA control group rats received EA at two points, 0.5 cm away from Zhibian and Shuidao, respectively. Histomorphological changes in spinal cord tissue were examined using hematoxylin-eosin staining. Neuronal apoptosis was detected by TUNEL assay. Bcl-2, Bax, and Bad protein levels were detected using immunohistochemistry. Additionally, hindlimb motor function, residual urine volume and maximum bladder capacity were measured. Results: HE staining revealed a morphologically and structurally intact spinal cord in the EA group, and the tissue contained scattered blood cells without edema. In the EA control group, there were small morphological defects in the spinal cord, and the tissue contained fewer blood cells with local edema. Compared with the EA control and model groups, Bax and Bad levels were significantly decreased in the EA group and Bcl-2 expression was increased (P < 0.05). After SCI, hindlimb function scores, residual urine volume, and maximum bladder capacity in rats of the EA group significantly differed from those of the EA control group (P < 0.05). Conclusion: EA may induce SCI-induced improvements in hindlimb motor and bladder functions by affecting neuronal apoptosis and relevant gene expression changes.

Bcl-2 in suppressing neuronal apoptosis after spinal cord injury

BACKGROUND： Apoptosis plays an important role in central neural diseases and trauma. B-cell lymphoma/Leukemia-2 （Bcl-2） can inhibit apoptosis in a wide variety of cells including neurons. In this experiment, by studying Bcl-2 over-expression transgenic （TG） mice subjected to spinal cord injury （SCI）, we investigated whether Bcl-2 could reduce posttraumatic neuronal apoptosis, reduce the range of damage, and improve the behavioral functional recovery after contusive SCI.METHODS： Nine Bcl-2 TG mice and nine control mice were subjected to SCI of moderate severity at T10, with the use of weight dropping （WD） method （impact force 2.5×3.0 g/cm）. At times up to 1 day, 7 days and 14 days after SCI, functional defi cits were evaluated with Basso, Beattie, and Bresnahan （BBB） scales, and apoptosis of neurons was investigated by using the TUNEL method. Another three control mice only underwent lamina opening, but were not subjected to SCI, to provide blank comparison.RESULTS： The mean functional scores for the control mice （5.05 ±0.35） were lower than those for the Bcl-2 TG mice （5.45 ±0.15）, although the unpaired T-test revealed no signifi cant difference （P=0.67）. On the other hand, the number of TUNEL positive neurons and integrated option density （IOD） scores for the Bcl-2 TG mice were both signifi cantly lower than those for the control mice （P〈0.05）.CONCLUSIONS： This experiment suggests that overexpression of Bcl-2 may suppress neuronal apoptosis after SCI. Bcl-2 may be an important factor within the central nervous system that can relieve the damage after trauma.

Effect of interleukin-2 on neurogliocyte and neuron apoptosis in rat models of acute spinal cord injury

BACKGROUND： lnterleukin-2 （IL-2） may influence the growth and survival of nerve cells following spinal cord injury and resuscitate the proliferation and maturation of oligodendrocytes. OBJECTIVE： To observe the effect of IL-2 on neuronal apoptosis of neurogliocytes at different times following acute spinal cord injury in rats. DESIGN, TIME AND SETTING： A randomized grouping trial based on cellular morphology was performed at the Institute of Traumatic Orthopedics of Shandong Province between October 2004 and January 2006. MATERIALS： A total of 72 adult, male, Sprague Dawley rats were included in this study and were divided into a control group and an IL-2 group. The Bcl-2 monoclonal antibody and TUNEL kit were purchased from Wunan Boster Biological Technology Corporation. METHODS： Spinal cord injury was induced in all the rats by dropping a weight from a height of 25 cm onto the exposed spinal cord at vertebral levels T7-11, thus producing a mild lesion. Immediately following the modeling, the rats were injected with daily IL-2 （10 uL） intramuscularly （the IL-2 group）. Other rats received an injection of physiological saline 0.5 mL/d （the control group）. MAIN OUTCOME MEASURES： Bcl-2 immunohistochemistry was applied to detect the Bcl-protein and positive cell expression. The TUNEL method was used to count the number of apoptotic cells. RESULTS： The expression level of Bcl-2 proteins increased significantly in spinal cord tissues during the first day after acute spinal cord injury, reaching a peak on days 3 and days 8 in the control and IL-2 groups, respectively. They were more prevalent in neurogliocytes than in neurocytes, and then began to decrease on day 14. From then until day 21, less expression was detected （P 〈 0.05）. In the control group, many apoptotic cells existed after 24 hours, and most of them were gliocytes; apoptotic cells reached a peak after 3-8 days. They then decreased gradually until day 21, when a small number of cells were still available. In the IL-2 group, the number of positive cells was significantly lower than in the control group （P 〈 0.05）. CONCLUSION： The expression of Bcl-2 and the number of apoptotic cells in neurogliocytes undergo similar changes with time after acute spinal cord injury. IL-2 may upregulate the expression of Bcl-2 proteins and decrease cell apoptosis in spinal cord tissue.

Extract of ginkgo biloba EGb761 inhibits cell apoptosis following spinal cord injury

The neuroprotective effects of ginkgo biloba extract have been shown in rats following spinal cord injury （SCI）. However, the precise protective mechanisms remain unclear. In the present study, low-acid water-soluble extract of ginkgo biloba EGb761 was used to treat rats with SCI. Xanthin oxidase, thiobarbituric acid, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling assay, and immunohistochemistry were utilized to detect lipid peroxidation, neural cell apoptosis, and inducible nitric oxide synthase activity in rats with SCI. Results revealed significantly increased superoxide dismutase activity, decreased malondialdehyde content, apoptotic index, and inducible nitric oxide synthase expression in SCI rats following EGb761 treatment. Therefore, EGb761 suppressed lipid peroxidation following SCI, relieved neural cell apoptosis, inhibited inducible nitric oxide synthase expression, and ultimately exerted protective effects on SCI.

Ependymal cell proliferation and apoptosis following acute spinal cord injury in the adult rat

BACKGROUND： Studies have reported that spinal cord injury can induce the reactive proliferation of ependymal cells and secondarily cause the apoptosis of nerve cells. However, there is no generally accepted theory on the apoptotic characteristics of ependymal cells in the injured spinal cord. OBJECTIVE： To observe the reactive proliferation and apoptosis of ependymal cells in adult rats following acute spinal cord injury. DESIGN, TIME AND SETTING： A randomized control study based on neuropathology was performed in the Third Military Medical University of Chinese PLA between 2005 and 2007. MATERIALS： Forty healthy, adult, Wistar rats were included in the present study. METHODS： Moderate spinal cord injury was established in twenty rats using Feeney＇s method, while the remaining 20 rats served as controls and were only treated with laminectomy. All rats were injected intraperitoneally with 1.25 mL of BrdU solution （10 mg BrdU/mL saline） 3 times at 4 hours intervals during the 12 hours prior to sacrifice. MAIN OUTCOME MEASURES： Ependymal cell proliferation and apoptosis in the rat spinal cord were determined by BrdU and nestin immunofluorescence double-labeling, as well as the TUNEL method, at 1, 3, 7, and 14 days after operation. RESULTS： In the moderate spinal cord injury rats, nestin expression was observed in the cytoplasm of ependymal cells. One day immediately following surgery, ependymal cells were BrdU-labeled. The number of BrdU-positive cells increased at 3 days, reached a peak at 7 days, and gradually reduced thereafter. The ependyma developed from a constitutive monolayer cells to a multi-layer cell complex. Some BrdU/Nestin double-positive ependymal cells migrated out from the ependyma. TUNEL-positive cells were also detected in the ependyma in the central region, as well as ischemic regions of the injured spinal cord. In addition, TUNEL-positive cells were visible in the ependyma. No TUNEL-positive ependymal cells were observed in the normal spinal cord. CONCLUSION： Proliferating ependymal cells induced apoptosis in the central and surrounding region following spinal cord injury.

APOPTOSIS AFTER SPINAL CORD INJURY IN RATS

Objective To confirm the role played by apoptosis in spinal cord injury. Methods 36 rats models of spinal cord injury were made by Allen method. Histological examinations using HE staining and in situ end-labeling were used to observe apoptosis in spinal cord tissues from 1h to 21d after injury. Results HE staining sections showed hemorrhage and necrosis, neuronal degeneration and glial cell proliferation. In situ end-labeling sections showed the appearance of apoptosis in both gray and white matter as well as in both central and surrounding region. The number of apoptotic cells increased from l2h after injury, increased to the peak at 4d and declined to normal at 21d. Conclusion The results suggest that apoptosis, especially glial apoptosis, plays a role in the pathogenesis of spinal cord injury.

Methylprednisolone intrathecal injections suppress neuronal apoptosis following acute spinal cord injury

High dose methylprednisolone intravenous injections are effective in treating acute spinal cord injury but can have severe side effects. In this study, we investigated intrathecal delivery of methylprednisolone for the treatment of spinal cord injury. In particular, we examined the effects of varying doses of methylprednisolone intrathecal injections on neuronal apoptosis induced by secondary damage. The results demonstrate that intrathecal injections inhibit the expression of interleukin-lβ, significantly lower expression of caspase-3, and reduce the number of apoptotic neurons, High dose methylprednisolone （0.75 mg/μL） was much more effective at reducing neuronal apoptosis than low dose methvlprednisolone （0.01 ma/μL.

Apoptosis of motor neurons in the spinal cord after ischemia reperfusion injury delayed paraplegia in rabbits

Objective To clarify the pathologic change of the motor neuron on spinal cord ischemia reperfusion injury delayed paraplegia.Methods The infrarenal aorta of White New Zealand rabbits(n=24) was occluded for 26 minutes using two bulldog clamps.Rabbits were killed after 8,24,72,or 168 hours(n=6 per group),respectively.The clamps was placed but never clamped in sham-operated rabbits(n=24).The lumbar segment of the spinal cord(L5 to L7) was used for morphological studies,including hematoxylin and eosin staining,the expression of bcl-2 and bax proteins in spinal cord was detected with immunohistochemistry.The apoptotic neurons in spinal cord were measured with terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end-labeling of DNA fragments(TUNEL) staining.Results Delayed paraplegia occurred in all rabbits of ischemia reperfusion group at 16-24 hours,but not in sham groups.Motor neurons were selectively lost at 7 days after transient ischemia.After ischemia,the positive expression of bcl-2 protein were in the sham controls but decreased significantly as compared with that of the IR group(P<0.01),especially in 72 hours reperfusion.The positive expression of bax protein were also in the sham controls, but increased in the IR group,especially in 72 hours reperfusion;In addition, TUNEL study demonstrated that no cells were positively labeled until 24 hours after ischemia,but nuclei of some motor neurons were positively labeled at peak after ischemia reperfusion at 72 hours.Conclusion Spinal cord ischemia in rabbits induces morphological and biochemical changes suggestive of apoptosis.These data raise the possibility that apoptosis contributes to neuronal cell death after spinal cord ischemia reperfusion.

Effects of MK-801 on apoptosis of spinal cord neurons after cord injury and fetal cord transplantation in rats

Objective: To study the effects of MK-801, an antagonist to N-methyl-D-aspartate (NMDA) receptors, on the apoptosis of spinal cord neurons after cord injury and fend cord transplantation in rats. Methods: Wistar rats were random- lzed into group A in which the animals were inflicted with spinal cord hemisection and treated with fetal cord transplantation and MK-801, group B in which the fats were injured with cord hemisection and beated with fend cord transplantation but no MK-80l are given and group C in which the rats received similar cord injury and the eavity in their cord was filled with gelfoam. All the rats were .killed on the lst, 3rd, 7th and 14th day after surgery respectively. The sections of the injured segment of the spinal cord were studied with TUNEL (terminal deoxynucleotidal transferase-mediated DUTP-biotin nick end labeling) and the expression of Bcl-2 was observed with immunohistochemistry. The positive cells were quantitatively analyzed with a computer image analysis system. Results: The Seventy of apoptosis of the cord neurons was in the order of group C > group B > group A (P < 0.005) while the ode of the intensity of Bcl-2 expression was grouP A > group B > group C (P < 0.05). Conclusion: Our findings indicate that fetal cord transplantation and the administration of MK-80l, an antagonist to NMDA receptors can attenuate apoptesis of the cord neurons ther spinal cold injury.