Function of SOD1, SOD2, and PI3K/AKT signaling pathways in the protection of propofol on spinal cord ischemic reperfusion injury in a rabbit model.

AIMS: To verify that co-application of propofol preconditioning and postconditioning protects spinal cord from ischemia/reperfusion injury by enhancing the different subtypes of SOD activity, which is related to PI3K/AKT signal pathway. MATERIALS AND METHODS: 60 rabbits were randomly equally assigned to 3 groups: Group S, sham-operation group; Group I/R., ischemia/reperfusion group; Group P, ischemia/reperfusion group with propofol treatment. Four rabbits per group were randomly executed at the time-points: days 1, 2, 3, 5, and 7 post-surgery. Spinal cord tissues at L3 to L4 levels were harvested. The bioactivities of SOD1 and SOD2, and the mRNA expression levels of SOD1, SOD2, PI3K, and AKT were detected. KEY FINDINGS: On day 1, the bioactivity of SOD1 increased significantly in Group I/R or Group P compared with Group S (P<0.05). On day 2, compared with Group S, the bioactivity of SOD1 increased significantly in Group P (P<0.05). On days 3, 5, and 7, the bioactivity of SOD1 decreased significantly respectively in Group I/R compared with Group S (P<0.05). On all timepoints, the bioactivity of SOD2 decreased significantly in Group I/R compared with Group S (P<0.05). There was a positive correlation between the SOD1 activity and the respective mRNA expression of SOD1, PI3K, and AKT. SIGNIFICANCE: Co-application of propofol preconditioning and postconditioning resulted in potent protective effects against spinal cord ischemia/reperfusion injury, which was associated with the increased expression of SOD1 in spinal cord tissues by activating PI3K/AKT signal pathway.

Erythropoietin activates the phosporylated cAMP [adenosine 3'5' cyclic monophosphate] response element-binding protein pathway and attenuates delayed paraplegia after ischemia-reperfusion injury.

OBJECTIVE: Paraplegia remains a devastating complication of complex aortic surgery. Erythropoietin (EPO) has been shown to prevent paraplegia after ischemia reperfusion, but the protective mechanism remains poorly described in the spinal cord. We hypothesized that EPO induces the CREB (cAMP [adenosine 3'5' cyclic monophosphate] response element-binding protein) pathway and neurotrophin production in the murine spinal cord, attenuating functional and cellular injury. METHODS: Adult male mice were subjected to 4 minutes of spinal cord ischemia via an aortic and left subclavian cross-clamp. Experimental groups included EPO treatment 4 hours before incision (n = 7), ischemic control (n = 7), and shams (n = 4). Hind-limb function was assessed using the Basso motor score for 48 hours after reperfusion. Spinal cords were harvested and analyzed for neuronal viability using histology and staining with a fluorescein derivative. Expression of phosphorylated (p)AKT (a serine/threonine-specific kinase), pCREB, B-cell lymphoma 2, and brain-derived neurotrophic factor were determined using immunoblotting. RESULTS: By 36 hours of reperfusion, EPO significantly preserved hind-limb function after ischemia-reperfusion injury (P < .01). Histology demonstrated preserved cytoarchitecture in the EPO treatment group. Cords treated with EPO expressed significant increases in pAKT (P = .021) and pCREB (P = .038). Treatment with EPO induced expression of both of the neurotrophins, B-cell lymphoma 2, and brain-derived neurotrophic factor, beginning at 12 hours. CONCLUSIONS: Erythropoietin-mediated induction of the CREB pathway and production of neurotrophins is associated with improved neurologic function and increased neuronal viability following spinal cord ischemia reperfusion. Further elucidation of EPO-derived neuroprotection will allow for expansion of adjunct mechanisms for spinal cord protection in high-risk thoracoabdominal aortic intervention.

Sevoflurane preconditioning ameliorates neuronal deficits by inhibiting microglial MMP-9 expression after spinal cord ischemia/reperfusion in rats.

BACKGROUND: Microglia are the primary immune cells of the spinal cord that are activated in response to ischemia/reperfusion (IR) injury and release various neurotrophic and/or neurotoxic factors to determine neuronal survival. Among them, matrix metalloproteinase-9 (MMP-9), which cleaves various components of the extracellular matrix in the basal lamina and functions as part of the blood spinal cord barrier (BSCB), is considered important for regulating inflammatory responses and microenvironmental homeostasis of the BSCB in the pathology of ischemia. Sevoflurane has been reported to protect against neuronal apoptosis during cerebral IR. However, the effects of sevoflurane preconditioning on spinal cord IR injury remain unclear. In this study, we investigated the role of sevoflurane on potential genetic roles of microglial MMP-9 in tight junction protein breakdown, opening of the BSCB, and subsequent recruitment of microglia to apoptotic spinal cord neurons. RESULTS: The results showed significant upregulation of MMP-9 in rats with IR-induced inflammation of the BSCB compared to that of the sham group, manifested as dysfunctional BSCB with increased Evans blue extravasation and reduced expression of occludin protein. Increased MMP-9 expression was also observed to facilitate invasion and migration of activated microglia, imaging as high Iba-1 expression, clustered to neurons in the injured spinal cord, as shown by double immunofluorescence, and increased proinflammatory chemokine production (CXCL10, CCL2). Further, sevoflurane preconditioning markedly improved motor function by ameliorating neuronal apoptosis, as shown by reduced TUNEL-positive cell counts and expression of cleaved caspase-3. These protective effects were probably responsible for downregulation of MMP-9 and maintenance of normal expression of occludin protein indicating BSCB integrity from inflammatory damage, which was confirmed by decreased protein levels of Iba-1 and MMP-9, as well as reduced production of proinflammatory chemokines (CXCL10, CCL2) and proinflammatory cytokines (IL-1ß). Intrathecal injection of specific siRNAs targeting MMP-9 had similar protective effects to those of sevoflurane preconditioning. CONCLUSIONS: Preconditioning with 2.4% sevoflurane attenuated spinal cord IR injury by inhibiting recruitment of microglia and secretion of MMP-9; thus inhibiting downstream effects on inflammatory damage to BSCB integrity and neuronal apoptosis.

The effect of safflower yellow on spinal cord ischemia reperfusion injury in rabbits.

Safflower yellow (SY) is the safflower extract and is the one of traditional Chinese medicine. The aim of the present work was to investigate the effect of SY on spinal cord ischemia reperfusion injury (SCIRI) in rabbits. The models of spinal cord ischemia reperfusion (SI/R) were constructed, and the degree of the post-ischemic injury was assessed by means of the neurological deficit scores and plasma levels of lipid peroxidation reactioin and neuronal morphologic changes. SCIRI remarkably affected the functional activities of the hind limbs and activated lipid peroxidation reaction. SY could attenuate apoptosis and SCIRI by enhancing Bcl-2 expression and inhibiting Bax and caspase-3 activation.

The vulnerability of nitrergic neurons to transient spinal cord ischemia: a quantitative immunohistochemical and histochemical study.

Spinal cord ischemia belongs to serious and relatively frequent diseases of CNS. The aim of the present study was to find out the vulnerability of nitrergic neurons to 15 min transient spinal cord ischemia followed by 1 and 2 weeks of reperfusion. We studied neuronal nitric oxide synthase (nNOS) and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) in structural elements of lumbosacral spinal cord along its rostrocaudal axis. In addition, a neurological deficit of experimental animals was evaluated. Spinal cord ischemia, performed on the rabbit, was induced by abdominal aorta occlusion using Fogarty catheter introduced into the right femoral artery for a period of 15 min. After surgical intervention the animals survived for 7 and 14 days. nNOS-immunoreactivity (nNOS-IR) was measured by immunohistochemical and NADPHd-positivity by histochemical method, and both immunohistochemical and histochemical stainings were quantified by densitometric analyses. Neurological deficit was evaluated according Zivin's criteria. The number of nNOS-IR and/or NADPH-d positive neurons and the density of neuropil were markedly increased in superficial dorsal horn (laminae I-III) after 15 min ischemia and 7 days of reperfusion. However, ischemia followed by longer time of survival (14 days) returned the number of nNOS-IR and NADPH-d positive neurons to control. In the pericentral region (lamina X) containing interneurons and crossing fibers of spinal tracts, than in lamina VII and in dorsomedial part of the ventral horn (lamina VIII) we recorded a decreased number of nNOS-IR and NADPH-d positive neurons after both ischemia/reperfusion periods. In the medial portion of lamina VII and dorsomedial part of the ventral horn (lamina VIII) we observed many necrotic loci. This area was the most sensitive to ischemia/reperfusion injury. Fifteen minute ischemia caused a marked deterioration of neurological function of hind limbs, often developing into paraplegia. A quantitative immunohistochemical and histochemical study have shown a strong vulnerability of nitrergic neurons in intermediate zone to transient spinal cord ischemia.

Protective effects of cold spinoplegia with fasudil against ischemic spinal cord injury in rabbits.

OBJECTIVE: Paraplegia remains a serious complication after surgical repair of thoracoabdominal aortic aneurysms. The aim of this study was to evaluate the neuroprotective efficacy of fasudil, a Rho kinase (ROCK) inhibitor, by reducing the number of infiltrating cells in the ventral horn and increasing the induction of eNOS against ischemic spinal cord injury in rabbits. METHODS: Eighteen Japanese white rabbits were divided into three groups: saline (group 1, n = 7, 4 degrees C) and fasudil (group 2, n = 6, 4 degrees C) were immediately infused into the isolated segmental lumbar arteries over 30 seconds after aortic clamping. Group 3 (n = 5) was the sham-operated group. Hind limb function was evaluated 4 and 8 hours, and 1 and 2 days after 15 minutes of transient ischemia. Cell damage was analyzed by hematoxylin and eosin staining and temporal profiles of endothelial nitric oxide synthase immunoreactivity were performed. The number of intact motor neuron cells and infiltrating cells in the ventral horn were compared. RESULTS: Two days after reperfusion, group 2 and group 3 showed better neurologic function, a greater number of intact motor neuron cells, and a smaller number of infiltrating cells in the ventral horn than group 1. The induction of endothelial nitric oxide synthase (eNOS) was prolonged up to 2 days after reperfusion in group 2. CONCLUSION: These results indicate that fasudil has neuroprotective effects against ischemic spinal cord injury in rabbits by reducing the number of infiltrating cells in the ventral horn and prolonging the expression of eNOS.

Sevoflurane preconditioning induces rapid ischemic tolerance against spinal cord ischemia/reperfusion through activation of extracellular signal-regulated kinase in rabbits.

BACKGROUND: The protective effect of sevoflurane preconditioning against spinal cord ischemia/reperfusion (I/R) is unclear. We designed this study to investigate whether sevoflurane preconditioning could induce rapid ischemic tolerance to the spinal cord in a rabbit model of transient spinal cord ischemia and how the role of extracellular signal-regulated kinase (ERK) is involved. METHODS: To test whether preconditioning with sevoflurane induces rapid ischemic tolerance, New Zealand White male rabbits were randomly assigned to three groups. Animals in the Sev group received preconditioning with 3.7% sevoflurane (1.0 minimum alveolar anesthetic concentration) in 96% oxygen for 30 min, whereas animals in the O(2) group serving as controls inhaled only 96% oxygen for 30 min. The Sham group received the same anesthesia and surgical preparation but no preconditioning or spinal cord I/R. To evaluate the role of ERK activation in sevoflurane preconditioning, rabbits were randomly assigned to four groups. U0126, an ERK inhibitor, was administered IV 20 min before the beginning of preconditioning in the U0126 + O(2) and U0126 + Sev groups. Dimethylsulfoxide was administered IV at the same time in the vehicle + O(2) and vehicle + Sev groups. At 1 h after preconditioning, the animals were subjected to spinal cord I/R induced by infrarenal aorta occlusion. All animals were assessed at 48 h after reperfusion with modified Tarlov criteria, and the spinal cord segments (L5) were harvested for histopathological examination, TUNEL staining, and Western blot of phosphor-ERK1/2. RESULTS: The animals in the Sev group had higher neurological scores and more normal motor neurons than those in the O(2) group (P < 0.01 for each comparison). Compared with vehicle + Sev group, the U0126 + Sev group had worse neurological outcomes, fewer viable neurons, more apoptotic neurons, and significantly decreased ERK1/2 phosphorylation (P

Intrathecally injected granulocyte colony-stimulating factor produced neuroprotective effects in spinal cord ischemia via the mitogen-activated protein kinase and Akt pathways.

Granulocyte colony-stimulating factor (G-CSF) is a potent hematopoietic factor. Recently, this factor has been shown to exhibit neuroprotective effects on many CNS injuries. Spinal cord ischemic injury that frequently results in paraplegia is a major cause of morbidity after thoracic aorta operations. In the present study, we examined the neuroprotective role of G-CSF on spinal cord ischemia-induced neurological dysfunctions and changes in the mitogen-activated protein kinase (MAPK) and Akt signaling pathways in the spinal cord. Spinal cord ischemia was induced in male Wistar rats by occluding the descending aorta with a 2F Fogarty catheter for 12 min 30 s. Immediately after ischemia surgery, the rats were administered G-CSF (10 mug) or saline by intrathecal (i.t.) injection. The rats were divided into four groups: control, ischemia plus saline, ischemia plus G-CSF and G-CSF alone. The neurological dysfunctions were assessed by calculating the motor deficit index after ischemia surgery. The expressions of MAPK and Akt were studied using Western blotting and double immunohistochemistry. First, we observed that ischemia plus i.t. G-CSF can significantly reduce the motor function defects and downregulate phospho-p38 and phospho-c-Jun N-terminal kinase protein expressions-this can be compared with the ischemia plus saline group. In addition, G-CSF inhibited the ischemia-induced activation of p38 in the astrocytes. Furthermore, we concluded that i.t. G-CSF produced a significant increase in phospho-Akt and phospho-ERK in the motor neurons and exhibited beneficial effects on the spinal cord ischemia-induced neurological defects.

Preventive effects of intrathecal methylprednisolone administration on spinal cord ischemia in rats: the role of excitatory amino acid metabolizing systems.

Spinal cord ischemic injury usually results in paraplegia, which is a major cause of morbidity after thoracic aorta operations. Ample evidence indicates that massive release of excitatory amino acids (EAAs; glutamate) plays an important role in the development of neuronal ischemic injuries. However, there is a lack of direct evidence to indicate the involvement of EAAs in the glutamate metabolizing system (including the glutamate transporter isoforms, i.e. the Glu-Asp transporter (GLAST), Glu transporter-1 (GLT-1), and excitatory amino acid carrier one (EAAC1); glutamine synthetase (GS); and glutamate dehydrogenase (GDH)) in spinal cord ischemia. In the present results, we found that methylprednisolone (MP; intrathecal (i.t.) injection, 200 mug twice daily administered for 3 days before ischemia), a synthetic glucocorticoid, is the therapeutic agent for the treatment of spinal injuries in humans, can significantly reduce the ischemia-induced motor function defect and down-regulate the glutamate metabolizing system (including GLAST, GLT-1, GS, and GDH) in male Wistar rats. The spinal cord ischemia-induced down-regulation of EAAC1 protein expression in the ventral portion of the lumbar spinal cord was partly inhibited by pretreatment with i.t. MP. However, MP did not affect the down-regulation of EAAC1 in the dorsal portion of the lumbar spinal cord after spinal cord ischemia. The i.t. injection of MP alone did not change the neurological functions and the expression of proteins of the glutamate metabolizing system in the spinal cord. Our results indicate that spinal cord ischemia-induced neurological deficits accompany the decrease in the expression of proteins of the glutamate metabolizing system in the lumbar portion of the spinal cord. The i.t. MP pretreatment significantly prevented these symptoms. These results support the observation that MP delivery through an i.t. injection, is beneficial for the treatment of spinal cord ischemic injuries.

The effects of prophylactic zinc and melatonin application on experimental spinal cord ischemia-reperfusion injury in rabbits: experimental study.

STUDY DESIGN: Experimental study. OBJECTIVES: To determine the neuroprotective effects of zinc and melatonin on spinal cord ischemia-reperfusion (I/R) injuries of rabbits. SETTING: The Experimental Research Centre of Selçuk University, Konya, Turkey. METHODS: Twenty-four male rabbits underwent spinal cord ischemia by clamping the thoraco-abdominal aorta for 20 min. Twenty minutes before the aortic clamping, animals received zinc, melatonin or a combination of both. Neurological examination of the animals was performed three times during reperfusion period. The animals were killed 24 h after reperfusion. Spinal cord samples were taken for biochemical and histopathological evaluation. RESULTS: Pre-treated animals with zinc, melatonin or combination displayed better neurological outcomes than the I/R group (P<0.05). Zinc, melatonin and combined treatment prevented spinal cord injury by reducing apoptosis rate (P<0.05) and preserving intact ganglion cell numbers (P<0.05). Zinc pre-treatment protected spinal cord by preventing malondialdehyde (MDA) formation (P=0.002), increasing glutathione peroxidase (GPx) activity (P=0.002) and decreasing xanthine oxidase enzyme activity (P=0.026) at molecular level. Melatonin treatment also resulted with MDA formation (P=0.002), increased GPx activity (P=0.002) and decreased xanthine oxidase activity (P=0.026). CONCLUSION: The results of the study showed that prophylactic zinc and melatonin use in spinal cord I/R not only suppressed lipid peroxidation by activating antioxidant systems but also had significant neuroprotective effects by specifically improving the neurological and histopathological situation.

Moderately different NADPH-diaphorase positivity in the selected peripheral nerves after ischemia/ reperfusion injury of the spinal cord in rabbit.

1. To vicariously investigate the nitric oxide synthase (NOS) production after spinal cord injury, NADPH-d histochemistry was performed on the selected peripheral nerves of adult rabbits 7 days after ischemia. The effect of transient spinal cord ischemia (15 min) on possible degenerative changes in the motor and mixed peripheral nerves of Chinchilla rabbits was evaluated. 2. The NADPH-diaphorase histochemistry was used to determine NADPH-diaphorase activity after ischemia/reperfusion injury in radial nerve and mediane nerve isolated from the fore-limb and femoral nerve, saphenous nerve and sciatic nerve separated from the hind-limb of rabbits. The qualitative analysis of the optical density of NADPH-diaphorase in selected peripheral nerves demonstrated different frequency of staining intensity (attained by UTHSCSA Image Tool 2 analysis for each determined nerve). 3. On the seventh postsurgery day, the ischemic spinal cord injury resulted in an extensive increase of NADPH-d positivity in isolated nerves. The transient ischemia caused neurological disorders related to the neurological injury--a partial paraplegia. The sciatic, femoral, and saphenous nerves of paraplegic animals presented the noticeable increase of NADPH-d activity. The mean of NADPH-diaphorase intensity staining per unit area ranged from 134.87 (+/-32.81) pixels to 141.65 (+/-35.06) pixels (using a 256-unit gray scale where 0 denotes black, 256 denotes white) depending on the determined nerve as the consequence of spinal cord ischemia. The obtained data were compared to the mean values of staining intensity in the same nerves in the limbs of control animals (163.69 (+/-25.66) pixels/unit area in the femoral nerve, 173.00 (+/-32.93) pixels/unit area in saphenous nerve, 186.01 (+/-29.65) pixels/unit area in sciatic nerve). Based on the statistical analysis of the data (two-way unpaired Mann-Whitney test), a significant increase (p< or =0.05) of NADPH-d activity in femoral and saphenous nerve, and also in sciatic nerve (p< or =0.001) has been found. On the other hand, there was no significant difference between the histochemically stained nerves of fore-limbs after ischemia/reperfusion injury and the same histochemically stained nerves of fore-limbs in control animals. 4. The neurodegenerative changes of the hind-limbs, characterized by damage of their motor function exhibiting a partial paraplegia after 15 min spinal cord ischemia and subsequent 7 days of reperfusions resulted in the different sensitivity of peripheral nerves to transient ischemia. Finally, we suppose that activation of NOS indirectly demonstrable through the NADPH-d study may contribute to the explanation of neurodegenerative processes and the production of nitric oxide could be involved in the pathophysiology of spinal cord injury by transient ischemia.

Effect of ischemia in vivo and oxygen-glucose deprivation in vitro on NOS pools in the spinal cord: comparative study.

1. This study was performed to compare both the Ca(2+)-dependent nitric oxide synthase (NOS) activity and the neuronal nitric oxide synthase immunoreactivity (nNOS-IR) in the rabbit lumbosacral spinal cord after 15 min abdominal aorta occlusion (ischemia in vivo) and oxygen-glucose deprivation of the spinal cord slices for 45 and 60 min (ischemia in vitro). All ischemic periods were followed by 15, 30 and 60 min reoxygenation in vitro. 2. Catalytic nitric oxide synthase activity was determined by the conversion of (L)-[(14)C]arginine to (L)-[(14)C]citrulline. Neuronal nitric oxide synthase immunoreactivity in the spinal cord was detected by incubation of sections with polyclonal sheep-nNOS-primary antibody and biotinylated anti-sheep secondary antibody. 3. Our results show that ischemia in vivo and the oxygen-glucose deprivation of spinal cord slices in vitro result in a time-dependent loss of constitutive NOS activity with a partial restoration of enzyme activity during 15 and 45 min ischemia followed by 30 min of reoxygenation. A significant decrease of enzyme activity was found during 60 min ischemia alone, which persisted up to 1 h of oxygen-glucose restoration. The upregulation of neuronal nitric oxide synthase was observed in the ventral horn motoneurons after all ischemic periods. The remarkable changes in optical density of neuronal nitric oxide synthase immunoreactive motoneurons were observed after 45 and 60 min ischemia in vitro followed by 30 and 60 min reoxygenation. 4. Our results suggest that the oxygen-glucose deprivation followed by reoxygenation in the spinal cord is adequately sensitive to monitor ischemia/reperfusion changes. It seems that 15 min ischemia in vivo and 45 min ischemia in vitro cause reversible changes, while the decline of Ca(2+)-dependent nitric oxide synthase activity after 60 min ischemic insult suggests irreversible alterations.

Regulation and localization of neuronal nitric oxide synthase in the ischemic rabbit spinal cord.

The expression and cellular localization of neuronal nitric oxide (NO) synthase (nNOS) were studied in the rabbit spinal cord following ischemic injury induced by clamping the descending aorta. In the normal spinal cord, nNOS immunoreactivity was localized to certain motor neurons located in the margin of the ventral horn. Following transient ischemia, immunoreactive spinal neurons increased in number, peaking five days after reperfusion. Quantitative evaluation by western blotting showed that nNOS peaked at 180% of control levels five days after reperfusion and decreased to 120% of controls by 14 days. These findings suggest that overproduced NO may act as a neurotoxic agent in the ischemic spinal cord.

Induction of phosphatidylinositol 3-kinase and serine-threonine kinase-like immunoreactivity in rabbit spinal cord after transient ischemia.

The mechanism of spinal cord injury has been thought to be related with tissue ischemia, and spinal motor neuron cells are suggested to be vulnerable to ischemia. To evaluate the mechanism of such vulnerability of motor neurons, we attempted to make a reproducible model of rabbit spinal cord ischemia. Using this model, the inductions of phosphatidylinositol 3-kinase (PI3-k) and serine-threonine kinase (Akt) were investigated with immunohistochemical analyses for up to 7 days of the reperfusion following 15 min of ischemia in rabbit spinal cord. It has been demonstrated that both PI3-k and its downstream effector, Akt mediate growth factor-induced neuronal survival. Spinal cord sections from animals sacrificed at 8 h, 1, 2, and 7 days following the 15 min of ischemia were immunohistochemically evaluated using monoclonal antibodies for PI3-k and Akt. Following the 15 min of ischemia, the majority of the motor neurons showed selective cell death at 7 days of reperfusion. Immunoreactivity of PI3-k and Akt were induced at 8 h of reperfusion selectively in motor neuron cells. No glial cells and inter neurons were stained in the spinal cord sections. The activation of PI3-k and Akt protein at the early stage of reperfusion may be one of the factors responsible for the delay in neuronal death after spinal cord ischemia.

A new antioxidant compound H-290/51 attenuates upregulation of constitutive isoform of heme oxygenase (HO-2) following trauma to the rat spinal cord.

Influence of a new antioxidant compound H-290/51 on carbon monoxide (CO) production following spinal cord injury was examined using immunohistochemistry of the constitutive isoform of heme oxygenase-2 (HO-2) in a rat model. Subjection of rats to 5 h spinal cord injury by making an incision into the right dorsal horn of the T10-11 segments resulted in upregulation of HO-2 in the injured and adjacent T9 and T12 segments. At this time, disruption of the blood-spinal cord barrier (BSCB) permeability, edema formation and cell injury were more pronounced. Pretreatment with H-290/51 (50 mg/kg, p.o., 30 min before trauma) significantly attenuated the HO-2 immunoreactivity along with breakdown of the BSCB permeability, edema and cell injury. These results for the first time demonstrate that the antioxidant compound H-290/51 is capable of attenuating HO-2 expression and thereby influencing CO production. Furthermore, our observations indicate that oxidative stress is involved in CO production, as reflected by HO-2 expression, which is injurious to the cord and H-290/51 exerts powerful neuroprotective effects in spinal cord injury.