Resveratrol,an antioxidant,protects spinal cord injury in rats by suppressing MAPK pathway

Resveratrol, a polyphenol found in various plants, including grapes, plums and peanuts has shown various medIRInal properties, including antioxidant, protection of cardiovascular disease and cancer risk. However, the effects of resveratrol on spinal cord reperfusion injury have not been investigated. Hence, the present study was designed to evaluate the effect of resveratrol on nitric oxide synthase (iNOS)/p38MAPK signaling pathway and to elucidate its regulating effect on the protection of spinal cord injury. Spinal cord ischemia–reperfusion injury (IRI) was performed by the infrarenal abdominal aorta with mini aneurysm clip model. The expressions of iNOS and p38MAPK and the levels of biochemical parameters, including nitrite/nitrate, malondialdehyde (MDA), advanced oxidation products (AOPP), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were measured in control and experimental groups. IRI-induced rats treated with 10 mg/kg resveratrol protected spinal cord from ischemia injury as supported by improved biological parameters measured in spinal cord tissue homogenates. The resveratrol treatment significantly decreased the levels of plasma nitrite/nitrate, iNOS mRNA and protein expressions and phosphorylation of p38MAPK in IRI-induced rats. Further, IRI-produced free radicals were reduced by resveratrol treatment by increasing enzymatic and non-enzymatic antioxidant levels such as GSH, SOD and CAT. Taken together, administration of resveratrol protects the damage caused by spinal cord ischemia with potential mechanism of suppressing the activation of iNOS/p38MAPK pathway and subsequent reduction of oxidative stress due to IRI.     

肢体远程预处理通过上调机体抗氧化酶活性诱导兔脊髓缺血耐受

目的:证实抗氧化酶活性上调是肢体远程预处理(remote preconditioning,RPC)诱导兔脊髓缺血耐受效应的主要机制之一。方法:60只雄性新西兰大白兔随机分成对照组、远程预处理组、缺血组及RPC 缺血组(对照组n=6,余组n=18)。RPC组行双下肢短暂缺血2次(每次10min,间隔10min);缺血组仅行脊髓缺血模型;RPC 缺血组在远程预处理后1h行脊髓缺血;对照组为假手术组。对照组于脊髓缺血再灌注后48h行神经功能评分后取脊髓,作为对照。余三组分别于再灌注后6h、24h及48h评分后取材,各时间点各取6只。所有动物于缺血前、缺血20min、再灌注20min及再灌注6h采动脉血测血清抗氧化酶活性和丙二醛(MDA)含量;于取材后测定脊髓匀浆抗氧化酶活性和MDA含量。结果:再灌注后6h、24h及48h时对照组、远程预处理组及远程预处理 缺血组神经功能评分均明显高于缺血组(P<0.05)。血浆超氧化物歧化酶(SOD)活性和过氧化氢酶(CAT)活性在每个时间点RPC组均高于对照组,RPC 缺血组高于缺血组(P<0.05);其中缺血20min时,缺血组血浆SOD、CAT活性低于对照组,RPC 缺血组低于RPC组(P<0.05);而与缺血前相比,缺血20min时缺血组及RPC 缺血组SOD和CAT活性显著下降(P<0.05)再灌注24h和48h时,脊髓匀浆SOD、CAT活性对照组低于RPC组,缺血组低于RPC 缺血组(P<0.01);而MDA含量再灌注24h时对照组高于RPC组,缺血组高于RPC 缺血组(P<0.05)。脊髓匀浆SOD、CAT活性与神经功能评分具有显著相关性。结论:RPC诱导脊髓缺血耐受的机制可能为上调抗氧化酶活性,增强机体在缺血再灌注过程中清除氧自由基的能力,从而减少氧自由基介导的损伤,发挥脊髓保护作用。     

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.     

Free Radicals in Rabbit Spinal Cord Ischemia: Electron Spin Resonance Spectroscopy and Correlation with SOD Activity

1. In nonanesthetized rabbits temporal occlusion of the abdominal aorta was used to induce oxidative stress in the lower part of the body including distal segments of the spinal cord.2. Spinal cord samples were taken from the animals exposed to 25-min aortic occlusion (AO ) or to occlusion followed by 1- or 2-hr reperfusion (AO/R1 or AO/R2, respectively) or from sham-operated animals (C). The presence of free radicals (FR) in the spinal cord samples frozen in liquid N₂ was assessed by ESR spectroscopy without spin trapping. Moreover, superoxide dismutase (SOD) activity and conjugated diene (CD) levels were measured in the samples.3. In the AO group FR were detected in the spinal cord regions close to the occlusion (lower thoracic and distal segments) along with a decrease in SOD activity. The calculated g value (g = 2.0291) indicated that the paramagnetic signal recorded might be attributed to superoxide radicals. FR were absent in the AO/R1 group. Concurrently, the SOD activity revealed a significant tendency to return to the control level. FR appeared again in the AO/R2 group, mostly in the upper and middle lumbar regions, along with a decrease in SOD activity. No sample from the C group revealed FR. A significant increase in CD levels was observed in the thoracolumbar region only in the AO/R2 group. The temporary absence of FR in the AO/R1 group suggests activation of defense antioxidant mechanisms (e.g., specific enzymatic systems such as SOD), which might have been exhausted later.4. Changes in SOD activity similar to those observed in the thoracolumbar region, though less noticeable, occurred in the obviously noncompromised tissue (upper cervical region). This points to a kind of generalized reponse of the animal to aortic occlusion.5. Direct ESR spectroscopy revealed the presence of FR as well as their time course in the spinal cord during the early phase of ischemia/reperfusion injury and the inverse relationship between FR and SOD activity.     

脊髓缺血再灌注损伤的防治概况

脊髓缺血-再灌注损伤(SCII)是一种严重的神经系统损伤,是缺血脊髓组织恢复血液灌注后,脊髓组织的损伤反而加重,表现为其神经损害体征和形态学改变较前更加明显,其发生机制是多因素的综合结果,治疗措施也具有多样性,脊髓缺血后脊髓微血管结构及功能的破坏和脊髓水肿等是脊髓功能损害的主要诱因,至今为止,脊髓缺血再灌注损伤的防治主要有药物及物理治疗等方法,本文作者通过查阅中外文献对脊髓缺血再灌注损伤的特征、发生机制及防治措施作一综述,希望对研究脊髓缺血再灌注损伤防治的学者能有所帮助。     

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.     

Selective sparing of NADPH-d positive spinal cord neurons affected by ischemia

Histochemical characterization of NADPH diaphorase positive neuronal pools in the rabbit lumbosacral segments was performed during and after transient spinal cord ischemia. Strongly enhanced staining of NADPH diaphorase positive structures appeared in the superficial dorsal horn, the pericentral region and in the neurons of the sacral parasympathetic nucleus at the end of 40 min of abdominal aorta ligation or after 1 day reperfusion. Four days after ischemia, NADPH-d positive neurons and vessels were detected in the central gray matter despite well developed necrosis in this location. Regional nitric oxide synthesis and its vasodilatatory effect during the period of aortic occlusion may account for the observed selective resistance of these spinal cord neurons to transient ischemia.     

Co-application of ischemic preconditioning and postconditioning provides additive neuroprotection against spinal cord ischemia in rabbits

Postconditioning can induce cardioprotection against ischemia. However, the data on postconditioning of the spinal cord is very limited. We investigated here whether co-application of ischemic preconditioning (IPC) and postconditioning can provide additive neuroprotection against prolonged spinal cord ischemia. Spinal cord ischemia was produced in rabbits by infrarenal aortic occlusion with a balloon catheter for 30 min. The four treatment groups were control (n=10): no intervention; IPC (n=10): a 5-minute aortic occlusion was performed 20 min before the prolonged ischemia; Postcon (n=10): postconditioning comprised of four cycles of 1-minute occlusion/1-minute reperfusion was applied one minute after the start of reperfusion. IPC+postcon (n=11): both IPC and postconditioning were applied. Functional evaluation with Tarlov score was performed during a 14-day observation period. Neurologic impairment was noticeably attenuated in the IPC+postcon group (compared with the control group, P<0.01, at day 1, day 2, day 7 and day 14, respectively), but not in either the IPC or Postcon group. Plasma malondialdehyde levels after reperfusion were significantly decreased to a similar extent in the IPC, Postcon and IPC+Postcon groups (compared with the control group (P<0.01). In the IPC+Postcon group, many more large motor neurons were preserved than in the control group (P<0.05) and white matter injury was also markedly attenuated as evidenced by reduction of the vacuolation area of the white matter (P<0.01) and decreased amyloid precursor protein immunoreactivity (P<0.01). From this, we conclude that the combination of IPC and postconditioning induces additive neuroprotective effects for spinal cord against ischemia and reperfusion injuries.     

Ischemia-reperfusion injury in the spinal cord of rabbits strongly enhances lipid peroxidation and modifies phospholipid profiles

The effect of spinal cord ischemia (10, 20, and 40 min) and post-ischemic reperfusion (10, 30, and 60 min) on lipid peroxidation and phospholipids was investigated. Spinal cord ischemia was accompanied by lipolytic processes with significant changes in concentration of lipid peroxidation products (LPP). Reestablishment of the blood supply after 10 min ischemia was accompanied by significantly increased levels of thiobarbituric acid reactive substances (TBA-RS) after 10 and 30 min of reperfusion. Following 20 and 40 min ischemia a significant increase was observed at all reperfusion periods. Ischemia itself significantly reduced the concentration of phosphatidyl inositol (IP), phosphatidyl ethanolamine (EP) and ethanolamine plasmalogens (Epls). Significant changes were observed in concentration of phosphatidyl serine (SP) too, but only after 20 and 40 min of ischemia. The concentration of phosphatidic acid (PA) was significantly reduced only after 10 min of ischemia. The onset of reperfusion after ischemia was accompanied by a diverse pattern of changes in PA, IP, Epls and SP, while the concentration of EP remained at the above mentioned ischemic intervals.     

The regional changes of the catalytic NOS activity in the spinal cord of the rabbit after repeated sublethal ischemia

The regional distribution of catalytic NOS activity was studied in the lumbosacral segments of the spinal cord of the rabbit during single (8-min), twice (8-, 8-min) and thrice repeated (8-, 8-, 9-min) sublethal ischemia followed each time by 1h of reperfusion. Single ischemia/reperfusion induced a significant increase of cNOS activity in almost all spinal cord regions, with the exception of non-significant increase in the dorsal horn. Sublethal ischemia repeated twice produced a significant decrease of enzyme activity in the intermediate zone and ventral horn and an increase in the white matter columns. Within thrice repeated ischemia, the activity of cNOS in the gray matter regions was similar to that found after a single ischemia/reperfusion. For all the animals subjected to single and twice repeated sublethal ischemic insults, there was no neurological impairment. Following thrice repeated ischemic insults, four out of five of the experimental animals recovered only partially and one was completely paraplegic. Our results do not indicate a cumulative effect of repeated sublethal ischemia on cNOS activity and, consequently, on NO production. The NO generated during thrice repeated ischemia/reperfusion appears to have a detrimental effect on the neurological outcome.     

Tat-DJ-1 Protects Neurons from Ischemic Damage in the Ventral Horn of Rabbit Spinal Cord Via Increasing Antioxidant Levels

The DJ-1 gene is highly conserved in diverse species and DJ-1 is known as an anti-oxidative stress factor. In this study, we investigated the neuroprotective effects of DJ-1 against ischemic damage in the rabbit spinal cord. Tat-DJ-1 fusion proteins were constructed to facilitate the penetration of DJ-1 protein into the neurons. Tat-1-DJ-1 fusion protein was administered to the rabbit 30 min after ischemia/reperfusion, and transient spinal cord ischemia was induced by occlusion of the aorta at the subrenal region for 15 min. The administration of Tat-DJ-1 significantly improved the Tarlov score compared to that in the Tat (vehicle)-treated group at 24, 48 and 72 h after ischemia/reperfusion. At 72 h after ischemia/reperfusion, the number of cresyl violet-positive neurons was significantly increased in the Tat-DJ-1-treated group compared to that in the vehicle-treated group. Lipid peroxidation as judged from the malondialdehyde levels was significantly decreased in the Tat-DJ-1-treated group compared to that in the vehicle-treated group. In contrast, superoxide dismutase and catalase levels were significantly increased in the Tat-DJ-1-treated group compared to that in the vehicle-treated group. This result suggests that DJ-1 protects neurons from ischemic damage in the ventral horn of the spinal cord via its antioxidant effects.     

Contradictory effects of superoxide dismutase after global or regional ischemia in the isolated rat heart

The effect of superoxide dismutase was investigated in two different models of ischemia and reperfusion in the isolated rat heart: global and regional ischemia. The results of this comparison show that reperfusion arrhythmias after 10 and 15 min of regional ischemia, induced by occlusion of the left coronary artery, can be prevented by SOD confirming the results of other investigators. Paradoxically SOD was without effect after 10 min of global ischemia, obtained by stopping coronary flow completely. After 15 min of global ischemia, SOD induced ventricle fibrillation. Apparently the effect of SOD depends on the model of ischemia and reperfusion that is used.     

Short-term changes of NADPH diaphorase-exhibiting neuronal pools in the spinal cord of rabbit after repeated sublethal ischemia

The aim of this study was the histochemical characterization of NADPH diaphorase-positive neuronal pools in the rabbit lumbosacral segments using a model of single, repeated and multiple sublethal spinal cord ischemia. Following a single 8-min sublethal spinal cord ischemia and 1-hour reperfusion, the staining of NADPH diaphorase-exhibiting neurons in the dorsal horn, pericentral region, dorsal gray commissure and sacral parasympathetic nucleus was comparable with the control sections. In contrast to the foregoing sublethal ischemia, a regionally different somatic NADPH diaphorase (NADPHd) staining was found after multiple sublethal spinal cord ischemia. Whereas an almost complete loss of the staining of large NADPHd-exhibiting somata in the pericentral region was detected, the staining of the NADPHd-exhibiting neuronal pools in the deep dorsal horn and sacral parasympathetic nucleus was fully preserved. Concomitantly, a prominent reduction of small NADPH diaphorase-positive neurons was noted in the superficial dorsal horn layers of lower lumbar and sacral segments.     

Effects of nerve graft on nitric oxide synthase, NAD(P)H oxidase, and antioxidant enzymes in chronic spinal cord injury

Oxidative stress and nitrosative stress play important roles in the pathogenesis of secondary spinal cord injury. Recently, we demonstrated that peripheral nerve grafts (PNG) with acidic fibroblast growth factor (aFGF) partially restore hind limb locomotion in adult rats with completely transected spinal cords. This study investigated the protein abundances of the superoxide (O2*)-generating enzyme nicotinamide adenine dinucleotide (phosphate) oxidase (NAD(P)H oxidase; gp91phox subunit), nitric oxide synthases (NOS), antioxidant enzymes, superoxide dismutases (Cu Zn SOD, Mn SOD), catalase, and glutathione peroxidase (GPX) as well as nitrotyrosine in the spinal cord tissue 4 months after spinal cord transection in rats with and without PNG and aFGF. The protein abundances of the gp91phox subunit of NAD(P)H oxidase, Mn SOD, catalase, GPX, eNOS, and nitrotyrosine were significantly upregulated, whereas Cu Zn SOD and nNOS were unchanged in the injury group compared to the sham controls. The nerve graft with aFGF treated group showed significantly better hind limb locomotion recovery than the injury group. Although the protein abundances of gp91phox, nitrotyrosine, and Cu Zn SOD were similar in the treated group (nerve graft with aFGF) compared to the injury group, Mn SOD, GPX, catalase, and eNOS protein abundances were significantly higher, whereas nNOS was markedly lower in the treated group. We conclude that the combination of nerve graft and aFGF enhances the local antioxidant defense system after spinal cord transection in rats.     

The influence of transient spinal ischemia on substance P positive nerve structures

The aim of this study was to investigate, if transient spinal ischemia and a period of 4-day reperfusion will change the distribution pattern of substance P in the spinal cord of rabbits. Strongly enhanced staining of substance P positive nerve structures appeared in the superficial dorsal horn (laminae I, II), the Lissauer's tract, the pericentral region (lamina X), and in the areas of autonomic nuclei (sympathetic-intermediolateral--IML nucleus and parasympathetic-sacral parasympathetic nucleus--SPN) in the control group. Transient spinal ischemia was produced by occlusion of the abdominal aorta just below the left renal artery. Neuropathology of the lesion 4 days after transient ischemia was characterized by selective necrosis of gray matter in the central part of dorsal horn and medial portions of anterior gray matter. Areas with the most dense accumulation of substance P positive structures stayed almost intact. Therefore, no significant change in the distribution pattern of substance P was found in the spinal cord of animals with ischemia-reperfusion-induced injury.     

黄芪皂苷IV对心肌缺血／再灌注损伤的保护及抗凋亡作用的研究

目的：探讨黄芪皂苷Ⅳ对大鼠心肌缺血／再灌注损伤的保护作用及抗凋亡作用。方法：研究黄芪皂苷Ⅳ对大鼠收缩压和舒张压的作用;建立大鼠心肌缺血／再灌注模型,在缺血前给予黄芪皂苷Ⅳ处理,观察心律失常的改变,测定血液中乳酸脱氢酶（LDH）、超氧化物歧化酶（SOD）和丙二醛（MDA）的变化,检测计算凋亡心肌细胞百分比及对P-STAT1、P-STAT3蛋白表达的调控作用。结果：黄芪皂苷Ⅳ可降低大鼠收缩压和舒张压,心肌缺血／再灌注前,预先给予黄芪皂苷Ⅳ有抗心律失常作用,降低血液中LDH和MDA含量,提高SOD活性,降低凋亡心肌细胞百分比,显著增加P-STAT1蛋白表达而同时降低P-STAT3蛋白表达。结论：黄芪皂苷Ⅳ对心肌缺血／再灌注损伤具有一定的保护作用,减少心肌细胞凋亡,其机制可能与抑制P—STAT1,诱导P—STAT3表达有关。     

Fluoro-Jade B evidence of induced ischemic tolerance in the rat spinal cord ischemia: physiological, neurological and histopathological consequences

Fluoro-Jade B, a marker of degenerating neurons, was used to label histopathological changes in the rat spinal cord after transient ischemia and ischemic preconditioning (IPC). To characterize postischemic neurodegenerations and consequent neurological changes, a particular attention was paid to the standardization of ischemic conditions in animals of both groups. 1. The control ischemic rats were submitted to a reversible occlusion of descending aorta by insertion and subsequent inflation of a 2F Fogarty catheter for 12 min. 2. In the IPC rats, an episode of short 3 min occlusion and 30 min reperfusion preceded the 12 min ischemia. Postischemic motor function testing (ambulation and stepping) was provided repeatedly for evaluation of neurological status 2 h and 24 h after surgery and at the end of postischemic survival, i.e. after 48 h. Fluoro-Jade B staining was used to demonstrate degenerated neurons. In the control rats, neurological consequences of histopathological changes in lumbosacral spinal cord, manifested as paraplegia, were present after 12 min ischemia. Thus, numbers of degenerated Fluoro-Jade B positive cells were visible in gray matter of the most injured L(4)-S(2) spinal cord segments. Slight motor function impairment, consequential from significant decreasing in Fluoro-Jade B-positivity in the L(4)-S(2) spinal cord segments of the IPC rats, was considered the pathomorpfological evidence that IPC induces spinal cord tolerance to ischemia. Our results are consistent with the previously published silver impregnation method for histopathological demonstration of ischemic degeneration.     

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.     

Degradation of Spectrin via Calpains in the Ventral Horn after Transient Spinal Cord Ischemia in Rabbits

In the present study, we investigated chronological changes of μ-calpain, m-calpain and cleaved spectrin αII immunoreactivity in the ventral horn after transient spinal cord ischemia to investigate relationship between calpains and vulnerability to ischemia using abdominal aorta occlusion model in rabbits. Spinal cord sections at the level of L₇ were immunostained with calpains and cleaved spectrin αII monoclonal antibodies. μ-Calpain and m-calpain immunoreactivity was significantly increased in the ischemic ventral horn at 30 min and 1 h after ischemia/reperfusion, respectively. Thereafter, they were decreased with time after ischemia/reperfusion: at 48 h after ischemia, their immunoreactivities nearly disappeared in the ischemic ventral horn. Cleaved spectrin αII immunoreactivity was significantly increased in the ventral horn of spinal cord at 12 h after ischemia/reperfusion, and thereafter, its immunoreactivity was decreased with time after ischemia/reperfusion. In addition, spectrin αII protein level (280 kDa) was decreased from 12 h after ischemia/reperfusion; in contrast, cleaved spectrin αII protein level (150 kDa) was significantly increased at 12 h after ischemia/reperfusion. In conclusion, our observations in this study indicate that calpain is associated with neuronal degeneration in the ventral horn at early time after transient spinal cord ischemia via the proteolysis of spectrin αII.Jae-Chul Lee and In Koo Hwang equally contribute to this article.     

Effect of repetitive ischemic preconditioning on spinal cord ischemia in a rabbit model

A completely randomized controlled study based on a rabbit model was designed to study the effect of repetitive ischemic preconditioning (IPC) on a spinal cord ischemic reperfusion injury. Twenty four white adult Japanese rabbits were randomly assigned to one of the 3 groups (n = 8 per group): Group I: sham-operation group, Group II: ischemic reperfusion group, and, Group III: IPC group. Spinal cord ischemia was induced by infra-renal aortic cross-clamp for 45 min in Group II. Before 45 min ischemia, the rabbits in Group III underwent four cycles of IPC (5 min of ischemia followed by 5 min of reperfusion). Post-operative neurological function, electromyography (EMG) of rear limbs, and spinal cord histopathological changes were measured. The concentrations of calcium, magnesium, copper, and zinc in spinal cord were measured in the 7th day. The neurological function and histopathological changes in Group II were significantly different from those in Group I or Group III (P < 0.05 or 0.01). There was a more significant change of EMG in Group II than that in Group III (P < 0.05). The concentrations of calcium and copper in Group II were significantly higher (P < 0.05 or 0.01), but magnesium and zinc were significantly lower (P < 0.05) than those in Group I. Calcium and copper in Group II were significantly higher (P < 0.05), but zinc was significantly lower (P < 0.01) than those in Group III. In conclusion, repetitive IPC can protect rabbit spinal cord from ischemic reperfusion injury in a timely manner, which is associated with corrections of imbalance of calcium, magnesium, copper, and zinc in the ischemic region.