对大鼠脊髓损伤应用红花注射液的保护作用

[目的]采用重物下降打击法,制备相当于中度大鼠脊髓损伤(spinal cord injury,SCI)的模型,探讨红花注射液对SCI的保护效果。[方法]将72只SD大鼠随机分为假手术组(A组)、脊髓打击损伤组(B组)、甲基强的松龙组(methylprednisolone sodium succinate,MPSS)(C组)、红花溶液组(D组),每组18只。B、C、D组根据改良的重物撞击装置制备脊髓急性打击损伤动物模型,C、D组在脊髓打击损伤后即刻分别腹腔注射MPSS 30 mg/kg和红花溶液100 mg/kg,观察并检测4组大鼠SCI后1、24、48 h 3个不同时间点后肢运动功能评分变化以及脊髓组织病理学、组织含水量、乳酸(lactic acid,LD)含量、乳酸脱氢酶(lactic dehydrogenase,LDH)活性、超氧化物歧化酶(superoxide dismutase,SOD)活性、丙二醛(malondialdehyde,MDA)含量的改变。[结果]术后A组大鼠功能完全恢复;C组或D组与B组相比,大鼠后肢运动功能24、48 h 2个时间点均有所改善,但24 h时已出现明显差异(P<0.05)...     

Mn (III) tetrakis (4-benzoic acid) porphyrin administered into the intrathecal space reduces oxidative damage and neuron death after spinal cord injury: a comparison with methylprednisolone

The metalloporphyrin Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) is a cell-permeable superoxide dismutase mimetic and a broad-spectrum scavenger of reactive species. Since MnTBAP may not cross the blood-brain barrier, this study evaluated the therapeutic potential of MnTBAP to treat spinal cord injury (SCI; 25 g x cm) by directly administering it into the intrathecal space of the rat spinal cord. The cells in spinal sections removed at 24 h post-SCI were immunohistochemically stained with anti-4-hydroxynonenal (HNE), a marker of membrane lipid peroxidation (MLP); anti-nitrotyrosine (Ntyr), a marker of protein nitration; and anti-neuron-specific enolase (NSE) antibodies. Immunostained neurons were counted for quantitative evaluation. Pre-treatment 30 min before SCI with 1 mg/kg MnTBAP or 4-h post-SCI treatment with 2.5 mg/kg MnTBAP administered into the intrathecal space significantly reduced MLP and protein nitration, and increased the number of surviving neurons compared to vehicle controls. However, post-SCI treatment with a standard regimen of methylprednisolone sodium succinate (MPSS; 30 mg/kg followed by 5.4 mg/kg for maintenance, iv administration), the only drug used for clinical treatment of SCI, not only did not reduce MLP and neuron loss, it increased protein nitration compared with vehicle controls (two-way analysis of variance [ANOVA] followed by the Tukey test). These results demonstrate that pre- and post-intrathecal treatments with the low doses of MnTBAP provide sustained neuroprotection by preventing oxidative stress and that post-treatment with MnTBAP is superior to post-treatment with MPSS in preventing oxidative stress and resulting neuron loss.     

Effects of multi-dose methylprednisolone sodium succinate administration on injured cat spinal cord neurofilament degradation and energy metabolism

Thirty minutes after experimental spinal cord contusion (500 gm-cm) injury, cats were treated with an initial intravenous dose of either vehicle (V) or 30 mg/kg of Solu-Medrol sterile powder (methylprednisolone sodium succinate; MPSS). Two hours later, cats received a second intravenous injection of either V or 15 mg/kg MPSS, giving three treatment groups: V/V; MPSS/V; MPSS/MPSS. At 4 1/2 hours following injury of the cat lumbar spinal cord, the gray and white matter neurofilament protein content was reduced by over 70% within the injured segment of V/V-treated animals. The three major cat spinal cord neurofilament protein subunits of 200,000, 152,000, and 76,000 daltons were reduced in parallel by the injury. Treatment of cats with a single 30-mg/kg dose of MPSS (MPSS/V) provided a clear, although not significant, protection against neurofilament degradation compared with V/V-treated cats when measured at 4 1/2 hours after injury. The lactic acid content of the injured spinal cord segment at 4 1/2 hours after injury was significantly elevated in both V/V- and MPSS/V-treated cats, while the adenosine triphosphate (ATP) content, total adenylates, and energy charge were significantly reduced. The administration of a second intravenous 15-mg/kg dose of MPSS 2 hours after the initial 30-mg/kg dose (MPSS/MPSS) provided complete (p less than 0.01) preservation of neurofilaments within the injured spinal cord segment measured at 4 1/2 hours after injury. The levels of lactate, ATP, total adenylates, and tissue energy charge in MPSS/MPSS-treated cats were not different from those of uninjured spinal cords following laminectomy. The (Na+ + K+)-ATPase activity in the injured spinal segment was enhanced, although highly variable, in MPSS/V-treated animals. On the other hand, spinal cord enzyme activity was significantly and consistently elevated in the MPSS/MPSS-treated group. The results demonstrate that a 30-mg/kg dose of MPSS followed at 2 hours by a 15-mg/kg dose provides significantly better protection against injury-induced ischemia and Ca++-dependent neurofilament degradation than a single 30-mg/kg dose. These findings are in agreement with the spinal cord tissue pharmacokinetics and time-action characteristics of methylprednisolone observed in earlier studies.     

The effects of systemically administered methylprednisolone and recombinant human erythropoietin after acute spinal cord compressive injury in rats

The study design was to decrease the damage of spinal cord on the experimentally induced acute spinal cord injury in rats. The objective of this study was to evaluate whether recombinant human erythropoietin (rHu-EPO) and methylprednisolone (MPSS) improve neurological function and histopathological changes if systemically administered after traumatic spinal cord injury. This study included 48 rats that underwent experimental SCI. Forty-eight animals were randomly divided into six groups. Animals constituted a moderate compression of 0.6 N that was produced by application of an aneurysm clip at level T3 for 1 min. rHu-EPO (1,000 and 3,000 U (Unit) per kg of body weight i.p.) and MPSS (30 mg/kg) were administered 5 min after injury, and control group was saline treated. (1) Control group (n=8), (2) MPSS group (n=8), (3) rHu-EPO 1,000 U group (n=8), (4) MPSS + rHu-EPO 1,000 U group (n=8), (5) rHu-EPO 3,000 U group (n=8), and (6) MPSS + rHu-EPO 3,000 U group (n=8). The neurological function and histopathology were evaluated at 24 and 72 h. According to the neurological functional test scores significant improvements between the control group and the other groups that had taken medical treatment were observed (P<0.001). Histopathologically severe ischemic findings were observed in the control group. A significant decrease in ischemic damage was detected in MPSS + rHu-EPO 3,000 U group (P<0.001). The most significant neurological functional and histopathological improvements were observed after systemical administration of MPSS + rHu-EPO 3,000 U and rHu-EPO 3,000 U. Furthermore, the MPSS + rHu-EPO 3,000 U group provides the most improved neurological functional and histopathological recovery.     

Effects of EPC-K1 on lipid peroxidation in experimental spinal cord injury

STUDY DESIGN: A study in which levels of lipid peroxidation were measured, the thiobarbituric acid-reactive substances were estimated in an experimental rat model, and the recovery was assessed. OBJECTIVE: To ascertain the occurrence of thiobarbituric acid-reactive substances in the damaged spinal cord, and to investigate the effectiveness of a hydroxyl radical scavenger EPC-K1, a phosphate diester linkage of vitamins E and C, in attenuating the severity of spinal cord injury. SUMMARY OF BACKGROUND DATA: Lipid peroxidation has been reported to play an important role in spinal cord injury. There is no report on the use of EPC-K1 to attenuate the severity of spinal cord injury in either animal or human studies. METHODS: Spinal cord injury was induced by placing a 25-g weight on T12, and the animals were divided into six groups. Group 1 (sham) received only laminectomy. Group 2 (control) received spinal cord injury. Group 3 received EPC-K1 5 minutes before injury. Group 4 received it 5 minutes after injury. Group 5 received it 3 hours after injury. Group 6 received it five times, respectively: at 5 minutes, then 1, 2, 3, and 4 hours after injury. The levels of thiobarbituric acid-reactive substances were measured in the spinal cord, and the recovery was assessed. RESULTS: The thiobarbituric acid-reactive substances content increased after injury, with two peaks, at 1 and 4 hours. Concentration at the 4-hour peak was lower in nitrogen mustard-induced leukocytopenia rats than in the control rats. The EPC-K1 injection reduced thiobarbituric acid-reactive substances content at 1 and 4 hours after injury in Group 3 (respectively, 34.3% and 42.7% vs. control) and only that at 4 hours in Group 6 (24.9% vs. control). Motor function recovery and histologic findings were better in these two groups than in Group 2. CONCLUSION: Repeated injection of EPC-K1 attenuated the severity of spinal cord injury.     

Dose-dependent neuroprotective effects of melatonin on experimental spinal cord injury in rats

BACKGROUND: This report examines the dose-dependent effects of melatonin on early lipid peroxidation levels, ultrastructural changes, and neurological function in experimental spinal cord injury (SCI) by comparing them with therapeutic levels of methylprednisone in rats. METHODS: SCI was performed by an aneurysm clip placed extradurally at the level of T10. Rats were randomly divided into six groups of 10 rats each. Group 1 (sham) received only laminectomy; group 2 (control) received SCI; group 3 (placebo) received SCI and physiological saline; group 4 received methylprednisone (30 mg/kg); groups 5 and 6 received melatonin at doses of 50 or 100 mg/kg, respectively, after SCI. Rats were neurologically tested 24 hours after trauma. Spinal cord samples were harvested for both lipid peroxidation levels and ultrastructural histopathological evaluation. RESULTS: Neurological scores of rats were not different in SCI groups. Lipid peroxidation levels are significantly restricted only in methylprednisone group at 24 hours. Melatonin-treated groups showed more ultrastructural improvement on electron microscope studies when compared with methylprednisone group. However, the therapeutic effects of melatonin were mainly observed on white matter of spinal cord in ultrastructural investigation. There was significant difference between melatonin dose groups increasing with dose. CONCLUSIONS: Results showed that melatonin has no significant dose-dependent effects on early lipid peroxidation bur rather some neuroprotective effects on both axons and myelin sheaths of white matter in ultrastructural observations when compared with methylprednisone. These effects significantly augmented with dose increase.     

Effect of methylprednisolone, tirilazad mesylate and vitamin E on lipid peroxidation after experimental spinal cord injury

Effect of methylprednisolone (MP), tirilazad mesylate (TM) and vitamin E on lipid peroxidation (LP) was evaluated in an experimental model of spinal cord compression injury in anesthetized rats. Forty rats, divided randomly into four groups, were injured by compressing on the spinal cord at Th 3 for 1 min. Bolus injections of saline solution, MP (30 mg/kg bolus and 5.4 mg/kg/h), TM (10 mg/kg four times per day), or vitamin E (30 mg/ kg four times per day) were begun 1 h after the spinal cord injury (SCI). Twenty-four hours after treatment, the rats were killed, and malondialdehyde (MDA), a LP product, was measured in the spinal cord tissues. Rats treated with MP, TM and vitamin E had significantly decreased MDA levels (P<0.01) than rats in the control group. The lowest MDA levels were found in the TM group. These results suggest that MP, TM and vitamin E may have a protective effect against SCI in rats by its antioxidant effect.     

Erythropoietin improves oxidative stress following spinal cord trauma in rats

Spinal cord injury (SCI) is a very destructive process for both patients and society. Lipid peroxidation is the main cause of the further secondary damage which starts after mechanical destruction of tissues. Recent studies have shown that erythropoietin (EPO) has neuroprotective properties. In this study, we aimed to see the effect of EPO treatment after spinal cord injury on the oxidant and anti-oxidant enzyme systems and the relationship with the N-methyl-d-Aspartate (NMDA) blockage. Spinal cord injury was produced by epidural compression with a cerebral vascular clip that has a closing force of 40 g for 30 s after a limited multilevel laminectomy (T9-11). Experiment was done in 5 groups: Group1: Sham-operated untraumatised, Group 2: SCI untreated, Group 3: 150 i.u./kg EPO injected i.p. at the end of the first hour following the trauma. Group 4: NMDA receptor antagonist ketamine (100 mg/kg) i.p. Group 5: EPO + ketamine i.p. The experiments were finished after 12 h of the trauma. The spinal cords were excised for biochemical examinations.Anti-oxidant enzymes; catalase and reduced glutathione (GSH) levels increased and lipid peroxidation product, malonyldialdehyde (MDA) level decreased in EPO treated group when compared to the other groups. TNF-α levels decreased in EPO treated group. Application of ketamine before EPO treatment decreased effects of EPO. In conclusion, our results suggest that 150 i.u./kg i.p. EPO, a therapeutic dose in anaemic patients, applied after 1 h of spinal cord injury significantly attenuated the oxidative damage of spinal cord injuries in rats. This activity is abolished via ketamine pretreatment.     

Antioxidant actions and early ultrastructural findings of thiopental and propofol in experimental spinal cord injury

Thiopental and propofol are effective antioxidant agents. The current study was undertaken to examine the neuroprotective effects of a single intraperitoneal dose of thiopental and propofol. Effects of the drugs were evaluated by lipid peroxidation and ultrastructural findings. Fifty male Wistar rats were divided into five groups. Group 1 was the control group. Rats underwent laminectomy only, and nontraumatized spinal cord samples were obtained 1 hour after surgical intervention. All other rats sustained a 50-g/cm contusion injury by the weight drop technique. Group 2 rats underwent spinal cord injury alone, group 3 rats received 1 mL intralipid solution intraperitoneally immediately after trauma as the vehicle group, group 4 rats received a 15-mg/kg single dose of thiopental, and group 5 rats received a 40-mg/kg single dose of propofol intraperitoneally following the trauma. Samples from groups 2, 3, 4, and 5 were obtained 1 hour after injury. Lipid peroxidation was determined by measuring the concentration of malondialdehyde in the spinal cord tissue. The ultrastructure of the spinal cord was determined by electron microscopy. The contusion injury was associated with a rise in lipid peroxidation. Compared with the trauma group there was significant attenuation in lipid peroxidation of groups 4 and 5. Ultrastructural findings showed that the rats of group 4 sustained minor damage after spinal cord injury, but there was more evident damage in group 5 rats. These results indicate that thiopental decreases lipid peroxidation and improves ultrastructure, whereas propofol decreases lipid peroxidation without improving ultrastructure 1 hour after spinal cord injury in rats.     

Effectiveness of FK506 on lipid peroxidation in the spinal cord following experimental traumatic injury

STUDY DESIGN: An in vivo study in Wistar albino rats with injured spinal cord. SETTING: Department of Neurosurgery, Biochemistry and Pathology, Gazi University, Ankara, Turkey. OBJECTIVES: The aim of this study was to investigate and compare the effects of FK506 an immunosupressive agent with methylprednisolone (MP) on lipid peroxidation (LP) in injured spinal cord tissue. METHOD: A total of 28 adult healthy Wistar albino rats were subjected to traumatic spinal cord injuries (SCI) by using an aneurysmal clip compression technique, and they were divided into four groups. The G1 group (n=8) received FK506 (1 mg/kg); the G2 group (n=8) received FK506 (1 mg/kg) and MP (30 mg/kg); the G3 group (n=6) received only MP (30 mg/kg); and the G4 group (n=6) received no medication. The injured spinal cord tissue was studied by means of lipid peroxides, malondialdehyde (MDA), with thiobarbituric acid reaction and additionally the FK506 (G1); the MP (G3) groups were studied for histopathologic alterations 72 h after SCI with eight separate animals. RESULTS: Although LP values of G1, G2, G3 showed no statistical difference between intergroup analyses (P=0.547), a histopathological examination revealed that in the group that received MP, the oedema pattern was more significant than the group that received FK506. Another interesting finding was the presence of polymorphonuclear leucocytes in the MP group, whereas no infiltration was found in the FK506 group. CONCLUSION: Analysis of the results indicated that FK506 is a valuable pharmacological agent that could be used to decrease the LP and polymorphonuclear leucocyte infiltration and inflamatory reactions in the injured spinal cord tissue.     

Blockade of sodium channels by phenytoin protects ultrastructure and attenuates lipid peroxidation in experimental spinal cord injury

Summary Spinal cord injury (SCI) involves a series of pathological events. Abnormal sodium influx has been implicated as one of the key events in the pathophysiology of the SCI. Pharmacological blockade of sodium channels can reduce secondary injury and increase recovery from trauma. The aim of the present study was to show the neuroprotective effect of phenytoin, a sodium channel blocker, after experimental SCI.Control and laminectomy-only groups were not injured. 50g-cm weight drop injury was produced in the trauma group. In the treatment groups, methylprednisolone (30mg/kg) and phenytoin (1mg/kg, 10mg/kg, or 30mg/kg) were given intraperitoneally immediately after injury. Malondialdehyde (MDA) levels in the spinal cord samples were examined for lipid peroxidation. Spinal cord ultrastructure was evaluated and grading system was used for quantitative evaluation.Trauma increased tissue MDA levels. Treatment with methylprednisolone and phenytoin decreased MDA levels compared to trauma in all doses. Significant ultrastructural neuroprotection was observed with 30mg/kg of phenytoin treatment according to general neural score. This ultrastructural neuroprotection of phenytoin was not different from methylprednisolone. Phenytoin appears to protect spinal cord against injury by decreasing lipid peroxidation and lessening neuronal damage associated with SCI in rats.     

重组人红细胞生成素治疗脊髓冲击性损伤的实验研究

[目的]研究重组人红细胞生成素(recombinant human erythropoietin,rh-EPO)对脊髓冲击性损伤的治疗效果。[方法]24只新西兰白兔采用重物坠落的方法造成脊髓冲击性损伤。损伤12 h后,对照组静脉给予生理盐水;小剂量组、中等剂量组和大剂量组分别静脉给予rh-EPO 100、500、1000 IU/kg。损伤后24 h、48 h、1周评估下肢神经功能。损伤后1周时处死动物,脊髓标本进行HE和Caspase-3组化染色,电子显微镜评估超微结构损伤。[结果]EPO治疗组的神经功能评分明显高于对照组,HE染色和电子显微镜显示组织和超微结构损伤明显轻于对照组,Caspase-3阳性细胞数明显少于对照组。中等剂量组和大剂量组的治疗效果无显著性差异。[结论]脊髓冲击性损伤后12 h给予人红细胞生成素可减轻脊髓的组织和超微结构继发性损伤,并可对抗神经细胞凋亡,促进脊髓功能恢复。中等剂量EPO是治疗脊髓损伤的适当选择。     

Neuroprotective effect of magnesium on lipid peroxidation and axonal function after experimental spinal cord injury.

STUDY DESIGN: An experimental study examining the neuroprotective effect of magnesium on axonal function and lipid peroxidation in a rat model of acute traumatic spinal cord injury. OBJECTIVE: To determine the effectiveness of postinjury treatment with magnesium on evoked potentials and lipid peroxidation after spinal cord injury (SCI). SETTING: Pamukkale University, Denizli, Turkey. METHODS: Spinal cord injury occurred in 30 rats with an aneurysm clip at T9 and the rats were randomly assigned to undergo subcutaneous administration of one of the following at 1 h after injury: (1) Physiological saline (n = 10); (2) MgSO4, 300 mg/kg (n = 10) and (3) MgSO4, 600 mg/kg (n = 10). Spinal somatosensory evoked potentials (SSEPs) were recorded before injury, 30 min after injury and 3 h after injections. Rats were killed 24 h after the injury, and malondialdehyde (MDA) levels were measured. RESULTS: Following SCI, there were significant decreases in the amplitudes of P1 and N1 (P<0.001) and only high-dose magnesium improved the SSEPs (P<0.01). On the other hand, there was significant difference in lipid peroxide content between high-dose magnesium treated group and both of saline treated and low-dose magnesium treated groups (P<0.01). CONCLUSION: These results suggest that magnesium has a dose-dependent neuroprotective effect on SSEPs and lipid peroxidation after experimental spinal cord injury.     

NBQX treatment improves mitochondrial function and reduces oxidative events after spinal cord injury

The purpose of this study was to examine the effects of inhibiting ionotropic glutamate receptor subtypes on measures of oxidative stress events at acute times following traumatic spinal cord injury (SCI). Rats received a moderate contusion injury and 15 min later were treated with one of two doses of 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzol[f]quinoxaline-7-sulfonamide disodium (NBQX), MK-801, or the appropriate vehicle. At 4 h following injury, spinal cords were removed and a crude synaptosomal preparation obtained to examine mitochondrial function using the MTT assay, as well as measures of reactive oxygen species (ROS), lipid peroxidation, and glutamate and glucose uptake. We report here that intraspinal treatment with either 15 or 30 nmol of NBQX improves mitochondrial function and reduces the levels of ROS and lipid peroxidation products. In contrast, MK-801, given intravenously at doses of 1.0 or 5.0 mg/kg, was without effect on these same measures. Neither drug treatment had an effect on glutamate or glucose uptake, both of which are reduced at acute times following SCI. Previous studies have documented that drugs acting on non-N-methyl-D-aspartate (NMDA) receptors exhibit greater efficacy compared to NMDA receptor antagonists on recovery of function and tissue sparing following traumatic spinal cord injury. The results of this study provide a potential mechanism by which blockade of the non-NMDA ionotropic receptors exhibit positive effects following traumatic SCI.     

Effects of dexmedetomidine or methylprednisolone on inflammatory responses in spinal cord injury

Background: The aim of this study was to compare the anti-inflammatory response of methylprednisolone and the α2-agonist dexmedetomidine in spinal cord injury (SCI).
Methods: Twenty-four male adult Wistar albino rats, weight 200–250 g, were included in the study. The rats were divided into four groups as follows: the control group ( n : 6) received only laminectomy; the SCI group ( n : 6) with trauma alone; the SCI+methylprednisolone group ( n : 6) with trauma and 30 mg/kg methylprednisolone, followed by a maintenance dose of 5.4 mg/kg/h; and the SCI+dexmedetomidine group ( n : 6) with trauma and 10 μg/kg dexmedetomidine treatment intraperitoneally. Twenty-four hours after the trauma, spinal cord samples were taken for histopathological examination and serum samples were collected for interleukin-6 (IL-6) and tumor necrosis factor (TNF)-α measurement.
Results: TNF-α ( P =0.009) and IL-6 ( P =0.009) levels were significantly increased in the SCI group. TNF-α and IL-6 levels were significantly decreased with methylprednisolone ( P =0.002, 0.002) and dexmedetomidine ( P =0.002, 0.009) treatment, respectively. Methylprednisolone and dexmedetomidine treatment reduced neutrophils' infiltration in SCI.
Conclusions: The current study does not clarify the definitive mechanism by which dexmedetomidine decreases inflammatory cytokines but it is the first study to report the anti-inflammatory effect of dexmedetomidine in SCI. Further studies are required to elucidate the effects of dexmedetomidine on the inflammatory response.     

Effect of erythropoietin on bcl-2 gene expression in rat cardiac myocytes after traumatic brain injury

The purpose of this study was to investigate whether erythropoietin (EPO) has an effect on the expression of bcl-2 in rat cardiac myocytes following experimental isolated traumatic brain injury (TBI). Forty-eight Wistar-Albino female rats were randomly allocated into eight groups. Groups AC and BC were controls; groups AS and BS were sham-operated animals. Groups A1 and B1 underwent head trauma without treatment. Groups A2 and B2, head traumas plus EPO intraperitoneally (1000 IU/kg); groups A3 and B3, the vehicle groups, head traumas and intraperitoneal albumin (0.4 ml/rat). The method of weight drop was used to produce impact trauma at 24 hours after injury. Samples obtained from the left ventricle were assayed for lipid peroxidation and bcl-2 gene expression using real-time quantitative polymerase chain reactions. Lipid peroxidation in the heart tissue was determined by the concentration of thiobarbituric acid reactive substances (TBARs). The results showed that administration of EPO significantly reduced the increase in lipid peroxidation by-products after moderate or severe trauma. The bcl-2 expression was significantly higher in EPO (A2 and B2) compared to trauma groups (A1 and B1) suggesting a protective effect. These findings suggest that EPO may play an important role in the expression of bcl-2 and decrease in TBARs-the end product of lipid peroxidation in myocytes-after moderate or severe TBI.     

Effects of a single large dose of methylprednisolone sodium succinate on experimental posttraumatic spinal cord ischemia. Dose-response and time-action analysis

The ability of a single large intravenous dose of methylprednisolone sodium succinate (MPSS: 15, 30, or 60 mg/kg) to modify the evolution of lumbar spinal cord ischemia in cats undergoing a contusion injury of 500 gm-cm is examined. Repeated measurements of spinal cord blood flow (SCBF) in the dorsolateral funiculus were made via the hydrogen clearance technique before and for 4 to 5 hours after injury. The mean preinjury SCBF for all animals was 12.29 +/- 0.77 ml/100 gm/min. Following injury, SCBF began to decrease progressively in vehicle-treated animals to a level of 7.71 ml/100 gm/min, a fall of 37.3%. In contrast, cats that received a 30-mg/kg intravenous dose of MPSS at 30 minutes after injury maintained SCBF within normal limits (p less than 0.05 at 3 and 4 hours after contusion). A 15-mg/kg MPSS dose was less effective at preventing posttraumatic white matter ischemia, and a 60-mg/kg dose was essentially ineffective. It was determined that the 30-mg/kg MPSS dose was optimal for supporting SCBF when the drug was given at 30 minutes after spinal trauma, and a second series of experiments was carried out to examine the ability of this dose, when given at longer latencies, to improve decreased flow. Methylprednisolone given at 1 1/2 hours after injury in four cats produced a slight (12.7%) but transient improvement in SCBF, and when administered at 4 1/2 hours in another three animals was totally ineffective. These results show that MPSS in a 30-mg/kg dose can prevent posttraumatic spinal cord ischemia. However, it would appear that the ability of the steroid to reverse the ischemia once it has developed is limited, and probably lost, within a few hours of onset. This further suggests that the ischemic process is irreversible and underscores the need for early treatment with a large MPSS dose in order to prevent full development of ischemia and to promote neurological recovery.     

Reduction of pathological and behavioral deficits following spinal cord contusion injury with the selective cyclooxygenase-2 inhibitor NS-398

Spinal cord injury (SCI) results in loss of locomotor function and development of abnormal chronic pain syndromes (mechanical allodynia, thermal hyperalgesia). Following injury, secondary mechanisms including release of excitatory amino acids, inflammation and lipid peroxidation damage neural cells through release of cytotoxic free radicals. We hypothesized that selective inhibition of cyclooxygenase-2 (COX-2), an inducible inflammatory mediator, would decrease tissue damage and subsequently reduce locomotor deficits and development of chronic central pain syndromes after injury. Fifteen minutes prior to receiving T13 spinal segment spinal cord contusion injury, 200-225-g male Sprague-Dawley rats received either vehicle (0.5 ml 1:1 v/v DMSO/saline, i.p., n = 20) or the selective COX-2 inhibitor NS-398 (5 mg/kg in DMSO/saline v/v, i.p., n = 20). Locomotor function via the BBB scale, and nociceptive behaviors measured by paw withdrawals to von Frey filaments and radiant heat stimuli were tested for 4 weeks postinjury. Histological examination and volumetric analysis of spinal cord tissue were performed concomitantly. Spinally contused animals receiving NS-398 demonstrated significantly (p < 0.05) reduced locomotor alteration and reductions in both fore- and hindlimb mechanical allodynia and thermal hyperalgesia when compared to vehicle controls. Histological examination of spinal segments at the lesion segment demonstrated reduced lesion extent and increased viable tissue when compared to vehicle controls. Prostaglandin E2 levels were significantly lowered in NS-398-treated but not vehicle-treated animals 12 h after injury. These results support the role of COX-2 in reducing pathological and behavioral deficits after spinal cord injury.     

Comparison of two ester prodrugs of methylprednisolone on early neurologic recovery in a murine closed head injury model

In prior work, methylprednisolone succinate, sodium salt (MPSS) has been shown to enhance the early neurologic recovery of moderately or severely head-injured mice. In the present study, the relative cerebroprotective potency and efficacy of MPSS was compared to another methylprednisolone ester prodrug, methylprednisolone suleptanate, sodium salt (U67590A). Male CF-1 mice received a 900 g-cm concussive head injury followed within 5 min by an intravenous bolus dose of vehicle, MPSS, or U67590A. At 1 h postinjury, the neurologic status was evaluated blindly using a grip test. Both methylprednisolone esters were found to enhance early neurologic recovery after this severe head injury. However, U67590A was four to eight times more potent than MPSS. Either a 7.5 or 15.0 mg/kg dose of U67590A produced a significant improvement in recovery while a 60.0 mg/kg dose of MPSS was required. The maximal efficacy of the two prodrugs was equal. These results indicate that the ester of methylprednisolone can greatly influence the steroid's cerebroprotective potency and that U67590A may be superior in this regard to MPSS for the acute treatment of CNS injury.     

Changes of free iron contents and its correlation with lipid peroxidation after experimental spinal cord injury

Objective: To observe the dynamic changes of free iron contents and its relationship to the changes of lipid peroxidation after experimental spinal cord injury (SCI). Methods: Sprague Dawley rats were randomly divided into three groups: Group A (n=6) received no operation; Group B (n=48) received only laminectomy (sham) ; and Group C (n=48) received both laminectomy and traumatic injury ( SCI model). The SCI animal models were made by using an modified Alien‘s weight-drop device (50 g. cm) on T12. Rats were sacrificed at 0.5, 1, 3, 6, 12, 24 hours after injury. The levels of free iron involved in spinal cord segments at different time points were measured by blcomycin assay. The malondialdehyde (MDA) was also measured by the thiobarbituric acid (TBA). Results: After SCI in Group C, the level of free iron showed a significant increase at 0.5 hour compared to Groups B and A, restored to the control level at 6 h; the level of MDA was increased at 0.5 hour, peaked at 3 hours, returned to the control level at 12 hours; the concentrations of free iron and lipid peroxidation in injured rats were significantly and positively correlated at 0.5-3 hours. Conclusions: After SCI the levels of free iron are increased quickly and might be a major contributor to lipid peroxidation in injured spinal cord.