Charybdotoxin improves motor recovery of the rat after spinal cord injury

Charybdotoxin, a highly specific inhibitor of calcium-activated potassium efflux, was found to protect rat spinal cord against dynamic impact injury. In a control (nontreated) group, a weight drop of 10 gram X 5 cm on the T-11 segment of the rat spinal cord paralyzed hindlimbs, and recovery was slow. After 4 weeks, Tarlov scores (a behavioral index) were 1 to 2; the hind legs could not support body weight. In contrast, with animals pretreated 30 minutes prior to the injury by 0.12 mg charybdotoxin/kg (IP), Tarlov scores increased to 3.5-4.5 by three weeks after injury; animals could walk with some deficit. A possible mechanism for the protective effect of this drug is discussed.     

5-HT receptor-mediated regulation of thyrotropin-releasing hormone release in rat spinal cord.

5-Hydroxytryptamine (5-HT, 10 microM) increased the veratridine-evoked release of thyrotropin-releasing hormone (TRH) from spinal cord slices. This effect of 5-HT was reduced by pre-exposure of the tissue to 10 microM ketanserin and methysergide, which both have 5-HT2 antagonistic activity. A 5-HT1 agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (10 microM), reduced the release of TRH. These results imply that 5-HT released from the terminals of descending fibers modulates the release of TRH, a cotransmitter contained in 5-HT fibers.     

Effect of thyrotropin-releasing hormone (TRH) in experimental spinal cord injury: a quantitative histopathologic study.

Spinal cord injuries in rats were experimentally produced by compressing the cord (T11 vertebra level) for 60 min with stainless steel screws. Morphometric analysis of the injured cord revealed that at 14 days post-injury, there were significant correlations between the neurologic score (NS) and all morphometric parameters, including total cross-sectional area (rs = 0.438), lesioned area (rs = -0.421) and area of the gray (rs = 0.377) and white matter (rs = 0.704). Although rats treated with thyrotropin-releasing hormone (TRH; 22.5 mg/kg, s.c., twice daily for 7 days starting 24 hr post-injury) showed significant improvement in NS 14 days post-injury, there were no significant differences in morphometric parameters between saline- and TRH-treated rats. In addition, no significant correlation was observed between NS and any of the morphometric parameters in TRH-treated rats, even though there was a significant correlation between the area of white matter and NS in saline-treated rats. These results suggest that neurologic recovery closely reflects the histopathological changes evident at the injury site in the present model, and that the improvement of neurologic status seen in rats with cord injury given TRH starting 24 hr post-injury is not due to protection against progression of neural damage at the injury site.     

甲状旁腺激素对大鼠脊髓损伤后骨质疏松的作用和机制

目的探究甲状旁腺激素(parathyroid hormone, PTH)对脊髓损伤(spinal cord injury, SCI)后大鼠骨质疏松的影响及其作用机制。方法 SD大鼠随机性分为假手术组(Sham)、SCI模型组(SCI)、SCI+甲状旁腺激素组(SCI+PTH)、SCI+PTH+转染miR-146a无关片段组(SCI+PTH+NC)以及SCI+PTH+转染miR-146抑制剂组(SCI+PTH+miR-146a inhibitor组)。分别每3 d一次尾静脉注射给予大鼠60μg·kg^-1PTH(SCI+PTH组)、60μg·kg^-1PTH和20 pm miR-146a NC(SCI+PTH+NC组)或60μg·kg^-1PTH和20 pm miR-146a inhibitor(SCI+PTH+miR-146a inhibitor组),连续8周。Sham组和SCI组大鼠同法给予等量的生理盐水。BBB评分法记录术后大鼠行为运动评分;试剂盒检测大鼠血清血钙(Ca)和碱性磷酸酶(ALP)含量;骨密度扫描仪测定股骨和胫骨的骨密度;HE染色观察大鼠脊髓形态变化;qRT-PCR检测miR-146a表达;Western blot检测p-PI3K、p-Akt蛋白表达。结果与Sham组相比,SCI组大鼠BBB评分降低(P<0.05或P<0.01)、血清Ca、股骨和胫骨骨密度含量以及miR-146a、p-PI3K、p-Akt表达均降低,ALP升高(P<0.01)。与SCI组相比,SCI+PTH组大鼠BBB评分升高(P<0.05或P<0.01)、血清Ca、股骨和胫骨骨密度含量以及miR-146 a、p-PI3K、p-Akt蛋白表达均增加,ALP降低(P<0.01)。与SCI+PTH组相比,SCI+PTH+miR-146a inhibitor组大鼠上述指标均显著被抑制。结论 PTH对SCI骨质疏松症具有一定的治疗作用,其机制可能通过调控miR-146a/PI3K/Akt信号实现。     

Fasudil促进大鼠损伤脊髓神经功能恢复的研究

目的研究Rho激酶抑制剂Fasudil对大鼠脊髓损伤的促修复作用。方法用健康成年SD大鼠建立脊髓损伤模型,通过腹腔注射盐酸法舒地尔,并设立对照。术后1、2、4周,运用BBB功能评分进行后肢运动功能评价;损伤后4周,脊髓损伤局部行SABC法ROCK2免疫组织化学染色。结果术后1、2、4周,Fasudil治疗组与对照组比较,评分明显增高(P<0.05);术后4周Fasudil治疗组损伤局部组织内ROCK2的表达较对照组明显减少(P<0.05)。结论腹腔注射Fasudil能够减少脊髓损伤局部ROCK2表达,改善大鼠的运动功能。     

The time course of noradrenaline decrease in rat spinal cord following transection

The time course of degeneration of bulbospinal monoamine neurones following spinal cord transection was studied biochemically and histochemically in 3 consecutive 1 cm parts distal to transection. In the part immediately below transection clear degenerative changes were found on day 2, in the more distal part on day 4, and latest in the most distal part. This time-sequence of nerve terminal degeneration is probably related to the interruption of the comparatively slow intra-axonal transport in these neurons. The results indicate a complex situation in the nerve terminal-receptor area in the caudal part of the spinal cord following transection.     

促红细胞生成素对大鼠脊髓损伤后运动功能恢复的影响

目的 研究促红细胞生成素（Erythropoietin,EPO）对大鼠脊髓损伤后运动功能恢复的影响。方法健康成年雄性Wistar大鼠30只,随机分为三组：对照组、损伤组、治疗组,Allen’s法制作成脊髓打击伤动物模型,伤后1、3、7、14d用改良的后Gale联合评分法（the combinebe havioral score,CBS）观察大鼠运动功能的恢复情况,通过HE染色观察EPO对损伤脊髓组织病理变化的影响。结果脊髓损伤组的大鼠各时间点CBS评分较对照组明显降低,差异具有显著性（P〈0．01）;EPO组的大鼠后肢运动、肌张力及损伤平面以下各种反射较损伤组有不同程度的提高。脊髓损伤第3天,治疗组脊髓组织可辨别神经元形态;第7～14d治疗组脊髓组织结构较清晰,神经元形态正常。结论EPO能促进大鼠脊髓损伤后运动功能的恢复,减轻和延缓伤后早期的病理损害。     

米诺环素对不完全脊髓损伤大鼠神经功能修复的影响

目的:研究早期应用米诺环素(MINO)对不完全脊髓损伤大鼠神经功能修复的影响。方法:112只大鼠随机分为4组,假手术组(SHAM组)、损伤组(SCI组)、米诺环素低剂量治疗组、米诺环素高剂量治疗组,每组28只,SHAM组仅作椎板切除术,SCI组及米诺环素低剂量组、米诺环素高剂量组用改良Allen’s法制作T10不完全脊髓损伤模型,MINO低剂量组在术后0.5,1 h及1～5 d分别给予腹腔注射米诺环素40 mg·kg-1,MINO高剂量组以同样方法注射米诺环素80 mg·kg-1,SHAM、SCI组在同样的时间点注射等量的生理盐水。每组大鼠随机抽出16只在术前及术后1,3,7,14,21,28 d进行BBB评分,其余大鼠在术后3,7,21 d分别处死取材,行病理形态学观察(HE染色)和胶质纤维酸性蛋白(GFAP)免疫组化测定。结果:术后7～28 d,MINO低剂量组、MINO高剂量组BBB评分明显高于SCI组(P<0.05);HE染色显示在病理学形态上MI-NO低剂量组、MINO高剂量组脊髓损伤较SCI组轻;且GFAP表达明显受到抑制,与SCI组比较有明显差异(P<0.05)。结论:早期应用米诺环素可以促进不完全脊髓损伤大鼠神经功能的修复。     

Beta-aminopropionitrile treatment can accelerate recovery of mice after spinal cord injury.

Modulations of the extracellular matrix and scar formation following central nervous system (CNS) injuries are considered prohibitive for axon regeneration, thus restricting functional recovery. Recent findings indicating that lysyl oxidase, an extracellular matrix-forming enzyme, appears in a time-dependent manner at brain injury sites have suggested that inhibition of this enzyme may be conducive for regeneration and functional recovery. Here, we report that after unilateral spinal cord transection in adult mice, daily treatment (for 20 days) with the lysyl oxidase inhibitor beta-aminopropionitrile (100 mg/kg intraperitoneal) resulted in accelerated and more complete functional recovery. The mode of functional recovery, however, indicates that axonal regeneration of long descending tracts did not occur.     

Segmental synaptic depression caused by diisopropylphosphorofluoridate and sarin is reversed by thyrotropin-releasing hormone in the neonatal rat spinal cord

The organophosphorus compounds diisopropylphosphorofluoridate (DFP) and isopropylmethylphosphonofluoridate (sarin) depressed the monosynaptic reflex (MSR) in spinal cords from 7- to 9-day-old male rats. The concentrations of DFP and sarin which depressed the MSR by nearly 50% were 100 microM and 100 nM, respectively. Simultaneous superfusion of the cords with thyrotropin-releasing hormone (TRH) with either DFP or sarin resulted in a reversal of the depression. The depression caused by DFP was reversed to 95% of control by 100 nM TRH whereas similar reversal of sarin-induced depression required a 10-fold greater concentration of TRH. The potentiating effect of TRH was not affected by atropine even at a high concentration (1 microM) although atropine easily reversed organophosphorus-induced depression of the MSR. It appears that reversal of organophosphorus-induced depression by TRH might occur through a noncholinergic, TRH-sensitive receptor mechanism and may be unrelated to acetylcholinesterase activity. This action represents a possible utility of TRH as an adjunct in organophosphorus toxicity.     

New spinal cord injury model produced by spinal cord compression in the rat

Graded spinal cord injuries were produced in rats by compressing the spinal cord at the level of the T11 vertebra for 5, 15, 30, 60, or 180 min with stainless steel screws of 2-mm diameter and 2.8-mm length, or for 60 min with screws of the same diameter and various lengths (2.5, 2.8, 3.1, or 3.4 mm). The main neurologic symptoms caused by spinal cord compression were motor deficits, sensory deficits, and urinary incontinence. Neurologic scores, based on both motor and sensory deficits, correlated significantly with both the screw length and the duration of compression at every observation point from 4 hr to 21 days after removal of the screw. The incidence of urinary incontinence (from 24 hr to 21 days) and the percentage of rats surviving (from 14 days to 21 days) also correlated closely with the two factors (screw length and duration of compression). These results suggest that the present procedure could be a useful and simple model for studying traumatic spinal cord injury in rats.     

大脑中枢部分神经肽在脊髓不同损伤后的变化

目的：神经与经典神经递质共同参与着神经系统突触间信息传递,同时脊髓损伤部位神经肽的变化与神经细胞继发性改变也有密切相关,因此探讨脊髓损伤后中枢神经肽的变化对进一步阐明中枢与脊髓之间关系非常有益。方法将Ｗｉｓｔａｒ大鼠手术处理后分为脊髓压迫组、挫伤组、离断组、假手术组、正常对照组。术后２４小时心肌灌注取脑,再冠状面分区切取不同部位脑片,常规操作进行β－内啡肽和神经肽Ｙ免疫组化反应。结果损伤组β－内啡     

Effect of bromantane on the rat neurologic status in two month course

The oral administration of bromantan for two months on a toxic dose level produced a sex-dependent psychodysleptic action upon rats: the effective (30 mg/kg), intermediate (150 mg/kg), and toxic (600 mg/kg) doses reduced the motor activity in males, while not affecting (or increasing) this activity in females. The effective dose stimulated, and the toxic dose suppressed, the research activity and increased the number of grooming episodes, while ambiguously influencing the emotional state of rats. In the initial stage of treatment, bromantan causes hypothermia; in the second month, this effect is replaced by slight hyperthermia. Prolonged administration of a large dose of bromantan oppressed food uptake and slightly increased drink uptake. Upon the bromantan treatment, the body weight increased in females and decreased in males. The bromantan treatment course increased the muscle strength of rats; the operant activity was optimized during the first month of the course. The general physiological and behavioral characteristics of animals restored within two months after termination of the treatment course. During this period, the test animals exhibited no significant behavioral symptoms indicative of the drug dependence. The two-month treatment did not lead to the development of tolerance with respect to the optimizing drug action upon the physical and operant capacity.     

N-乙酰半胱氨酸对大鼠急性脊髓损伤后继发性脊髓损伤的保护作用

目的 探讨N-乙酰半胱氨酸(NAC)对大鼠脊髓急性损伤后继发性脊髓损伤的保护机制.方法 成年SD大鼠18只随机均分成单纯椎板切除(对照组)、急性脊髓损伤(损伤组)和急性脊髓损伤后NAC治疗(治疗组)三组.用30 g力量动脉瘤夹从两侧夹闭脊髓30 s建立脊髓损伤模型.治疗组术后15 min、1、2和3d分别予NAC 150 mg/kg腹腔注射;对照组和损伤组腹腔注射等量生理盐水.所有动物于术后3d处死取材,用凝胶电泳迁移率分析和免疫组化检测脊髓组织中核因子κB(NF-κB),ELISA法检测肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)和IL-6表达.结果 损伤组脊髓组织中NF-κB、TNF-α、IL-1β和IL-6水平均比对照组升高(P＜0.05),治疗组脊髓组织中各因子水平均比损伤组显著降低(P＜0.05).结论 NAC可以通过抑制大鼠急性脊髓损伤后NF-κB的活性,进一步下调TNF-α、IL-1β和IL-6的表达,从而减轻继发性炎症反应所导致的脊髓损伤.     

Cardiovascular control after spinal cord injury

Spinal cord injury (SCI) leads to profound haemodynamic changes. Constant outflows from the central autonomic pattern generators modulate the activity of the spinal sympathetic neurons. Sudden loss of communication between these centers and the sympathetic neurons in the intermediolateral thoracic and lumbar spinal cord leads to spinal shock. After high SCI, experimental data demonstrated a brief hypertensive peak followed by bradycardia with escape arrhythmias and marked hypotension. Total peripheral resistance and cardiac output decrease, while central venous pressure remains unchanged. The initial hypertensive peak is thought to result from direct sympathetic stimulation during SCI and its presence is anaesthetic agent dependent. Hypotension improves within days in most animal species because of reasons not totally understood, which may include synaptic reorganization or hyper responsiveness of alpha receptors. No convincing data has demonstrated that the deafferented spinal cord can generate significant basal sympathetic activity. However, with the spinal shock resolution, the deafferented spinal cord (in lesions above T6) will generate life-threatening hypertensive bouts with compensatory bradycardia, known as autonomic hyperreflexia (AH) after stimuli such as pain or bladder/colonic distension. AH results from the lack of supraspinal control of the sympathetic neurons and altered neurotransmission (e.g. glutamatergic) within the spinal cord. Despite significant progress in recent years, further research is necessary to fully understand the spectrum of haemodynamic changes after SCI.     

Neural plasticity after spinal cord injury

Spinal cord injury (SCI) has devastating physical and socioeconomical impact. However, some degree of functional recovery is frequently observed in patients after SCI. There is considerable evidence that functional plasticity occurs in cerebral cortical maps of the body, which may account for functional recovery after injury. Additionally, these plasticity changes also occur at multiple levels including the brainstem, spinal cord, and peripheral nervous system. Although the interaction of plasticity changes at each level has been less well studied, it is likely that changes in subcortical levels contribute to cortical reorganization. Since the permeability of the blood-brain barrier (BBB) is changed, SCI-induced factors, such as cytokines and growth factors, can be involved in the plasticity events, thus affecting the final functional recovery after SCI. The mechanism of plasticity probably differs depending on the time frame. The reorganization that is rapidly induced by acute injury is likely based on unmasking of latent synapses resulting from modulation of neurotransmitters, while the long-term changes after chronic injury involve changes of synaptic efficacy modulated by long-term potentiation and axonal regeneration and sprouting. The functional significance of neural plasticity after SCI remains unclear. It indicates that in some situations plasticity changes can result in functional improvement, while in other situations they may have harmful consequences. Thus, further understanding of the mechanisms of plasticity could lead to better ways of promoting useful reorganization and preventing undesirable consequences.     

Effect of experimental spinal cord injury on salicylate bioavailability after oral aspirin administration

The purpose of the present work was to study whether spinal cord injury (SCI) alters salicylate bioavailability after oral aspirin administration. Female Sprague-Dawley rats were subjected to SCI at the T8 level by two procedures, contusion by the weight-drop method and severance by knife, and received a single oral aspirin dose (15 mg/kg) 24 h after injury. Blood samples were drawn and aspirin (ASA) and salicylic acid (SA) concentrations in whole blood were determined at selected times over a period of 240 min. Both SCI procedures produced similar alterations on salicylate bioavailability. ASA bioavailability was not significantly changed by SCI. On the other hand, SA peak concentrations were significantly reduced in 20% to 30%, compared with sham-lesioned controls. The area under the SA concentration against time curve was decreased in 10% to 25%, although this difference did not reach statistical significance. Results suggest that SCI at the T8 level decreases the rate, but not the extent, of aspirin absorption from the gastrointestinal tract. SCI-induced alterations in aspirin absorption appeared to be modest compared with those previously reported for other analgesic agents, such as paracetamol (acetaminophen).     

GABAergic modulation of a substance P-mediated reflex of slow time course in the isolated rat spinal cord.

The effects of gamma-aminobutyric acid (GABA) and other drugs which interact with GABA receptors were studied on a reflex of slow time course in the spinal cord preparation isolated from the neonatal rat. A single shock to a dorsal root (L3-L5) elicited a stereotyped series of reflexes, consisting of fast and slow components, recorded from the contralateral ventral root of the corresponding segment. The slow component, i.e. the contralateral slow ventral root potential (v.r.p.) had a time-to-peak of 2-5 s and lasted 20-30 s. Bath-application of GABA (5-20 microM) or muscimol (0.05-0.5 microM) caused a decrease in the amplitude of the contralateral slow v.r.p. without producing any change in the d.c. potential recorded from the ventral root. The monosynaptic reflex recorded from the ipsilateral ventral root was not changed by the drugs at these concentrations. Diazepam (0.1-1 microM) potentiated the depolarizing response of the dorsal root to GABA and markedly depressed the contralateral slow v.r.p. Neither the d.c. potential of the ventral root nor the dorsal root was changed by diazepam. The monosynaptic reflex was also unaffected by the drug. Bicuculline (1 microM) suppressed the GABA-induced depolarization recorded from the dorsal root whilst it markedly potentiated the contralateral slow v.r.p. Baclofen at concentrations from 0.01 to 0.1 microM reduced the contralateral slow v.r.p. The inhibitory action of baclofen on the contralateral slow v.r.p. was more marked than on the monosynaptic reflex.(ABSTRACT TRUNCATED AT 250 WORDS)     

甲基强的松龙对脊髓损伤后卵磷脂胆固醇脂酰转移酶基因表达的影响

目的 研究甲基强的松龙对脊髓损伤后卵磷脂胆固醇脂酰转移酶(LCAT)基因表达的影响.方法 SD大鼠30只,体重200～250 g,雌雄不拘.随机分为假手术组、单纯脊髓损伤组(损伤组)、脊髓损伤 大剂量甲基强的松龙组(甲基强的松龙组).每组10只.损伤后24小时将损伤平面上下0.5 cm的脊髓组织切取,进行RT-PCR反应.结果 假手术组在术后24小时LCAT mRNA的表达的相对丰度为0.6743±0.0043,损伤组在伤后24小时LCAT mRNA的表达相对丰度降至0.0589±0.0281,差异有统计学意义(P<0.01).甲基强的松龙组在伤后24小时LCAT mRNA的表达的相对丰度为0.7036±0.2225,与损伤组比较差异有统计学意义(P<0.01).结论 大剂量甲基强的松龙能促进LCAT的表达,发挥保护作用,减少脊髓继发损伤.     

大鼠脊髓损伤后NEK6表达的实验研究

目的 探讨大鼠急性脊髓损伤后脊髓组织中NEK6的表达变化及意义.方法 采用改良Allen's打击法,构建大鼠脊髓T8-T10撞击伤模型,利用蛋白免疫印迹、免疫荧光双标的方法,研究大鼠脊髓损伤后脊髓组织中NEK6表达的时间和空间分布特征.结果 脊髓损伤后NEK6表达于撞击后2h有轻微抬高趋势,损伤后8h达到高峰,随后逐渐...