周围神经损伤后再生的药物调控研究

目的　探讨神康灵对损伤的坐骨神经再生的作用。方法　采用 2 8只成年体重为 2 0 0g的Wistar大鼠 ,随机分成 2组 (实验组和对照组 ) ,分别于术后 4周和 6周 ,通过肌电图检测坐骨神经运动诱发电位的传导速度和波幅 ;组织学检测有髓神经轴突数目、横截面积 ,从而探讨神康灵对坐骨神经损伤后再生的作用。结果　实验组神经传导速度、再生的有髓神经纤维横截面积、数目均优于对照组。结论　神康灵对坐骨神经损伤后的再生有明显的促进作用。     

Autotomy following peripheral nerve lesions: experimental anaesthesia dolorosa

(1) When hindlimb peripheral nerves are cut across in rats and mice, there is a tendency for the animal to attack the anaesthetic limb. We have called this attack "autotomy". In this paper we describe the time course and degree of autotomy following various types of nerve injury. (2) Four different types of lesion were applied to the sciatic nerve of rats. The most serious autotomy was produced by section of the nerve and encapsulation of its cut end in a polythene tube. Section followed by immediate resuturing also produced serious autotomy. Simple ligation of the nerve end was followed by less autotomy than encapsulation or cut and resuture. A crush lesion caused only minimal attack. (3) Section of the saphenous branch of the femoral nerve produced no autotomy. However, if the saphenous and sciatic nerves were ligated at the same time so that the entire foot became anaesthetic there was a great increase of autotomy over that seen when the sciatic nerve alone was ligated. This increase with the double lesion occurred even if the saphenous nerve was ligated more than 100 days after the sciatic nerve had been cut. (4) Mice showed autotomy very similar to that seen in rats but the onset was somewhat faster. (5) Reasons are given to propose that autotomy is triggered by an abnormal afferent barrage generated in the cut end of the nerve. Autotomy from peripheral nerve lesions is a different phenomenon from that seen after dorsal root section. Autotomy occurs under conditions which produce anaesthesia dolorosa in man. This simple model may be suitable for studies of the prevention of irritations originating from chronic lesions of peripheral nerves.     

Involvement of glutamate receptors on hyperexcitability of wide dynamic range neurons in the gracile nucleus of the rats with experimental mononeuropathy.

In order to clarify the functional role of glutamate receptors of the gracile nucleus neurons in rats with nerve injury-induced hyperalgesia, pharmacological, electrophysiological and in situ hybridization techniques were used in rats with chronic constriction nerve injury (CCI) of the sciatic nerve. A total of 54 wide dynamic range neurons were recorded from the gracile nucleus in the rats with CCI. Mechanical evoked responses were significantly depressed following application of AMPA receptor antagonist, CNQX, with noxious and non-noxious responses being similarly affected. AP-5, an NMDA receptor antagonist, induced depression of the pressure-evoked response only after application of the 1-microM concentration of this drug. The size of the receptive fields was significantly decreased after CNQX, but not MK-801 or AP-5, application. Afterdischarge was significantly depressed following the application of CNQX (1000 microM). The expression of ionotropic glutamate receptor subunit mRNAs in the gracile nucleus was studied using the in situ hybridization technique. The signals for NMDA subunits, NR2A, -2B and -2C, in the gracile nucleus neurons were not prominent, suggesting a low level expression of functional NMDA receptor complex. AMPA receptor subunits GluR1, -R2, -R3 and -R4 mRNAs were expressed in a large number of gracile nucleus neurons. These data are consistent with the pharmacological results that AMPA receptor antagonists depressed nociceptive neuronal activity, but NMDA receptor antagonists showed limited effects. These results suggest that the ionotropic glutamate receptors, i.e. the AMPA and NMDA receptors, are differentially involved in modulation of the wide dynamic range neuronal activity in the gracile nucleus following peripheral nerve injury.     

Regulatory T cells attenuate neuropathic pain following peripheral nerve injury and experimental autoimmune neuritis

Neuroimmune crosstalk in neuropathic pain is a key contributor to pain hypersensitivity following nervous system injury. CD4+CD25+Foxp3+ regulatory T cells (Tregs) are endogenous immune suppressors, reducing T-cell proliferation and proinflammatory cytokine production. Currently, the role of Tregs in neuropathic pain is unknown. In this study, we tested the effects of expanding Tregs on pain hypersensitivity and neuroinflammation in 2 models of neuropathy; sciatic nerve chronic constriction injury and experimental autoimmune neuritis in rats. Following chronic constriction injury, treatment with CD28 superagonist (CD28SupA), a Treg population expander, significantly increased Tregs in the lymphoid tissues, injured sciatic nerve, and lumbar spinal cord of rats. CD28SupA treatment led to a significant reduction in mechanical pain hypersensitivity, alongside a decrease in the numbers of infiltrating T cells, macrophages, and antigen-presenting cells in the sciatic nerve and dorsal root ganglia. In experimental autoimmune neuritis-affected rats, CD28SupA treatment resulted in a significant improvement in disease severity and in mechanical pain hypersensitivity. This was associated with a reduction in the numbers of T cells, macrophages, and antigen-presenting cells in the sciatic nerve and dorsal root ganglia, and reduced activation of microglia and infiltration of T cells in the spinal cord. Furthermore, depletion of Tregs by a CD25 antibody in mice with a partial sciatic nerve ligation resulted in prolonged mechanical pain hypersensitivity. These findings suggest that Tregs play a role in endogenous recovery from neuropathy-induced pain. Thus, this T-cell subset may be specifically targeted to alleviate chronic neuropathic pain.     

Expression of c‐Fos in the parabrachial nucleus following peripheral nerve injury in rats

Chronic constriction injury (CCI) of the sciatic nerve in rats evokes c‐Fos expression at spinal cord level. Using immunohistochemical methods we studied changes in c‐Fos expression in the brain stem area, which is suggested as one of the major targets of projection neurons in the superficial dorsal horn laminae, i.e., the parabrachial area. During the first week following injury, the animals developed tactile allodynia. At this time we found an increase of c‐Fos positive neurons in the parabrachial area, mainly in the pontine part where the group of c‐Fos immunoreactive neurons was present in the dorsal part of lateral parabrachial subnuclei. The number of c‐Fos positive neurons gradually decreased up to 14 days following CCI. The specific activation of brain stem neurons during onset of mechanical allodynia could underlie the changes in central nociceptive processing following peripheral nerve injury.     

A selective increase in Fos expression in spinal dorsal horn neurons following graded thermal stimulation in rats with experimental mononeuropathy

In order to clarify the central mechanisms of thermal hyperalgesia produced by peripheral nerve injury, Fos protein-like immunoreactive (Fos-LI) cells in spinal dorsal horn neurons were studied in rats with chronic constriction nerve injury (CCI) following graded thermal stimulation of the hind paw. The graded thermal stimuli (cold: 5, 10 and 15°C, heat: 42, 46 and 54°C) were applied to the planter surface of the operated hind paw 14 days after CCI or sham operation, and the number of Fos-LI cells in the spinal dorsal horn was quantified. Many Fos-LI cells were expressed in the superficial laminae of the spinal dorsal horn both in sham-operated and CCI rats following thermal stimulation. Fos-LI cells were mainly restricted to the medial half of the superficial laminae of the spinal dorsal horn, and were sparsely distributed in the deeper laminae. The number of Fos-LI cells in the superficial laminae (laminae I–II) of the dorsal horn was significantly higher in CCI rats after stimulation at 10 and 46°C, but not at the other stimulating temperatures (5, 15, 42, and 54°C) as compared to that in sham-operated rats. In laminae III–IV, the number of Fos-LI cells was significantly higher at all stimulus temperatures in CCI rats when compared to the sham-operated rats. No distribution difference of Fos-LI cells was observed between CCI and sham-operated rats in laminae V–VI. Thus, in the spinal dorsal horn of the CCI rats, there was a selective increase in thermal stimulus-induced Fos-LI cells in the superficial dorsal horn after stimulating at near noxious threshold intensities and a non-selective increase in Fos-LI cells in laminae III-IV after both noxious and innocuous thermal stimuli. The increase of Fos-LI cells in the superficial laminae may be related to hypersensitivity to noxious stimuli while the increase of Fos-LI cells in laminae III–IV may be related to an increased sensitivity to both noxious and innocuous stimuli that leads to increased reflex activity following nerve injury.     

实验性汞中毒大鼠周围神经损伤的机制

目的:观察慢性汞中毒大鼠行为学和组织中汞含量变代,探讨慢性汞中毒周围神经的病理损伤及机制。方法:8只雄性WisterKA大鼠,随机分为实验组和对照组两组各4只,对照组正常饲养,实验组采用氯化甲基汞4mg/kg隔日灌胃,制作了大鼠亚急性汞中毒动物模型,观察了坐骨神经,脊神经节和前后神经根的病理改变。结果:对照组各项指标均正常,无行为变化。服药第21天,实验组动物出现神经系统损害症状,表现为步态不稳,体质量由服药前(267.0±6.0)g降至(253.0±4.5)g。苏木精-伊红、Bodian及KB染色均显示坐骨神经纤维弯曲、断裂、呈空胞样改变,并见多个髓磷脂小球。甲苯胺兰染色示神经纤维数量减少,可见多个高电子密度的有髓纤维,髓鞘及轴索破坏。NF-200免疫组化染色显示轴索断裂,成块状深染及空胞化。ED-1染色可见神经组织内有大量的单核吞噬细胞浸润。神经剥离的单个纤维,光镜下可见神经轴索断裂成块状,而髓鞘相对完整。脊髓后根明显变性,前根未见明显的变化。脊神经节内神经纤维呈现明显的变性,但神经节细胞保留完好。结论:亚急性汞中毒最早的病理变化发生在周围神经轴索,表现为原发性轴索变性,可能与汞中毒干预了细胞的代谢有关。     

脑性瘫痪合并听神经通路损伤的临床研究

目的 调查脑性瘫痪合并听神经通路损伤的发生率，探讨脑性瘫痪合并听神经通路损伤与性别、脑性瘫痪型别及脑性瘫痪高危因素的关系。方法 回顾性调查272例脑性瘫痪患儿的临床资料，了解脑性瘫痪合并听神经通路损伤的发生率，并对脑性瘫痪合并听神经通路损伤发生与性别、脑性瘫痪型别及脑性瘫痪高危因素的关系进行分析。结果 272例脑性瘫痪合并听神经通路损伤的发生率为29．8％，其发生率与性别无关（P〉0．05），与脑性瘫痪型别有关（P〈0．05），其中以手足徐动型和混合型脑性瘫痪合并听神经通路损伤发生率更高（P〈0．0071），病理性黄疸、宫内感染与脑性瘫痪合并听神经通路损伤显著相关。结论 脑性瘫痪合并听神经通路损伤较普遍，以手足徐动型和混合型脑性瘫痪为著，病理性黄疸、宫内感染是脑性瘫痪合并听神经通路损伤的高度危险因素。     

糖尿病大鼠脊髓损伤后神经行为学和组织病理学研究

目的:了解糖尿病大鼠脊髓损伤(SCI)后神经功能恢复的情况。方法:将SD大鼠随机分成假手术对照组、假手术糖尿病组、SCI对照组和SCI糖尿病组。一次性腹腔注射链脲佐菌素建立糖尿病模型,Allen法制作SCI模型。在伤后10d内每天对各实验组大鼠进行斜板试验评价神经功能,并于伤后第1天和第10天观察大鼠脊髓组织形态学变化。结果:SCI糖尿病组大鼠伤后斜板试验临界角度明显低于SCI对照组,差异有显著性意义。组织病理学显示SCI糖尿病组大鼠脊髓组织灰质和白质严重受损,神经细胞稀少、尼氏体消失。结论:糖尿病大鼠脊髓容易遭受自由基损害,导致SCI后神经功能恢复不佳。     

Systemic adenosine infusion reduces the area of tactile allodynia in neuropathic pain following peripheral nerve injury: a multi-centre, placebo-controlled study.

Systemic adenosine has been shown in earlier case reports and a small placebo-controlled study to reduce pathological sensory dysfunction such as tactile allodynia in neuropathic pain. To evaluate this further, the effects of systemic adenosine infusion (50 microg/kg/min for 60 min) on tactile sensory dysfunction and pain was evaluated in 26 patients suffering peripheral neuropathic pain characterized by dynamic tactile allodynia. A randomized, cross-over, double-blind, placebo-controlled technique was used in this multi-centre study.Psychophysical methods were used to evaluate sensory dysfunction and spontaneous pain. The area of dynamic tactile allodynia was significantly reduced by adenosine compared with placebo (p=0.043), but spontaneous pain and tactile pain threshold were not significantly improved compared with the effects of placebo treatment. As a secondary outcome, a higher incidence of positive subjective effects on the clinical pain condition, in a few cases with long duration (several months), following adenosine treatment was found when the global effect of respective treatment was assessed (p=0.028). The results demonstrate involvement of adenosine receptor-sensitive pain mechanisms in some aspects of the sensory dysfunction often found in neuropathic pain.     

急性外周神经损伤时大鼠c-fos和c-jun mRNA表达的时序性变化

目的了解c-fos,c-jun mRNA在大鼠背根神经节细胞的表达情况,探讨急性外周神经损伤对大鼠背根神经节的c-fos,c-jun mRNA表达的影响.方法建立大鼠的坐骨神经切断模型,利用反转录-聚合酶链反应(RT-PCR)半定量法,检测急性外周神经损伤后,在不同的时间点(5,15,30,60,120 min)大鼠的背根神经节的c-fos,c-jun mRNA表达.结果损伤后5 min损伤组与对照组间c-fos,c-jun表达[(0.51±0.18)%,(0.63±0.17)%]差异无显著性意义(P＞0.05).c-fos于损伤后30～120 min表达为(1.41±0.22)%,(1.22±0.21)%,(0.98±0.17)%,与对照组比较,差异有显著性意义(P＜0.05);c-jun于损伤后15～120 min表达为(0.63±0.17)%,(0.80±0.20)%,(1.47±0.17)%,(2.68±0.22)%,(1.60±0.18)%,与对照组比较,差异有显著性意义(P＜0.05).损伤后c-fos,c-jun mRNA表达逐渐升高,呈时间依赖性.结论c-fos,c-jun是神经细胞损伤的敏感标志,急性外周神经损伤能引起c-fos,c-jun mRNA表达的时序性变化,为基因水平认识和防护外周神经损伤提供理论依据.     

大鼠急性甲醇中毒视神经损伤实验研究

目的探讨大鼠急性甲醇中毒视神经损伤时间窗及程度。方法用SD大鼠经口灌注甲醇,灌注后分不同时段处死大鼠取血测甲醇浓度、取视神经做病理检查。结果LD50从2h开始出现较为明显的损伤,4h后程度最重。LD0损伤最重的时间段在8h后。不论是LD0、LD50在损伤程度达到最严重之后,连续观察24h、48h、72h随着血液中甲醇浓度的降低,视神经的损伤仍然明显地持续存在。结论急性甲醇中毒对视神经早期（0.5h）就有损伤,损伤程度和剂量浓度有关,视神经的损伤最严重出现在血液中甲醇浓度高峰值的4h后,随时间推移甲醇在大鼠体内的继续弥散,致使损害迁延。     

Downregulation of spinal glutamate transporter EAAC1 following nerve injury is regulated by central glucocorticoid receptors in rats

Previous studies have shown that glucocorticoid receptors (GR) were upregulated, whereas glutamate transporters were downregulated, within the spinal cord dorsal horn after peripheral nerve injury. However, the relationship between the expression of spinal GR and glutamate transporter after nerve injury remains unknown. In the present study, we examined the hypothesis that central GR would regulate the expression of spinal glutamate transporter EAAC1 following chronic constriction nerve injury (CCI) in rats. CCI induced a significant downregulation of EAAC1 expression primarily within the ipsilateral spinal cord dorsal horn when examined on postoperative day 7 using both Western blot and immunohistochemistry. The downregulation of EAAC1 was significantly diminished after either the GR antagonist RU38486 (4 > 2 = 0.5 microg = vehicle) or a GR antisense oligonucleotide was administered intrathecally twice daily for postoperative day 1-6. Moreover, CCI induced a significant downregulation of nuclear factor kappaB (NF-kappaB) within the ipsilateral spinal cord dorsal horn, which also was attenuated by either RU38486 (4 > 2 = 0.5 microg = vehicle) or a GR antisense oligonucleotide. The immunohistochemical data indicated a pattern of colocalization between GR and EAAC1 as well as GR and NF-kappaB within the spinal cord dorsal horn. Since, NF-kappaB has been shown to regulate the expression of those cellular elements linked to inflammation and tissue injury and its activity can be negatively regulated by GR activation, these results suggest that spinal GR through NF-kappaB may play a significant role in the regulation of EAAC1 expression after peripheral nerve injury, a cellular pathway that may contribute to the development of neuropathic pain behaviors in rats.     

Dorsal root section elicits signs of neuropathic pain rather than reversing them in rats with L5 spinal nerve injury

Mechanical allodynia- and hyperalgesia-like behavior which develops in rats after L5 spinal nerve lesion has been suggested to be due to ectopic activity in the lesioned afferent neurons originating at the lesion site and/or in the dorsal root ganglion because it is eliminated by section of the dorsal root. Here we reevaluated the effect of a dorsal rhizotomy in rats after L5 spinal nerve lesion. Using calibrated von Frey hairs, paw withdrawal threshold to single stimuli and paw withdrawal incidence to repetitive stimulation were tested before and after nerve section. Neuropathic pain behavior of similar time course and magnitude also developed after cutting the L5 dorsal root, and L5 spinal nerve lesion-induced abnormal behavior could not be reversed by dorsal rhizotomy. The neuropathic pain behavior elicited by dorsal root section also developed when impulse conduction in the dorsal root axons was blocked during rhizotomy by a local anesthetic, i.e. when the immediate injury discharge was prevented from reaching the spinal cord. These results challenge the widely accepted idea that neuropathic pain behavior developing after spinal nerve lesion is dependent on ectopic activity in the lesioned afferent neurons. However, the present results do not rule out the possibility that after the two nerve lesions the mechanisms generating neuropathic pain behavior are different. After dorsal rhizotomy neuropathic pain behavior may be related to deafferentation whereas after spinal nerve lesion it may be caused by ectopic activity.     

Stress-related pain behavior in rats with peripheral nerve injuries

The effects of cold stress were studied on rats with unilaterally sectioned sciatic nerves. Behaviors suggestive of pain occurred in a number of these animals. These behaviors vanished when removing the rats from the stressful environment. Some severely painful syndromes in man might in part be due to mechanisms similar to those underlying the described behaviors in rats.     

脉冲电磁场促进周围神经再生的实验研究

目的：探索脉冲电磁场对周围神经再生的影响及其作用机理。方法：用ＳＤ雄性大鼠２４只,在距梨状肌下缘约１ｃｍ处切断坐骨神经后原位吻合,随机分成１／２、１、２月３组,每组又分成对照和实验组,实验组用微电脑电磁脉冲发生器进行治疗,两组均在不同时间通过肉眼观察、肌电图检测及取材组织学检测。结果：实验组较对照组Ｗａｌｅｒｉａｎ变性明显、加速、血管增生明显、纤维组织增生轻、神经再生及传导速度加快。结论：脉冲电磁场治疗能促进周围神经再生