Effect of lumbar 5 ventral root transection on pain behaviors: a novel rat model for neuropathic pain without axotomy of primary sensory neurons

A peripheral nerve injury often causes neuropathic pain but the underlying mechanisms remain obscure. Several established animal models of peripheral neuropathic pain have greatly advanced our understanding of the diverse mechanisms of neuropathic pain. A common feature of these models is primary sensory neuron injury and the commingle of intact axons with degenerating axons in the sciatic nerve. Here we investigated whether neuropathic pain could be induced without sensory neuron injury following exposure of their peripheral axons to the milieu of Wallerian degeneration. We developed a unilateral lumbar 5 ventral root transection (L5 VRT) model in adult rats, in which L5 ventral root fibers entering the sciatic nerve were sectioned in the spinal canal. This model differs from previous ones in that DRG neurons and their afferents are kept uninjured and intact afferents expose to products of degenerating efferent ventral root fibers in the sciatic nerve and the denervated muscles. We found that the L5 VRT produced rapid (24 h after transection), robust and prolonged (56 days) bilateral mechanical allodynia, to a similar extent to that in rats with L5 spinal nerve transection (L5 SNT), cold allodynia and short-term thermal hyperalgesia (14 days). Furthermore, L5 VRT led to significant inflammation as demonstrated by infiltration of ED-1-positive monocytes/macrophages in the DRG, sciatic nerve and muscle fibers. These findings demonstrated that L5 VRT produced behavioral signs of neuropathic pain with high mechanical sensitivity and thermal responsiveness, and suggested that neuropathic pain can be induced without damage to sensory neurons. We propose that neuropathic pain in this model may be mediated by primed intact sensory neurons, which run through the milieu of Wallerian degeneration and inflammation after nerve injury. The L5 VRT model manifests the complex regional pain syndrome in some human patients, and it may provide an additional dimension to dissect out the mechanisms underlying neuropathic pain.     

Comparison of effects of anandamide at recombinant and endogenous rat vanilloid receptors

Background. Anandamide, an endogenous lipid, activates bothcannabinoid (CB₁) and vanilloid (VR1) receptors, both of whichare co-expressed in rat dorsal root ganglion (DRG) cells. Activationof either receptor results in analgesia but the relative contributionof CB₁ and VR1 in anandamide-induced analgesia remains controversial.Here we compare the in vitro pharmacology of recombinant andendogenous VR1 receptors using calcium imaging, in clonal andDRG cells, respectively. We also consider the contribution ofCB₁ and VR1 receptors to anandamide-induced analgesia. Methods. Using a Flurometric Imaging Plate Reader (FLIPR^TM),calcium imaging has been used to study the effects of severalvanilloid and cannabinoid ligands in rat VR1-transfected HEK293(rVR1-HEK) cells and in DRG cells. The effect of pre-exposureof several vanilloid and cannabinoids has also been comparedin DRG cells. Results. The VR1 agonists capsaicin, olvanil, (N-(4-hydroxyphenyl-arachinoylamide)(AM404) and anandamide caused a concentration-dependent increasein intracellular calcium concentration ([Ca²⁺]_i), with similartemporal profiles in both rVR1-HEK and DRG cells, and potency(pEC₅₀) values of 8.25 (SEM 0.11), 8.37 (0.04), 6.96 (0.06),5.85 (0.01) and 7.45 (0.10), 7.55 (0.07), 6.10 (0.13), approximately5.5, respectively. These responses were inhibited by the VR1antagonist capsazepine (1 µM). In contrast, applicationof synthetic cannabinoid antagonists failed to inhibit the anandamide-inducedincrease in [Ca²⁺]_i. Reapplication of VR1 agonists significantlyinhibited a subsequent challenge to either capsaicin or anandamidein either cell type, whilst pre-exposure to cannabinoid agonistswere without effect. Conclusion. Here we provide evidence that the pharmacology ofrecombinant rVR1 receptors is similar to those endogenouslyexpressed in DRG cells. Moreover, we have shown that VR1, butnot CB₁, receptors are involved in anandamide-induced responsesin dorsal root primary neurones in vitro. Therefore, the analgesicproperties of anandamide are likely to be mediated, at leastin part, by VR1 activation in DRG cells in vivo. Br J Anaesth 2002; 89: 882–7     

肌萎缩性侧索硬化症患者神经传导速度的研究

目的：探讨肌萎缩性侧索硬化症（ALS）患者神经传导速度（NCV）的改变及其在诊断和鉴别诊断中的价值。方法：以106例确诊为ALS的患者和123例正常人为研究对象，应用Keypoint肌电图仪进行正中、尺、胫和腓总神经的NCV检查，记录和刺激电极均为表面电极。结果：ALS组正中神经感觉神经传导速度（SCV）和正中、尺、腓总神经运动神经传导速度（MCV）较正常对照组明显降低，除正中神经感觉神经潜伏期外，两组比较，差异均有显著性意义；正中、尺、胫神经复合肌肉动作电位波幅ALS组明显低于正常组，但多无神经传导阻滞。结论：ALS组的MCV和SCV较正常对照组明显减慢，但在诊断和鉴别诊断方面，临床表现及针极肌电图比NCV更有价值。     

糖尿病周围神经病变代谢与分子机制研究进展

糖尿病周围神经病变是糖尿病最常见的慢性并发症之一。目前已发现与高血糖相关的多个病理机制。近年胰岛素和C肽的作用得到重视,胰岛素和C肽缺乏能够干扰神经纤维中神经营养因子代谢并引起氧化应激,同时可能与周围和中枢神经系统中出现的细胞凋亡有关。对糖尿病周围神经病变机制进一步的研究将为其预防和治疗提供更好的理论基础。     

复方丹参注射液对氧化损伤血管内皮细胞的保护作用

[目的]探讨复方丹参注射液对氧化损伤血管内皮细胞的保护作用及其机制.[方法]用过氧化氢损伤内皮细胞,MTT法检测其存活率,分光光度法检测细胞培养上清液中的MDA含量,免疫细胞化学染色法检测细胞表面细胞间ICAM-1的表达.[结果]血管内皮细胞受到氧化损伤后,细胞存活率明显降低,MDA含量明显增加,细胞间ICAM-1表达明显增加,而预先加入复方丹参注射液可改善上述结果.[结论]复方丹参注射液通过其抗脂质过氧化作用,对氧化损伤的血管内皮细胞具有保护作用.     

铍针治疗下位胸神经后支卡压综合征380例

目的探讨下位胸神经后支卡压对腰部疼痛的影响及治疗方法。方法对380例下位胸神经后支卡压致腰部疼痛的患者,采用铍针松解治疗。应用目测类比评分法结合临床症状、体征对治疗效果进行评估。结果380例患者治疗前、后疼痛视觉模拟指数间差别有显著性意义(P<0.001)。经1～12个月的随访治愈205例,显效65例,好转95例,无效15例。结论铍针治疗下位胸神经后支卡压综合征安全、简便,疗效确切。     

神经生长因子对新生大鼠缺氧缺血性脑病的保护作用

目的探讨神经生长因子(NGF)对新生大鼠缺氧缺血性脑病(H IE)的保护作用。方法建立H IE新生大鼠模型,给予腹腔注射NGF后,通过组织学观察、分光光度法及原位末端标记法对比观察NGF对H IE模型鼠脑组织结构、超氧化物歧化酶(SOD)活性、丙二醛(MDA)及一氧化氮(NO)的含量和凋亡细胞数的影响。结果NGF组MDA、NO含量及凋亡细胞数明显低于模型组的测定值;SOD活性显著高于模型组的测定值。结论NGF能提高抗氧化酶活性,抑制氧自由基生成,阻断NO的异常代谢,降低细胞凋亡数,对H IE具有保护作用。     

榆树根皮的化学成分(Ⅱ)

目的研究榆树(Ulmus pumilaL.)根皮中的化学成分。方法采用反复硅胶柱色谱法,凝胶柱色谱法等进行分离纯化;通过理化常数测定和光谱分析鉴定其化学结构。结果分离得到了8个化合物,即1十七烷酸甘油单酯(1 heptadecanoyl glycerol,1)、花生酸(eicosanoic acid,2)、1十六烷酸甘油单酯(1 hexadecanoyl glycerol,3)e、pifriedelanol(4)、无羁萜(friedelin,5)c、amaldulenic acid(6)、arjunolic acid(7)、异莨菪亭(isoscopoletin,8)。结论化合物1为首次从自然界分离得到,化合物2、3、6、7、8为属内首次分离得到,化合物4、5为种内首次分离得到。     

金翘感冒口服液的质量标准研究

目的研究金翘感冒口服液的质量标准。方法对金翘感冒口服液中主要药物金银花、连翘、甘草进行薄层色谱鉴别;采用RP-HPLC法测定绿原酸的含量。结果薄层色谱检出绿原酸、连翘药材、甘草次酸特征斑点,绿原酸进样量在0.224~1.120μg线性关系良好,平均加样回收率99.81%,RSD为0.89%。结论方法简便易行,灵敏,结果准确,重现性好,可有效控制金翘感冒口服液的质量。     

Feature detection of visual neurons in the nucleus of the basal optic root in pigeons

Previous studies have shown that the nucleus of the basal optic root in birds is involved in optokinetic nystagmus, and its neurons respond not only to large-field stimuli but also to a single object moving through their excitatory receptive fields. The present study provides electrophysiological evidence that basal optic neurons in pigeons respond vigorously to motion of a black leading edge. The orientation of the edge is also an essential factor affecting visual responses of these cells, showing that any deviation of the edge from the direction perpendicular to the preferred direction decreases visual responses in most cases. Furthermore, visual responses increase as the edge is lengthened within the excitatory receptive field. However, a square, semicircle and isosceles with an area ratio of 1.00: 0.39: 0.50 but with an identical leading edge elicit almost the same responses, which are not dependent on the shape and area of visual stimuli. It suggests that these feature extraction properties, similar to those of neurons in the nucleus lentiformis mesencephali, may be specialized for detecting optokinetic stimuli rich in luminance contrasts, but not for realizing pattern recognition.