Intracisternal administration of mitogen-activated protein kinase inhibitors reduced mechanical allodynia following chronic constriction injury of infraorbital nerve in rats

The present study investigated the role of mitogen-activated protein kinase (MAPK) in orofacial neuropathic pain following chronic constriction injury of the infraorbital nerve (ION-CCI). Experiments were carried out on male Sprague-Dawley rats weighing between 200 and 230 g. The ION was separated from adhering tissue, and two ligatures (5-0 chromic gut) were tied loosely around it. We examined the air-puff thresholds (mechanical allodynia), scores of pinprick (mechanical hyperalgesia), and face grooming frequency for acetone application (hypersensitivity for cold stimulation) - 3, 3, 6, 9, 12, 15, 20, 25, 30, and 40 days after surgery. ION-CCI produced mechanical allodynia, hyperalgesia, and cold hypersensitivity. We investigated whether administration of MAPKs inhibitors blocks ION-CCI-induced mechanical allodynia. Intracisternal administration with PD98059 or SB203580, a MEK inhibitor or a p38 MAPK inhibitor, respectively, significantly inhibited ION-CCI-induced mechanical allodynia in the orofacial area. These results indicate that the ION-CCI produced behavioral alterations in the orofacial area and those central MAPKs pathways contribute to orofacial neuropathic pain. Our findings suggest that MAPKs inhibitors have a potential role in treatment for orofacial neuropathic pain.     

The influence of thiamin on the efficacy of pregabalin in rats with spinal nerve ligation (SNL)-induced neuropathic pain

Objective: The thiamin is often used in the treatment of neuropathy, and pregabalin is often used to treat neuropathic pain. Our study examined the influence of thiamin on the efficacy of pregabalin in a rat model of spinal nerve ligation (SNL)-induced neuropathic pain.

Methods: Sprague-Dawley male rats were randomly divided into six groups. The neuropathic pain-relieving properties were measured by plantar test, cold plate test, and hot plate test after administration of pregabalin (i.v) and/or thiamin (i.p) in SNL rats 14 days after operation.

Results: In the therapy period, pregabalin, or thiamin alone all produced antinociceptive effects in rats with neuropathic pain. And combination treatment of thiamin and pregabalin resulted in an enhanced pain relief compared to the administration of pregabalin or thiamin alone.

Conclusion: Combination of thiamin and pregabalin produces an additive antinociceptive effect in neuropathic pain rats, this drug combination may offer a bene?cial treatment option for neuropathic pain.     

Effects of koumine, an alkaloid of Gelsemium elegans Benth., on inflammatory and neuropathic pain models and possible mechanism with allopregnanolone

Crude alkaloidal extraction from Gelsemium elegans Benth. produces analgesic property. However, its clinical utility has been obstructed by its narrow therapeutic index. Here, we investigated the potential of koumine, a monomer of Gelsemium alkaloids, to reduce both inflammatory and neuropathic pain. Interestingly, allopregnanolone, a neurosteroid, appeared to mediate the reduction of neuropathic pain. The potential anti-inflammatory pain effects of koumine were evaluated by acetic acid-, formalin- and complete Freund's adjuvant (CFA) -induced nociceptive behaviors in mice. Chronic constriction injury (CCI) and L5 spinal nerve ligation (L5 SNL), inducing thermal hyperalgesia and mechanical allodynia in rats, were used to test whether repeated treatment of koumine ameliorated neuropathic pain. Finally, we explored if koumine altered the level of neurosteroids in rat spinal cord of CCI neuropathy using liquid chromatography-tandem mass spectrometry. Koumine dose-dependently reduced the acetic acid-induced writhes and formalin-induced licking/biting time of Phase II in mice. Repeated administrations of koumine also dose-dependently reversed the CFA-, CCI- and L5 SNL-induced thermal hyperalgesia, as well as, CCI- and L5 SNL-induced mechanical allodynia in rats. The level of allopregnanolone, but not pregnenolone, in the L5-6 spinal cord was elevated by repeated treatment of koumine in CCI-induced neuropathic rats. These results demonstrate that koumine has a significant analgesic effect in rodent behavioral models of inflammatory and neuropathic pain, and that the reduction in neuropathic pain may be associated with the upregulation of allopregnanolone in the spinal cord.     

眼镜蛇镇痛素najanalgesin对大鼠神经病理性疼痛脊髓GLT-1的影响

目的:观察眼镜蛇镇痛素najanalgesin对L5脊神经结扎并剪断(spinal nerve ligation and transection,SNL)大鼠脊髓胶质细胞谷氨酸转运体亚型1(GLT-1)表达的影响,探讨najanalgesin脊髓镇痛机制.方法:100只雄性SD大鼠,随机分为假手术组(A),SNL模型组(B),SNL+najanalgesin组(C),SNL+生理盐水对照组(D),SNL+najanalgesin+脂质体组(E),SNL+najanalgesin+脂质体+GLT-1反义寡核苷酸(As-ODNs,F)6组.鞘内分别注射10μL生理盐水(A,D),40ng·kg-1najanalgesin(C,E,F),每日1次,在注射najanalgesin的同时于第3天一次性注射脂质体+GLT-1As-ODNs10μL(F)以及脂质体10μL(E),术后1,4,7 d(A,B,C,D)及第7天(E,F)取各组大鼠L4～L6脊髓节段,检测各组GLT-1 mRNA和蛋白表达改变.结果:采用SNL成功建立了神经病理性疼痛模型.与假手术组相比,B,D组大鼠GLT-1 mRNA和蛋白表达先增加再降低,C组大鼠GLT-1 mRNA和蛋白表达明显增加,但不随时间变化.与D组相比,C组大鼠第7天GLT-1 mRNA和蛋白表达明显增高.与椎管内注射najanalgesin组相比,椎管内注射GLT-1As-ODNs后,F组GLT-1表达明显下降,而脂质体对照组GLT-1的表达基本不变.结论:najanalgesin可以增加脊髓GLT-1 mRNA和蛋白表达,是其脊髓镇痛机制之一.     

常见SD大鼠神经病理性疼痛模型研究

本文旨在总结常见SD大鼠神经病理性疼痛模型优缺点,为NP研究者提供模型选择参考遥目前主流NP模型主要可分 CCI尧SNI尧SNL尧CCD 模型四大类遥四大类根据不同疾病的研究需要分不同小类,具体文中细述遥     

SNL细胞作为饲养层细胞培养人胚胎干细胞

目的为便于人胚胎干细胞(ES细胞)的培养和研究,寻找一种建系细胞作为人ES细胞的饲养层细胞。方法以小鼠成纤维细胞系SNL细胞作为饲养层细胞培养人ES细胞株hES1。传代17代后,检测hES细胞表面特异性标志,包括碱性磷酸酶(AKP)、Oct-4、阶段特异性胚胎抗原(SSEA)-3和SSEA-4的表达;同时观察细胞的多向分化潜能。结果hES1细胞在SNL细胞饲养层上能持续生长。经多次传代后持续表达人ES细胞表面特异性标志,其注射于重症联合免疫缺陷小鼠皮下仍能形成畸胎瘤组织。结论SNL细胞能够作为饲养层细胞用于人ES细胞的培养,且操作更方便;该细胞已转染了耐受新霉素的基因,为将来对人ES细胞基因操作时进行药物筛选提供了可能。     

Axon reflexes in axolotl limbs: evidence that branched motor axons reinnervate muscles selectively.

Numerous axon reflexes were found in grafted forelimbs, regenerated forelimbs, and forelimbs with regenerated nerves in the axolotl Ambystoma mexicanum. They were not seen in normal limbs. Each reflex was due to a single motor axon which branched, generally at a point central to the limb. In most cases several consecutive electrical stimuli were necessary to cause a visible contraction or a muscle action potential in the motor units concerned. I observed a total of 13 axon reflexes between the supernumerary limb and the ipsilateral host limb. All but one could be stimulated in either direction. In other animals I demonstrated 13 axon reflexes by cutting a small nerve in the distal limb and stimulating its proximal stump. In at least five, and possibly as many as 14 of these 26 axon reflexes, the two muscles involved were synonymous. In 20 of the 26, the muscles involved were situated in the same limb region and were synergistic or synonymous. Only in five axon reflexes were the muscles in widely different parts of the limb and clearly unrelated in function. Random innervation or mechanical guidance alone cannot account for these muscle-specific axon reflexes. Axon branches innervated muscles selectively, although the mechanism remains unclear. The selectivity was not perfect, though, because axon reflexes between dissimilar muscles did occur occasionally. Although it has been proposed that an axon may remain in an inappropriate muscle but be functionally “repressed,” no evidence of such repressed synapses was found.