NMDA受体NR2B亚单位在慢性内脏痛觉敏化中的作用

目的探讨外周与脊髓NMDA受体NR2B亚单位在慢性内脏痛觉敏化中的作用。方法模型组大鼠出生后d8～15,每天接受一次伤害性结直肠扩张刺激,8wk龄后用腹壁撤退反射(AWR)评估大鼠肠道敏感性。对腰骶背根神经节及胸腰与腰骶脊髓背角神经元进行免疫组织化学染色,比较对照与模型大鼠NR2B的表达。并比较对照与模型两组大鼠腹腔注射AP-7(NMDA受体拮抗剂)前后原发传入神经对结直肠扩张刺激的反应。结果①模型组大鼠AWR评分显著增高。②模型大鼠脊髓背根神经节NR2B亚单位表达增强。③模型大鼠脊髓内脏相关神经元NR2B亚单位表达增强。④AP-7显著抑制模型大鼠腰骶传入神经纤维对结直肠刺激的反应。结论NMDA受体NR2B亚单位可能参与慢性内脏痛外周与脊髓痛觉敏化的过程。     

雌激素对慢性内脏痛雌鼠的敏化作用及其机制

目的探讨雌激素对慢性内脏痛雌鼠痛反应的影响及其与脊髓NMDA受体的关系。方法在♀大鼠新生期给予数次结直肠扩张刺激,成年后分为高、低雌激素组,用腹外斜肌放电水平来评价成鼠内脏痛觉敏感性,用NMDA受体拮抗剂D(-)-2-amino-5-phosphonopentanoic acid(AP-5)鞘内给药比较两组大鼠脊髓NMDA受体的功能。结果 (1)模型鼠高雌激素组的内脏痛反应比低雌激素组的反应强。(2)AP-5鞘内给药对内脏痛反应的抑制作用在模型鼠两组中的差异无统计学意义。结论高雌激素可加重模型雌鼠的内脏痛反应,雌激素不能使模型雌鼠脊髓背角的NMDA受体功能上调。     

脊髓5-HT_(2A)受体对大鼠慢性内脏痛敏反应及其电针治疗的影响

目的探讨脊髓5-羟色胺2A(5-HT2A)受体对大鼠慢性内脏痛敏反应及其电针治疗的影响。方法 SD大鼠分为正常对照组,慢性内脏痛模型组、模型加溶媒对照组、模型加酮色林组、模型加电针组、模型加针药合用组等6组。慢性内脏痛模型采用对新生幼鼠给予结直肠扩张刺激方法制备;电针选取双侧"足三里"和"上巨虚",疏密波,强度1 mA,持续30 min,隔日1次,持续4次。记录各组大鼠在结直肠扩张刺激诱导下腹壁撤退反射评分和腹外斜肌放电幅值。结果①在20和40mmHg压力刺激下,模型加酮色林组大鼠腹壁撤退反射评分高于模型组(P<0.05,P<0.01)和模型加针药合用组大鼠(P<0.05,P<0.01)。②在3种不同压力刺激下,模型加酮色林组大鼠腹外斜肌放电幅值皆高于模型组和模型加针药合用组大鼠(P<0.05)。结论脊髓5-HT2A受体能够降低慢性内脏痛大鼠的痛觉敏化,但在电针治疗慢性内脏痛敏反应中可能不起主要作用。     

左旋硝基精氨酸甲酯和地佐环平和硝苯地平对吗啡致NG108-15细胞内钙浓度变化的影响

目的　探讨一氧化氮合酶抑制剂左旋硝基精氨酸甲酯 (L NAME)、N 甲基 D 天冬氨酸 (NMDA)受体拮抗剂地佐环平 (MK 80 1)和钙通道阻滞剂硝苯地平对吗啡作用的影响是否与细胞 [Ca2 + ]i 有关。方法　体外培养NG10 8 15细胞 ,用荧光指示剂Fura2 AM负载 ,荧光分光光度计动态测定细胞 [Ca2 + ]i。结果　吗啡、MK 80 110 μmol·L- 1、硝苯地平 1,2和3μmol·L- 1急性处理能降低由NMDA刺激 (模拟兴奋性刺激 )所致的细胞 [Ca2 + ]i 升高。MK 80 110μmol·L- 1和硝苯地平 3μmol·L- 1与吗啡合用均能完全对抗NMDA的作用。吗啡处理细胞 4 8h后 ,再用纳洛酮处理 ,细胞 [Ca2 + ]i 可增加约 39% ,L NAME ,MK 80 1和硝苯地平与吗啡合用均能降低纳洛酮引起的细胞 [Ca2 + ]i 的升高。结论　MK 80 1,L NAME和硝苯地平对吗啡调节的作用均与胞内Ca2 + 浓度的变化密切相关     

脊髓NMDA受体在慢性内脏高敏大鼠中作用研究Ⅰ

目的从整体行为学角度探讨脊髓NMDA受体在慢性内脏高敏大鼠中的作用。方法选用SD大鼠,模型组大鼠在出生后d8~d15内,每天接受一次结直肠扩张刺激;对照组除了不行结直肠扩张刺激外,其他情况同模型组。大鼠成年后用腹壁撤退反射(AWR),进行肠道敏感性评估。观察两组鞘内注射MK-801前后AWR评分和腹外斜肌对结直肠扩张刺激的反应是否存在差异。结果①在20~60mm-Hg CRD时,模型组AWR评分明显高于对照组(P<0.05)。②鞘内注射不同浓度MK-801后,模型组AWR测痛阈呈剂量依赖性升高(P<0.05),而对照组没有表现出明显的剂量依赖性。③鞘内注射MK-801(1.5mol·L-1)后,模型组腹外斜肌对CRD反应较给药前明显降低(P<0.05),肌电测痛阈明显升高(P<0.05);而对照组给药前后无改变。④模型组结直肠病理检查未见明显病理性改变。结论大鼠脊髓NMDA受体可能参与慢性肠道高敏感机制。     

NMDA受体数量在吗啡增敏、耐受和依赖形成过程中的重要性

阿片受体激动剂可使阿片受体下调,而其拮抗剂则可使阿片受体上调,此上调与阿片药物作用增敏有关,因此阿片受体拮抗剂可用于防治阿片类药物所致耐受。近年来还发现NMDA受体拮抗剂可减轻或逆转耐受及依赖程度;相反,预先用NMDA受体拮抗剂则可加重耐受,表明NMDA受体在阿片类药物耐受形成过程中有作用。本文旨在研究纳曲酮和NMDA受体拮抗剂地佐环平(dizocilpine,MK801)在吗啡所致耐受和依赖过程中的作用以及对脑NMDA受体动力学(Kd,Bmax)的影响。方法　将大鼠随机分为6组:盐水-盐水组、盐水-吗啡组、纳曲酮-盐水组、纳曲酮-吗啡组、地佐…     

雷莫司琼降低幼鼠内脏痛觉敏感性

目的:采用行为学和电生理学评价方法,探讨应用5-羟色胺3(5-HT3)受体拮抗剂雷莫司琼对幼鼠内脏痛觉敏感性影响。方法:新生期反复结直肠刺激(colorectal irritation,CI)建立幼鼠内脏痛觉高敏感性模型。32只SD新生大鼠按2×2析因设计分成4组,每组8只,A1B1组:新生期反复CI,15～21d腹腔注射雷莫司琼;A1B2组:新生期反复CI,15～21d腹腔注射生理盐水;A2B1组:新生期未接受CI,15～21d腹腔注射雷莫司琼;A2B2组:新生期未接受CI,15～21d腹腔注射生理盐水。常规饲养到幼鼠期(6周龄),通过观察幼鼠在不同压力结直肠扩张(colorectaldistension,CRD)刺激后的腹壁撤退反射(AWR)评分、内脏痛阈和腹外斜肌放电测量进行内脏痛觉敏感性评价。结果:幼鼠痛阈受建立内脏痛敏化模型和早期雷莫司琼干预两因素影响。建立内脏痛敏化模型可使幼鼠痛阈降低11.56mm Hg,早期雷莫司琼干预则使幼鼠痛阈提高9.06mm Hg,两者存在交互作用。应用雷莫司琼使AWR评分及腹外斜肌放电幅值降低,对于AWR评分的主效应在各个CRD压力下有统计学意义;对腹外斜肌放电幅值的主效应在各不同CRD压力下亦有统计学意义。结论:应用5-HT3受体拮抗剂雷莫司琼能够降低幼鼠内脏痛觉的高敏感性。     

侧脑室微量注射NMDA受体拮抗剂对神经病理疼痛的作用

目的:观察大鼠侧脑室微量注射N-甲基-D-天冬门氨酸(N-methyl-D-aspartate,NMDA)受体拮抗剂对神经病理性疼痛的影响,探讨脊髓上水平镇痛的机制,为临床上开发新的镇痛药物提供实验依据.方法:建立大鼠坐骨神经结扎(partial scicticnerve ligature,PSL)神经病理性疼痛模型,采用压爪-缩腿法和辐射热缩腿法测定大鼠的机械痛阈和热痛阈,观测侧脑室微量注射MK-801(NMDA受体非竞争性拮抗剂)与APV(NMDA受体竞争性拮抗剂)对神经病理性疼痛模型大鼠痛阈的影响.结果:PSL模型大鼠术后数小时痛阈即明显降低(P＜0.05),出现机械痛敏和热痛敏.侧脑室微量注射MK-801(5 nmol)、APV(2 nmol)后,大鼠机械痛阈和热痛阈明显升高,痛敏现象明显减轻(P＜0.05).结论:NMDA受体在中枢脊髓上水平与痛觉的形成和维持过程中可能起重要的作用.     

电针对吗啡耐受大鼠辣椒素受体磷酸化水平变化的影响

目的:探讨电针对大鼠吗啡耐受和辣椒素受体成员—瞬时受体电位辣椒素亚家族成员1(TRPV1)磷酸化水平变化的影响。方法:24只健康雄性SD大鼠随机分为3组(n=8),分别经鞘内给予生理盐水10μL为N组,吗啡10μg为M组,吗啡10μg并于每天首次给药后2Hz电针刺激大鼠足三里和阳陵泉两穴为H组,3组均一日2次给药,连续7d。用50%机械缩爪阈值及热板缩爪潜伏期评价大鼠机械痛敏及热痛敏。于给药后第8天取L4~5背根神经节(DRG),采用Westernblotting分析其中TRPV1总蛋白及TRPV1磷酸化水平。结果:M组在连续给予吗啡后形成稳定的吗啡耐受。2Hz电针处理可缓解吗啡耐受形成。M组TRPV1总蛋白表达高于N组、H组,差异有统计学意义,N组与H组比较差异无统计学意义。M组背根神经节内TRPV1磷酸化水平增加,H组TRPV1磷酸化水平与M组相比明显减少,差异均有统计学意义。结论:低频2Hz电针可抑制慢性吗啡耐受及耐受相关痛觉过敏,可能与抑制背根神经节内TRPV1磷酸化有关。     

大鼠鞘内注射AP5的抗内脏伤害作用

目的观察鞘内注射竞争性N-甲基-D-天冬氨酸（NMDA）受体拮抗剂2-氨基-5-磷酰基戊酸酯（AP5）对大鼠结直肠扩张（CRD）诱发的内脏伤害性刺激的影响及剂量关系。方法利用大鼠CRD模型诱导的内脏伤害性刺激,经鞘内引入药物,观察对腹壁撤回反射（AWR）达到3级时痛阈的影响。结果AP5剂量依赖地抑制CRD诱导的内脏伤害性刺激,并有时间作用特点。结论竞争性NMDA受体拮抗剂AP5可以抑制CRD诱导的内脏伤害性刺激,NMDA受体在内脏伤害性刺激脊髓水平的传递中起重要作用。     

Modulation of NMDA receptors by intrathecal administration of the sensory neuron-specific receptor agonist BAM8-22

The sensory neuron-specific receptor (SNSR) is exclusively distributed in dorsal root ganglion (DRG) cells. We have demonstrated that intrathecal (i.t.) administration of SNSR agonists inhibits formalin-evoked responses and the development of morphine tolerance [Chen, T., Cai, Q., Hong, Y., 2006. Intrathecal sensory neuron-specific receptor agonists bovine adrenal medulla 8-22 and (tyr(6))-gamma2-msh-6-12 inhibit formalin-evoked nociception and neuronal fos-like immunoreactivity in the spinal cord of the rat. Neuroscience 141, 965-975]. The present study was undertaken to examine the possible impact of the activation of SNSR on NMDA receptors. I.t. administration of NMDA (6.8 nmol) induced nociceptive behaviors, including scratching, biting and lifting, followed by thermal hypoalgesia and hyperalgesia. These responses were associated with the expression of Fos-like immunoreactivity (FLI) throughout the spinal dorsal horn with highest effect seen in laminae I-II. I.t. NMDA also induced an increase in nitric oxide synthase (NOS) activity in superficial layers of the dorsal horn, but not around the central canal, as revealed by NADPH diaphorase histochemistry. Pretreatment with the SNSR agonist bovine adrenal medulla 8-22 (3, 10 and 30 nmol) dose-dependently diminished NMDA-evoked nocifensive behaviors and hyperalgesia. This agonist also reduced NMDA-evoked expression of FLI and NADPH reactivity in the spinal dorsal horn. Taken together, these data suggest that the activation of SNSR induces spinal analgesia by suppressing NMDA receptor-mediated activation of spinal dorsal horn neurons and an increase in NOS activity.     

Spantide抑制甲醛炎性痛大鼠脊髓一氧化氮合酶表达和一氧化氮含量的增加(英文)

目的　观察鞘内注射P物质 (SP)拮抗剂spantide { [D Arg1,D Trp7,9,Leu11] substanceP}对炎性痛大鼠L5节段脊髓后角一氧化氮合酶 (NOS)表达和腰膨大一氧化氮 (NO)含量的影响 ,以探讨痛及痛过敏时脊髓NOS表达和NO生成增多的机制。方法　大鼠右后掌足底皮下注射 5 %甲醛 0 .2mL诱发炎性痛及痛过敏 ,NADPH d组化法观察脊髓后角NOS表达的变化 ,硝酸还原酶法测定NO含量的变化。结果　皮下注射甲醛 2 4h后 ,双侧L5节段脊髓后角NOS表达及腰膨大部位NO生成明显增加 ;注射甲醛前 5min鞘内注射spantide (5 μg ,10 μL) ,则明显抑制甲醛所致的NOS表达及NO生成增加。结论　初级传入末梢释放的SP在甲醛炎性痛及痛过敏时脊髓NOS表达及NO生成增多中发挥作用     

The role of CNS NMDA receptors and nitric oxide in visceral hyperalgesia.

The studies summarized here document the role of NMDA receptors and nitric oxide in the lumbosacral spinal cord and rostral ventromedial medulla in the maintenance of visceral hyperalgesia. Experiments were conducted in rats in which drugs were administered into either the lumbosacral intrathecal space or directly into the rostral ventromedial medulla. The visceral stimulus was noxious colorectal distension, administered before and 3 h after intracolonic instillation of either saline or 25% zymosan. The visceromotor response to colonic distension was quantified and found to be significantly enhanced in rats in which the colon had previously been treated with zymosan. Enhanced responses to distension were attenuated dose-dependently by intrathecal administration of the NMDA receptor channel blocker MK-801 and by inhibition of the neuronal isoform of nitric oxide synthase (nNOS). In corresponding studies wherein drugs were administered directly into the rostral ventromedial medulla, NMDA receptor antagonism and NOS inhibition dose-dependently attenuated exaggerated responses to colonic distension. Taken together, these data suggest that zymosan-produced visceral hyperalgesia is influenced both at the level of the spinal cord and rostral ventromedial medulla, and that descending facilitatory influences from the rostral ventromedial medulla are important to the maintenance of visceral hyperalgesia.     

Activation of spinal ERK signaling pathway contributes to pain-related responses induced by scorpion Buthus martensi Karch venom

It has been demonstrated that spontaneous nociceptive behaviors, cutaneous hyperalgesia and paw edema can be induced by intraplantar injection of scorpion Buthus martensi Karch (BmK) venom in rats. In the present study, activation of spinal extracellular signal-regulated kinase (ERK) signaling pathway and its contribution to pain-related responses induced by scorpion BmK venom were investigated. It was found that ERK was activated not only in the superficial layers but also in deep layers of L4–L5 spinal cord dorsal horn, which started at 2 min, peaked at 30–60 min and almost disappeared at 4 h following intraplantar injection of BmK venom. Intrathecal injection of U0126 (0.1, 1.0 and 10 μg), a widely used specific MAP kinase kinase (MEK) inhibitor, suppressed spontaneous nociceptive responses and reduced primary heat hyperalgesia and bilateral mechanical hyperalgesia induced by BmK venom. In addition, BmK venom-induced spinal c-Fos expression could be inhibited by U0126 dose-dependently. Intrathecal delivery of NMDA receptor antagonist (5R, 10S)-(+)-5-methyl-10, 11-dihydro-5H-dibenzo [a,d]-cyclohepten-5-10-imine hydrogen maleate (MK-801) and the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) could partially inhibit activation of spinal ERK induced by BmK venom at 30 min. Thus, activation of ERK in spinal cord dorsal horn, partially mediated by NMDA and non-NMDA receptor, potentially contributes to BmK venom-induced pain-related behaviors.     

N-methyl-D-aspartate receptor antagonist MK-801 suppresses glial pro-inflammatory cytokine expression in morphine-tolerant rats

Chronic opioid therapy induces tolerance and hyperalgesia, which hinders the efficacy of opioid treatment. Previous studies have shown that inhibition of neuroinflammation and glutamatergic receptor activation prevents the development of morphine tolerance. The aim of the present study was to examine whether N-Methyl-d-aspartate receptors are involved in the regulation of chronic morphine-induced neuroinflammation in morphine-tolerant rats.Morphine tolerance was induced in male Wistar rats by intrathecal infusion of morphine (15 μg/h) for 5 days. Tail-flick latency was measured to estimate the antinociceptive effect of morphine. Morphine challenge (15 μg, intrathecally) on day 5 at 3 h after discontinuation of morphine infusion produced a significant antinociceptive effect in saline-infused rats, but not in morphine-tolerant rats. Pretreatment with MK-801 (20 μg, intrathecally) 30 min before morphine challenge preserved its antinociceptive effect in morphine-tolerant rats. Morphine-tolerant rats expressed high levels of the pro-inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α and the increase in interleukin-1β and interleukin-6, and tumor necrosis factor-α levels was prevented by MK-801 pre-treatment at both the protein and mRNA levels.The results show that a single dose of MK-801 reduces the increase in pro-inflammatory cytokines in the spinal cord, thus re-sensitizing neurons to the antinociceptive effect of morphine in morphine-tolerant rats. This study provides a piece of theoretical evidence that NMDA antagonist can be a therapeutic adjuvant in treating morphine tolerant patients for pain relief.     

Attenuation of morphine tolerance, withdrawal-induced hyperalgesia, and associated spinal inflammatory immune responses by propentofylline in rats.

The activation of glial cells and enhanced proinflammatory cytokine expression at the spinal cord has been implicated in the development of morphine tolerance, and morphine withdrawal-induced hyperalgesia. The present study investigated the effect of propentofylline, a glial modulator, on the expression of analgesic tolerance and withdrawal-induced hyperalgesia in chronic morphine-treated rats. Chronic morphine administration through repeated subcutaneous injection induced glial activation and enhanced proinflammatory cytokine levels at the lumbar spinal cord. Moreover, glial activation and enhanced proinflammatory cytokine levels exhibited a temporal correlation with the expression of morphine tolerance and hyperalgesia. Consistently, propentofylline attenuated the development of hyperalgesia and the expression of spinal analgesic tolerance to morphine. The administration of propentofylline during the induction of morphine tolerance also attenuated glial activation and proinflammatory cytokines at the L5 lumbar spinal cord. These results further support the hypothesis that spinal glia and proinflammatory cytokines contribute to the mechanisms of morphine tolerance and associated abnormal pain sensitivity.     

Intrathecal Raf-1-selective siRNA attenuates sustained morphine-mediated thermal hyperalgesia

Studies have demonstrated that long-term opioid treatment leads to an increased sensitivity to painful (hyperalgesia) or normally innocuous (allodynia) stimuli. The molecular mechanisms that lead to paradoxical pain sensitization upon chronic opioid treatment are not completely understood. Enhanced excitatory pain neurotransmitter (such as calcitonin gene-related peptide (CGRP)) release in the dorsal horn of the spinal cord may play a role in sustained morphine-mediated paradoxical pain. Recently we have demonstrated that inhibition of Raf-1 attenuates sustained morphine treatment-mediated augmentation of CGRP release in vitro, in cultured primary sensory neurons. In the present study, we show that knockdown of spinal Raf-1 levels in vivo by intrathecal administration of Raf-1-specific siRNA attenuates sustained morphine-mediated thermal hyperalgesia in rats.     

鞘内注射促皮质素抑制甲醛痛敏大鼠脊髓NOS阳性神经元增多

目的:研究鞘内注射促皮质素(Cor)对甲醛痛敏大鼠脊髓背角一氧化氮合酶(NOS)阳性神经元增多的影响。方法:采用痛级均数(PIR)测定、NADPH-d组织化学法、Fos免疫组织化学法染色,观察鞘内注射(ith)Cor对甲醛痛敏大鼠脊髓背角NOS阳性神经元、Fos免疫反应神经元、NOS/Fos双标记神经元及痛敏的影响。结果:ith Cor(0.5-1.5U)均能显著抑制甲醛引起的大鼠脊髓背角NOS、Fos、NOS/Fos阳性神经元的增多和痛敏反应,其作用为ith NOS底物左旋精氨酸(Arg,5-15nmol)部分翻转。结论:Cor通过抑制大鼠脊髓背角NOS阳性神经元的增多抑制痛敏。     

Differential efficacy of intrathecal NMDA receptor antagonists on inflammatory mechanical and thermal hyperalgesia in rats

Spinal cord dorsal horn N-methyl-D-aspartate (NMDA) receptors have been implicated in central sensitization, enhanced responsiveness to peripheral stimuli following peripheral injury. Since hyperalgesia is a behavioral consequence of central sensitization, it should be attenuated at the level of the dorsal horn with NMDA receptor antagonists. However, responsiveness to thermal and mechanical hyperalgesia may be distinct, and have thus far not been directly compared in chronic inflammatory pain models. In the present study, inflammation was induced with complete Freund's adjuvant (CFA) injected into the rat hind paw and NMDA receptor antagonists dizocilpine (MK-801) or 2-amino-5-phosphonovaleric acid (AP-5) were intrathecally injected in rats to determine the effects on both mechanical and thermal hyperalgesia. Locomotor tests and reflexes were also conducted to evaluate potential motor side effects. The NMDA receptor antagonists dose-dependently ameliorated mechanical hyperalgesia, but had marginal effects on thermal hyperalgesia. In ranges near antihyperalgesic doses, significant disruption of motor coordination was observed for both antagonists. These results suggest that, depending on the stimulus, NMDA receptors may have variable significance for central sensitization-mediated hyperalgesia, and that NMDA receptor antagonists may have therapeutic potential for some, but not all components in the clinical manifestation of inflammatory pain.     

Modulating actions of NMDA receptors on pronociceptive effects of locally injected remifentanil in diabetic rats

BackgroundIn this study, we investigated the effects of locally (intraplantar) applied remifentanil, a μ opioid receptor agonist, to the paws and tested whether locally N-methyl d-aspartate (NMDA) receptors agonist or antagonist can modify remifentanil-induced effects in diabetic rats.MethodsEffects of locally (intraplantar) remifentanil, NMDA and MK801 or their combinations were investigated by measuring the latencies, thresholds and two biochemical parameters (malondialdehyde (MDA) and nitric oxide (NO)), in streptozotocin induced diabetic rats.ResultsDiabetic rats exhibited hyperalgesia and allodynia and remifentanil treatment aggravated the hyperalgesia and allodynia. The hyperalgesic and allodynic effects of remifentanil decreased in diabetic rats as compared to healthy rats. MK801 suppressed the hyperalgesic and allodynic actions of remifentanil in diabetic rats. However, hyperalgesic and allodynic actions of NMDA increased in diabetic rats. In contrast to age matched group, the combination of NMDA and remifentanil did not produce synergistic actions in diabetic rats. The levels of MDA and NO in the paw tissues of the diabetic rats significantly increased. MK801 significantly decreased NO levels, but not MDA, in diabetic rats.ConclusionsThe hyperalgesic and allodynic actions of locally treated remifentanil may decrease in diabetic conditions. Increases in NMDA receptors activation, reactive oxygen species production and NO release may modify the sensitivity to remifentanil in diabetes induced neuropathic pain states.