水溶性脂质体运载基因药物复合物治疗大鼠神经病理性痛

背景：有研究报道病毒载体运载N-甲基-D天冬氨酸受体1小干扰RNA可有效缓解大鼠炎性疼痛,但病毒载体存在安全隐患。 目的：探讨水溶性脂质体运载N-甲基-D天冬氨酸受体1小干扰RNA在体内外沉默N-甲基-D天冬氨酸受体1的效应和治疗神经病理性痛的可行性。 方法：将PC12随机分为阴性转染组、对照转染组和水溶性脂质体转染组,分别以N-甲基-D-天冬氨酸受体1 小干扰RNA、聚乙烯亚胺与N-甲基-D-天冬氨酸受体1 小干扰RNA的复合物及水溶性脂质体与N-甲基-D-天冬氨酸受体1 小干扰RNA的复合物转染PC12细胞,检测各组N-甲基-D-天冬氨酸受体1 基因mRNA及蛋白水平表达的变化。将48只SD大鼠随机分为假手术组、模型组、聚乙烯亚胺组及水溶性脂质体组,后3组建立大鼠神经病理性疼痛模型,并分别鞘内注射生理盐水、聚乙烯亚胺与N-甲基-D-天冬氨酸受体1 小干扰RNA的复合物和水溶性脂质体与N-甲基-D-天冬氨酸受体1 小干扰RNA的复合物;假手术组只暴露坐骨神经。 结果与结论：水溶性脂质体转染组N-甲基-D-天冬氨酸受体1的 mRNA与蛋白表达水平明显低于其他两组(P < 0.01)。与假手术组比较,模型组、聚乙烯亚胺组及水溶性脂质体组N-甲基-D-天冬氨酸受体1 的mRNA和蛋白表达上调,累积疼痛评分升高(P < 0.01);与模型组比较,水溶性脂质体转染组脊髓背角N-甲基-D-天冬氨酸受体1 mRNA与蛋白表达及累积疼痛评分下降(P < 0.01),聚乙烯亚胺组上述指标无明显变化(P > 0.05)。表明在体内条件下水溶性脂质体可有效运载N-甲基-D-天冬氨酸受体1 小干扰RNA,抑制N-甲基-D-天冬氨酸受体1 的过度表达,还可减轻大鼠神经病理性痛。     

鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛大鼠脊髓背角N-甲基-D-天冬氨酸受体表达的影响

目的:研究丹参酮ⅡA对坐骨神经慢性压迫性痛大鼠脊髓背角内N-甲基-D-天冬氨酸受体2B亚基(NR2B)表达的影响,探讨丹参酮ⅡA的镇痛机制。方法:SD雄性大鼠随机分为假手术组和模型组。模型组又分为生理盐水组和处理组。模型组在手术当日及术后每日在大鼠鞘内注射生理盐水0.1 ml和丹参酮ⅡA 20 mg/kg,连续注射14 d。检测各组大鼠在手术前及术后14 d的机械痛阈和热痛阈;术后第14天,免疫组织化学检测大鼠脊髓背角内NR2B的表达。结果:与假手术组比较,生理盐水组大鼠的机械痛阈和热痛阈明显降低,NR2B的表达增多;与生理盐水组比较,处理组的机械痛阈和热痛阈明显升高,脊髓背角内NR2B的表达下降,差异均有统计学意义。结论:鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛模型大鼠的镇痛作用可能与降低脊髓背角内NR2B的表达有关。     

鞘内注射丹参酮ⅡA对神经病理性疼痛大鼠的镇痛作用

目的:研究丹参酮ⅡA对坐骨神经慢性压迫大鼠的的镇痛效果及大鼠脊髓背角内半胱氨酸天冬氨酸蛋白酶3(caspase-3)和胶质纤维酸性蛋白(GFAP)表达的影响.方法:检测大鼠在手术前及术后14d的机械痛阈和热痛阈;PCR及免疫组织化学分别检测大鼠脊髓背角内caspase-3和GFAP基因及蛋白的表达,TUNEL法检测脊髓背角内的细胞凋亡.结果:与假手术组比较,模型组大鼠的机械痛阈和热痛阈明显降低,caspase3和GFAP的表达均增多,凋亡染色阳性细胞数目也增多;与模型组比较,丹参酮ⅡA处理组大鼠的机械痛阈和热痛阈明显升高,脊髓背角内caspase-3和GFAP的表达均下降,凋亡染色阳性细胞数目也减少,差异均有统计学意义.结论:鞘内注射丹参酮ⅡA对坐骨神经慢性压迫模型大鼠有镇痛作用,其机制可能与降低脊髓背角内caspase-3和GFAP的表达有关.     

鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛大鼠脊髓背角CHOP的影响

目的 :研究丹参酮ⅡA对坐骨神经慢性压迫性痛大鼠脊髓背角CCAAT/增强子结合蛋白同源蛋白(CHOP)和caspase-3表达的影响,探讨丹参酮ⅡA的镇痛机制。方法 :SD雄性大鼠随机分为假手术组和模型组。模型组又分为生理盐水组和处理组,分别在手术当日及术后每日鞘内注射生理盐水0.1 ml和丹参酮ⅡA 20 mg/kg,连续注射14 d。检测各组大鼠在手术前及术后14 d的机械痛阈和热痛阈;术后第14天,免疫荧光组织化学检测大鼠脊髓背角内CHOP和caspase-3的表达。结果 :与假手术组比较,生理盐水组大鼠的机械痛阈和热痛阈降低,CHOP和caspase-3的表达增多;与生理盐水组比较,处理组的机械痛阈和热痛阈升高,脊髓背角内CHOP和caspase-3的表达下降,差异均有统计学意义。结论 :鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛模型大鼠的镇痛作用可能与降低脊髓背角内CHOP的表达有关。     

鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛大鼠脊髓背角内磷酸化p38MAPK的影响

目的:研究丹参酮ⅡA(TSA)对坐骨神经慢性压迫性痛大鼠脊髓背角内磷酸化p38丝裂原活化蛋白激酶(p-p38MAPK)表达的影响,探讨丹参酮ⅡA的镇痛机制。方法:SD雄性大鼠随机分为假手术组(sham组)和模型组。模型组又分为生理盐水组(NS组)和处理组(TSA组)。模型组在手术当日及术后每日鞘内注射生理盐水0.1 ml和丹参酮ⅡA20 mg/kg,连续注射10 d。检测各组大鼠在手术前及术后10 d的机械痛阈和热痛阈;术后第10天,免疫组织化学和免疫蛋白印迹检测大鼠脊髓背角内p-p38MAPK的表达。结果:与假手术组比较,生理盐水组大鼠的机械痛阈和热痛阈明显降低,p-p38MAPK的表达增多;与生理盐水组比较,处理组的机械痛阈和热痛阈明显升高,脊髓背角内p-p38MAPK的表达下降,差异均有统计学意义。结论:鞘内注射丹参酮ⅡA对坐骨神经慢性压迫性痛模型大鼠的镇痛作用可能与降低脊髓背角内p-p38MAPK的表达有关。     

鞘内注射丹参酮ⅡA对坐骨神经慢性压迫大鼠脊髓背角c-fos表达的影响

目的研究丹参酮ⅡA对坐骨神经慢性压迫大鼠脊髓背角内c-fos蛋白的表达,探讨丹参酮ⅡA(TanshinoneⅡA,TSA)的镇痛机制。方法 30只SD雄性大鼠随机分为假手术组(sham组,n=10)和模型组(n=20)。模型组又分为生理盐水组(NS组)和处理组(TSA组,n=10)。模型组在手术当日及术后每日在模型大鼠鞘内注射生理盐水0.1 m L和丹参酮ⅡA20 mg/kg,连续注射14 d。检测各组大鼠在手术前及术后14 d的机械痛阈和热痛阈;术后第14天,免疫组织化学法检测大鼠脊髓背角内c-fos的表达。结果与假手术组比较,生理盐水组大鼠的机械痛阈和热痛阈明显降低,c-fos的表达增多;与生理盐水组比较,处理组的机械痛阈和热痛阈明显升高,脊髓背角内c-fos的表达下降,差异均有明显统计学意义。结论鞘内注射丹参酮ⅡA对坐骨神经慢性压迫模型大鼠的镇痛作用可能与降低脊髓背角内c-fos的表达有关。     

鞘内移植微囊化转前脑啡肽原基因细胞对大鼠痛行为及脊髓背角相关蛋白表达的影响

目的:观察海藻酸钠-聚赖氨酸-海藻酸钠(APA)微囊化转鼠前脑啡肽原基因NIH3T3细胞(APA-NIH3T3/rPENK)移植对大鼠神经痛的影响及相关机制.方法:制作SD大鼠坐骨神经慢性压迫模型(CCI),随机分为APA空囊组、NIH3T3/rPENK组和APA-NIH3T3/rPENK组.测定移植后各组CCI术侧热痛阈,大鼠脊髓背角N-甲基-D-天冬氨酸受体2B亚基(NR2B)蛋白的表达情况.结果:移植后NIH3T3/rPENK组和APA-NIH3T3/rPENK组热痛阈明显高于APA空囊组.移植15d后APA-NIH3T3/rPENK组热痛阈显著高于NIH3T3/rPEN组.NIH3T3/rPENK组、 APA-NIH3T3/rPENK组结扎侧背角NR2B蛋白表达低于APA组;APA-NIH3T3/rPENK组背角NR2B蛋白表达低于NIH3T3/rPENK组.结论:NIH3T3/RPENK或APA-NIH3T3/rPENK植入大鼠的蛛网膜下腔可以明显减轻神经痛大鼠的热痛敏感行为,并降低脊髓背角NR2B蛋白的表达.     

NR2B参与脊髓损伤致慢性疼痛的机制研究

目的:研究N-甲基-D-天冬氨酸(NMDA)受体2B型受体(NR2B)参与脊髓损伤后慢性神经病理性痛的机制。方法:制作脊髓半横断大鼠模型,von Frey纤维丝测量机械性刺激缩足阈值变化,Western Blot观察脊髓背角NR2B表达时程变化;同时采用行为药理学方法,鞘内给予NR2B特异性拮抗剂ifenprodil,观察对机械性刺激缩足阈值及NR2B表达的影响。结果:脊髓半横断术后大鼠双侧后足出现触诱发痛状态,NR2B在腰段脊髓双侧背角表达上调。鞘内给予ifenprodil逆转了大鼠的痛敏状态,伴随着NR2B在脊髓背角表达下调。结论:NR2B可能参与脊髓损伤后慢性神经病理性痛的发生发展,特异性拮抗NR2B可能是临床治疗脊髓损伤致慢性神经病理性痛的潜在策略。     

鞘内注射丹参酮ⅡA对CCI大鼠脊髓内TAK1及IL-1β、IL-6表达的影响

目的研究丹参酮IIA对坐骨神经慢性压迫大鼠脊髓背角内TAK1及IL-1β、IL-6表达的影响,探讨丹参酮IIA的镇痛机制。方法 60只SD雄性大鼠随机分为假手术组(sham组)(n=20)和模型组(n=40)。模型组又分为生理盐水组(NS组)和处理组(TSA组)(n=20)。模型组在手术当日及术后每日在模型大鼠鞘内注射生理盐水0.1ml和丹参酮IIA 20mg/kg,连续注射10 d。检测各组大鼠在手术前及术后的机械痛阈和热痛阈;术后第10天,免疫组织化学法检测大鼠脊髓背角内TAK1的表达;采用ELISA方法测定各组大鼠脊髓组织中IL-1β、IL-6表达。结果与假手术组比较,生理盐水组大鼠的机械痛阈和热痛阈明显降低,TAK1的表达增多,脊髓组织中IL-1β、IL-6的含量均增高;与生理盐水组比较,处理组的机械痛阈和热痛阈明显升高,脊髓背角内TAK1的表达下降,脊髓组织中IL-1β、IL-6的含量均减少,差异均有明显统计学意义。结论鞘内注射丹参酮IIA对坐骨神经慢性压迫模型大鼠的镇痛作用可能与降低脊髓背角内TAK1及IL-1β、IL-6的表达有关。     

蛛网膜下腔注射pcDNA3．1（＋）-hPPE对大鼠神经病理性痛的镇痛效应

目的:观察蛛网膜下腔注射重组质粒pcDNA3.1(+)-hPPE对大鼠神经痛的镇痛作用.方法:SD大鼠随机分为坐骨神经慢性压迫(CCI)组、CCI假手术组、实验组和空质粒组.CCI组和CCI假手术组,用于观察疼痛持续时间;实验组和空质粒组分别于CCI术后第15天蛛网膜下腔注射重组质粒pcDNA3.1(+)-hPPE和空质粒pcDNA3.1(+).测定各组注射质粒前后CCI模型鼠双后肢热痛阈(PWTL),观察纳洛酮对镇痛效应的影响,用放射免疫法检测脑脊液灌流液中脑啡肽(L-ENK)的含量,同时采用免疫组织化学方法测定两组大鼠脊髓背角N-甲基-D-天冬氨酸(NMDA)受体2B亚基(NR2B)表达的变化.结果:CEI术后7～33 d,术侧PWTL明显低于对照侧.空质粒组注射前后热痛阈未见明显变化;与空质粒组相比,实验组大鼠蛛网膜下腔注射重组质粒pcDNA3.1(+)-hPPE后的第3天产生明显的抗伤害效应(FTWL升高),持续镇痛长达18d,且镇痛效应能被纳洛酮翻转.实验组脑脊液灌流液L-ENK含量显著高于空质粒组.与空质粒组比较,实验组大鼠脊髓背角NR2B阳性蛋白表达明显受到抑制.结论:蛛网膜下腔注射重组质粒pcDNA3.1(+)-hPPE能够减轻大鼠神经病理性疼痛的热痛敏行为.     

Antinociception induced in rats by intrathecal administration of antiserum against calcitonin gene-related peptide

To determine whether or not endogenous calcitonin gene-related peptide (CGRP) participates in pain transmission in the spinal dorsal horn, effects of an intrathecal injection of anti-CGRP antiserum on nociceptive threshold in the paw-pressure test was examined in non-arthritic and adjuvant arthritic rats. An intrathecal injection of the antiserum increased the nociceptive threshold in non-arthritic animals, while 0.9% saline, pre-immune serum and antiserum, previously absorbed by synthetic CGRP, were without effect. Adjuvant arthritic rats showed a hyperalgesia, and improvement occurred with intrathecal injection of the antiserum. Saline and absorbed antiserum were without effect on the hyperalgesia. These results suggest that the endogenous CGRP present in primary afferents probably has a facilitating function in nociceptive transmission in the spinal dorsal horn.     

Differential effects of calcitonin gene-related peptide and calcitonin gene-related peptide 8-37 upon responses to N-methyl-D-aspartate or (R, S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate in spinal nociceptive neurons with knee joint input in the rat

Calcitonin gene-related peptide is involved in the spinal processing of nociceptive input from the knee joint and in the generation and maintenance of joint inflammation-evoked hyperexcitability of spinal cord neurons. The present study examined whether this peptide influences the excitation of nociceptive spinal cord neurons by agonists at the N-methyl-D-aspartate and the non-N-methyl-D-aspartate [(R, S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate] receptors, both of which are essential for the excitation and hyperexcitability of spinal cord neurons. In anaesthetized rats extracellular recordings were made from dorsal horn neurons with knee input, and compounds were administered ionophoretically close to the neurons recorded. When calcitonin gene-related peptide was administered the responses of the neurons to the application of both N-methyl-D-aspartate and AMPA were increased. The coadministration of the antagonist calcitonin gene-related peptide 8-37 had no effect on the responses to N-methyl-D-aspartate, but it prevented the enhancement of the responses to N-methyl-D-aspartate by calcitonin gene-related peptide. By contrast, the administration of calcitonin gene-related peptide 8-37 enhanced the responses of the neurons to AMPA, and it did not antagonize but rather increased the effects of calcitonin gene-related peptide on these responses.The data suggest that the facilitatory role of calcitonin gene-related peptide on the development and maintenance of inflammation-evoked hyperexcitability is caused at least in part by the modulation of the activation of the dorsal horn neurons through their N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors. The different effects of calcitonin gene-related peptide 8-37 on the respones to N-methyl-D-aspartate and AMPA suggest that different intracellular pathways may facilitate the activation of N-methyl-D-aspartate and ionotropic non-N-methyl-D-aspartate receptors.     

电针对慢性内脏痛大鼠脊髓背角降钙素基因相关肽的影响

目的:检测电针对慢性内脏痛大鼠脊髓背角内降钙素基因相关肽(calcitonin gene-related peptide,CGRP)表达的影响。方法:SD大鼠随机分成正常对照组,慢性内脏痛模型组和模型加电针组,每组6只。慢性内脏痛模型采用新生幼鼠结直肠刺激方法制备;模型加电针组选取双侧"足三里"和"上巨虚",疏密波,强度1mA,持续30min,隔日一次,持续四次。记录结直肠扩张刺激下腹外斜肌放电幅值;免疫组织化学法检测各组大鼠胸腰段、腰骶段脊髓背角内CGRP的表达变化。结果:电针能够显著降低内脏痛大鼠结直肠扩张刺激诱导的腹外斜肌放电幅值(P0.05);免疫组织化学染色法显示:CGRP样免疫阳性物质的表达在模型组大鼠的胸腰段、腰骶段脊髓背角内均显著升高(P0.01),而模型加电针组的胸腰段、腰骶段脊髓背角内CGRP的表达与模型组相比有显著降低(P0.01)。结论:电针降低慢性内脏痛敏反应的镇痛机制与减少脊髓背角内CGRP样免疫阳性物质的表达有关。     

Receptor for calcitonin gene-related peptide: localization in the dorsal and ventral spinal cord.

Although the distribution of calcitonin gene-related peptide has been extensively studied in the spinal cord, little is known about the precise subcellular localization of receptors for calcitonin gene-related peptide. The present study was undertaken to localize calcitonin gene-related peptide receptors in both the dorsal and ventral horns of the rat spinal cord. Immunocytochemical localization with specific monoclonal antibodies was performed at the light and electron microscopic levels. Calcitonin gene-related peptide receptor was expressed in neuronal but not glial elements. Discrete postsynaptic localization of receptor for the calcitonin gene-related peptide was evident in the cells and dendrites of the superficial dorsal horn. Some of the terminal endings apposing the stained synapses formed the central terminals of glomerular complexes. The endings were scallop shaped (Type I), typical of primary afferent terminations. Other dorsal horn structures with postsynaptic labeling were contacted by dome-shaped or elongated axonal endings. Presynaptic localization on some dorsal horn terminations may serve an autoreceptor function. Motoneurons, on the other hand, were contacted by axonal terminals with presynaptic calcitonin gene-related peptide receptors. These data suggest that (i) dorsal horn neurons are capable of direct primary afferent, calcitonin gene-related peptide receptor-mediated interactions and (ii) neuronal terminals contacting motor horn cells can be influenced through presynaptic paracrine-like calcitonin gene-related peptide receptor-mediated interactions. Thus, calcitonin gene-related peptide can have multiple modulatory effects on spinal cord neurons through site-specific receptors.     

大鼠外周神经损伤后脊髓背角HMGB1表达上调参与机械性痛觉超敏

目的:研究HMGB1(high mobility group box-1)在神经病理性痛大鼠脊髓水平的表达变化,探索HMGB1在神经病理性痛发生发展中的作用,为治疗神经病理性痛提供新的理论依据和治疗靶点。方法:(1)雄性SD大鼠(180～220)g 12只,随机均分为三组:NS组:鞘内注射生理盐水;A组:鞘内注射HMGB1 1μg;B组:鞘内注射HMGB1 10μg。盲法用von Frey测定给药前及给药后1 h、1、3、7、14、21、28 d大鼠50%机械缩足阈值(me-chanical withdrawal threshold,MWT);(2)雄性SD大鼠(180～220)g 5只,免疫荧光双标观察HMGB1在脊髓背角的表达定位;(3)雄性SD大鼠(180～220)g 42只,随机均分为对照组(6只),SNL模型组(每时间点6只),West-ern Blot方法观察大鼠脊髓背角HMGB1对照及术后1、3、7、14、21、28 d的表达变化。结果:(1)大鼠脊髓鞘内注射HMGB1后诱发长时程机械性痛敏,A组在鞘内给药后7 d MWT明显下降(P<0.01),B组给药后1 h MWT即显著下降,且持续存在至少28 d;(2)免疫荧光双标显示:HMGB1主要表达于NeuN标记的神经元,而GFAP阳性的星形胶质细胞以及OX42阳性的小胶质细胞几乎不表达HMGB1;(3)Western Blot结果显示,脊髓背角HMGB1在SNL模型术后缓慢增高,7 d时增高最为显著,且持续至少28 d。结论:以上结果表明,外周神经损伤后脊髓水平HMGB1的表达上调可能在神经病理性痛的产生和维持中起着重要作用。     

Involvement of stem cell factor and its receptor tyrosine kinase c-kit in pain regulation

The c-kit receptor tyrosine kinase is expressed in a subpopulation of small- and medium-sized neurons of the dorsal root ganglia (DRG) and in the superficial layer of the spinal cord. Stem cell factor (SCF), a ligand of the c-kit receptor, induces neurite outgrowth from DRG and supports the survival of c-kit-expressing neurons. To clarify the possible function of the SCF/c-kit receptor system in the adult animal, we investigated the expression of c-kit receptor in the spinal cord and DRG in relation to pain by using H2C7, a newly developed anti-c-kit monoclonal antibody. S.c. and intrathecal injection of SCF markedly reduced the paw withdrawal threshold to mechanical stimuli and intrathecal SCF at 10 pg maximally induced mechanical allodynia in conscious mice. Intrathecal SCF also reduced the paw withdrawal latency to heat stimuli significantly but transiently. The c-kit receptor was co-expressed in 58.4% of calcitonin gene-related peptide (CGRP) -positive, but only 5.1% of isolectin B4-positive, DRG neurons. In the spinal cord, the c-kit receptor was detected in the superficial layer of the dorsal horn and co-localized there with CGRP in central terminals of DRG neurons. Selective elimination of unmyelinated C-fibers by neonatal capsaicin treatment resulted in marked reduction of the c-kit receptor and CGRP expression in the superficial layer of the spinal cord. Cell-size profiles showed that c-kit receptor expression was significantly up-regulated and down-regulated in medium-sized DRG neurons after neonatal capsaicin treatment and nerve injury, respectively. These results suggest that the c-kit receptor is mainly expressed in peptidergic small-sized DRG neurons and may be involved in pain regulation both peripherally and centrally.     

Immunoreactive calcitonin gene-related peptide and substance P coexist in sensory neurons to the spinal cord and interact in spinal behavioral responses of the rat

Using immunohistochemistry evidence was obtained for the coexistence of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivity in spinal sensory neurons. Analysis of caudally directed biting and scratching (CBS) behavior was carried out after intrathecal administration of CGRP and SP alone or in combination. Thus, SP (up to 20 micrograms) alone caused CBS only for a few minutes after injection, whereas SP (10 micrograms) plus CGRP (20 micrograms) caused a response with a duration up to 40 min. CGRP (20 micrograms) alone had no effects in this model. These findings provide support for a possible interaction of the two peptides at synapses in the dorsal horn of the spinal cord.     

Effects of intrathecal injection of prednisolone acetate on expression of NR2B subunit and nNOS in spinal cord of rats after chronic compression of dorsal root ganglia

N-methyl-D-aspartate receptor subunit 2B (NR2B) and neuronal nitric oxide synthase (nNOS) play important roles in the mechanism of neuropathic pain. To elucidate how glucocorticoids affect this mechanism, we studied the effects of intrathecal (it) injection of prednisolone acetate (PA) on a nociceptive stimulus and the changes of nNOS and NR2B subunit expression in the spinal dorsal horn of Sprague Dawley rats following chronic compression of the dorsal root ganglia (CCD). Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured for 15 days postoperatively. An it injection of PA (2.0 mg/kg) every 3 days for postoperative days 1 to 15 inhibited the thermal hyperalgesia and tactile allodynia of CCD rats. Chronic compression of the dorsal root ganglia induced time-dependent upregulation of nNOS and NR2B subunits of N-methyl-D-aspartate receptor within the spinal cord dorsal horn ipsilateral to CCD. Both upregulations were significantly diminished by it administration of PA (2.0 mg/kg), but not by lower doses of PA (0.5 or 1.0 mg/kg). The results suggest that PA upregulation of neuronal nitric oxide synthase and NR2B subunit expression in the spinal dorsal horn contributes to PA inhibition of hyperalgesia induced by chronic compression of dorsal root ganglia.     

Calcitonin gene-related peptide in primary afferent neurons of rat: co-existence with fluoride-resistant acid phosphatase and depletion by neonatal capsaicin

Immunohistochemical and histochemical techniques were used to re-examine the extent to which neonatal capsaicin treatment depletes calcitonin gene-related peptide in the dorsal horn of the spinal cord, to determine the localization of calcitonin gene-related peptide in relation to that of fluoride-resistant acid phosphatase in lumbar dorsal root ganglia, and to compare the distribution of these primary afferent markers in the dorsal horn. A substantial depletion of calcitonin gene-related peptide was observed in the dorsal horn of adult rats treated neonatally with capsaicin suggesting that a large proportion of this peptide in the dorsal horn is contained within capsaicin-sensitive primary afferent fibers. In dorsal root ganglia 30% of all or 44% of small- and medium-sized calcitonin gene-related peptide-immunoreactive cells were positive for fluoride-resistant acid phosphatase. Conversely, 50% of cells positive for the phosphatase enzyme also displayed immunoreactivity for the peptide. In lamina II of the dorsal horn calcitonin gene-related peptide and fluoride-resistant acid phosphatase were found to have an overlapping distribution. The presence of fluoride-resistant acid phosphatase in a substantial proportion of neuropeptide-containing primary sensory neurons suggests a lack of segregation of sensory neuronal populations into peptide- and non-peptide-containing subgroups at least on the basis of non-peptide neurons defined as those containing fluoride-resistant acid phosphatase.