目的 本研究拟通过建立坐骨神经慢性缩窄损伤(chronic constriction injury,CCI)小鼠模型,分析和探讨白芷在神经病理性疼痛中的镇痛效果及其对MrgprD-TRPA1信号通路的调控作用.方法 无菌外科手术结扎缠绕30只小鼠坐骨神经制备CCI小鼠模型;VonFrey实验检测白芷对小鼠机械刺激疼痛行为学变化,热辐射实验评估白芷对小鼠热痛觉过敏情况;Western Blot、免疫荧光、RT-PCR检测白芷对小鼠MrgprD和TRPA1蛋白表达水平、DRG阳性神经元数量、MrgprD和TRPA1 mRNA水平的影响;通过对HEK293细胞分别单转染和共转染MrgprD、TRPA1质粒后的钙成像实验,分析荧光信号强度差异性.结果 共成功制备了 25只CCI小鼠模型,造模率达到83.33％(25/30);白芷灌胃的CCI小鼠机械性阈值和缩足潜伏时间均显著大于对照组(P＜0.05);白芷灌胃的CCI小鼠中MrgprD和TRPA1蛋白表达水平均显著低于对照组(P＜0.05);白芷灌胃的CCI小鼠DRG中MrgprD和TRPA1阳性神经元的数量显著低于对照组(P＜0.05);白芷灌胃的CCI小鼠中MrgprD和TRPA1 mRNA相对表达水平均显著低于对照组(P＜0.05);共转染MrgprD和TRPA1质粒的HEK293细胞中荧光强度显著高于单转染和对照组(P＜0.05).结论 本研究通过探究白芷在CCI小鼠模型中镇痛的效果,证明了 MrgprD-TRPA1是神经病理性疼痛的重要作用靶点,揭示了白芷可以通过调控MrgprD-TRPA1信号转导通路来抑制神经病理性疼痛程度,这为后续开发新型临床镇痛药物及镇痛机制的深入研究奠定了基础.

中医药在止痒、镇痛方面具有副作用小、疗效明确的优势,但是其作用的分子生物学机制并不清楚.MrgprD(Mas-re-lated gene D)是G蛋白偶联受体Mrg(Mas-related genes)家族的一个成员,特异表达于外周初级感觉神经元上.综述了Mrg-prD近20年的研究现状,为认识M rgprD的新功能并为相关疾病治疗提供参考.鉴于M rgprD在痛觉和痒觉产生中的作用,可能成为中医药镇痛、止痒的作用靶点,为中医药的研究提供思考.

Noxious mechanical information is transmitted through molecularly distinct nociceptors,with pinprickevoked sharp sensitivity via A-fiber nociceptors marked by developmental expression of the neuropeptide Y receptor 2 (Npy2r) and von Frey filament-evoked punctate pressure information via unmyelinated C fiber nociceptors marked by MrgprD.However,the molecular programs controlling their development are only beginning to be understood.Here we demonstrate that Npy2r-expressing sensory neurons are in fact divided into two groups,based on transient or persistent Npy2r expression.Npy2r-transient neurons are myelinated,likely including A-fiber nociceptors,whereas Npy2r-persistent ones belong to unmyelinated pruriceptors that co-express Nppb.We then showed that the transcription factors NFIA and Runx1 are necessary for the development of Npy2r-transient A-fiber nociceptors and MrgprD+ C-fiber nociceptors,respectively.Behaviorally,mice with conditional knockout of Nfia,but not Runx1 showed a marked attenuation of pinprick-evoked nocifensive responses.Our studies therefore identify a transcription factor controlling the development of myelinated nociceptors.

目的 探索Runx1是否能够结合Mrgprd基因启动子序列,从而直接激活其转录.方法 构建包含小鼠Mrgprd基因转录起始点上下游不同序列的一系列Mrgprd荧光素酶报告基因质粒及小鼠Runx 1基因的表达质粒,在PC12细胞系中共转染其中一种Mrgprd荧光素酶报告基因质粒和Runx1表达质粒或者空载体对照质粒,利用双荧光素酶报告基因系统检测Runx1对这种Mrgprd荧光素酶报告基因的转录激活作用.通过比较Runx1对不同Mrgprd荧光素酶报告基因的转录激活作用的差异,寻找Runx1在Mrgprd基因上发挥调控作用的关键位点.结果 Mrgprd基因转录起始点上游562?200位点序列对于Runx1发挥转录激活作用至关重要,该段序列包含2个Runx1保守结合位点,但这两个位点的突变并不影响Runx1发挥对Mrgprd的转录激活作用.结论 Runx1对Mrgprd基因的转录调控机制可能有多种,并非只是通过结合在Mrgprd基因上游的结合位点来直接调控其转录,也可能通过其他方式间接调控Mrgprd基因的转录.

Peripheral inflammation is always accompanied by a noxious sensation,either pain or itch,pro-viding a protective warning for the occurrence of pathological changes;however,the mechanisms determining whether pain,itch,or both will be elicited under certain inflammatory statuses are still far from clear.Complete Freund's adjuvant(CFA)contains heat killed and dried Mycobacterium tuberculosis widely used to induce inflammatory pain models,but how CFA treatment affects itch sensation and the possible mechanisms are still unclear.In this study,using itch behavior testing and calcium imaging,we showed that both the behaviors and calcium responses associ-ated with Transient Receptor Potential Vanilloid 1(TRPV1)-mediated histamine-dependent itch and Transient Receptor Potential Ankyrin 1(TRPA1)-mediated histamine-independent itch were signif-icantly suppressed by CFA treatment.Furthermore,to explore the possible cellular mechanisms,high-throughput single-cell RNA sequencing and real-time PCR were used to detect CFA-induced changes of itch-related genes in dorsal root ganglion(DRG)neurons.Our results revealed that although both nociceptive Trpv1+and Trpa1+DRG neurons were increased after CFA treatment,most known pruriceptors,including Hrh1+,Mrgpra3+,Mrgprd+,Htr3a+,Htr1f+,IL31ra+,Osmr+,and Lpar3+DRG neurons,were significantly decreased,which may explain that CFA treatment caused itch suppression.This study indicated that itch sensation was affected after CFA treatment,although negatively,and comprehensive but not specific suppression of different pruriceptors was observed after CFA treatment,suggesting that a unified adaptive change of increased pain and decreased itch will occur simultaneously under CFA-induced inflammatory conditions.

眼部瘙痒是眼表疾病的常见症状之一,人们对眼部瘙痒发生机制了解甚少,临床上往往只能通过使用滴眼液来暂缓眼部不适,眼部瘙痒常常令患者感到无比痛苦和不适.瘙痒感由初级神经元传入,主要是小直径无髓鞘的传入神经元纤维,其胞体位于背根神经节或三叉神经节,这些神经元将瘙痒感从皮肤传递到中枢神经系统.在脊髓中,这些传入神经与背角中的次级神经元突触相连并向大脑发出信号.瘙痒感觉神经元通常被认为是痛觉神经元的一个亚群.强度编码理论认为,在低发射率下,神经元的活动会导致瘙痒的感觉.随着分子生物学和神经科学技术的进步,发现Mas相关G蛋白偶联受体(Mrgpr)蛋白的一个主要功能是瘙痒,并且多数Mrgprs(所有MrgprA、MrgprB和MrgprC亚家族成员、MrgprD)几乎是排他的表达于特定的背根和三叉神经节神经元.本综述将介绍眼部瘙痒的发生机制及信号通路、Mrgpr蛋白在眼部瘙痒方面的作用,并为眼部瘙痒的治疗提供参考.

Peripheral nerve injury could lead to chronic neuropathic pain.Understanding transcriptional changes induced by nerve injury could provide fundamental insights into the complex pathogenesis of neuropathic pain.Gene expression profiles of dorsal root ganglia(DRG)in neuropathic pain condition have been studied.However,little is known about transcriptomic changes in individual DRG neurons after peripheral nerve injury.Here we performed single-cell RNA sequencing on dissociated mouse DRG cells after spared nerve injury(SNI).In addition to DRG neuron types.that are found under physiological conditions,we identified three SNI-induced neuronal clusters(SNIICs)characterized by the expression of Atf3/Gfra3/Gal(SNIIC1),Atf3/Mrgprd(SNIIC2)and Atf3/S100b/Gal(SNIIC3).These SNIICs originated from Cldn9+/Gal+,Mrgprd+ and Trappc3l+ DRG neurons,respectively.Interestingly,SNIIC2 switched to SNIIC1 by increasing Gal and reducing Mrgprd expression 2 days after nerve injury.Inferring the gene regulatory networks after nerve injury,we revealed that activated transcription factors Atf3 and Egr1 in SNIICs could enhance Gal expression while activated Cpeb1 in SNIIC2 might suppress Mrgprd expression within 2 days after SNI.Furthermore,we mined the transcriptomic changes in the development of neuropathic pain to identify potential analgesic targets.We revealed that cardiotrophin-like cytokine factor 1,which activates astrocytes in the dorsal horn of spinal cord,was upregulated in SNIIC1 neurons and contributed to SNI-induced mechanical allodynia.Therefore,our results provide a new landscape to understand the dynamic course of neuron type changes and their underlying molecular mechanisms during the development of neuropathic pain.