慢性炎症性疼痛小鼠丘脑中单核细胞趋化因子1表达变化

The expression of Monocyte Chemoattractant Protein-1 in the thalamus of mice with chronic inflammatory pain

目的:观察完全弗氏佐剂诱导小鼠慢性炎症性疼痛模型中,单核细胞趋化因子1(MCP-1)mRNA在丘脑中线核群和板内核群中的表达变化以及细胞定位情况。方法:(1)足底皮下注射完全弗氏佐剂,诱导小鼠产生慢性炎症性疼痛,用行为学方法检测小鼠的机械性刺激缩爪阈值和热刺激缩爪潜伏期的变化;(2)用Real-time PCR法检测丘脑中线核群和板内核群中MCP-1 mRNA的表达变化;(3)用免疫荧光双标染色来定位表达MCP-1的细胞类型。结果:(1)完全弗氏佐剂注射1 h后引起小鼠同侧后爪机械性缩爪阈值和热缩爪潜伏期显著降低(P<0.001),并维持7d以上;(2)Real-time PCR结果显示,完全弗氏佐剂注射后1 d,丘脑中线核群和板内核群中MCP-1 mRNA表达量达高峰(P<0.05),然后逐渐降低至基础水平;(3)免疫荧光双标染色显示,MCP-1荧光染色主要与神经元核标记物(Ne-uN)共标,而不与星形胶质细胞标记物(GFAP)共标。结论:足底皮下注射完全弗氏佐剂能诱导小鼠产生痛觉过敏,丘脑中线核群和板内核群中MCP-1 mRNA表达增加,且MCP-1表达于神经元,提示MCP-1可能在炎症早期参与炎症性疼痛的调节。

Objective： To observe the mRNA expression of monocyte chemoattractant protein-1 and its cellular distribution in the midline and intralaminar thalamic nuclei following complete Freund＇s adjuvant （CFA）-induced chronic inflammatory pain. Methods： （1）CFA was intraplantar injected to induce chronic inflammatory pain. Mechanical allodynia and heat hyperalgesia were examined by behavioral test. （2）The expression of MCP-1 mRNA in the midline and intralaminar thalamic nuclei was detected by real-time PCR. （3）The cellular distribution of MCP-1-IR was checked by immunofluorescence double-staining. Results： （1）The ipsilateral hind paw withdrawal threshold and withdrawal latency decreased significantly at 1 h after CFA injection （P〈0.001）, and maintained this low level for more than 7 days. （2）Realtime PCR showed the expression of MCP-1 mRNA in the midline and intralaminar thalamic nuclei reached its peak at 1 day after CFA injection （P〈0.05）, and then gradually decreased to the basic level. （3）Immunofluorescence double -staining showed the MCP-I-IR cells were colocalized with the neuronal marker, NeuN, but not with astrocytic marker, GFAP. Conclusion： Mechanical allodynia and heat hyperalgesia were observed after CFA intraplantar injection. The expression of MCP-1 mRNA was increased and the MCP-1 protein was expressed in neurons in the midline and intralaminar thalamic nuclei. The MCP-1 may be involved in the modulation of inflammatory pain at the early phase.