目的:观察持续机械压迫(CCD)对瞬时感受器电位离子通道4(TRPV4)基因、蛋白表达及功能的影响,明确TRPV4是否参与CCD导致的机械和热痛敏。方法:建立CCD模型后,分别于手术前及手术后第7天、第14天及第28天取材前测量运动功能、机械刺激缩爪反应阈值和热辐射刺激缩爪反应潜伏期。为了测量TRPV4反义核苷酸干扰对机械和热痛阈值的影响,在蛛网膜下腔内注入TRPV4寡脱氧核苷酸(ODN)40μg/d,每天1次,第7天后测量大鼠行为学变化。使用实时定量RT-PCR检测TRPV4基因表达的变化,Western blot检测TRPV4蛋白质表达量的变化,激光共聚焦检测低渗溶液和佛波醇(4α-PDD)刺激背根神经节(DRG)神经元后细胞内钙离子浓度的变化。结果:所有动物在损伤前后步态均正常,持续压迫明显降低大鼠的机械和热痛阈,TRPV4干扰可部分逆转该痛敏。持续机械压迫可以明显增加TRPV4基因和蛋白的表达,手术后第7天,第14天和第28天,TRPV4mRNA的表达分别为假手术组大鼠的4.29倍、2.95倍和2.48倍,蛋白表达量分别为假手术组大鼠的4.34倍,3.88倍和2.47倍。持续机械压迫后,对低渗溶液和4α-PDD产生反应的DRG神经元的比例数增加,细胞内钙的峰值增高。这种反应被TRPV4反义ODN所抑制。结论:CCD可以上调TRPV4的基因、蛋白表达,敏化通道的功能;TRPV4参与介导CCD导致的机械和热痛敏。
Objective:To investigate the role of transient receptor potential vanilloid 4(TRPV4) in mediating mechanical and thermal allodynia in rodent models of chronic compression of dorsal root ganglion (CCD).Method:The levels of TRPV4 mRNA and protein expressions in dorsal root ganglion (DRG) were assessed using real-time RT-PCR and Western blot analysis respectively at the 7th,14th and 28th d post-CCD.The effects of spinal administration of TRPV4 antisense oligodeoxynucleotide(ODN) and mismatch ODN on CCD-induced mechanical and thermal allodynia were evaluated.The calcium responses to hypotonic solution and 4α-phorbol 12,13-didecanoate (4α-PDD) were assessed following sham surgery,CCD,spinal application of TRPV4 antisense ODN and mismatch ODN.Result:The levels of TRPV4 mRNA and protein expression increased significantly at the 7th-28th d post-CCD with the highest level at the 7th d post-CCD when compared with the sham group.TRPV4 antisense ODN,but not mismatch ODN,partly reversed the CCD-induced mechanical and thermal allodynia.Additionally,TRPV4 antisense ODN had no effect on the baseline nociceptive response.The percentage of DRG neurons responsive to hypotonic solution and 4α-PDD and the fluorescence ratio of calcium response also enhanced significantly in both CCD group and mismatch ODN group.These increased responses were significantly inhibited by TRPV4 antisense ODN.Conclusion:TRPV4 plays a crucial role in CCD-induced mechanical and thermal allodynia.