骨癌痛大鼠初级感觉神经元兴奋性的研究  

STUDIES ON THE EXCITABILITY OF THE PRIMARY AFFERENT SENSORY NEURONS IN A RAT BONE CANCER PAIN MODEL

作　　者：郑琴[1] 方东[1] 刘敏[1] 姜红[1] 蔡捷[1] 万有[1] 邢国刚[1] 

机构地区：[1]北京大学神经科学研究所基础医学院神经生物学系教育部和卫生部神经科学重点实验室,北京100191

出　　处：《中国疼痛医学杂志》2011年第3期166-170,共5页Chinese Journal of Pain Medicine

基　　金：国家自然科学基金(30370470;81072951;61027001);北京自然科学基金(7112079);教育部留学回国人员科研启动基金(2008890);科技部国家重点基础研究发展计划"973"资助项目(2007CB512501)资助课题

摘　　要：目的:研究骨癌痛大鼠背根神经节(DRG)初级感觉神经元兴奋性的改变,探讨外周敏化在骨癌痛发生中的作用。方法:在雌性SD大鼠,采用胫骨骨髓腔内注射MRMT-1大鼠乳腺癌细胞(4×104,4μl)的方法建立骨癌痛大鼠模型,术后14天用von Frey纤维丝测定大鼠同侧后爪的50%缩足阈值(paw withdrawal threshold,PTW)以检测造模是否成功。对照组分别注射等体积的热杀死癌细胞(HK组)或磷酸盐缓冲液(PBS组)。造模后14天,在急性分离的小直径DRG神经元,采用全细胞膜片钳技术,记录骨癌痛及其对照组大鼠DRG神经元的静息膜电位(resting membrane po-tential,RMP)、诱发动作电位的去极化电流阈值(current threshold,CT)以及恒定去极化电流(300pA,1 s)诱发动作电位爆发的个数,观察骨癌痛大鼠初级感觉神经元兴奋性的变化。结果:建立模型后14天,与对照组相比,(1)骨癌大鼠同侧后爪的50%PWT分别由HK组、PBS组和空白对照组(Na ve组)的13.75±0.64 g、13.30±0.64 g和15.10±0.01 g降低到4.43±0.42 g,经统计学分析,差异有极显著性(P<0.001,n=7～10),表明MRMT-1癌细胞接种大鼠具有明显的机械性痛敏行为;(2)在骨癌痛大鼠的小直径DRG神经元中,低(LT)、中(MT)兴奋阈值神经元的静息膜电位(RMP)绝对值和诱发动作电位的去极化电流阈值(CT)均明显降低(P<0.05,P<0.001),相同去极化强度刺激下动作电位爆发的频率均显著增加(P<0.05,P<0.001),而以上记录指标在高兴奋阈值(HT)的神经元则变化不明显(P>0.05)。结论:骨癌痛大鼠伤害性初级感觉神经元的兴奋性显著升高,这种小直径DRG神经元超兴奋性(hyperexcitability)的变化可能是引起骨癌痛大鼠外周敏化(peripheral sensitization)的基础。Objective：To investigate the excitabilities of primary sensory neurons in dorsal root ganglia（DRG） in a rat bone cancer pain model,and to explore the role of peripheral sensitization in the development of bone cancer pain.Methods：A rat bone cancer pain model was established by intra-tibial injections of syngeneic MRMT-1 rat mammary gland carcinoma cells（4×104,4 μl） in female Sprague-Dawley rats.The 50% paw withdrawal thresholds（PWT） of rats were tested with von Frey filaments on day 14 after cancer cells inoculation to assess the mechanical allodynia,which indicated the success of bone cancer pain model.An equal volume of heat-killed carcinoma cells（HK） or vehicle（phosphorylated buffer solution,PBS） was injected into the tibial bone cavity as controls.14 days after surgery,whole-cell patch-clamp recordings were performed in acute isolated small-sized DRG neurons to examine the resting membrane potential（RMP）,the depolarized current threshold（CT） for evoked-action potential（AP）,and the numbers of APs evoked by a depolarized current（300 pA,1s） injection.Results：（1） The 50% PWTwas decreased to 4.43±0.42 g of MRMT-1 rats from13.75±0.64 g,13.30±0.64 g,and 15.10±0.01g of HK-,PBS-,and na ve rats,respectively（P0.001,n =7～10）.The results suggested that the mechanical allodynia was occurred in bone cancer pain rats.（2） In contrast to control rats,the absolute values of resting membrane potential and the depolarized current threshold（CT） for evoked-action potential decreased significantly（p 0.05,p 0.001）,and the numbers of APs evoked by a depolarized current（300 pA,1 s） injection increased significantly（P0.05,P0.001） in neurons showing low-or mediate-firing threshold,butnothigh-firing threshold in bone cancer pain rats.Conclusions：Excitabilities of primary sensory neurons increase significantly in bone cancer pain rats,and this kind of hyperexcitability of small-sized DRG neurons may underlie the occurrence of peripheral sensitization that is re

关 键 词：骨癌痛 初级感觉神经元 兴奋性 膜片钳 大鼠 

分 类 号：R738[医药卫生—肿瘤]