臂丛神经下干不同损伤诱发神经病理性疼痛大鼠后足的痛行为学特征

目的 比较颈胸椎前路和后路臂丛神经下干切断伤与根性撕脱伤诱发神经病理性疼痛大鼠术侧后足的痛行为学特征.方法 18只成年雌性SD大鼠随机接受右侧前路下干切断、前路及后路下干根性撕脱手术(每组6只),另外6只健康大鼠作为对照组.臂丛损伤术前及术后3、7、14和28 d,检测大鼠术侧后足的机械痛缩足阈值、冷刺激诱发痛评分及热刺激缩足潜伏期.结果 对照组与3个损伤组之间术前三项痛行为学指标的差异无统计学意义.与术前相比,前路切断伤组冷刺激诱发痛评分明显增高(P<0.01),机械痛缩足阈值及热刺激缩足潜伏期则无明显变化;前路及后路撕脱伤组术后各时间点机械痛缩足阈值均显著降低(P<0.01),冷刺激诱发痛评分均明显增高(P<0.01),而热刺激缩足潜伏期则无显著变化.与切断伤组相比,两撕脱伤组术后各时间点热刺激缩足潜伏期则无显著差异,而后足机械痛缩足阈值均显著降低(P<0.05),冷刺激诱发痛评分亦显著增高(P<0.01),这种痛行为学的变化可持续至28 d(最长观察期);两撕脱伤组间各痛行为学指标的差异无统计学意义.结论 大鼠前、后入路臂丛下干根性撕脱伤均可作为理想的神经病理性疼痛模型,而臂丛下干切断伤因致痛效果较差则不宜用作神经病理性痛模型.

Behavioral comparisons of neuropathic pain Induced by transection and avulsion injuries of the rat brachial plexus

Objective To compare the neuropathic pain behaviors of the rat ipsilateral foot after transection or root avulsion of the right lower trunk of brachial plexus via anterior Or posterior approaches.Methods Eighteen adult female Sprague-Dawley rats were randomly divided into three groups with 6 each,in which the animals received transection of the right lower trunk via anterior approach,root avulsion via anterior approach,and root avulsion via posterior approach,respectively.Another 6 animals without any plexus injury were used as the normal control.Mechanical withdrawal threshold(MWT),cold allodynia scores(CAS) and thermal withdrawal latency(TWL) of the ipsilateral hindpaws Were evaluated before and 3,7,14 and 28 days after the surgery. Results No significant difference in the pain parameters was detected among the control and experimental animals in the 3 plexus injury groups preoperatively.In comparison of the parameters before the surgery,CAS increased markedly(P<0.01) but MWT and TWL remained unchanged in the anterior transection group;MWT significantly declined(P<0.01)and CAS elevated(P<0.01)at all postoperative time points but no changes in TWL were observed in both anterior and posterior avulsion groups.Comparing with the transection group,MWT significantly decreased(P<0.05)and CAS increased markedly(P<0.01)while TWL remained unchanged after surgery in both avulsion groups.These behavioral changes remained for 28 days,the longest observation period.No difference could be found between the two avulsion groups. Conclusion Lower trunk avulsion of the brachial plexus via both anterior and posterior approaches can be used as an ideal model to induce neuropathic pain,while lower trunk transection can hardly be a pain model as it induces no classic neuropathic pain.