未损伤背根神经节GABAA受体在大鼠神经病理性痛中的作用

目的 评价未损伤背根神经节(L4 背根神经节)γ氨基丁酸A受体(GABAA受体)在大鼠神经病理性痛中的作用.方法 成年雌性SD大鼠30只,体重200～250 g,随机分为3组(n=10):对照组(C组)、蝇蕈醇组(M组)和荷包牡丹碱组(B组).采用结扎L5脊神经的方法制备大鼠神经病理性痛模型.C组于L4 背根神经节局部注射生理盐水50μl;M组于L4背根神经节局部注射GABAA受体激动剂蝇蕈醇50μl;B组于L4背根神经节局部注射GABAA受体拮抗剂荷包牡丹碱50μl;各组注射时间均大于1 min.于术前1 d至术后10 d,每天测定大鼠的热痛阈和机械痛阈.结果 与C组比较,M组热痛阈差异无统计学意义(P＞0.05),机械痛阈升高,B组热痛阈和机械痛阈均降低(P＜0.05).结论 未损伤背根神经节GABAA受体激活参与了神经病理性痛大鼠机械痛敏的发生发展,对热痛敏的发生发展可能不起主导作用.

Role of GABAA receptors in uninjured dorsal root ganglion in a rat model of neuropathic pain

Objective To evaluate the role of GABAA receptors in uninjured dorsal root ganglion(L4DRG)in a rat model of neuropathic pain.Methods Thirty adult female SD rats weighing 200-250 g were randomly divided into 3 groups(n = 10 each): control group(group C),muscimol group(group M)and bicuculline group(group B).Neuropathic pain was produced by L5 spinal nerve ligation.Normal saline 50 μl,GABAA receptor agonist-muscimol 50 μl or GABAA receptor antagonist- bicucullin 50 μl was injected into the L4 DRG.The thermal pain threshold and mechanical pain threshold were measured and recorded from 1 day before operation to 10 days after operation.Results Compared with group C,the mechanical pain threshold was significantly increased(P ＜ 0.05),while no significant difference was found in thermal pain threshold in group M(P ＞ 0.05),and the thermal pain threshold and mechanical pain threshold were significantly decreased in group B(P ＜ 0.05).Conclusion Activation of GABAA receptors in uninjured DRG is involved in mechanical hyperalgesia in a rat model of neuropathic pain,but it dose not play a leading role.