大鼠背根神经节γ氨基丁酸A受体在慢性神经痛中的作用

摘要

Objective To investigate the role of GABA-A receptors in the mechanism of neuropathic pain. Methods Fifty adult female SD rats were randomly divided into five groups with 10 each. After L5 spinal nerve ligation, the rats were immediately injected with muscimol 20 μg (group A), bicuculline 0.15 μg (group B), both muscimol 20 μg and bicuculline 0.15 μg (group C), muscimol 20 μg five days later (group D), and saline 20 μl (group E). The mechanic and thermal threshold of the injured paw was measured the day before ligation and every day after the ligation until ten days later. Results L5 spinal nerve ligation induced the syndrome of neuropathic pain, such as licking injured paw and limp. The mechanic and thermal threshold of group E started to decrease on 1st day and 3rd day after pain respectively (P<0. 05). Then, the thresholds were stable at the 10th day (P<0. 05). Compared with group E, the mechanic and thermal thresholds of group A were increased and maintained a high level for 10 days. In group B, the mechanic and thermal threshold decreased on the 1st day (P<0. 05). Compared with group E, the mechanic and thermal thresholds of group B on the 10th day significantly decreased (P<0. 05). In group D, the mechanic and thermal thresholds were increased since the 6th day and followed by a transient peak on the 7th day (P<0. 05). Conclusion Activation of GABA-A receptors on the dorsal root ganglion can prevent the neuropathic pain, and it is just a transient effect when used afterwards.%目的 观察调控大鼠背根神经节(DRG)γ氨基丁酸A(GABA-A)受体的功能对神经痛动物痛阈的影响,探讨DRG GABA-A受体在神经痛发病机制中的作用.方法 选用成年雌性SD大鼠50只,随机均分为五组,制作脊神经结扎模型,A组脊神经结扎术后立即于L5 DRG局部运用蝇蕈醇20 μg(50 μl);B组予荷包牡丹碱0.15 μg(50 μl);C组给予蝇蕈醇20 μg+-荷包牡丹碱0.15 μg;D组于脊神经结扎术后5 d DRG局部注射蝇蕈醇20 μg;E组注射生理盐水50μl.于术前1d至术后10 d,每天行行为学检测大鼠术侧后爪机械痛阈和热痛阈.结果 L5脊神经结扎术后动物出现跛足,舔脚等神经痛症状.E组机械痛阈于术后1d开始下降,持续至术后10 d,热痛阈于术后3d开始下降,持续至术后10 d.与E组比较,A组术后各时点机械痛阈和热痛阈明显升高(P＜0.05),B组术后1d机械痛阈和热痛阈即明显下降,并持续至术后10 d(P＜0.05),且明显低于E组(P＜0.05).D组术后6d,机械痛阈和热痛阈开始上升(P＜0.05),于术后7d达到高峰,术后8d机械痛阈和热痛阈开始下降.结论 DRG GABA-A受体在神经痛的发生中起重要作用,激动GABA-A受体可以预防神经痛的发生,但对已经发生的神经痛只起到暂时缓解的作用.