GABA_B受体mRNA在慢性神经痛大鼠脊髓中的表达

Expression of mRNA for isoforms of GABA_B receptor in the spinal cord in a rat model of chronic neuropathic pain

目的 通过半定量法检测大鼠腰段脊髓GABAB受体各亚型 mRNA的量,探讨 GABAB受体在慢性神经痛中的作用。方法 结扎大鼠左侧L5脊神经根建立慢性神经痛模型。SD大鼠24只随机分成4组,每组6例。A组;假手术后观察7d;B组:结扎后观察7d;C组:假手术后观察14d;D组:结扎后观察14d。于术前、术后1、3、7、10、14d测双后肢光热刺激性痛阈。分别于术后7、14d取出大鼠腰段脊髓,行冰冻切片,运用地高辛法原位杂交技术对脊髓中GABAB受体各亚型mRNA半定量检测。结果 左L5脊神经根结扎术后7、10、14d大鼠的左后肢痛阈明显低于假手术大鼠(P<0.01)。B组大鼠脊髓GABAB受体各亚型 mRNA量明显少于 A组(P<0.01),而D组的明显少于C组(P<0.01)。结论SD大鼠脊髓中GABAB受体各亚型基因表达有可塑性,在慢性神经痛时表达减少,提示GABAB受体各亚型可能参与慢性神经痛的调节。

Objective To investigate the effect of GABAB receptor in spinal cord by detecting semi-quantitatively the mRNA for isoforms of GABAB receptor in a chronic neuropathic pain model. Methods Twenty-four male SD rats weighing 200-250g were anesthetized with intraperitoneal pentobarbital. Lamina of L5 vertebra and superior articular process of L6 were removed and posterior root of left L5 spinal nerve was exposed and tightly ligated with 7/0 atraumatic suture. The animals were randomly divided into 4 groups of 6 animals in each group: group A in which animals were observed for 7 days after sham operation; group B in which animals were observed for 7 days after ligation of posterior root of L5 spinal nerve; in group C animals were observed for 14 days after sham operation and in group D animals were observed for 14 days after ligation. Pain threshold was measured by heat stimulation of bilateral hindlimbs before and on the 1st , 3rd , 7th , 10th and 14th day after operation. Lumbar spinal cord was removed on the 7th or 14th day after operation and mRNA for isoforms of GABAB receptor in the spinal cord was detected semi-quantitatively by digoxin hybridization in situ.Results Pain threshold of left hindlimb (ligated side) was significantly lower than that of right hindlimb on the 7th, 10th and 14th day after operation as measured by heat stimulation. There were less mRNA for three isoforms of GABAB receptor in group B and D as compared with group A and C respectively. Conclusion The gene expression of three isoforms of GABAB receptor in the spinal cord has plasticity and is reduced during chronic neuropathic pain.