神经病理性疼痛大鼠中脑导水管周围灰质腹外侧区GABAA_(α3)表达的性别差异

Gender difference of GABAA_(α3) expression in the ventrolateral periaqueductal gray of rats with neuropathic pain

目的探讨不同性别神经病理性疼痛大鼠中脑导水管周围灰质腹外侧区(vLPAG)γ-氨基丁酸A型α3亚基(GABAA_(α3))受体表达的差异。方法大鼠24只,雌(F组)雄(M组)各12只;坐骨神经分支选择性损伤(SNI)复制大鼠神经病理性疼痛模型;记录大鼠在各时间点(术前1 d及术后1、3、7和14 d)的机械痛阈和冷痛阈。Western blot检测vLPAG处GABAA_(α3)受体的蛋白表达。结果与术前相比,F组与M组大鼠均出现明显的机械痛敏和冷痛敏反应,F组较M组机械痛阈更低(P<0.05),F组冷缩足次数多于M组(P<0.05);术后14 d vLPAG处GABAA_(α3)受体蛋白表达增加,F组明显高于M组(P<0.05)。结论神经病理性疼痛雌性大鼠较雄性大鼠更敏感,vLPAG处GABAA_(α3)受体表达的上调可能与大鼠痛阈降低有关。

Objective To investigate the gender difference of GABAA α3 receptor expression in the ventrolateral periaqueductal gray (vLPAG) of rats with neuropathic pain. Methods Twenty-four SD rats were divided into 2 groups: 12 females in group F and 12 males in group M. Neuropathic pain model was established by spared nerve injury (SNI) of sciatic nerve branches. The mechanical pain threshold and cold pain threshold were recorded at each time point (1 day before operation and 1, 3, 7, 14 days after operation). Western blotting was used to detect the expression level of GABAA α3 receptor at vLPAG. Results The mechanical and cold allodynia were significantly higher in both group F and group M after operation. The mechanical pain threshold of group F was lower than that of group M ( P <0.05), and the frequency of cold foot contraction in group F was higher than that in group M ( P <0.05). 14 days after the model establishment, the expression level of GABAA α3 receptor protein increased significantly at vLPAG, and it was higher in group F than that in group M ( P <0.05). Conclusions Female rats are more sensitive to neuropathic pain than male rats and the up-regulation of GABAA α3 receptor expression at vLPAG is related to the decrease of pain threshold in rats.