急性疼痛大鼠中脑导水管周围灰质腹外侧区GABA_B受体的变化

Change of GABA_B Receptors in Ventrolateral Periaqueductal Gray of Acute Pain on Rats

目的评价大鼠足底福尔马林急性疼痛模型的疼痛行为学表现,并对该模型大鼠中脑导水管周围灰质腹外侧区(v LPAG)GABA_B受体在大鼠急性疼痛过程中随时间的变化规律进行分析,探讨GABA_B受体在疼痛调制过程中的相关作用。方法大鼠足底注射甲醛的方式复制经典的大鼠急性疼痛模型,随机将18只健康清洁级雄性SD大鼠分为3组:生理盐水组(NS组)、甲醛0.5h组、甲醛1h组。记录大鼠疼痛机械痛阈、热痛阈等指标,采用Western blotting法检测GABA_B受体含量的变化情况。结果与NS组比较,甲醛0.5h组和甲醛1h组在注射甲醛后机械痛阈降低(P<0.05),大鼠术侧热痛较健侧明显升高。甲醛0.5h组和甲醛1h组GABA_B受体含量较NS组明显升高(P<0.05)。结论 v LPAG参与大鼠急性疼痛的传导与调制,其机制可能是GABA_B受体表达增加,从而增强GABA的抑制性作用,造成痛觉过敏。

Objective To evaluate the behavioral expressions of acute pain in rat model injected with formalin in plantar,and in- vestigate the role of GABA, receptors in the ventrolateral periaqueduc.tal gray in development of paw acute pain in rats. Methods Eighteen male SD rats,aged 8 weeks,were randondy divided into three groups：normal saline group（ NS group,6 rats） ,sixty minutes formaldehyde-in- duced pain group （ 1 h group ,6 rats ） , thirty minutes formaldehyde-induced pain group （ 0.5 h group ,6 rats ）. Rats were subcutaneously injected with normal saline or formaldehyde into the ventral surface of fight hind paw. Results Compared with NS group,0.5h group and I h group of formaldehyde in mechanical pain threshold decreased after injection of formalin（ P 〈 0.05） ,rats with side heat pain than the healthy side was significantly increased. The levels of GABA, receptor in the 0.5h group and formaldehyde lh group were significantly higher than that of NS group （ P 〈 0.05 ）. Conclusion The rat acute pain model induced by the plantar injection of formalin has credible sustained hyperalgesia, and has an increased expression lever of GABA, receptor of ventrolateral periaqueductal gray.