眼镜蛇神经毒素中枢性镇痛作用脑内受体的研究

A STUDY OF BRAIN RECEPTORS ON THE CENTRAL ANALGESIC ACTION OF COBRA NEUROTOXIN

目的 :探讨纯化的眼镜蛇神经毒素 (α- Cobrotoxin,α- CBT)中枢性镇痛作用的有关受体 ,为研究α- CBT的中枢镇痛作用机理提供依据。方法 :给大鼠腹腔注射阿托品 1m g.kg- 1或纳洛酮 3m g.kg- 1后 ,再向大鼠中脑导水管周围灰质 ( PeriaqueductalGray,PAG)微量注射 2 g/ L的α- CBT生理盐水溶液 0 .5μl (相当于 5μg.kg- 1 ) ,用光辐射甩尾法观察大鼠的痛阈变化。结果 :阿托品能明显拮抗 α- CBT的中枢镇痛作用 ,其痛阈提高抑制率为 91%。纳洛酮仅能轻度降低 α- CBT的中枢镇痛作用 ,痛阈提高抑制率为 18%。结论 :α- CBT的中枢性镇痛作用与中枢乙酰胆碱能系统密切相关 。

Objective:To study the brain receptors on the central analgesic action of a purified cobra neurotoxin(αCobrotoxin)Methods:The tested rats were injected ipwith atropine or naloxone,and then the rats were injected with microquantity of αCobrotoxin into the position of periaqueductal gray of midbrainThe analgesic action was evaluated by the pain threshold index of swinging its tail after receiving the heat radiationResults:The central analgesic action of αCobrotoxin was blocked by injection of atropine(1 mg·kg 1 ip)and was slightly antagonized by injection of naloxone (3 mg·kg 1 ip)Conclusion:For central analgesic action,αCobrotoxin may not interact directly with opiat receptor,but muscarinic cholinergic receptors may be implicated in the central analgesic action ofαCobrotoxin