眼镜蛇神经毒素的镇痛作用

眼镜蛇神经毒素(NT)在小鼠热板及大鼠电尾嘶叫测痛模型,都显示出明显的镇痛作用,并有剂量-效应关系。注射NT 0.022mg/kg,2h后,大鼠痛阈出现显著上升,3h后达到较佳效果,并能保持其效应强度达24h。连续给小鼠注射NT 0.023mg/kg,持续9d,小鼠并不产生耐受现象。结果提示,NT的镇痛机理可能与吗啡不同。

THE ANALGESIC EFFECT OF NEUROTOXIN FROM COBRA ( NAJA NAJA ) VENOM

Two models, mouse hot plate and vocalization indused by electrical stimulation of rat's tail were used to demonstrate the antinocice-ptive action of the neurotoxin ( NT ) from cobra venom. The paw-lick latencies of mice of both NT groups in different dose (0.023 mg/kg, 0.03 mg/kg, im ) were significantly prolonged than that of the control group. In the rats, the vocalization threshold of NT group was significantly higher than that of the control group too. This action of NT showed in these models was in good dose-resp-onse relationship. The onset of antinociceptive action of NT was 2 h and reached highe level 3h after intramuscular injection. This effect could be maintained for more than 24 h 3 groups of mice were continuously given normal saline, NT and morphine respectively for 9 days, and no tolerance showed in NT group of mice, but the acute tolerance to morphine occured in morphine group of mice. These result suggested that the analgesic mechanism of NT may be quite different from that fo morphine.