口服依托咪酯对大鼠伤害性刺激的抑制作用

Inhibitory effects of orally taken etomidate on nociceptive stimulation in rats

目的 :研究口服依托咪酯是否具有镇痛作用 .方法 :口服给药 ,观察依托咪酯对福尔马林和蜜蜂毒诱发的持续自发缩足反射的影响以及对蜜蜂毒诱发的热和机械性痛敏的影响 .结果 :口服不同剂量依托咪酯 (5 ,2 0 ,30 ,4 0和 5 0mg/kg) ,在剂量为 5mg/kg时 ,依托咪酯只对福尔马林诱发的自发缩足反射的第二相有抑制作用 ,增加剂量后 ,依托咪酯对福尔马林诱发的自发缩足反射的第一和第二相都有明显的抑制作用 ,最大抑制率为 (5 1 .4 8± 9.1 8) % ;不同剂量的依托咪酯对蜜蜂毒诱发的自发缩足反射行为产生剂量依赖性抑制作用 ,其最大抑制率为 (5 1 .5 9± 3.92 ) % ,但口服 5mg/kg和 2 0mg/kg的依托咪酯 ,对于蜜蜂毒注射后热刺激潜伏期缩短和机械刺激阈值降低并没有影响 .结论 :口服依托咪酯可明显抑制福尔马林和蜜蜂毒诱发的自发缩足反射行为 ,表现出镇痛效果 。

AIM: To investigate whether orally taken etomidate has any inhibitory effects on the tissue injury induced pain in rats. METHODS: Subcutaneous formalin or bee venom injection was administrated into the plantar surface of one hindpaw. Spontaneous nociceptive response was immediately scored by counting the number of flinches of the injected hindpaw at every 5 minute interval during a 60 minute period. Thermal hyperalgesia was measured by recording the paw withdrawal reflex latency to heat stimulus by a radiant heat stimulator. The paw withdrawal thermal latency (PWTL) was determined as the duration from start of the thermal stimulation to the occurrence of the hindpaw withdrawal reflex and was averaged from four heat stimuli. Mechanical hyperalgesia was measured with von Frey type nylon filaments. The occurrence of 50% frequency of paw withdrawal was expressed as the paw withdrawal mechanical threshold (PWMT) averaged from 10 times stimuli. RESULTS: Orally taken etomidate 5 mg/kg only inhibited the phase 2 of persistent spontaneous pain induced by subcutaneous formalin injection. With higher doses, etomidate inhibited both the phases 1 and 2 of persistent spontaneous pain induced by subcutaneous formalin injection. Orally taken etomidate also dose dependently inhibited persistent spontaneous pain induced by subcutaneous bee venom injection. However, the reduction in PWTL and PWMT induced by bee venom was not influenced by etomidate. CONCLUSION: Orally taken etomidate is effective in the inhibition of the persistent spontaneous pain induced by both formalin and bee venom injection, while it is ineffective in the suppression of the heat and mechanical hyperalgesia induced by subcutaneous bee venom injection.