Mechanism of Analgesic and Anti-Inflammatory Effects of Asarum Volatile Oil
Objective:To assess the analgesic and anti-inflammatory effects of Asarum volatile oil and explore its mechanism of action.Methods:The analgesic and anti-inflammatory effects of asarum volatile oil were evaluated by acetic acid writhing test,formalin stimulation test,hot plate test and xylene induced ear swelling test,and the analgesic mechanism was investigated by receptor blocking test and nitric oxide(NO)detection test.Results:In the acetic acid writhing test,the volatile oil of asarum(24,12 g/kg)significantly inhibited the number of writhing times in mice(P<0.01),with inhibition rates of 57.8%and 34.8%,respectively.In the formalin induced pain test,the volatile oil of asarum(24,12 g/kg)significantly shortened the foot licking time of phase Ⅰ and phase Ⅱ(P<0.05,P<0.01),and the pain inhibition rates of phase Ⅱ were 52.93%and 37.33%,respectively.In the hot plate induced pain test,the volatile oil of asarum(24,12 g/kg)significantly prolonged the pain latency period in mice(P<0.05,P<0.01),and the analgesic effect reached its peak within 2 hours.In the mouse ear swelling test,the volatile oil of asarum(24,12 g/kg)significantly inhibited xylene induced ear swelling in mice(P<0.01),with inhibition rates of 82.09%and 63.79%,respectively.The receptor blockade test showed that the analgesic effect of high dose of asarum volatile oil(24 g/kg)could be blocked by γ-aminobutyric acid(GABA)receptor blocker pastronine(3 mg/kg).The NO detection test showed that high-dose asarum volatile oil(24 g/kg)could inhibit the serum NO level in acetic acid induced pain mice.Conclusion:Asarum volatile oil has obvious analgesic and anti-inflammatory effects,and its analgesic mechanism may be related to the activation of GABA receptor and the inhibition of NO level.