Objective: To evaluate the analgesic effect of Corydalis yanhusuo on trigeminal neuropathic pain.in a rat model.
Method: Rat model of trigeminal neuralgia pain were established by inducing chronic constriction injury (CCI) of the infraorbital branch of the trigeminal nerve (ION). The effect of Corydalis yanhusuo, a traditional Chinese medicine, in ameliorating the pain was tested. Western blotting was performed to investigate the change of cannabinoid CB1 receptors in the Vc the injury of the infraorbital branch of the trigeminal nerve (ION-CCI). CB1 receptor antagonist AM 251 was applied to observe its effect on the analgesic effect of Yanhusuo.
Result: Administration of dl-THP (2 mg/kg) intraperitoneally increased the response threshold and the cut-off threshold to the mechanical stimulation in ION-CCI rat models. ION-CCI induced an upregulation of cannabinoid CB1 receptors within the ipsilateral of Vc. The effect of Yanhusuo was antagonized by the application of AM 251.
Conclusion: The analgesic effect of Yanhusuo involves the participation of CB1 receptors, suggesting that Yanhusuo may offer a useful therapeutic approach for trigeminal neuropathic pain.