Study In The Effect Of Emodin On Trigeminal Neuralgia Mediated By P2X_2/3 Receptor

Objective: To investigate the effects of emodin on trigeminal neuralgiamediated by P2X_2/3receptor.Methods: The trigeminal neuralgia rat model (a chronic constriction injury ofthe infraorbital branch of the trigeminal nerve, CCI-ION) was established. Adult maleSprague-Dawley rats were randomly assigned to five groups for varied purpose:blank control group (Control), sham operation group (Sham), trigeminal neuralgiamodel group (TN), TN rats treated with emodin (TN+E) and TN rats treated withA-317491(TN+A). The mechanical hyperalgesia threshold of trigeminal neuralgia(TN) rats was tested by the von Frey filaments. The change of the expression ofP2X_2/3receptors in rats' trigeminal ganglions (TGs) was detected with in situ hybridi-zation, RT-PCR, immunohistochemical staining, immunofluorescence, Western Blot.Results:14days after operation, compared with Control group, Sham group,TN+E group or TN+A group, TN group had a significant decrease of mechanicalhyperalgesia threshold in the territory of ligated infraorbital nerve (P <0.01), and anobvious increase in expression of P2X_2/3receptor in rats' TGs (P <0.01). After thetreatment with emodin, the mechanical hyperalgesia in TN+E group was higher thanTN rats.(P<0.01), and there was an obvious decrease in expression of P2X_2/3receptors in rats' TGs of TN+E group compared with TN group (P <0.01).Conclusion: P2X_2/3receptor may play a key role in the pain transmission oftrigeminal neuralgia, and emodin could have inhibitory effects on trigeminalneuralgia mediated by P2X_2/3receptor.