| Objective:Trigeminal neuralgia(TN)is one of the most intense forms of maxillofacial pain,which is also named as tic douloureux.It has been reported that the calcitonin-gene-related peptide(CGRP)in trigeminal ganglia(TGs)might play a crucial role in TN pain transmission.To search for the new methods of prevention and treatment for TN,the present study will investigate the effects of palmatine on the expression of CGRP in TGs and its mechanism in a rat model of TN.Methods:We selected healthy male Sprague-Dawley rats and randomly divided them into four groups : sham control group(Sham),sham treated with palmatine group(Sham+Palmatine),TN model group(TN)and TN treated with palmatine group(TN+Palmatine).Then we chose the method of chronic constriction injury of the infraorbital nerve(ION-CCI)to establish the rat TN model.After operation,rats in Sham+Palmatine group and TN+Palmatine group were intraperitoneally injected with 10mg/ml palmatine solution(dose: 2mg/100g)once a day for two weeks;meanwhile,the electronic von Frey filaments were used to test the mechanical response threshold of rats for 15 days.On day 15 after operation,qPCR and immunohistochemical staining were used to detect the expressions of CGRP and its receptors in the trigeminal ganglia of rats on the operative side.Meanwhile,the concentration of IL-1? and TNF-? of serum were measured by ELISA.In addition,the expressions of PKC and p-PKC were detected through the method of Western blotting.Results: In 15 days after operation,the mechanical response threshold of TN group rats decreased obviously as compared with sham group(P<0.05).When compared with TN group,the mechanical response threshold of TN treated with Palmatine group rats showed a significantly increase from day 7 to day 15 after operation(P<0.05).On day 15 after surgery,results of qPCR,immunohistochemicalstaining and Western blot analysis showed a distinct increase in expression level of CGRP,its receptors and p-PKC in TGs of TN group compared with sham group respectively.But palmatine treatment could significantly down-regulate those changes(P < 0.05).In addition,the concentration of IL-1? and TNF-? in serum showed a obvious increase in TN group compared to Sham group(P<0.01);However,with the palmatine treatment,IL-1? and TNF-? levels in serum have decreased significantly(P<0.01).Conclusion: CGRP and its receptor in TGs may be closely related to the pain transmission of TN.Palmatine probably has the potential to cure TN by down-regulating the expressions of CGRP and its receptors in the TGs,and its mechanism may be involved in inhibiting phosphorylation of PKC signal pathway and suppressing the IL-1? and TNF-? levels in serum. |
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