| Objective:Trigeminal Neuralgia(TN)is a kind of oral-facial pain disease,which is characterized by unilateral and recurrent localized pain,limited to the maxillofacial sensory distribution of the trigeminal nerve.Trigeminal neuralgia most often involves the second and third branches of the trigeminal nerve.Typically,the onset of pain is triggered by some harmless tactile sensation in the trigeminal nerve region.The brain-derived neurotrophic factor(BDNF)in the trigeminal ganglia(TGs)is secreted in a painful state,and its high-affinity receptor TrkB can affect the transmission of pain.Our experimental group has previously found that palmatine can alleviate trigeminal neuralgia by inhibiting CGRP in the trigeminal ganglion.Therefore,this study intends to investigate the effect of palmatine on the expression of BDNF/TrkB in TGs of trigeminal neuralgia model rats and the possible molecular mechanism,so as to provide new ideas for the prevention and treatment of TN.Methods:The rat TN model was established using a chronic compression injury method of the infraorbital nerve(ION-CCI)of rats.Healthy adult male Sprague-Dawley rats were randomly divided into sham group,trigeminal neuralgia model group(TN group),sham+palmatine group,trigeminal neuralgia model group + palmatine(TN + palmatine group)four groups.The mechanical withdrawalthreshold of each group was detected by electromechanical pain tester on the 1st,3rd,5th,7th,9th,11 th and 13 th postoperative day.Two weeks later,the right side of the trigeminal ganglion was taken.Real-time quantitative PCR,immunohistochemistry,immunofluorescence and Western blotting were used to observe BDNF,its receptor TrkB,IL-1?,TNF-? mRNA and protein expression in the trigeminal ganglion.At the same time,the effects of palmatine treatment(10mg/ml)on the pain threshold of rats with trigeminal neuralgia were observed.The effects of palmatine on the expression of BDNF,TrkB,IL-1? and TNF-? in TGs were also observed.Western blotting was used to observe the phosphorylation of ERK1/2 pathway in TGs of each group.Results:Within 14 days after surgery,the mechanical pain sensitivity threshold of the right side of the face in the TN group was significantly lower than that in the sham group(p < 0.05).The TN+palmatine group had a higher mechanical pain sensitivity threshold on the right side of the face than the TN group(p < 0.05).Real-time fluorescence quantitative PCR,immunohistochemistry and immunofluorescence results showed that the expression of BDNF and TrkB in the TN group was higher than that in the sham group,while the expression of TN+palmatine group was lower than that in the TN group.Western blotting results showed that palmatine solution(10mg/ml)may achieve pain inhibition effect by reducing the phosphorylation form of ERK1/2.Conclusion:The BDNF/TrkB pathway may be involved in the pain transmission process of trigeminal neuralgia.Palmatine treatment can counteract the pain allodynia of TN rats,and reduce the expression of BDNF?TrkB?IL-1? and TNF-? in TGs of TN rats.The mechanism may be related to inhibit ERK1/2 phosphorylation,so as to alleviate or treat trigeminal neuralgia. |
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