Expression And Role Of MiR-186-5p In The Trigeminal Ganglion Of Rats With Trigeminal Neuralgia

Objective Trigeminal neuralgia is a common chronic pain that seriously affects the quality of life of patients.Although trigeminal neuralgia has a variety of treatments,there are still no effective cures.The chemokine CXCL13 and mi R-186-5p play important roles in neuropathic pain induced by spinal nerve ligation(SNL)in mice.The expression of CXCL13 is increased in the spinal cord after SNL and the expression of mi R-186-5p is decreased.Mi R-186-5p overexpression can reduce the expression of CXCL13 in the spinal cord of mice treated with SNL and alleviate the neuropathic pain induced by SNL.However,whether mi R-186-5p is expressed in the trigeminal ganglion and whether it affects the expression of CXCL13 remain unclear.In this study,a rat model of trigeminal neuralgia was established by chronic constriction injury of the infraorbital nerve(ION-CCI)to investigate the expression and mechanism of mi R-186-5p and CXCL13 in the trigeminal ganglion of the rat with trigeminal neuralgia,hoping to provide a new method for the treatment of trigeminal neuralgia.Methods Adult male SD rats were randomly divided into the ION-CCI group and the sham operation group(Sham).Rats in the ION-CCI group underwent chronic constriction injury of the left infraorbital nerve in general anesthesia.The operation of the Sham group was basically the same as that of the ION-CCI group,but the treatment of chronic constriction injury was not performed after the left infraorbital nerve was exposed.The behavioral test was used to detect the mechanical withdrawal threshold of the left vibrissa pad in the two groups before and 3 weeks after surgery.The mechanical withdrawal threshold of the two groups was recorded and compared to evaluate whether the constructed rat model of trigeminal neuralgia was successful.The expression of miR-186-5p and CXCL13 m RNA in the trigeminal ganglion of the two groups was detected by Q-RT PCR.The expression of CXCL13 protein in the trigeminal ganglion of the two groups was detected by Western blot.11 days after the chronic constriction injury,the rats were injected with saline solution containing mi R-186-5p mimic or simply injeced with saline solution in the left infraorbital foramen.Normal(Naive)rats were injected with saline solution containing mi R-186-5p inhibitor or simply injected with saline solution in the left infraorbital foramen.All the rats were administered once a day for 3 consecutive days.The behavioral test was used to detect the change of mechanical withdrawal threshold in the left vibrissa pads of rats before and after administration.The expression of CXCL13 protein in the left trigeminal ganglion of rats were detected by Western blot.Results Compared to the Sham group,the mechanical withdrawal threshold of the left vibrissa pad of the ION-CCI group was significantly decreased after chronic constriction injury of the infraorbital nerve,the expression level of mi R-186-5p in the trigeminal ganglion was significantly decreased,the expression levels of CXCL13 m RNA and protein were significantly increased.Compared to the ION-CCI group of rats simply injected with saline solution,the mechanical withdrawal threshold of the ION-CCI group of rats injected with saline solution containing mi R-186-5p mimic was increased and the expression level of CXCL13 protein in the trigeminal ganglion was decreased.Compared to Naive rats simply injected with saline solution,the mechanical withdrawal threshold of Naive rats injected with saline solution containing mi R-186-5p inhibitor was decreased and the expression level of CXCL13 protein in the trigeminal ganglion was increased.Conclusions The expression of mi R-186-5p is down-regulated in the trigeminal ganglion of a rat after chronic constriction injury,and mi R-186-5p is involved in the development and progression of trigeminal neuralgia by negatively regulating the expression of CXCL13.This pathway may provide a new method for the treatment of trigeminal neuralgia.