The Relation Between Trigeminal Neuralgia Behaviors Following Chronic Constriction Injury And Histological Changes Of Trigeminal Nerve In The Rat

Objective Trigeminal neuralgia animal models of chronic constrictive injury was made to observe the pain-related behaviors and histological changes before and after chronic constriction injury of the rat trigeminal nerve,to explore the pathogenesis of trigeminal neuralgia and to provide a new experimental basis for the clinical treatment of trigeminal neuralgia.Methods72adult male SD rats were randomly divided into3groups.24rats were in the normal control group,24rats were in the model group, and24rats were in the sham group. All of the rats were raised under the same condition.The normal control group did not do any treatment.The right infraorbital nerves were ligated to cause the chronic constriction injury to the infraorbital nerve (CCI-ION) model, and the sham group were only exposed the infraorbital nerves, but not ligated it.The rats of each group were decapitated and taken out the trigeminal ganglia at the end of the2th,4th,6th,8th,10th and12th weeks.The pain-related behaviors and histological changes were observed at the different times before and after chronic constriction injury of the rat trigeminal nerve.All statistical analysis was performed using spss13.0software.Results An allodynia to mechanical stimulation was found from the1th to the8th week after operation. There was significant difference (P<0.01) in pain threshold, compared with the control group and sham group.Compared with the control group, the pain threshold of the sham group did not have significant changes which altered around15g(P>0.05).The thresholds started to increase gradually from the4th week and reached the original level on12th week after operation.2. TG nerve stain unevenly nerve fibers demyelination and structure disappeared from the2th to the6th week after operation. The injured nerve fiber density is gradually uniform from the8th to the10th week after operation. After12weeks, the size of the nerve fibers are consistent, uniform distribution,and similar to the normal structure of nerve.Conclusion According to behavior and the histological changes of the TG neurons of the rat CCI-ION model, we found that:1. CCI-ION method has many advantages, such as clearer vision field for operation, more completely nerve exposed, less bleeding and operated infection, which improve the success rate of modeling. After CCI-ION, the rats appear mechanical hyperalgesia responses, and pain characteristics are similar to this of clinical of TN. Thus this method can be used as a reliable method of TN model.2. CCI-ION rats pain reaction threshold and trigeminal ganglion demyelination are close relationship,The characteristics of CCI-ION rats with postoperative pain performance is similar to the clinical manifestations of the TN, its behavior of the reaction is consistent with local tissue changes at different times which is consonant with the change of TN organizational on the clinical observation.