Chronic Constriction Injury To The Infraorbital Nerve Induces The Dynamic Changes Of P2 Receptor Expression

Objective To investigate the dynamic changes of the P2X2 receptor, P2X3 receptor and P2Y1 receptor in the rat trigeminal ganglion (TG) neurons with trigeminal neuralgia, which was done by the chronic constriction injury model to the infraorbital nerve (CCI-ION) in order to seek for the possible variant role of P2X2 receptor, P2X3 receptor and P2Y1 receptor and to provide a new theoretical basis for the clinical treatment of trigeminal neuralgia.Methods 52 adult male SD rats were randomly divided into 9 groups. 4 rat were in normal control group which did not do any pre-treatment. The operated group of CCI-ION and sham operated group were divided into 8 groups according to time points after operation, and each group was 6 rats. All of rats were raised at the same time and were operated according to the experimental plan. The right infraorbital nerves were ligated to prepare the CCI-ION model (operated group) on four rats and the sham-operated with no nerve ligation (sham operated group) were done on two rats in each group. The rats of each group were decapitated and taken out the trigeminal ganglia in 3 days. The behavioristics was to observate animal pain behavior, the HE staining was to evaluate modeling method, and immunohistochemistry was to measure the expression of the P2X2 receptor, P2X3 receptor and P2Y1 receptor in different periods. All statistical analysis was performed using Prism 3.0 software.Results Using the immunohistochemical staining method, the results showed that:â‘ In the control group, the TG neurons had weak immunoreactive positive staining of the three types of receptors. P2X3 receptor only expressed in small diameter neurons; P2X2 receptor and P2Y1 receptor expressed in large, middle and small diameter neurons, and mainly expressed in large diameter neurons.â‘¡The expressions of P2X2 receptor, P2X3 receptor and P2Y1 receptor at all timeframes in the the surgery side of CCI-ION were higher than that of in the control group, in which P2X2 receptor and P2Y1 receptor were significantly increased in the middle and small diameter neurons and P2X3 receptor was remain in the middle and small diameter neurons.â‘¢The changes of P2X2 receptor, P2X3 receptor and P2Y1 receptor expression had some differences at all timeframe between the surgery side of CCI-ION and sham surgery group, in which P2X3 receptor increased fast and sustained in a high level and P2X2 receptor and P2Y1 receptor increased slow and gradually declined. Overall, the expressions of the three kinds of receptors in the surgery side of CCI-ION were higher than that of in the sham surgery group.â‘£The changes of P2X2 receptor, P2X3 receptor and P2Y1 receptor expression had a few differences at all timeframe between the surgery side and contralateral side of CCI-ION.Conclusion According to the dynamic changes of P2X2 receptor, P2X3 receptor and P2Y1 receptor in the TG neurons of the CCI-ION model, the three kinds of receptors are increased in variously. The results suggest that the three kinds of receptors may be involved in the pain elicitation and conduction of trigeminal neuralgia, in which P2X2 receptor may involve in acute pain or inflammatory pain, P2Y1 receptor may involve in the pain maintenance, and P2X3 receptor may involve in the acute pain and pain maintenance.