CaMK?-NMDAR Pathway Study On Remifentanil-induced Postoperative Hyperalgesia In Mice

Objective: To investigate the effect of ketamine on CaMKII phosphorylation in primary somatosensory cortical neurons involved in the inhibition of remifentanil induced hyperalgesia in mice.To explore the CaMKII-NMDAR pathway on remifentanil induced postoperative hyperalgesia in mice.Method-s:In the first part,45 Male adult ICR mice weighed 30 g to 35 g were devided into five groups randomly :group C(saline only)?group I(incision only)?group R(Incision +Remifentanil)?group RK(incision+Remifentanil+Ketamine)?group K(incision +Ketamine).Behavior test was carried out at 1h before and 0.5h,2h,5h,24 h after treatment.120 male adult health ICR mice were allocated into group I?group R?group RK?group K.Mice were killed immediately and taken out the somatose-nsory cerebral cortex(S1).Then western blot was executed 0h,0.5h,2h,5h and 24 h after administration of drugs to evaluate the expression of p-CaMK? and t-CaMK?.Three mice were fixd with 4% paraformaldehyde,then the brains were taken out per group I?group R?group RK?group K.Subsequently,immunohistochemistry and immunofluorescence were carried out to observe the location of the expression of the p-CaMK?.In the second part,110 male adult health IC R mice were devided into ten groups: group I(incision only+ intrathecal injection of DMSO)?group R(incision+Remifentanil+ intrathecal inject-tion of KN92)?group RK(incision+Remifentanil+Ketamine+ intrathecal injection of DMSO)?group R+KN93(incision+Remifentanil+ intrathecal injection of KN93)?group bayk8644(saline+incision+ intrathecal injection of bayk8644)?group NMDA(saline+incision+ intrathecal injection of NMDA)?group RK+bayk8644(Remifentanil +Ketamine+incision+ intrathecal injection of bayk8644)?group RK +NMDA(Remifentanil +Ketamine+incision+ intrathecal injection of NMDA)?group RK+KN93(Remifentanil +Ketamine+incision+ intrathecal injection of KN93)?group R+NMDA(Remifentanil + incision+ intrathecal injection of NMDA).Behavior test were did in eight mice per each group 1h beore and 0.5h,2h,5h,24 h after treatment.Western blot and coimmunoprecipitation were carried out 2h after treatment.Results:In the first part,the mechanical withdrawal threshod of group R is lower than Group C 0.5h,2h,5h after treatment and the thermal latency is shorter than group C in the same moment.Compared with group R,the mechanical withdrawal threshod of group R is higher and the thermal latency is longer.The expression of p-CaMK?is upgrade in primary somatosensory cortical neurons of group R 0.5h,2h,5h after treatment compared to group I.The expression of p-CaMK?is downgrade in primary somatosensory cortical neurons of group RK 0.5h,2h,5h after treatment compared to group R.In second part,the mechanical withdrawal threshod of group RK+bayk8644 and group RK+NMDA is significantly lower in contrast to group RK 0.5h,2h,5h after treatment.The thermal latency of group RK+bayk8644 and group RK +NMDA is significantly shorter in contrast to group RK 0.5h,2h,5h after treatment.Compared with group I,the mechanical withdrawal threshod of group bayk8644 and group NMDA is lower,and the thermal latency is shorter 0.5h,2h,5h after treatment.Compared with group R,intrathecal injection of KN93 before intraoprerativeadministration of remifentanil during incision operation significantly increased the mechanical withdrawal threshod and the thermal latency 0.5h,2h,5h after treatment.Compared with group R,intrathecal injection of NMDA before intraoprerative administration of remifentanil during incision operation significantly decreased the mechanical withdrawal threshod and the thermal latency 0.5h,2h,5h after treatment.Cr-oss-talk between NMDA and p-Ca MK? happened in coImmunoprecipitation 2h after treatment.Conclusions: CaMKII phosphorylation is involved in the in-hibition of remifentanil-induced hyperalgesia by ketamine in mice.CaMKII-N-MDAR pathway plays an important role on remifentanil-induced postoperative hyperalgesia in mice.