Expression Of Orexin-A And OX1R In The Prefrontal Cortex Of Traumatic Brain Injury-induced Comatose Rats After Vagus Nerve Stimulation

Objective: To investigate the wake-promoting effects of vagus nerve stimulation(VNS)in comatose rats caused by Traumatic brain injury(TBI)and its mechanisms.Method: SD rats were randomly assigned to four different groups: control,sham-stimulated(TBI),stimulated(TBI+VNS),and an antagonist(TBI+SB334867+VNS)group.The effects of VNS in a rat model of TBI-induced coma were observed.Additionally,ELISA,western blot,and immunohistochemistry techniques were used to detect the levels of Orexin-A and orexin 1 receptor(OX1R)expression in prefrontal cortex(PFC)tissue.Result: Results have shown that 8 of 30 rats were awakened in the TBI group,20 of30 awakened in the stimulated group and 12 of 30 rats were awakened in the antagonist group.ELISA results indicated that the concentration of orexin-A in the different groups showed the following trend: antagonist group < control group <model group < stimulated group at 6,12,and 24 hours(P < 0.05).However,The relative levels of OX1 R expression are different in each time point,at 6 hours: control group < antagonist group < model group < stimulated group(P < 0.05);at 12 hours:control group < model group < antagonist group < stimulated group(P < 0.05);at 24hours: antagonist group < control group < model group < stimulated group(P < 0.05).Conclusion: Our findings suggest that VNS can promote consciousness recovery in rats which are comatose due to a traumatic brain injury.Additionally,upregulation of OX1 R and orexin-A expression in the prefrontal cortex may be one mechanism involved in the consciousness-promoting effects of VNS.