Objective:To investigate the expression of 5-HT 2A receptor in the prefrontal cortex of traumatic brain injuryinduced coma rats after median nerve electrical stimulation.Method:A total of 72 SD rats (weighing 250-300g) were randomly divided into 4 groups:a stimulationgroup,an antagonist group,a sham-stimulation group and a control group.This traumatic brain injury model was established by a weight-drop head injury,and we evaluated the change of behavior through the six classical levels of consciousness.The animals were sacrificed and their brain tissues were removed at 6,12,and 24 hours after injury.5-HT 2A protein expression was examined by immunohistochemistry.Result:Thirteen rats exhibited righting reflex in the stimulation group.In the antagonist group,9 rats exhibited righting reflex.5 rats in the sham-stimulation group had the same response.The mean rank of consciousness degree were degree 9.50 in the control group,degree 52.75 in the sham-stimulation group,degree 37.61 in the stimulation group,degree 46.14 in the antagonist group.Comparison among groups presented an increasing consciousness degree:control group＜stimulation group＜antagonist group＜sham-stimulation group(P＜0.01).Resuits from immunohistochemistry showed that significant differences in the 5-HT 2A expression among the four groups (sham-stimulation＜control＜antagonist＜stimulation))(P＜0.05),and a within-group comparison showed that the 5-HT 2A expression level was as follows:6 hours＜24 hours ＜12 hours(P＜0.05).Conclusion:Median nerve electrical stimulation might modulate wakefulness by promoting the 5-HT 2A expression via orexin-A in the prefrontal cortex of rats with traumatic brain injury-induced coma.