Changes In The Expression Of The NMDA NR1 Protein In TBI-induced Coma Rats Following Median Nerve Electrical Stimulation

Objective: To investigate the expression of NMDA NR1 protein in the prefrontal contex of traumatic brain injury-induced rat coma models after median nerve electrical stimulation.Method: A total of 144 adult Sprague-Dawley rats were randomly and equally divided into 4 groups: a stimulated group, an OX1 R antagonist group, a sham-stimulated group and a control group.This traumatic brain injury model was established by a weight-drop head injury, and evaluated 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. NMDA NR1 protein expression was examined by Western-blot and immunohistochemistry.Result: 25 rats(25/36) exhibited righting reflex in stimulated group, In OX1 R antagonist group,17 rats(17/36) exhibited righting reflex.11 rats(11/36) of sham-stimulated group had the same responses. The results of western blot showed that significant differences in NR1 expression in the prefrontal cortex between the four groups at 6, 12, 24h(OX1R antagonist< sham-stimulated <control<stimulated)(P<0.05). A within-group comparison showed that the NR1 expression level was as follows: 6 hours<12 hours<24 hours in the control, sham-stimulated group(P<0.05),stimulated groups(P>0.05); 6 hours<24 hours<12 hours in the OX1 R antagonist group(P<0.05).Results from immunohistochemistry showed that significant differences in NR1 expression between the four groups(OX1R antagonist<sham-stimulated<control<stimulated)(P<0.05), and a within-group comparison showed that the NMDA NR1 expression level was as follows: 6hours<12 hours <24 hours(P>0.05).Conclusion: Median nerve electrical stimulation might modulate wakefulness by promoting the activities of NMDA NR1 expression via orexin-A in the prefrontal contex of rats with traumatic brain injury-induced coma.