The effects of electrical stimulation on the expression of H1 receptor in the prefrontal cortex of brain injured, comatose rats

Abstract

Objective To investigate the expression of H1 protein in the prefrontal cortex of comatose rats which have suffered traumatic brain injury (TBI) after electrical stimulation of the median nerve (MNS). Methods Seventy-two Sprague-Dawley rats (weighing 250 to 300 g) were randomly divided into a stimulated group (MNS+ TBI), an antagonist group (MNS+ TBI+ OXR1 antagonist), a model group (TBI) and a control group, with 18 rats in each group. Traumatic brain injury was modeled in all of the rats except those of the control group. After the modeling, the stimulated group was given MNS, the antagonist group was provided with MNS and an OXR1 injection, and the model group was given MNS with a current intensity of 0. One hour after the experiment, the consciousness of each rat was evaluated using a double-blind method. Animals were sacrificed at 6, 12 and 24 hours after the intervention and brain tissue was removed. H1 protein expression was examined using immunohistochemistry. Results One hour after the experiment, significant differences were observed in the consciousness of the 4 groups, with the 18 rats of the control group on consciousness level one. Thirteen rats in the stimulated group exhibited a righting reflex, compared with 9 in the antagonist group and 5 in the model group. Immunohistochemistry showed that H1 expression was strongest in the stimulated group, followed by the antagonist, control and model groups. The H1 expression was highest at 24 hours after the experiment, followed by that at 6 h and 12 h, but those differences were not statistically significant. Conclusion Median nerve electrical stimulation might modulate wakefulness after traumatic brain injury by promoting H1 expression via orexin-A in the prefrontal contex. Key words: H1 receptor; Orexin-A; Median nerve; Electrical stimulation; Trauma; Brain injury; Coma