Effects of dexmedetomidine on expression of c-fos in hippocampus and dentate gyrus in a rat model of endotoxic shock

Objective To evaluate the effects of dexmedetomidine on the expression of c-fos in hippocampus and dentate gyrus in a rat model of endotoxic shock. Methods Thirty-five pathogen-free healthy male Sprague-Dawley rats, aged 3-4 months, weighing 250-300 g, were divided into 5 groups (n=7 each) using a random number table: normal saline group (group NS), dexmedetomidine group (group D), endotoxic shock group (group ES), low-dose dexmedetomidine plus lipopolysaccharide (LPS) group (group LD) and high-dose dexmedetomidine plus LPS group (group HD). Dexmedetomidine 0.5 μg/kg was injected via the tail vein in D and LD groups, and dexmedetomidine 4.5 μg/kg was given in group HD.Normal saline 0.5 ml/kg was injected in NS and ES groups, 5 min later normal saline 0.5 ml/kg was injected in NS and D groups and LPS 5 mg/kg was injected in the other groups, and the injection time was 10 min in all groups.Rats were sacrificed at 6 h after LPS injection, brains were removed, and the hippocampus and dentate gyrus were isolated for detection of the expression of c-fos by immunohistochemistry. Results Compared with group NS or group D, the expression of c-fos in the hippocampus and dentate gyrus was significantly up-regulated in group ES (P<0.05). Compared with group LPS, the expression of c-fos in the hippocampus and dentate gyrus was significantly down-regulated in LD and HD groups (P<0.05). Compared with group LD, the expression of c-fos in hippocampal CA1 and CA3 areas was significantly down-regulated in group HD (P<0.05). Conclusion The neuroprotective mechanism of dexmedetomidine is related to inhibiting the up-regulated expression of c-fos in the hippocampus and dentate gyrus in a rat model of endotoxic shock. Key words: Dexmedetomidine; Endotoxemia; Hippocampus; Dentate gyrus; Proto-oncogene proteins c-fos