Effects of dexmedetomidine on lippolysaccharide-induced brain injury in rats

Abstract

Objective To investigate the effects of dexmedetomidine on lipopolysaccharide (LPS)-induced brain injury in rats.Methods Thirty-six pathogen-free Sprague-Dawley rats,aged 6 weeks,weighing 200-250 g,were randomly divided into 3 groups (n =12 each):control group (group C),LPS group (group L) and dexmedetomidine group (group D).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 350 mg/kg,tracheostomized and mechanically ventilated.Dexmedetomidine 100 μg/kg was injected intraperitoneally and LPS 7.5 mg/kg was injected via the femoral vein 15 min later in group D.Normal saline 2 ml was injected intraperitoneally and LPS 7.5 mg/kg was injected via the femoral vein 15 min later in group L.Normal saline 2 ml was injected intraperitoneally and then injected via the femoral vein 15 min later in group C.Blood samples were obtained from the femoral artery at 2 and 4 h after LPS administration for determination of serum TNF-α concentration by ELISA.Six rats were chosen at 12 h after LPS administration,Evan's blue (EB) was injected via the femoral vein,and then the rats were sacrificed and brains removed for determination of EB content.Another six rats were sacrificed and their brains were immediately removed for determination of brain water content and for microscopic examination.Results The brain water content,EB content and serum TNF-α concentration were significantly increased in groups L and D as compared with group C (P ＜ 0.05).The brain water content,EB content and serum TNF-α concentration were significantly lower in group D than in group L (P ＜ 0.05).The microscopic examination showed that brain injury was attenuated in group D compared with group L.Conclusion Dexmedetomidine can reduce LPS-induced brain injury and reduction of the inflammatory response in the brain tissues and improvement in the permeability of the blood-brain barrier may be involved in the mechanism. Key words: Dexmedetomidine; Endotoxemia; Brain Injuries