Effect of dexmedetomidine on sevoflurane anesthesia-induced cortical epileptiform electroencephalogram activity in neonatal rats

Abstract

Objective To evaluate the effect of dexmedetomidine on sevoflurane anesthesia-induced cortical epileptiform electroencephalogram (EEG) activity in the neonatal rats. Methods Forty clean-grade healthy Sprague-Dawley rats, aged 4-6 days, weighing 8-15 g, were divided into 5 groups (n=8 each) using a random number table method: control group (C group), sevoflurane group (S group), dexmedetomidine plus sevoflurane group (D+ S group), dexmedetomidine plus alpha 2-adrenoceptor antagonist atipamezole plus sevoflurane group (D+ A+ S group), and atipamezole plus sevoflurane group (A+ S group). After the electrode was correctly placed, the EEG was continuously monitored, and normal saline 5 μl/g was intraperitoneally injected at 58 min of monitoring in group C, dexmedetomidine 25 μg/kg was intraperitoneally injected in group D+ S, dexmedetomidine 25 μg/kg and atipamezole 250 μg/kg were intraperitoneally injected in group D+ A+ S, and atipamezole 250 μg/kg was intraperitoneally injected in group A+ S.Anesthesia was induced by inhaling 6% sevoflurane for 3 min starting from 60 min of monitoring and then maintained by inhaling 2.1% sevoflurane for 1 h. The total duration, the number and average duration of epileptic waves were recorded during anesthesia.Blood samples were obtained from the left ventricle after the end of anesthesia for blood gas analysis.Rats were then sacrificed and blood samples were collected for measurement of the serum corticosterone concentration. Results No epileptic wave was found in group C. The serum concentration of corticosterone was significantly higher in the other four groups than in group C (P 0.05). Compared with group D+ S, the total duration of epileptic wave was significantly prolonged, the number of epileptic wave was increased, and the serum concentration of corticosterone was increased in D+ A+ S and A+ S groups (P<0.05). Conclusion Dexmedetomidine can inhibit the occurrence of cortical epileptiform EEG activity induced by sevoflurane anesthesia in the newborn rats, and the mechanism may be related to improving the hypothalamus-pituitary-adrenocortical axis hyperfunction mainly through activating the central 2-adrenoceptor. Key words: Dexmedetomidine; Anesthetics, inhalation; Infant, newborn; Electroencephalograpy