The effect of estradiol on sevoflurane-induced epileptiform cortical EEG waves in neonatal rats

Abstract

Objective To investigate the effect of estradiol on sevoflurane-induced epileptiform cortical EEG waves in neonatal rats. Methods Forty neonatal rats, aged 4-6 days, weighting 8-15 g, were divided into 5 groups according to random number table: normal saline control group (group C), estradiol group (group E), ICI182780 (group I), Formestane group (group O) and estradiol + ICI182780 (group EI). After establishing the monitoring model of cortical electroencephalogram in neonatal rats, EEG was recorded continuously for 30 minutes, then different treatment drugs were given according to different groups. After 30 minutes of continuous recording of EEG, anesthesia induction was started with inhalation of 6% sevoflurane for 3 minutes, followed by inhalation of 2.1% sevoflurane to maintain anesthesia. Sevoflurane anesthesia lasted for 1 hour.The righting reflex disappearance time was recorded after sevoflurane anesthesia.The total duration, single duration and frequency of EEG convulsion waves were recorded.Spike frequencies were recorded at different periods.Animal respiratory rate was recorded after sevoflurane induction. Results One rat in group I and one rat in group EI showed convulsion wave before treatment, which were excluded from the study.The righting reflex disappearance time of group S, group E, group I, group O and group EI were (24.4±2.5)s, (16.4±4.2)s, (31.8±5.2)s, (29.8±1.8)s, (24.8±2.7)s respectively, and there were statistically significant differences among the 5 groups (F=16.693, P 0.05). Compared with group S, the total duration, single duration and frequency of convulsion wave were significantly increased in group E during anesthesia, and the differences were statistically significant (P<0.05). Compared with group E and group S, the total duration, single duration and frequency of convulsion wave during anesthesia were significantly reduced in group I, group O and group EI, and the differences were statistically significant (P<0.05). Compared with group S, the spike frequency of group E increased significantly in each period, and the differences were statistically significant (P<0.05). The frequency of spike wave in group I, group O and group EI at 65-70 min and 90-95 min were lower than that in group S, and the differences were statistically significant (P<0.05). The frequency of spike wave between group O and group EI during 115-120 min was statistically different with group S and group E(P<0.05). Conclusion The mechanism of epileptiform EEG wave induced by sevoflurane anesthesia may be related with neuroactive steroidal estradiol. Key words: Sevoflurane; Neonatal rats; Epileptiform electroencephalography; Estradiol