2008 Volume 42 Issue 2 Pages 131-135
How the orexins, which are neuropeptides that play an important role in maintaining wakefulness, modulate the hypnotic effect of general anesthetics is not well understood. We administered orexin A to rats under sevoflurane anesthesia to investigate its effect on the electroencephalogram (EEG), cerebral blood flow (CBF), and mean arterial pressure (MAP). After confirmation of the presence of burst suppression patterns by EEG, rats anesthetized with 3% sevoflurane received intraventricular administration of orexin A at 1nmol/5μL. We observed changes in EEG, CBF, and MAP before and after the admini-stration. Burst suppression patterns on the EEG disappeared in some rats and the frequency of bursts was increased in others. CBF was increased after administration of orexin A. It is believed that orexin nerves activate the brainstem, which regulates sleep and wakefulness. The induction of waking EEG patterns by intraventricular administration of orexin A indicates that it modulates the anesthetic effect of sevoflurane.
