Effects of Isoflurane Anesthesia on Post-Anesthetic Sleep-Wake Architectures in Rats

The sleep homeostatic response significantly affects the state of anesthesia. In addition, sleep recovery may occur during anesthesia, either via a natural sleep-like process to occur or via a direct restorative effect. Little is known about the effects of isoflurane anesthesia on sleep homeostasis. We investigated whether 1) isoflurane anesthesia could provide a sleep-like process, and 2) the depth of anesthesia could differently affect the post-anesthesia sleep response. Nine rats were treated for 2 hours with ad libitum sleep (Control), sleep deprivation (SD), and isoflurane anesthesia with delta-wave-predominant state (ISO-1) or burst suppression pattern-predominant state (ISO-2) with at least a 1-week interval. Electroencephalogram and electromyogram were recorded and sleep-wake architecture was evaluated for 4 hours after each treatment. In the post-treatment period, the duration of transition to slow-wave-sleep decreased but slow wave sleep (SWS) increased in the SD group, but no sleep stages were significantly changed in ISO-1 and ISO-2 groups compared to Control. Different levels of anesthesia did not significantly affect the post-anesthesia sleep responses, but the deep level of anesthesia significantly delayed the latency to sleep compared to Control. The present results indicate that a natural sleep-like process likely occurs during isoflurane anesthesia and that the post-anesthesia sleep response occurs irrespective to the level of anesthesia.

Effect of Modafinil and Methylphenidate on Sleep-Wake Architecture and EEG Power Spectra in Rats / 대한정신약물학회지

OBJECTIVE : Modafinil, methylphenidate, and caffeine are wakefulness-promoting substances. Previously, it was reported that caffeine-induced wakefulness differs from natural wakefulness in terms of the EEG spectral profiles. In order to evaluate whether wakefulness induced by other psychostimulants differs from both caffeine-induced and natural wakefulness, we examined the effects of the psychostimulants on sleep-wake architecture and EEG spectral profiles. METHODS : Eighteen Sprague-Dawley male rats underwent an EEG/EMG recording session from 10 : 30 to 17 : 30. They received caffeine (7.5, 15, 30 mg/kg i.p.), methylphenidate (1, 2, 5, 10 mg/kg i.p.) or modafinil (5, 10, 25, 50, 100 mg/kg i.p.) at 13 : 30. The number, total duration, and average duration of sleepwake states were obtained. EEG band powers were calculated by spectral analysis. Frequency bands were divided into the following ranges : D1, 1-2.5 Hz ; D2, 2.5-4.5 Hz ; T1, 4.5-7 Hz ; T2, 7-10 Hz ; SI, 10-14 Hz ; B1, 14-22 Hz ; B2, 22-34 Hz ; GA, 34-50 Hz. RESULTS : All three psychostimulants significantly and dose-dependently increased active wake duration and decreased slow-wave sleep. Equipotent doses of caffeine, methylphenidate, and modafinil for increasing active wake and decreasing slow-wave sleep were 7.5 mg/kg, 10 mg/kg, and 100 mg/kg, respectively. In equipotent doses, an increase of active wake duration by caffeine and methylphenidate was attributed to increases of both frequency and average duration of active wake state, whereas increase of active wake duration by modafinil was attributed to increase of average duration of active wake state only. In equipotent doses, caffeine and methylphenidate decreased the power of lower frequency bands (1-22 Hz), whereas modafinil did not. During slow-wave sleep, modafinil and methylphenidate increased the power of lower frequency bands, but caffeine did not. All the psychostimulants increased the power of the GA band, which was more prominent in the frontal cortex than the parietal cortex. CONCLUSION : These results suggest that moda-nil-induced wakefulness differs from caffeine- or methylphenidate-induced wakefulness in terms of EEG spectral profiles and sleep-wake architecture.