Time- and Behavioral State-Dependent Changes in Posterior Hypothalamic GABAA Receptors Contribute to the Regulation of Sleep
Figure 7
Hourly percentage amounts of sleep-wake states and motor activity during the recording session conducted at different times of day and different levels of sleep drive.
A: antagonism of GABAA receptors in the hypothalamic PF region moderately reduced the amount of SWS when applied both at the beginning and in the second half of the rest period (AM and PM recording sessions, respectively), and particularly strongly suppressed the amount of REM sleep during the second half of the sleep period when the amount of this stage of sleep is normally increased. Following sleep deprivation (SD), the effects of bicuculline (BIC) perfusion on sleep were diminished. For the curves marked “BIC,” perfusion with the antagonist was fully established during the two middle intervals, whereas the first and last time points represent the hourly periods during which BIC flow was started and terminated, respectively. In all recording sessions, the effects of BIC waned after termination of the perfusion with the antagonist and most variables returned to the levels recording during continuous perfusion with artificial cerebrospinal fluid (acsf) only. B: hourly counts of movements weighted by the hourly amount of wakefulness. BIC had small and inconsistent effects on motor activity, indicating that the changes in sleep-wake states were not secondary to excessive motor activation. Data from 7 rats; marks for statistical significance refer to paired comparisons between acsf and BIC perfusion session at each interval.