GABAergic regulation of REM sleep in reticularis pontis oralis and caudalis in rats.
The nucleus reticularis pontis oralis (RPO) and nucleus reticularis pontis caudalis (RPC) are implicated in the generation of rapid eye movement sleep (REM). Work in cats has indicated that GABA in RPO plays a role in the regulation of REM. We assessed REM after local microinjections into RPO and RPC of the gamma-aminobutyric acid-A (GABA(A)) agonist, muscimol (MUS), and the GABA(A) antagonist, bicuculline (BIC). Rats (90-day-old male Sprague-Dawley) were implanted with electrodes for recording electroencephalographs (EEG) and electromyographs (EMG). Guide cannulae were aimed into RPO (n = 9) and RPC (n = 8) for microinjecting MUS (200, 1,000.0 microM) and BIC (0.056, 0.333, 1.0, 1,000.0, and 10,000.0 microM). Animals received bilateral microinjections of saline, MUS, and BIC (0.2 microl microinjected at 0.1 microl/min) into each region followed by 6-h sleep recordings. In RPO, MUS (1,000.0 microM) suppressed REM and BIC (1,000.0 microM) enhanced REM. In RPC, MUS (200, 1,000.0 microM) suppressed REM, but BIC (1,000.0 microM and less) did not significantly affect REM. Higher concentrations of BIC (10,000.0 microM) injected into RPO (n = 9) and RPC (n = 4) produced wakefulness and escape behavior. The results indicate that GABA in RPO/RPC is involved in the regulation of REM and suggest site-specific differences in this regulation.
Sanford
Larry D
LD
Sleep Research Laboratory, Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk 23501, USA. Sanforld@evms.edu
Tang
Xiangdong
X
Xiao
Jihua
J
Ross
Richard J
RJ
Morrison
Adrian R
AR
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004569:Electroencephalography; D004576:Electromyography; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D012154:Reticular Formation / Q000187:drug effects / Q000502:physiology*; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000187:drug effects / Q000502:physiology*
D018755:GABA Agonists; D018756:GABA Antagonists; D011963:Receptors, GABA-A; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline