GABAergic antagonism of the central nucleus of the amygdala attenuates reductions in rapid eye movement sleep after inescapable footshock stress.
OBJECTIVE
Rapid eye movement sleep (REM) appears to be especially susceptible to the effects of stress; inescapable footshock stress (IS) can produce reductions in REM that can occur without recovery sleep. The amygdala has well-established roles in stress and emotion; the central nucleus of the amygdala (CNA) projects to REM regulatory regions in the brainstem and has been found to play a key role in the regulation of REM. The objective of this study was to determine whether the reduction in REM induced by IS could be regulated by CNA and brainstem regions.


METHODS
The GABAergic agonist muscimol (MUS) and GABAergic antagonist bicuculline (BIC) were microinjected into CNA before IS, and sleep was recorded for 20 h. In a second experiment using the same manipulations, sleep was recorded for 2 h, after which the rats were killed to evaluate Fos expression (a marker of neuronal activity) in the locus coeruleus (LC), a brainstem REM regulatory region.


METHODS
NA.


METHODS
The subjects were male, outbred Wistar rats.


METHODS
The rats were surgically implanted with standard electrodes or with telemetry transmitters for determining arousal state.


RESULTS
IS preceded by control or MUS microinjections selectively reduced REM and increased Fos expression in LC. By comparison, microinjection of BIC into CNA prior to IS attenuated both the reduction in REM and Fos expression in LC to levels seen in non-shocked controls.


CONCLUSIONS
The results suggest that the effects of IS on REM may involve local GABAergic inhibition in CNA and activation of LC.
Liu
Xianling
X
Sleep Research Laboratory, Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
Yang
Linghui
L
Wellman
Laurie L
LL
Tang
Xiangdong
X
Sanford
Larry D
LD
D000679:Amygdala / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D000704:Analysis of Variance; D000818:Animals; D001640:Bicuculline / Q000031:analogs & derivatives / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000008:administration & dosage / Q000378:metabolism*; D006614:Hindlimb; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology*; D012965:Sodium Chloride / Q000008:administration & dosage; D013312:Stress, Physiological / Q000502:physiology*
D015415:Biomarkers; D018755:GABA Agonists; D018756:GABA Antagonists; D016760:Proto-Oncogene Proteins c-fos; D009118:Muscimol; C017069:bicuculline methiodide; D012965:Sodium Chloride; D001640:Bicuculline