[Abstract Title]. - Society for Neuroscience

Authors: C.-L. LIANG 1 , *G. A. MARKS 2,1 ;
1 Veterans Affairs Med. Ctr., Dallas, TX; 2 Dept Psych, Univ. Texas Southwestern Med. Ctr.,
Dallas, TX
Abstract: Microinjection of GABAA receptor antagonists into the rat nucleus pontis oralis (PnO)
induces a long lasting increase in REM sleep similar to that produced by cholinergic agonists.
We have shown that this REM sleep induction can be completely blocked by a muscarinic
antagonist, indicating that the REM sleep-inducing effect of GABAA receptor blockade is
dependent upon the cholinergic system. Coupled with the finding that GABAA receptor
antagonists microdialyzed into PnO of cat results in increased levels of acetylcholine, it appears
that GABA may act to inhibit acetylcholine release from presynaptic terminals. We hypothesize
that GABAA receptors located on cholinergic terminals in the PnO, through disinhibition of
acetylcholine release, are responsible for the REM sleep induction. Here we report our initial
investigation to determine if GABAA receptors are present on cholinergic terminals in PnO and
what receptor subtypes they may be.
Rats were sacrificed by intracardial perfusion under deep pentobarbital anesthesia and their
brains prepared for double or triple immunofluorescence, laser scanning, confocal microscopy.
Cholinergic terminals were identified in PnO by labeling the vesicular acetylcholine transporter
(VAChT). GABAA receptor subunits were identified by antibodies directed against one of
several GABAA receptor subunits. In some tissue, a third antibody was directed against glutamic
acid decarboxylase-67 to label presynaptic GABAergic terminals.
We found that GABAA receptor subunits can be localized to cholinergic terminals in PnO and,
thus far, identify one as gamma2. GABAA receptors containing gamma2 subunits have
benzodiazepine binding sites and tend to cluster at synaptic locations. Identification of additional
subunits is in progress and will inform as to the properties of the GABAA receptors in PnO
mediating effects on REM sleep.
Disclosures: C. Liang, None; G.A. Marks , None.
Poster
285. Sleep: Molecular, Cellular and Pharmacology I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 285.21/QQ37
Topic: E.08.c. Sleep: Molecular, cellular, and pharmacology
Support: IRSC Grant MOP 74472
NSERC Grant # 155211