[Abstract Title]. - Society for Neuroscience

285. Sleep: Molecular, Cellular and Pharmacology I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 285.23/QQ39
Topic: E.08.c. Sleep: Molecular, cellular, and pharmacology
Support: CONACyT Grant 50633
Title: Participation of muscarinic receptors in the regulation of sleep at hypothalamic preoptic
area and brain stem pedunculopontine tegmentum
Authors: *A. JIMENEZ-ANGUIANO, J. RAMÍREZ-ACOSTA, A. BARRETO-
MALFAVON, J. VELAZQUEZ-MOCTEZUMA;
Dept Biol de la Reproduccion, Univ. Autónoma Metropolitana, Mexico, Mexico
Abstract: It has been reported that muscarinic-M2 agonists administered into the pontine
reticular formation (PRF) modulates preferentially REM sleep in relation with selective M1
agonist. However, the cholinergic inputs to this site during the physiological onset of REM sleep
are given by the brain stem pedunculopontine tegmentum (PPT). On the other hand,
hypothalamic preoptic area (POA) also regulates sleep, contains cholinergic neurons and
receives inputs from the PPT. However, unknown if the stimulation or blockade of muscarinic
M2 receptors (M2R) in the PPT and in the POA has the same effect in the architecture of sleep
and the possible relation between PPT and POA in the regulation of sleep. The purpose of the
present study was to analyze the possible participation of M2R subtype of POA and PPT in the
regulation of sleep. Five cats (2.5-3.5 kg) were chronically implanted with the standard set of
electrodes for sleep recording. In addition, stainless steel guide cannulas were implanted oriented
towards the PPT and in the POA. After two weeks of recovery period, the animals were recorded
for 8 hrs after the following injections: A: 0.1 µl of saline into the PPT. B: Methoctramine
(MET), a M2 muscarinic antagonist (1.8 µM/0.1µl). C: Cis-Dioxolane (CISD) a M2 muscarinic
agonist (1 µM/0.1µl). D: CISD into the PPT in combination with MET into the POA. In addition,
the same injections were performed into the POA, but additionally tested one group with
Trihexiphenydil (TRIH) (10 ng/0.1µl), a M1 muscarinic antagonist. Results showed that CISD
into the PPT increases REM sleep and decreases SWS II. MET in PPT decreases REM sleep and
SWS II with an increase of wakefulness. When CIS-DIOXO was administered into the PPT in
combination with MET into the POA the increases of REM sleep was not observed, but the total
time was similar to the controls. In POA not effect was observed with the infusion of CISD and
MET, however, TRIH decreases REM sleep. The present results suggest a differential effect
between muscarinic M1 and M2 receptors subtype into the POA and PPT on REM sleep
regulation.
Disclosures: A. Jimenez-Anguiano , CONACyT # 50633, B. Research Grant (principal
investigator, collaborator or consultant and pending grants as well as grants already received); J.
Ramírez-Acosta, None; A. Barreto-Malfavon, None; J. Velazquez-Moctezuma, None.