UNIGE document Scientific Article
previous document  unige:10431  next document
add to browser collection
Title

Nicotinic enhancement of the noradrenergic inhibition of sleep-promoting neurons in the ventrolateral preoptic area

Authors
Bisetti, Arnaud
Machard, Daniele
Jones, B. E.
Published in Journal of Neuroscience. 2004, vol. 24, no. 1, p. 63-67
Abstract According to multiple lines of evidence, neurons in the ventrolateral preoptic area (VLPO) that contain GABA promote sleep by inhibiting neurons of the arousal systems. Reciprocally, transmitters used by these systems, including acetylcholine (ACh) and noradrenaline (NA), exert an inhibitory action on the VLPO neurons. Because nicotine, an agonist of ACh, acts as a potent stimulant, we queried whether it might participate in the cholinergic inhibition of these sleep-promoting cells. Indeed, we found that ACh inhibits the VLPO neurons through a nicotinic, as well as a muscarinic, action. As evident in the presence of atropine, the non-muscarinic component was mimicked by epibatidine, a nonselective nicotinic ACh receptor (nAChR) agonist and was blocked by dihydro-beta-erythroidine, a nonselective nAChR antagonist. It was not, however, blocked by methyllycaconitine, a selective antagonist of the alpha7 subtype, indicating that the action was mediated by non-alpha7 nAChRs. The nicotinic inhibition was attributed to a presynaptic facilitation of NA release because it persisted in the presence of tetrodotoxin and was blocked by yohimbine and RS 79948, which are both selective antagonists of alpha2 adrenergic receptors. Sleep-promoting VLPO neurons are thus dually inhibited by ACh through a muscarinic postsynaptic action and a nicotinic presynaptic action on noradrenergic terminals. Such dual complementary actions allow ACh and nicotine to enhance wakefulness by inhibiting sleep-promoting systems while facilitating other wake-promoting systems.
Keywords Acetylcholine/ pharmacologyAnimalsCells, CulturedDrug SynergismElectric ConductivityMuscarinic Agonists/pharmacologyMuscarinic Antagonists/pharmacologyNeural InhibitionNeurons/drug effects/ physiologyNicotinic Agonists/ pharmacologyNorepinephrine/ metabolismPatch-Clamp TechniquesPotassium Channels/metabolismPreoptic Area/anatomy & histology/cytology/ physiologyPresynaptic Terminals/metabolismRatsReceptors, Muscarinic/metabolismReceptors, Nicotinic/metabolismSleep/physiology
Stable URL http://archive-ouverte.unige.ch/unige:10431
Full text
Article - document accessible for UNIGE members only Limited access to UNIGE
Other version: http://www.jneurosci.org/cgi/reprint/24/1/63.pdf
Identifiers
PMID: 14715938
Structures
104 hits and 0 download since 2010-08-06
Update
Export document
Format :
Citation style :