The sulphydryl reagent, N-ethylmaleimide, disrupts sleep and blocks A1 adenosine receptor-mediated inhibition of intracellular calcium signaling in the in vitro ventromedial preoptic nucleus

Citation
M. Ikeda et al., The sulphydryl reagent, N-ethylmaleimide, disrupts sleep and blocks A1 adenosine receptor-mediated inhibition of intracellular calcium signaling in the in vitro ventromedial preoptic nucleus, NEUROSCIENC, 106(4), 2001, pp. 733-743
Citations number
60
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
NEUROSCIENCE
ISSN journal
0306-4522 → ACNP
Volume
106
Issue
4
Year of publication
2001
Pages
733 - 743
Database
ISI
SICI code
0306-4522(2001)106:4<733:TSRNDS>2.0.ZU;2-L
Abstract
To explore the neuronal signaling mechanisms underlying sleep regulation in the rat, the present study examined continuous intra-third ventricle infus ion of N-ethylmaleimide (NEM), a sulphydryl reagent that inhibits G(i/o) pr otein-coupled receptor-mediated signaling pathways. The diurnal infusion of NEM (0.01-10 mu mol/10 h) dose-dependently inhibited both non-rapid eye mo vement sleep and rapid eye movement sleep. A maximal dose of NEM (10 mu mol /10 h) dramatically inhibited day-time sleep (-57% for non-rapid eye moveme nt sleep and -89% for rapid eye movement sleep) with a compensatory increas e of sleep during the subsequent night-time (+33% for non-rapid eye movemen t sleep and +259% for rapid eye movement sleep). The day-time brain tempera ture was also increased by NEM, demonstrating effects of NEM on both sleep and body temperature levels. Immunostaining of the rat hypothalamus with a monoclonal antibody against the Al adenosine receptor (AIR) was used to exp lore the distribution of a sleep-related G(i/o) protein-coupled receptor. R obust AIR-like immunoreactivity was found in the ventromedial preoptic nucl eus and the supraoptic nucleus. Fura-2-based Ca2+ imaging analysis of acute hypothalamic slices further demonstrated that the AIR agonist N-6-cyclopen tyladenosine (CPA; 200 nM) inhibited spontaneous Ca2+ oscillations and high potassium (80 mM)-induced Ca2+ flux in the ventromedial preoptic nucleus, while NEM (100-300 LM) and an AIR antagonist 8-cyclopentyl-dipropylxanthine (300 nM) blocked the CPA actions and increased the high potassium-induced Ca2+ flux. From these results we suggest that NEM-sensitive G protein-coupled receptor (s) may play an important role in the regulation of sleep and body temperat ure in the rat and one possible mechanism is an AIR-mediated regulation of intracellular Ca2+ concentrations in the ventromedial preoptic nucleus. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.