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Rat Oligodendrocytes Express Muscarinic Receptors Coupled to Phosphoinositide Hydrolysis and Adenylyl Cyclase
Author(s) -
Cohen R. I.,
Almazan G.
Publication year - 1994
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1994.tb00620.x
Subject(s) - carbachol , muscarinic acetylcholine receptor , muscarinic acetylcholine receptor m3 , muscarinic acetylcholine receptor m1 , chemistry , inositol phosphate , pirenzepine , endocrinology , medicine , muscarinic acetylcholine receptor m2 , muscarinic antagonist , second messenger system , inositol , biology , receptor , biochemistry
Muscarinic receptors expressed by rat oligodendrocyte primary cultures were examined by measuring changes in second messengers following exposure to carbachol, an acetylcholine analog, and by polymerase chain reaction. Inositol phosphate levels were measured in [ 3 H]myo‐inositol‐labelled young oligodendrocyte cultures following stimulation with carbachol. Atropine, a specific muscarinic antagonist, prevented the carbachol‐induced accumulation of inositol phosphates. The formation of inositol trisphosphate was concentration‐ and time‐dependent, with the peak at 100 μM carbachol and 10 min. Carbachol increased intracellular calcium levels, which were dependent both on the mobilization of intracellular stores and influx of extracellular calcium. In initial experiments with more selective antagonists, the mobilization of intracellular calcium was preferentially inhibited by pirenzepine, a selective M1 antagonist, but not methoctramine, a selective M2 antagonist, suggesting M1 muscarinic receptor involvement. A role for protein kinase C in the regulation of carbachol‐stimulated inositol phosphate formation and intracellular calcium mobilization was demonstrated, as acute pretreatment with phorbol‐12, 13‐myristate acetate abolished the formation of both second messengers. Pretreatment with 100 μM carbachol abolished the 40% increase in the cyclic AMP accumulation stimulated by isoproterenol, a specific β‐adrenergic agonist. In turn, the inhibition was alleviated by pretreatment with atropine, suggesting muscarinic receptor involvement. Polymerase chain reaction carried out with specific ml and m2 muscarinic receptor oligonucleotide primers, confirmed that these cells express, at least, the two muscarinic receptor subtypes. Without excluding the expression of other subtypes, these results suggest that developing oligodendrocytes express ml (M1) and m2 (M2) muscarinic receptors capable of mediating phosphoinositide hydrolysis, mobilization of intracellular calcium and the attenuation of β‐adrenergic stimulation of cyclic AMP formation.