MUSCARINIC RECEPTORS MEDIATE CARBACHOL-INDUCED PHASE-SHIFTS OF CIRCADIAN ACTIVITY RHYTHMS IN SYRIAN-HAMSTERS

Authors
Citation
Kg. Bina et B. Rusak, MUSCARINIC RECEPTORS MEDIATE CARBACHOL-INDUCED PHASE-SHIFTS OF CIRCADIAN ACTIVITY RHYTHMS IN SYRIAN-HAMSTERS, Brain research, 743(1-2), 1996, pp. 202-211
Citations number
62
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
Brain research → ACNP
ISSN journal
0006-8993
Volume
743
Issue
1-2
Year of publication
1996
Pages
202 - 211
Database
ISI
SICI code
0006-8993(1996)743:1-2<202:MRMCPO>2.0.ZU;2-C
Abstract
Carbachol, a non-specific cholinergic agonist, when administered intra ventricularly or directly into the suprachiasmatic nucleus (SCN), caus es phase-dependent shifts in circadian rhythms of wheel-running activi ty in rodents. The cholinergic receptor subtype involved in mediating these carbachol-induced phase shifts, however, remains uncertain. In o rder to investigate this issue we injected carbachol into the SCN thro ugh indwelling cannulas at circadian times (CT) 6, 14 and 22 in Syrian hamsters (Mesocricetus auratus) maintained in constant darkness. Carb achol elicited large phase advances at CT 6 (69.8 +/- 15.7 min; mean /- S.E.M.) and CT 22 (83.9 +/- 24.8 min) and phase delays at CT 14 (59 .7 +/- 18 min). We attempted to block the carbachol-induced phase shif ts at these three phases using specific antagonists of nicotinic and m uscarinic receptors. Mecamylamine, a nicotinic receptor antagonist, di d not block carbachol-induced phase shifts at any of the phases tested . Atropine, a muscarinic receptor antagonist, blocked carbachol-induce d phase shifts at CT 6 (-11.6 +/- 4.8 min; Mean phase shift +/- S.E.M. ) and CT 22 (-20 +/- 6.6 min), suggesting that carbachol mediates its phase-shifting effects at these phases through muscarinic receptors.