title: Chronic ethanol intake alters circadian phase shifting and free-running period in mice.
abstract: Chronic alcohol intake is associated with widespread disruptions in sleep and circadian rhythms in both human alcoholics and in experimental animals. Recent studies have demonstrated that chronic and acute ethanol treatments alter fundamental properties of the circadian pacemaker--including free-running period and responsiveness to photic and nonphotic phase-shifting stimuli--in rats and hamsters. In the present work, the authors extend these observations to the C57BL/6J mouse, an inbred strain characterized by very high levels of voluntary ethanol intake and by reliable and stable free-running circadian activity rhythms. Mice were housed individually in running-wheel cages under conditions of either voluntary or forced ethanol intake, whereas controls were maintained on plain water. Forced ethanol intake significantly attenuated photic phase delays (but not phase advances) and shortened free-running period in constant darkness, but voluntary ethanol intake failed to affect either of these parameters. Thus, high levels of chronic ethanol intake, beyond those normally achieved under voluntary drinking conditions, are required to alter fundamental circadian pacemaker properties in C57BL/6J mice. These observations may be related to the relative ethanol insensitivity displayed by this strain in several other phenotypic domains, including ethanol-induced sedation, ataxia, and withdrawal. Additional experiments will investigate chronobiological sensitivity to ethanol in a range of inbred strains showing diverse ethanol-related phenotypes.
authors.affiliation: School of Biology and Ecology, University of Maine, Orono, ME 04469-5742, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Seggio
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fixaris
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Reed
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Logan
authors.forename: Alan M
authors.initials: AM
authors.lastname: Rosenwasser
mesh_terms: D000428:Alcohol Drinking / Q000503:physiopathology; D000704:Analysis of Variance; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002492:Central Nervous System Depressants / Q000494:pharmacology; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D000431:Ethanol / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol