Influence of shock training and explicit fear-conditioned cues on sleep architecture in mice: strain comparison.
Fear conditioning is thought to model anticipatory anxiety. Inbred mouse strains exhibit different levels of reactivity to aversive environmental stimuli, which may reflect anxiety. We examined the effects of fear conditioning on sleep in mouse strains that differ on behavioral measures of anxiety. Mice (BALB/cJ [C], C57BL/6J [B6], CB6F1/J [CB6], n = 7-10 per strain) were implanted with transmitters for recording sleep by telemetry. Baseline sleep was recorded, and the mice were trained to associate a cue (tone) with footshock (15 cue-shock pairings on 4 consecutive days). Sleep was recorded after shock training and again 4 to 5 days later after presentation of the cue alone. Shock training produced a relatively selective suppression of rapid eye movement sleep (REM) that was greater in the C strain compared to the B6 and CB6 mice. Post-training exposure to the cue alone suppressed REM in all strains. The C strain exhibited a relatively greater immediate suppression of REM, and the CB6 hybrid mice showed the greatest overall suppression of REM. These data demonstrate that stimuli associated with an aversive event can alter sleep and suppress REM in much the same way as exposure to the event itself. Fear conditioning may provide a model for examining genetic and neural mechanisms underlying the influence of anxiety on sleep.
Sanford
Larry D
LD
Sleep Research Laboratory, Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, Virginia 23501, USA. Sanforld@evms.edu
Tang
Xiangdong
X
Ross
Richard J
RJ
Morrison
Adrian R
AR
D000704:Analysis of Variance; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D003463:Cues; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D005824:Genetics, Behavioral / Q000379:methods; D006824:Hybridization, Genetic; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013216:Reflex, Startle; D012890:Sleep / Q000235:genetics* / Q000502:physiology; D012895:Sleep, REM; D013686:Telemetry; D013997:Time Factors