Behavioral and cardiac responses to a sudden change in environmental stimuli: effect of forced shift in food intake.
In order to test the possibility of a change in stress susceptibility induced by a forced change in activity rhythm, during control weeks food availability was restricted to the dark period only (fa-D) and to the light period only during the test week (fa-L). Stress susceptibility was measured on the basis of the decrease in heart rate (bradycardia) and an increase in freezing behavior in response to a sudden reduction in background noise. A significant increase in bradycardia both in magnitude and duration was observed during fa-L conditions as compared to the control fa-D condition. Also the duration of freezing behavior was increased during the fa-L condition. These results support the hypothesis that forced changes in circadian activities affect stress susceptibility. The significance of this finding for the incidence of stress pathologies is discussed.
Steenbergen
J M
JM
Department of Animal Physiology, University of Groningen, Haren, The Netherlands.
Koolhaas
J M
JM
Strubbe
J H
JH
Bohus
B
B
D000204:Activity Cycles; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002940:Circadian Rhythm; D004562:Electrocardiography; D005247:Feeding Behavior; D006339:Heart Rate; D008297:Male; D009622:Noise; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000503:physiopathology*