The effect of ambient temperature cycles upon circadian running and drinking activity in male and female laboratory rats.
The effect of a cycle of warm and cool ambient temperature (Ta) upon the free-running circadian running and drinking rhythms of male and female laboratory rats was investigated. Rats free-running in constant darkness and constant cool Ta (21 degrees C +/- 2 degrees C) were exposed to a 12:12 cycle of high (34 degrees C +/- 2 degrees C) and cool (21 degrees C +/- 2 degrees C) Ta. Three male rats and one female rat entrained to the Ta cycle. Ten of 12 male and 9 of 11 female rats exhibited post-Ta cycle phases not predictable from pre-Ta cycle phases. Most rats exhibited positive and negative masking of activity during the Ta cycle. Activity periods shortened for all rats during the Ta cycle, and male free-running periods lengthened upon cessation of the Ta cycle to values significantly greater than precycle periods. It was concluded that Ta acts as a weak zeitgeber in laboratory rats and has greater effects on males compared to females.
Francis
A J
AJ
Department of Psychology, La Trobe University, Bundoora, Victoria, Australia.
Coleman
G J
GJ
D000818:Animals; D001833:Body Temperature Regulation; D002940:Circadian Rhythm; D003623:Dark Adaptation; D004326:Drinking; D005260:Female; D008297:Male; D009043:Motor Activity; D051381:Rats; D011919:Rats, Inbred Strains