AJP - Regulatory, Integrative and Comparative Physiology, Vol 261, Issue 1 14-R19, Copyright © 1991 by American Physiological Society
Meal-related and rhythmic drinking: effects of abolition of rat's eating rhythm
R. F. Johnson and A. K. Johnson
Department of Psychology, University of Iowa, Iowa City 52242.
Eating and drinking in the rat, which are both highly rhythmic and
nocturnal activities, are temporally and quantitatively associated. The
present study abolished the rhythmicity of eating by temporally and
quantitatively restricting food access to 12 equally sized bihourly meals
daily (total food available was equal to 80% of daily ad libitum intake).
Water access remained ad libitum and was monitored and quantified in terms
of 1) nocturnality, 2) association with meals, and 3) changes in the
association of food and water intake across the phases of the light-dark
cycle. Similar parameters were obtained from the same rats with ad libitum
access to both food and water. The results indicate that both rhythmic and
meal-induced effects are detectable in the drinking of rats with restricted
food access, although both the rhythmic and meal-associated factors are
reduced compared with drinking under ad libitum food access. Most
important, the data clearly demonstrate large changes in the association of
food and water intake across the phases of the light-dark cycle. These
findings indicate a complex interaction of meal-associated and rhythmic
factors in the control of drinking.
