Variations in brain temperature in relation to food intake☆

Temperature records obtained from preoptic and other subcortical as well as cortical areas of rats and cats showed a reliable increase during feeding, suggesting that the muscular effort involved in chewing may be the cause of at least some of the feeding-related increase.

Abstract

Temperature records obtained from preoptic and other subcortical as well as cortical areas of rats and cats showed a reliable increase during feeding (as well as during the transition from sleep to wakefulness and from inactivity to activity). That this temperature change is not a necessary or even sufficient condition for satiety or the regulation of food intake, as suggested by a “thermoregulatory” hypothesis, is indicated by the following observations: (1) animals often continued feeding long after the peak brain temperature had been reached; (2) the recovery time to prefeeding baselines was often very short and showed no correlation with meal size or duration; (3) all animals consumed normal sized meals when the food was presented during periods of activity (when brain temperatures are high) and ate no more when the food was presented during periods of inactivity (when brain temperatures are low); (4) cats ate normal quantities of cold (5°C) food which immediately produced marked temperature changes in the preoptic area; (5) two cats showed no correlation between brain temperature and food deprivation; two others showed a small rise after 12 to 18 hr of deprivation (presumably related to a concurrent increase in activity) rather than the decrease predicted by a thermoregulatory hypothesis; (6) a liquid diet produced reliably smaller brain temperature changes than a diet of dry, solid food, suggesting that the muscular effort involved in chewing may be the cause of at least some of the feeding-related increase.