Effect of food intake on oxygen consumption in cold-acclimated rats

The objective of the present study was to determine the relative importance of thermoregulatory and energy conservation mechanisms in cold-exposed, food-restricted rats at thermoneutrality. Oxygen consumption was measured at 25 degrees C and 10 degrees C in rats acclimated at 30 degrees C and fed ad libitum and in animals acclimated at 10 degrees C and either fed ad libitum or subjected to food restriction. Rectal temperature was taken before and after each oxygen consumption measurement. Rats from all three groups showed a similar oxygen consumption measured at 10 degrees C. At 25 degrees C, the cold-acclimated rats on ad libitum intake displayed a higher oxygen consumption than did non-acclimated animals. The food-restricted rats at thermoneutrality showed an oxygen consumption similar to that of non-acclimated animals. Rectal temperature did not change significantly under any type of condition. It is concluded that the energy conservation mechanism in food-restricted rats is present only when the thermoregulatory drive is not too strong.