Compared effects of cold ambient temperature and cytokines on macronutrient intake in rats

To compare the effects of cold and cytokines on spontaneous dietary self-selection, rats (n = 14) were given free access to carbohydrate, protein and fat diets for 4 hours a day. After a 10-day period of habituation to this regimen, they were injected with physiological saline, IL-1 beta (4 micrograms/rat ip) or LPS (83 micrograms/rat ip) or exposed to cold (5 degrees C), the order of treatments being randomized. LPS- and IL-1 beta-treated rats ate less, but ingested relatively more carbohydrate and less protein whereas relative fat intake remained unchanged. In contrast, cold exposed rats slightly increased their food intake but in a non significant manner. They also increased their relative intake of fat but did not change their relative intake of carbohydrate and protein. These results are discussed with respect to the pyrogenic and metabolic effects of cytokines.