Meeting Abstract

P3.120  Saturday, Jan. 5  Temperature-dependent self-selection of dietary lipid saturation by an obligate homeotherm, Mus musculus GILCHRIST-SCOTT, D.H.; YOON, D.Y.J.; HIEBERT, S.M.*; Swarthmore College shieber1@swarthmore.edu

Consistent with the predictions of both the homeoviscous adaptation and membrane pacemaker hypotheses, previous studies have shown that a daily heterotherm, the Djungarian hamster (Phodopus sungorus), exhibits an increased preference for unsaturated fatty acids in the diet when ambient temperature is reduced. To determine whether this phenomenon is specific to heterotherms or is a more general behavioral characteristic of mammals, we compared the dietary self-selection patterns of white mice (Mus musculus) when exposed to different ambient temperatures. The baseline preference of mice for simultaneously offered isocaloric diets, rich in saturated and unsaturated fatty acids, respectively, was first established at 25 ˚C. Experimental mice (N = 15) were then moved to 5 ˚C, whereas control mice (N = 15) remained at 25 ˚C. Over the two subsequent weeks, average percent consumption of the diet rich in unsaturated fatty acids in the cold-exposed mice (74.9 +/- 4.8%) was significantly greater than that of warm-exposed mice (48.4 +/- 4.3%; P = 0.0004). These results demonstrate that temperature-dependent preference for dietary lipid saturation is not restricted to heterotherms, but can also be expressed in an obligate homeotherm and is therefore not dependent, as previously thought, on large changes in core body temperature. We also compare fatty acid composition of phospholipids and triglycerides in various tissues, as well as several measures of performance (grip strength test, tail flick and hot plate tests for nociception, and tests of object recognition and spatial memory) in the two temperature treatment groups.