Meeting Abstract

P3.143  Thursday, Jan. 6  The Effect of Temperature on the Sensitivity to and Preference for an n-3 and an n-6 Polyunsaturated Fatty Acid in Mice HOUGEN, H.Y.; HIEBERT, S.M.*; Swarthmore College, PA shieber1@swarthmore.edu

Previous work in our laboratory has shown that within 10 days of exposure to an ambient temperature (T_a) of 5&degC, mice (Mus musculus) increase their preference for diets rich in polyunsaturated fatty acids (PUFAs) relative to controls held at 23&degC. However, it is not known whether this change in preference is driven by an increased preference for specific PUFAs or for unsaturated fats in general. Ruf and Arnold (2008) have proposed that heterotherms increase the n-6 to n-3 PUFA ratio in cardiac myocyte membranes to decrease the risk of arrhythmia. We therefore tested the hypothesis that mice would prefer an n-6 PUFA over an n-3 PUFA in the cold, and that changes in preference are driven by T_a-dependent changes in ability to detect n-6 and n-3 PUFAs. In a 48-h 2-bottle preference test using 0.25% PUFA solutions in 0.3% xanthan gum, mice strongly preferred linoleic acid (n-6 PUFA, 18:2) over &alpha-linolenic acid (n-3 PUFA, 18:3) after 10 days at either 5&degC or 23&degC. To measure sensitivity, animals held at 5&degC and 23&degC for 10 days were presented with a bottle containing vehicle and a bottle containing either linoleic acid or &alpha-linolenic acid solution of increasing concentrations (0% – 1% m/v) to determine the threshold at which they differentiated between the solutions. Mice at 5&degC detected both PUFAs at lower concentrations than did mice at 23&degC. Together, the results suggest that the increased PUFA preference in the cold may be driven by increased sensitivity to both linoleic and &alpha-linolenic acid but not by a change in relative preference. However, if n-6 PUFAs, particularly linoleic acid, are the predominant PUFA in the natural diet, then a general increase in preference for PUFAs might be favored in the cold because it would perforce result in increased n-6 PUFA consumption.