Differential satiating effects of fats in the small intestine of obesity-resistant and obesity-prone rats

The effects of duodenal infusions of fats on sham feeding was measured in t wo strains of rats that differ in their susceptibility to fat-induced obesi ty. Osborne-Mendel rats are prone to developing obesity on a high-fat diet and preferentially choose fats over carbohydrates in macronutrient selectio n paradigms. In contrast, S 5B/PL rats are resistant to developing obesity when eating a high-fat diet, and preferentially choose carbohydrates in mac ronutrient selection paradigms. To test the hypothesis that differences in the satiating potency of fats in the small intestine contributed to these d ifferences between the two strains, we measured the effects of duodenal inf usions of Intralipid and sodium linoleate on sham-feeding intakes. The resu lts were consistent with the hypothesis. Duodenal infusions of either of th ese fats decreased intake significantly more in S5B/PL rats than in Osborne -Mendel rats. Both rat strains sham fed similar amounts when intestinally i nfused with 0.15 M NaCl. These results suggest that differences in response s to intestinal satiating mechanisms may contribute to the differences in s usceptibility to fat-induced obesity in these rat strains. (C) 1999 Elsevie r Science Inc.