Plasma and white adipose tissue lipid composition in marmots [Composition lipidique du plasma et du tissus adipeux blanc chez les marmottes].

Résumé

White adipose tissue biopsies and plasma samples were obtained from hibernating yellow-bellied marmots (Marmota flaviventris) maintained in the laboratory. In addition, biopsies and plasma samples were obtained from normothermic animals in the field and laboratory. Measurement of plasma free fatty acid (FA) levels indicated that winter labotory animals exhibited increased lipolysis. Additionally, analysis of white adipose tissue triacylglycerol revealed that the FA composition of the storage fat in animals maintened on the standard is rematkably simple and uniform between different adipose depots in the same animal. Three FFAs (palmitic, oleic, and linoleic acids) made up >195% of the total. Triene (alpha-linolenate) was found in newly capture animals, but the percentage of this FA decreased rapidly when the animals were maintend on the standard laboratory diet. Throughout the hibernation season (October to April), white adipose tissue-saturated FA percentage decresed monoene percentage remained constant, and diene percentage increased. Analysis of plasma FA composition suggested that these animals tended to metabolize saturated FAs from stored lipid during hibernation and that dienes were mobillzed brierly after the last arousal from hibernation in spring. From these observations, we hypothesize that marmots preferentially metabolize saturated fats during the hibernation period and that essential FAs of the o6 series tend to be metabolized more slowly than other FAs. These characteristics suggest that marmots are a valuable a model in which to study lipid metabolism.