THE EFFECT OF A LOW ESSENTIAL FATTY-ACID DIET ON HIBERNATION IN MARMOTS

We investigated the effect of an essential fatty acid (EFA)-deficient diet on hibernation patterns in yellow-bellied marmots (Marmota flaviv entris). Fatty acid (FA) analysis of white adipose tissue (WAT) from a nimals maintained for 2 mo on the EFA-deficient diet suggested that li ttle or no EFAs were present in the gonadal or omental fat depots. Hib ernation bout lengths of the EFA-deficient animals were significantly shorter (P < 0.01) than control animals. Stated another way, these ani mals aroused twice as frequently compared with control animals and use d more energy to survive winter. Analysis of WAT composition and blood samples revealed that animals were highly lipolytic during winter. Fu rthermore, the release of FAs was not random: linoleate (cis-9,cis-12- octadecadienoic acid; 18:2, a diene EFA) was significantly (P < 0.05) under-represented in venous outflow from the gonadal WAT pad based on the percentage of this species in WAT. The concentration of saturated FAs was higher than that predicted from the WAT-FA composition. We con clude that linoleate is preferrentially retained within WAT and that c oncentrations of this EFA may influence hibernation behavior. Thus EFA s may have a thermoregulatory role in hibernation in addition to their role as essential precursors for physiologically important lipids aft er hibernation is over.