The relationship between lipid peroxidation, hibernation, and food selection in mammals

A diet that has high levels of polyunsaturated fatty acids enhances mammalian torpor. Polyunsaturated fatty acids are not synthesized by mammals, but are incorporated into both membrane and storage lipids when they occur in the diet. Polyunsaturated fatty acids also undergo autoxidation more readily than other fatty acids, thereby producing highly toxic lipid peroxides. Lipid peroxidation increases during torpor. Natural selection in mammalian hibernators should thus have favored the evolution of dietary preferences that maximize hibernation ability while simultaneously minimizing the degree of lipid peroxidation during torpor. This hypothesis was tested in laboratory experiments and field studies involving golden-mantled ground squirrels (Spermophilus lateralis). We found that the intake of polyunsaturated fatty acids is restricted during the fall and autoxidation in tissues occurs mostly during the later phases of hibernation