Influence of polyunsaturated and saturated dietary lipids on adipose tissue, brain and mitochondrial membrane fatty acid composition of a mammalian hibernator.

Dietary lipid composition profoundly influences the hibernation pattern of the chipmunk Eutamias amoenus. The object of the present study was to investigate whether these physiological changes following feeding of saturated and unsaturated lipids were associated by compositional changes of fatty acids of tissues and membranes. Animals were fed with rodent chow (control diet), rodent chow with 10% sunflower seed oil (unsaturated diet) and rodent chow with 10% sheep fat (saturated diet). Diet-induced changes in the fatty acid composition of depot fat and brain total lipids and of mitochondrial phospholipids were determined. The fatty acid unsaturation index was lower in animals on saturated diet than in animals on unsaturated diet (depot fat 86.1 vs. 145.9; heart mitochondria 207.6 vs. 247.1; liver mitochondria 148.4 vs. 173.5). Pronounced differences between dietary groups were also observed in n-3 or n-6 fatty acids or their ratios of depot fat, brain and liver mitochondria. Generally, the diet-induced differences in tissue and membrane fatty acid composition in E. amoenus were more pronounced than those observed previously in non-hibernating species. Selective feeding and incorporation of high amounts of unsaturated fatty acids into tissues and cell membranes may be an important preparation for hibernation of E. amoenus which lowers its body temperature during torpor to about 0 degrees C.