Wild semipalmated sandpipers (Calidris pusilla) eat n-3 fatty acids to prime their muscles for long migrations. Sedentary bobwhite quails (Colinus virginianus) were used as a model to investigate the mechanisms for this natural doping. Our goal was to characterize the stimulating effects of n-3 eicosapentaenoic acid (EPA) and n-3 docosahexaenoic acid (DHA) on oxidative capacity. Mechanisms linked to changes in membrane composition and in gene expression for peroxisome proliferator-activated receptors (PPAR) were investigated. Dietary n-3 fatty acids stimulated the activities of oxidative enzymes by 58–90% (citrate synthase, cytochrome oxidase, carnitine palmitoyl transferase and hydroxyacyl dehydrogenase), and sedentary quails showed the same changes in membrane composition as sandpipers preparing for migration. EPA and DHA have the same doping effect. The substitution of n-6 arachidonic acid by n-3 EPA in membrane phospholipids plays an important role in mediating the metabolic effects of the diet, but results provide no significant support for the involvement of PPARs (as determined by changes in gene expression). The fatty acid composition of mitochondrial membranes and sarcoplasmic reticulum can be monitored by measuring total muscle phospholipids because all phospholipids are equally affected by diet. Only extreme regimes of endurance training can lead to increments in oxidative capacity matching those induced here by diet. As they prepare for long migrations, semipalmated sandpipers improve their physical fitness by eating! Choosing n-3 fatty acid doping over endurance training strikes us as a better strategy to boost aerobic capacity when rapid storage of energy is critical.
- lipid metabolism
- membrane phospholipid
- peroxisome proliferator-activated receptor gene expression
- mitochondrial enzyme
- sarcoplasmic reticulum
- Colinus virginianus
We thank Sean Kennedy (Canadian Wildlife Service) for essential advice on the measurement of PPARs, Pierre Pilon for the isolation of mitochondria and sarcoplasmic reticulum, Eric Vaillancourt for building the quail facility, and Ocean Nutrition Canada Ltd (Dartmouth, Nova Scotia, Canada) for donating the n-3 fatty acids used for the diets. J.T.P. was the recipient of an Ontario Graduate Scholarship and this research was supported by an NSERC discovery grant to J.-M.W.