Do fats isolated from different trophic levels affect the aerobic potential of terrestrial mammals?

Abstract

Fats serve as a primary fuel source for the metabolism of animals. Certain fatty acids, like polyunsaturated ones, can influence myoglobin concentration and enzymatic activity. This can enhance oxygen utilization in muscle, which is essential for animals relying on aerobic metabolism. Shifts in dietary composition, such as shifts in fatty acids, can have significant implications regarding the physiological adaptations of various species, especially in response to climate change. This study aimed to investigate if fats isolated from different trophic levels, specifically fish and krill, would have physiological differences in mammalian cell culture. C2C12 mouse skeletal muscle cells supplemented with krill and fish oil had significantly reduced media fat concentrations after the seventh day of differentiation, with no crude fat measured in the media for cells supplemented with fish oil. Intracellular crude fat levels mirrored these observations, with the highest concentrations in the fish treatment, followed by krill, and then the lipid cocktail. Fish oil was also measured to have the greatest variation of fatty acids, while krill oil had significantly higher concentrations of omega-3 fatty acids other than docosahexaenoic acid. This led to the hypothesis that cells supplemented with fats isolated from fish would reflect increased markers of aerobic capacity, specifically myoglobin concentration and citrate synthase activity. An increase trend of myoglobin expression in all treatment conditions was observed, aligning with previous work, but only the cells supplemented with the standard lipid cocktail showed a statistically significant increase compared to the control. An observed trend of decreased citrate synthase enzymatic activity supported that crude fat levels cell culture media had passed the established 5% threshold from previous studies known to induce cell death. This work developed a reliable method for creating sterile lipid-supplemented media, ensuring consistent incorporation of hydrophobic lipids into aqueous cell culture systems, and highlights how understanding the impact of different fatty acids on skeletal muscle metabolism is crucial for comprehending the effects on metabolism in a changing environment.