Unveiling systemic organ disorders associated with impaired lipid catabolism in fasted SOD1-deficient mice

Abstract

Oxidative stress triggers the formation of lipid droplets in the liver by stimulating lipogenesis and simultaneously suppresses lipoprotein secretion under hypernutritional conditions. Herein we report on the observation of systemic organ failure that is associated with lipid droplet accumulation in fasting, SOD1-knockout (KO) mice. Upon a three-day fasting period, the KO mice were observed to be vulnerable, could not be rescued by refeeding and had largely died, while wild-type mice were totally recovered. Visceral fat was rapidly consumed during fasting, which resulted in energy shortage and increased fatality in the KO mice. Lipid droplets had accumulated and continued to remain in KO mouse organs that routinely catalyze fatty acids via β-oxidation, even though the levels of free fatty acids and β-hydroxybutyrate, a ketone body, in blood plasma were less in KO mice compared to WT mice during the fasting period. The fasting-triggered organ failure in the KO mice was effectively mitigated by feeding a high calorie-diet for 2 weeks prior to fasting, even though the mice had an excessive accumulation of lipid droplets in the liver. These collective data suggest that the lipid-catabolizing system is the sensitive target of oxidative stress triggered by fasting conditions in the KO mice.

Keywords: Fasting; Fatty acids; Lipid droplets; Lipophagy; Superoxide dismutase.