Driven by sustainability, plant oils are increasingly used to replace fish oil in aquafeeds, thereby altering muscle fatty acid composition and potentially affecting volatile profiles. Lipoxygenases (LOXs) participate in fatty-acid bioconversion, but the role of 5-lipoxygenase (5-LOX) in non-immune fish muscle remains unclear. We hypothesized that acute intragastric exposure to plant-derived C18 fatty acids would be associated with changes in muscle 5-LOX protein abundance and volatile profiles in triploid rainbow trout. Using an acute oral gavage model, trout received oleic, linoleic, or α-linolenic acid, alone or with the selective 5-LOX inhibitor zileuton. Muscle samples were analyzed for 5-LOX mRNA expression, detectable protein abundance, and volatile profiles. Detectable 5-LOX protein abundance was low under basal conditions and changed after fatty-acid administration, with linoleic acid showing the clearest increase. Several major volatiles also changed across treatments. Under acute fatty-acid exposure, zileuton reduced hexanal concentration by 85.7% (221.2 to 31.6 ng/g) and decreased the nonanal odor activity value by 34.4%. These results indicate that acute plant-derived C18 fatty acid exposure was associated with changes in detectable muscle 5-LOX protein abundance and volatile profiles in triploid rainbow trout. The inhibitor-associated volatile changes further support the possibility that multiple oxidative processes may be involved under these acute conditions.
Si et al. (Mon,) studied this question.