Abstract
Omega-3 fatty acids, particularly DHA, are potent modulators of adipose tissue biology. However, reported effects on adipogenesis vary with dose and adipocyte maturation. We examine the effects of prolonged exposure to 60 μM DHA on lipogenesis, lipolysis, and glucose uptake in 3T3-L1 adipocytes. DHA was administered either during early differentiation (days 1-9, followed by maturation in maintenance medium) or during the mature stage (days 9-18), with all analyses performed on day 18. DHA supplementation of immature adipocytes markedly inhibited adipogenesis. Intracellular lipid accumulation was reduced by 56%, accompanied by a strong downregulation of Pparγ and Fasn, and undetectable levels of Gpr120. Correspondingly, Slc2a4 (GLUT4) was suppressed, accompanied by a 44% reduction in glucose uptake. The strong suppression of the adipogenic program and increased Cpt1-linked mitochondrial β-oxidation in immature adipocytes align with DHA's well-known anti-inflammatory and ROS-lowering effects. When applied to mature adipocytes at the same dose and duration, DHA also decreased intracellular lipid accumulation and glucose utilization, although more modestly (by 30% and 8%, respectively). However, unlike in immature adipocytes, the lipolysis rate in mature cells was increased by 34% and Pparγ expression remained unchanged, indicating an entirely different metabolic pathway of modulation. In mature adipocytes, DHA promoted lipid mobilization rather than the general suppression of lipogenesis and glucose uptake. Overall, these findings highlight a distinct, stage-specific antiadipogenic mechanism of DHA action, but also underline that its context-dependent effects may become detrimental when high physiological doses overlap with conditions of energy surplus.