DHA-dominant Omega-3 compositions enhance PSD-95 organization and glutamatergic protein expression.

Abstract

Introduction: Docosahexaenoic acid (DHA), the predominant omega-3 (ω-3) fatty acid in the brain, which contributes to synaptic membrane organization and plasticity, is commonly recommended for brain health. However, ω-3 formulations commonly combine DHA with eicosapentaenoic acid (EPA) in varying proportions, and the impact of the DHA ratio on postsynaptic scaffold regulation remains unclear.

Methods: In this study, differentiated human SH-SY5Y neurons were cultured in the presence of DHA, EPA, or defined DHA ratios (2:1, 1:1, 1:2) at equivalent total concentrations. PSD-95 expression, puncta density, colocalization with the presynaptic marker synaptophysin (SYN), and glutamatergic signaling proteins were quantified by immunofluorescence and Western blot analysis. Metabolic activity was assessed using a colorimetric MTT assay.

Results: DHA produced the largest increase in PSD-95 protein abundance by immunoblot and the strongest effects on PSD-95 puncta density and SYN colocalization, accompanied by coordinated upregulation of N-methyl-D-aspartate receptor (NMDAR), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), and calcium/calmodulin-dependent protein kinase II (CaMKII). DHA-enriched compositions preserved this profile, whereas balanced or EPA-dominant compositions showed attenuated responses relative to DHA-dominant conditions. EPA alone failed to enhance postsynaptic scaffold abundance and reduced NMDAR levels relative to control. These effects occurred without a detectable reduction in cellular metabolic activity.

Discussion: Collectively, these findings demonstrate that the composition of ω-3 fatty acid has a significant bearing on postsynaptic scaffold organization and glutamatergic signaling in differentiated neurons, with DHA serving as the chief mediator of observed effects. This composition-dependent framework provides an experimental basis for considering DHA ratio when evaluating omega-3 effects on postsynaptic protein organization.