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

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.