Eicosapentaenoic acid (EPA) increases cell viability and expression of neurotrophin receptors in retinoic acid and brain-derived neurotrophic factor differentiated SH-SY5Y cells

The n-3 polyunsaturated fatty acid, eicosapentaenoic acid (EPA) has been found to process neuroprotective effects. However, the exact cellular mechanisms are not well understood. Brain-derived neurotrophic factor (BDNF) is one of neurotrophins, which is involved in neuron differentiation, survival, and synaptogenesis.

In this study, the potential neuroprotective effects of EPA, and its possible effects on BDNF and BDNF receptor expression were investigated in SH-SY5Y cells.

Both undifferentiated and retinoic acid (RA)-BDNF differentiated SH-SY5Y cells were treated with EPA and/or BDNF. The cell viability was determined by MTT assay. The expression of BDNF receptors, tyrosine kinase receptor B (TrkB) and p75^NTR were tested by RT-PCR and Western blotting.

In undifferentiated SH-SY5Y cells, either EPA or BDNF, or both did not affect the cell viability. In RA-BDNF differentiated SH-SY5Y cells, treatment with different doses of EPA (0.01, 0.1, 1.0, 10.0 µM) and BDNF (1 ng/ml) for 24 hours significantly increased the cell viability, while EPA or BDNF alone showed no effect. More importantly, RT-PCR and Western blotting results revealed that 24 hours treatment with EPA (0.01, 0.1, 1.0 µM) significantly increased the full-length TrkB (TrkB^TK+), but not truncated TrkB (TrkB^TK−) expression in these cells. An increase in p75^NTR expression was also observed with 10.0 µM EPA treatment. Finally, co-incubation with either 100 nM staurosporine, a protein kinase inhibitor, or 500 nM K252a, a tyrosine kinase inhibitor completely abolished the EPA-induced increase in cell viability.

Our results indicate that EPA exerts beneficial effects on cell survival through modulating neurotrophin receptor expression.