Immunoregulatory effects of DHEA and EPEA on activated microglia in vitro: The role of cannabinoid receptors.

Activation of microglia contributes to the pathogenesis of central neuropathic pain (CNP), yet effective treatments remain limited. Docosahexaenoyl-ethanolamine (DHEA) and eicosapentaenoyl-ethanolamine (EPEA) are omega-3-derived ethanolamides with reported immunoregulatory and neuroprotective actions. We examined the effects of DHEA and EPEA, alone and in combination, on microglial activation, microglia-neuron crosstalk, and cannabinoid receptor-associated signalling. In LPS-activated microglia, DHEA and EPEA reduced pro-inflammatory mediator expression, attenuated inflammatory cytokine and chemokine profiles, and increased anti-inflammatory mediators including BMP7. Conditioned medium from activated microglia induced neuronal stress, whereas conditioned medium from DHEA-treated microglia, as well as BMP7 alone, attenuated this effect. DHEA and EPEA promoted via CB1R- and CB2R-dependent Gαi and β-arrestin interaction, receptor internalisation, ERK activation, and reduced cAMP accumulation. Together, these findings show that DHEA and EPEA suppress microglial inflammatory signalling and reduce microglia-induced neuronal stress, support a role for CBR-receptor signalling in their actions and provide evidence for their therapeutic potential in central neuropathic pain.