Biosynthesis of N-Docosahexanoylethanolamine from Unesterified Docosahexaenoic Acid and Docosahexaenoyl-Lysophosphatidylcholine in Neuronal Cells.

Karl Kevala,Hee-Yong Kim,Arthur A Spector,Michel Lagarde

doi:10.3390/ijms21228768

Abstract

We investigated the synthesis of N-docosahexaenoylethanolamine (synaptamide) in neuronal cells from unesterified docosahexaenoic acid (DHA) or DHA-lysophosphatidylcholine (DHA-lysoPC), the two major lipid forms that deliver DHA to the brain, in order to understand the formation of this neurotrophic and neuroprotective metabolite of DHA in the brain. Both substrates were taken up in Neuro2A cells and metabolized to N-docosahexaenoylphosphatidylethanolamine (NDoPE) and synaptamide in a time- and concentration-dependent manner, but unesterified DHA was 1.5 to 2.4 times more effective than DHA-lysoPC at equimolar concentrations. The plasmalogen NDoPE (pNDoPE) amounted more than 80% of NDoPE produced from DHA or DHA-lysoPC, with 16-carbon-pNDoPE being the most abundant species. Inhibition of N-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD) by hexachlorophene or bithionol significantly decreased the synaptamide production, indicating that synaptamide synthesis is mediated at least in part via NDoPE hydrolysis. NDoPE formation occurred much more rapidly than synaptamide production, indicating a precursor–product relationship. Although NDoPE is an intermediate for synaptamide biosynthesis, only about 1% of newly synthesized NDoPE was converted to synaptamide, possibly suggesting additional biological function of NDoPE, particularly for pNDoPE, which is the major form of NDoPE produced.

Highlights

N-docosahexaenoylethanolamine is an endocannabinoid-like metabolite of docosahexaenoic acid (DHA) that is synthesized in the brain [1]
These findings demonstrate that DHA from either unesterified DHA or DHA-lysoPC can be incorporated into NDoPE and converted to synaptamide by neuronal cells
The amount of synaptamide produced was substantially reduced when NAPE-PLD was inhibited by either hexachlorophene or bithionol. These results indicate that synaptamide, like its ω-6 structural analogue anandamide that is synthesized from arachidonic acid [13,14,15,16,17], can be produced in neuronal cells at least in part by NAPE-PLD-mediated hydrolysis of a NAPE intermediate

Summary

Introduction

N-docosahexaenoylethanolamine (synaptamide) is an endocannabinoid-like metabolite of docosahexaenoic acid (DHA) that is synthesized in the brain [1]. It attenuates the lipopolysaccharide-induced neuroinflammatory response [4] These effects are mediated by a cAMP (cyclic adenosine monophosphate)/protein kinase A-dependent pathway that is activated by synaptamide binding to GPR110 (ADGRF1), a Gsα protein-coupled receptor expressed in neural stem cells and the developing brain [5]. The predominant mechanism of anandamide production in the brain is considered to be the N-acylation phosphodiesterase pathway [12,13,14,15,16,17] This involves the addition of arachidonate to the ethanolamine moiety of phosphatidylethanolamine (PE), forming an N-acylphosphatidylethanolamine (NAPE) intermediate, followed by hydrolysis of the N-acylethanolamine (NAE) group to form anandamide. The NAPE that is formed is present as both diacyl and plasmalogen forms [18,19,20,21]

Methods

Results

Conclusion