Membrane localization of N-acylphosphatidylethanolamine in central neurons: studies with exogenous phospholipases.
We studied the localization of N-acyl phosphatidylethanolamine (NAPE), a putative cannabinoid precursor, in primary cultures of striatal and cortical neurons from the rat brain. We probed intact neurons with various exogenous phospholipases, including S. chromofuscus phospholipase D (PLD). S. chromofuscus PLD does not penetrate into neurons (as demonstrated by a lack of internalization of 125I-labeled PLD), and does not cause gross damage to the neuronal membrane (as demonstrated by a lack of effect of PLD on [3H]gamma-aminobutyric acid release). When neurons, labeled to isotopic equilibrium with [3H]ethanolamine, were incubated for 10 min with S. chromofuscus PLD, approximately 50% of neuronal NAPE was hydrolysed. This hydrolysis was accompanied by the release of a family of N-acyl ethanolamines (NAE) (assessed by high performance liquid chromatography), which included the cannabinoid receptor agonist, anandamide. Exogenous phospholipase A2 (PLA2) (Apis mellifera) and PLC (B. cereus) mobilized [3H]arachidonate and [3H]diacylglycerol, respectively, but had no effect on NAE formation under these conditions. These experiments indicate that approximately 50% of neuronal NAPE is localized in a compartment that is easily accessible to extracellular PLD, possibly the plasmalemma, where it would also be easily hydrolyzed upon stimulation to produce NAE.
Neurosciences Institute, San Diego, CA 92121, USA.
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Cadas
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Schinelli
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Piomelli
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002186:Cannabinoids / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D004983:Ethanolamines / Q000032:analysis*; D010740:Phospholipases / Q000378:metabolism*; D051381:Rats
D002186:Cannabinoids; D004983:Ethanolamines; C022203:N-acylethanolamines; D010740:Phospholipases