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3173205 
Journal Article 
The anti-inflammatory mediator palmitoylethanolamide enhances the levels of 2-arachidonoyl-glycerol and potentiates its actions at TRPV1 cation channels 
Petrosino, S; Schiano Moriello, A; Cerrato, S; Fusco, M; Puigdemont, A; De Petrocellis, L; Di Marzo, V 
2016 
Yes 
British Journal of Pharmacology
ISSN: 0007-1188
EISSN: 1476-5381 
173 
7 
1154-1162 
English 
25598150 
BACKGROUND AND PURPOSE: Palmitoylethanolamide (PEA) is an endogenous congener of anandamide and potentiates its actions at cannabinoid CB1 and CB2 receptors, and at transient receptor potential vanilloid type-1 (TRPV1) channels. The other endocannabinoid, 2-arachidonoylglycerol (2-AG), was recently suggested to act as a TRPV1 channel agonist. We investigated if PEA enhanced levels of 2-AG in vitro or in vivo and 2-AG activity at TRPV1 channels.

EXPERIMENTAL APPROACH: Endogenous lipid levels were measured by LC-MS in (i) human keratinocytes incubated with PEA (10-20 μM, 40 min, 6 and 24 h, 37°C); (ii) the blood of spontaneously Ascaris suum hypersensitive beagle dogs given a single oral dose of ultramicronized PEA (30 mg·kg(-1) , 1, 2, 4 and 8 h from administration); (iii) the blood of healthy volunteers given a single oral dose of micronized PEA (300 mg, 2, 4 and 6 h from administration). Effects of 2-AG at TRPV1 channels were assessed by measuring intracellular Ca(2+) in HEK-293 cells over-expressing human TRPV1 channels.

KEY RESULTS: PEA elevated 2-AG levels in keratinocytes (∼3-fold) and in human and canine plasma (∼2 and ∼20-fold respectively). 2-AG dose-dependently raised intracellular Ca(2+) in HEK-293-TRPV1 cells in a TRPV1-dependent manner and desensitized the cells to capsaicin. PEA only slightly enhanced 2-AG activation of TRPV1 channels, but significantly increased 2-AG-induced TRPV1 desensitization to capsaicin (IC50 from 0.75 ± 0.04 to 0.45 ± 0.02 μM, with PEA 2 μM).

CONCLUSIONS AND IMPLICATIONS: These observations may explain why several effects of PEA are attenuated by cannabinoid receptor or TRPV1 channel antagonists.

LINKED ARTICLES: This article is part of a themed section on Endocannabinoids. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.7/issuetoc.