'Entourage' effects of N-palmitoylethanolamide and N-oleoylethanolamide on vasorelaxation to anandamide occur through TRPV1 receptors.
OBJECTIVE
The endocannabinoid N-arachidonoylethanolamide (anandamide) is co-synthesized with other N-acylethanolamides, namely N-palmitoylethanolamide (PEA) and N-oleoylethanolamide (OEA), which have been shown to potentiate anandamide responses (so-called 'entourage effects') in non-vascular tissues. It remains unclear whether such interactions occur in the circulation.


METHODS
In rat isolated small mesenteric arteries, the effects of PEA and OEA on relaxation to anandamide and tissue contents of the N-acylethanolamides were examined under myographic conditions.


RESULTS
Anandamide-induced relaxation was potentiated by pretreatment with PEA (10 microM) or OEA (1 microM), or in combination. The potentiation by PEA and OEA was endothelium-independent and abolished by treatment with capsaicin (10 microM), which desensitizes the transient receptor potential vanilloid type 1 (TRPV1) receptor system, or by the TRPV1 receptor antagonist, N-(3-methoxyphenyl)-4-chlorocinnamide (SB366791) (2 microM). It was also observed at molar ratios of anandamide and PEA (or OEA) similar to those found in mesenteric arteries. PEA and inhibition of anandamide hydrolysis by 3'-carbamoyl-biphenyl-3-yl-cyclohexylcarbamate (URB597) (1 microM) additively potentiated anandamide responses. On the other hand, PEA and OEA also induced vasorelaxation per se (rank order of potency: anandamide>OEA>PEA), but relaxation to the three N-acylethanolamides displayed different sensitivity to treatment with capsaicin, SB366791 and URB597. For example, relaxations to anandamide and OEA, but not PEA, were attenuated by both capsaicin and SB366791.


CONCLUSIONS
This study shows that PEA and OEA potentiate relaxant responses to anandamide through TRPV1 receptors in rat small mesenteric arteries. The congeners also induce vasorelaxation per se, suggesting a function for the N-acylethanolamides in vascular control.
Ho
W-S V
WS
School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK. vho@sgul.ac.uk
Barrett
D A
DA
Randall
M D
MD
D000577:Amides; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D063388:Endocannabinoids; D004983:Ethanolamines; D008297:Male; D017538:Mesenteric Artery, Superior / Q000187:drug effects / Q000502:physiology; D009829:Oleic Acids / Q000494:pharmacology*; D010169:Palmitic Acids / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000187:drug effects* / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*
D000577:Amides; D001095:Arachidonic Acids; D004338:Drug Combinations; D063388:Endocannabinoids; D004983:Ethanolamines; D009829:Oleic Acids; D010169:Palmitic Acids; D053284:Polyunsaturated Alkamides; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; C488250:oleoylethanolamide; C005958:palmidrol; C078814:anandamide