A role for the anandamide membrane transporter in TRPV1-mediated neurosecretion from trigeminal sensory neurons.
Many n-acylethanolamines utilize the anandamide membrane transporter (AMT) to gain facilitated access to the intracellular compartment, hence, we hypothesized that this mechanism might be important for anandamide (AEA)- and N-arachidonoyl-dopamine (NADA)-evoked CGRP release from cultured trigeminal ganglion (TG) neurons. Using [14C]AEA we demonstrated that TG neurons transported AEA in a FAAH- and AMT-inhibitable fashion. Although TRPV1-positive TG neurons were found to express fatty acid amide hydrolase, the application of FAAH inhibitors had no effect on AEA-evoked CGRP release. In contrast, application of the AMT inhibitors OMDM-2 or VDM-11 significantly reduced the potency and efficacy of AEA-, NADA- and capsaicin-evoked CGRP release. Moreover OMDM-2 (IC50 values ranging from 6.4-9.6 microM) and VDM-11 (IC50 values ranging from 5.3-11 microM) inhibited CGRP release evoked by EC80 concentrations of AEA, NADA and CAP and these values were consistent with IC50s obtained for inhibition of uptake. OMDM-2 had no effect on CGRP release per se while VDM-11 evoked CGRP release on its own (EC50 approximately 35 microM) in a CPZ-insensitive, but ruthenium red (RR)-sensitive fashion. This is the first demonstration that TG sensory neurons possess an AMT-like mechanism suggesting that this mechanism is important for the pharmacological action of AEA and NADA at native TRPV1 channels.
Price
Theodore J
TJ
Department of Endodontics, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr, San Antonio, TX 78229, USA. theodore.price@mail.mcgill.ca
Patwardhan
Amol M
AM
Flores
Christopher M
CM
Hargreaves
Kenneth M
KM
D000581:Amidohydrolases / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D001593:Benzyl Compounds / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D053284:Polyunsaturated Alkamides; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D050916:TRPV Cation Channels / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000166:cytology*; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D001593:Benzyl Compounds; D015740:Calcitonin Gene-Related Peptide; D002247:Carbon Isotopes; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D053284:Polyunsaturated Alkamides; D050916:TRPV Cation Channels; D000099252:Fatty Acid Amide Hydrolases; C462953:N-(2-methyl-3-hydroxyphenyl)-5,8,11,14-eicosatetraenamide; C474343:OMDM-2 cpd; C493922:Trpv1 protein, rat; C078814:anandamide