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.
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
Theodore J
TJ
Price
Amol M
AM
Patwardhan
Christopher M
CM
Flores
Kenneth M
KM
Hargreaves
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