Anandamide administration alone and after inhibition of fatty acid amide hydrolase (FAAH) increases dopamine levels in the nucleus accumbens shell in rats.
Although endogenous cannabinoid systems have been implicated in the modulation of the rewarding effects of abused drugs and food, little is known about the direct effects of endogenous ligands for cannabinoid receptors on brain reward processes. Here we show for the first time that the intravenous administration of anandamide, an endogenous ligand for cannabinoid receptors, and its longer-lasting synthetic analog methanandamide, increase the extracellular dopamine levels in the nucleus accumbens shell of awake, freely moving rats, an effect characteristic of most drugs abused by humans. Anandamide produced two distinctly different effects on dopamine levels: (1) a rapid, transient increase that was blocked by the cannabinoid CB1 receptor antagonist rimonabant, but not by the vanilloid VR1 receptor antagonist capsazepine, and was magnified and prolonged by the fatty acid amide hydrolase (FAAH) enzyme inhibitor, URB597; (2) a smaller delayed and long-lasting increase, not sensitive to CB1, VR1 or FAAH blockade. Both effects were blocked by infusing either tetrodotoxin (TTX, 1 microm) or calcium-free Ringer's solution through the microdialysis probe, demonstrating that they were dependent on the physiologic activation of dopaminergic neurotransmission. Thus, these results indicate that anandamide, through the activation of the mesolimbic dopaminergic system, participates in the signaling of brain reward processes.
Solinas
Marcello
M
Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, Baltimore, Maryland 21224, USA.
Justinova
Zuzana
Z
Goldberg
Steven R
SR
Tanda
Gianluigi
G
D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D001549:Benzamides / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D002186:Cannabinoids / Q000494:pharmacology; D002219:Carbamates / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D004298:Dopamine / Q000378:metabolism*; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D053284:Polyunsaturated Alkamides; D051381:Rats; D017207:Rats, Sprague-Dawley; D043884:Receptor, Cannabinoid, CB1 / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D050916:TRPV Cation Channels / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D001549:Benzamides; D002118:Calcium; D002186:Cannabinoids; D002219:Carbamates; D004298:Dopamine; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D053284:Polyunsaturated Alkamides; D043884:Receptor, Cannabinoid, CB1; D050916:TRPV Cation Channels; D013779:Tetrodotoxin; D000099252:Fatty Acid Amide Hydrolases; C494484:TRPV1 receptor; C500528:cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester; C078814:anandamide