The endogenous cannabinoid anandamide has effects on motivation and anxiety that are revealed by fatty acid amide hydrolase (FAAH) inhibition.
Converging evidence suggests that the endocannabinoid system is an important constituent of neuronal substrates involved in brain reward processes and emotional responses to stress. Here, we evaluated motivational effects of intravenously administered anandamide, an endogenous ligand for cannabinoid CB1-receptors, in Sprague-Dawley rats, using a place-conditioning procedure in which drugs abused by humans generally produce conditioned place preferences (reward). Anandamide (0.03-3 mg/kg intravenous) produced neither conditioned place preferences nor aversions. However, when rats were pre-treated with the fatty acid amide hydrolase (FAAH) inhibitor URB597 (cyclohexyl carbamic acid 3'-carbamoyl-3-yl ester; 0.3 mg/kg intraperitoneal), which blocks anandamide's metabolic degradation, anandamide produced dose-related conditioned place aversions. In contrast, URB597 alone showed no motivational effects. Like URB597 plus anandamide, the synthetic CB1-receptor ligand WIN 55,212-2 (50-300 microg/kg, intravenous) produced dose-related conditioned place aversions. When anxiety-related effects of anandamide and URB597 were evaluated in a light/dark box, both a low anandamide dose (0.3 mg/kg) and URB597 (0.1 and 0.3 mg/kg) produced anxiolytic effects when given alone, but produced anxiogenic effects when combined. A higher dose of anandamide (3 mg/kg) produced anxiogenic effects and depressed locomotor activity when given alone and these effects were potentiated after URB597 treatment. Finally, anxiogenic effects of anandamide plus URB597 and development of place aversions with URB597 plus anandamide were prevented by the CB1-receptor antagonist AM251 (3 mg/kg intraperitoneal). Thus, additive interactions between the effects of anandamide on brain reward processes and on anxiety may account for its aversive effects when intravenously administered during FAAH inhibition with URB597.
Scherma
Maria
M
Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, MD, USA.
Medalie
Julie
J
Fratta
Walter
W
Vadivel
Subramanian K
SK
Makriyannis
Alexandros
A
Piomelli
Daniele
D
Mikics
Eva
E
Haller
Jozsef
J
Yasar
Sevil
S
Tanda
Gianluigi
G
Goldberg
Steven R
SR
D000581:Amidohydrolases / Q000378:metabolism*; D000700:Analgesics / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000188:drug therapy / Q000201:enzymology*; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology; D048588:Benzoxazines / Q000494:pharmacology; D002219:Carbamates / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D009281:Naphthalenes / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D000700:Analgesics; D001095:Arachidonic Acids; D001549:Benzamides; D048588:Benzoxazines; D002219:Carbamates; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D009025:Morpholines; D009281:Naphthalenes; D053284:Polyunsaturated Alkamides; D000099252:Fatty Acid Amide Hydrolases; C500528:cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; C078814:anandamide