Evaluation of fatty acid amide hydrolase inhibition in murine models of emotionality.
BACKGROUND
Manipulations of the endocannabinoid/fatty acid amide hydrolase (FAAH) signaling systems result in conflicting and paradoxical effects in rodent models of emotional reactivity.


OBJECTIVE
In the present study, we tested the hypothesis that the inhibition of FAAH would elicit significant effects in murine models used to screen anxiolytic and antidepressant drugs.


METHODS
FAAH (-/-) mice and wild-type mice treated with FAAH inhibitors (URB597 and OL-135) were evaluated in standard behavioral screening models for antidepressant (i.e., tail suspension and forced-swim tests) and anxiolytic (i.e., elevated plus maze) agents. The doses of URB597 and OL-135 selected were based on their ability to augment the pharmacological effects (i.e., analgesia, catalepsy, and hypothermia) of exogenously administered anandamide.


RESULTS
FAAH (-/-) mice, anandamide-injected FAAH (-/-) mice, or wild-type mice injected with FAAH inhibitors or anandamide failed to exhibit significant effects in standard tests of emotional reactivity, although the antidepressant desipramine and the anxiolytic agent midazolam were active in the appropriate assays. FAAH- (-/-) and URB597-treated mice finally displayed significant effects in the tail suspension test when substantial methodological changes were made (i.e., altered ambient light and increased sample sizes).


CONCLUSIONS
Although FAAH suppression can elicit significant effects under some instances in which consequential procedural modifications are made, the present results indicate that the pharmacological inhibition or genetic deletion of FAAH is ineffective in standard mouse models of emotional reactivity. It remains to be established whether the effects of FAAH inhibition in these modified tasks are predictive of their efficacy in treating emotional disorders.
Naidu
Pattipati S
PS
Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613, USA.
Varvel
Stephen A
SA
Ahn
Kyunghye
K
Cravatt
Benjamin F
BF
Martin
Billy R
BR
Lichtman
Aron H
AH
D000581:Amidohydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001007:Anxiety / Q000188:drug therapy; D001095:Arachidonic Acids; D001522:Behavior, Animal / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology*; D063385:Cannabinoid Receptor Modulators / Q000502:physiology; D002219:Carbamates / Q000494:pharmacology*; D003863:Depression / Q000188:drug therapy; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004644:Emotions / Q000187:drug effects* / Q000502:physiology; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008029:Lighting; D018782:Maze Learning; D051379:Mice; D018345:Mice, Knockout; D053284:Polyunsaturated Alkamides; D011725:Pyridines / Q000494:pharmacology*; D015398:Signal Transduction; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D001549:Benzamides; D063385:Cannabinoid Receptor Modulators; D002219:Carbamates; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D053284:Polyunsaturated Alkamides; D011725:Pyridines; D000099252:Fatty Acid Amide Hydrolases; C495479:1-oxo-1-(5-(2-pyridyl)-2-yl)-7-phenylheptane; C500528:cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester; C078814:anandamide