CB1 receptor-mediated control of the release of endocannabinoids (as assessed by microdialysis coupled with LC/MS) in the rat hypothalamus.
In the present study, we examined the occurrence and potential regulation of endocannabinoid release by cannabinoid CB1 receptors in the rat brain. To this end, we developed a highly sensitive (limit of sensitivity 30-300 amol) new analytical method, combining online brain microdialysis with solid-phase extraction-liquid chromatography-tandem mass spectrometry, which allowed the detection in real time of trace amounts of endocannabinoids in the extracellular fluid. In the hypothalamus, anandamide and 2-arachidonoyl-glycerol release was stimulated following depolarization via local administration of K(+), with or without addition of Ca(2+), or glutamate application. Inhibition of fatty acid amide hydrolase by systemic administration of intraperitoneal (i.p.) URB597 (0.5 mg/kg) induced an increase of anandamide, but not 2-arachidonoyl-glycerol, outflow. The CB1 receptor antagonist rimonabant (10 mg/kg i.p.) increased, whereas the CB1 agonist WIN55,212-2 (2.5 mg/kg i.p.) decreased, anandamide release. Interestingly, the same treatments induced opposite changes in 2-arachidonoyl-glycerol release. At a dose of 3 mg/kg i.p., which by itself did not affect endocannabinoid release, rimonabant fully antagonized the effect of WIN55,212-2 (2.5 mg/kg i.p.). Taken together, these results suggest that CB1 receptors are able to control the local release of endocannabinoids in the hypothalamus via a feedback mechanism and strengthen the view that anandamide and 2-arachidonoyl-glycerol have distinct physiological roles.
Béquet
Frédéric
F
Discovery Analytics, sanofi-aventis R&D, 195 route d'Espagne, BP1169 31036 Toulouse cedex 1, France. frederic.bequet@sanofi-aventis.com
Uzabiaga
Françoise
F
Desbazeille
Mathieu
M
Ludwiczak
Pascal
P
Maftouh
Mohamed
M
Picard
Claudine
C
Scatton
Bernard
B
Le Fur
Gerard
G
D000581:Amidohydrolases / Q000037:antagonists & inhibitors; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D048588:Benzoxazines / Q000494:pharmacology; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D002186:Cannabinoids / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002219:Carbamates / Q000494:pharmacology; D002853:Chromatography, Liquid; D063388:Endocannabinoids; D045604:Extracellular Fluid / Q000378:metabolism; D005989:Glycerides / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D000077285:Rimonabant; D053719:Tandem Mass Spectrometry; D000099252:Fatty Acid Amide Hydrolases
D000581:Amidohydrolases; D001095:Arachidonic Acids; D001549:Benzamides; D048588:Benzoxazines; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D002219:Carbamates; D063388:Endocannabinoids; D005989:Glycerides; D009025:Morpholines; D009281:Naphthalenes; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D011188:Potassium; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D000077285:Rimonabant; 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; C094503:glyceryl 2-arachidonate; C078814:anandamide