The endocannabinoid system in rat gliosomes and its role in the modulation of glutamate release.
The endocannabinoid system and endocannabinoid receptor-driven modulation of glutamate release were studied in rat brain cortex astroglial gliosomes. These preparations contained the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol, as well their major biosynthetic (N-acyl-phosphatidylethanolamines-hydrolyzing-phospholipase D and diacylglycerol-lipase) and catabolic (fatty acid amide-hydrolase and monoacylglycerol-lipase) enzymes. Gliosomes expressed type-1 (CB1R), type-2 (CB2R) cannabinoid, and type-1 vanilloid (TRPV1) receptors, as ascertained by Western blotting and confocal microscopy. Methanandamide, a stable analogue of anandamide acting as CB1R, CB2R, and TRPV1 agonist, stimulated or inhibited the depolarization-evoked gliosomal [(3)H]D: -aspartate release, at lower and higher concentrations, respectively. Experiments with ACEA (arachidonyl-2'-chloroethylamide), JWH133 ((6aR,10aR)-3-(1,1-dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]-pyran) and capsaicin, selective agonists at CB1R, CB2R and TRPV1, respectively, demonstrated that potentiation of [(3)H]D: -aspartate release was due to CB1R while inhibition to CB2R and TRPV1 engagement. These findings were confirmed by using selective receptor antagonists. Furthermore, CB1R activation caused increase of intracellular IP3 and Ca(2+) concentration, suggesting an involvement of phospholipase C.
Bari
Monica
M
Centro Europeo per la Ricerca sul Cervello/Fondazione Santa Lucia, Rome, Italy. bari@med.uniroma2.it
Bonifacino
Tiziana
T
Milanese
Marco
M
Spagnuolo
Paola
P
Zappettini
Simona
S
Battista
Natalia
N
Giribaldi
Francesco
F
Usai
Cesare
C
Bonanno
Giambattista
G
Maccarrone
Mauro
M
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism / Q000502:physiology*; D002186:Cannabinoids / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D063388:Endocannabinoids; D018698:Glutamic Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D050916:TRPV Cation Channels / Q000378:metabolism
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D063388:Endocannabinoids; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C119325:arachidonyl-2-chloroethylamide; C088155:methanandamide; D018698:Glutamic Acid; D002211:Capsaicin; C432747:1,1-dimethylbutyl-1-deoxy-Delta(9)-THC