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Mechanisms for recycling and biosynthesis of endogenous cannabinoids anandamide and 2‐arachidonylglycerol
Author(s) -
Placzek Ekaterina A.,
Okamoto Yasuo,
Ueda Natsuo,
Barker Eric L.
Publication year - 2008
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2008.05659.x
Subject(s) - anandamide , endocannabinoid system , ionomycin , cannabinoid receptor , chemistry , biochemistry , extracellular , 2 arachidonoylglycerol , depolarization induced suppression of inhibition , biosynthesis , microbiology and biotechnology , cannabinoid , intracellular , biology , enzyme , receptor , agonist
The mechanisms of endogenous cannabinoid biosynthesis are not completely understood. We hypothesized that anandamide could be recycled by the cell to form new endocannabinoid molecules and released into the extracellular space. We determined that new endocannabinoids derived from exogenous anandamide or arachidonic acid were synthesized and released from RBL‐2H3 cells in response to ionomycin. Treatment of RBL‐2H3 cells with nystatin and progesterone, agents that disrupt organization of lipid raft/caveolae, resulted in the attenuation of anandamide and 2‐arachidonyl glycerol synthesis and/or release in response to stimulation with ionomycin suggesting a role for these membrane microdomains in endocannabinoid biosynthesis. Furthermore, anandamide synthesis may be independent of N ‐acyl phosphatidylethanolamine phospholipase D as expression of the enzyme was not detected in RBL‐2H3 cells. We also established that extracellular calcium is necessary for endocannabinoid biosynthesis because release of intracellular calcium stores alone does not promote endocannabinoid biosynthesis. Next, we examined the role of calcium as a ‘switch’ to activate the synthesis of anandamide and simultaneously reduce uptake. Indeed, [ 3 H] anandamide uptake was reduced in the presence of calcium. Our findings suggest a mechanism indicative of calcium‐modulated activation of anandamide synthesis and simultaneous termination of uptake.