RT Journal Article SR Electronic T1 The Central Cannabinoid Receptor (CB1) Mediates Inhibition of Nitric Oxide Production by Rat Microglial Cells JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1357 OP 1366 VO 288 IS 3 A1 Yaakov Waksman A1 John M. Olson A1 Steven J. Carlisle A1 Guy A. Cabral YR 1999 UL http://jpet.aspetjournals.org/content/288/3/1357.abstract AB Upon activation, brain microglial cells release proinflammatory mediators, such as nitric oxide (NO), which may play an important role in the central nervous system antibacterial, antiviral, and antitumor activities. However, excessive release of NO has been postulated to elicit immune-mediated neurodegenerative inflammatory processes and to cause brain injury. In the present study, the effect of cannabinoids on the release of NO from endotoxin/cytokine-activated rat cortical microglial cells was evaluated. A drug dose-dependent (0.1 μM–8 μM) inhibition of NO release from rat microglial cells was exerted by the cannabinoid receptor high-affinity binding enantiomer (−)-CP55940. In contrast, a minimal inhibitory effect was exerted by the lower affinity binding paired enantiomer (+)-CP56667. Pretreatment of microglial cells with the Gαi/Gαo protein inactivator pertussis toxin, cyclic AMP reconstitution with the cell-permeable analog dibutyryl-cAMP, or treatment of cells with the Gαsactivator cholera toxin, resulted in reversal of the (−)-CP55940-mediated inhibition of NO release. A similar reversal in (−)-CP55940-mediated inhibition of NO release was effected when microglial cells were pretreated with the central cannabinoid receptor (CB1) selective antagonist SR141716A. Mutagenic reverse transcription-polymerase chain reaction, Western immunoblot assay using a CB1 receptor amine terminal domain-specific antibody, and cellular colocalization of CB1 and the microglial marker Griffonia simplicifolia isolectin B4 confirmed the expression of the CB1 receptor in rat microglial cells. Collectively, these results indicate a functional linkage between the CB1 receptor and cannabinoid-mediated inhibition of NO production by rat microglial cells. The American Society for Pharmacology and Experimental Therapeutics