Pharmacological and molecular characterization of a dorsal root ganglion cell line expressing cannabinoid CB1 and CB2 receptors

The behavioral effects evoked by cannabinoids are primarily mediated by the CB1 and CB2 cannabinoid receptor subtypes. In vitro pharmacology of cannabinoid receptors has been elucidated using recombinant expression systems expressing either CB1 or CB2 receptors, with limited characterization in native cell lines endogenously expressing both CB1 and CB2 receptors. In the current study, we report the molecular and pharmacological characterization of the F-11 cell line, a hybridoma of rat dorsal root ganglion neurons and mouse neuroblastoma (N18TG2) cells, reported to endogenously express both cannabinoid receptors. The present study revealed that both receptors are of mouse origin in F-11 cells, and describes the relative gene expression levels between the two receptors. Pharmacological characterization of the F-11 cell line using cannabinoid agonists and antagonists indicated that the functional responses to these cannabinoid ligands are mainly mediated by CB1 receptors. The non-selective cannabinoid ligands CP 55,940 and WIN 55212-2 are potent agonists and their efficacies in adenylate cyclase and MAPK assays are inhibited by the CB1 selective antagonist SR141716A (SR1), but not by the CB2 selective antagonist SR144528 (SR2). The endocannabinoid ligand 2AG, although not active in adenylate cyclase assays, was a potent activator of MAPK signaling in F-11 cells. The analysis of CB1 and CB2 receptor gene expression and the characterization of cannabinoid receptor pharmacology in the F-11 cell line demonstrate that it can be used as a tool for interrogating the endogenous signal transduction of cannabinoid receptor subtypes.