The endocannabinoid system in immortalized neural progenitors (ST14A cells): a role for CB2 receptors

According to recent views, endocannabinoids may constitute a new group of lipid signalling cues involved in the regulation of neurogenesis, in addition to actively intervening in different physiological brain contexts. The presence of a functional endocannabinoid system (eCBs) in neural progenitor (NP) cells may indicate a role of these molecules in important processes such as cell proliferation and differentiation. We have investigated this occurrence in the ST14A immortalised neural progenitors cell line, derived from embryonic day 14 rat striatum primordia. We found by RT-PCR, ICC and WB that ST14A cells express various components of the eCBs, including synthetic and degradative enzymes, several receptors among which TRPV1, cannabinoid receptor1 (CB1) and 2 (CB2). In particular, CB2 was more abundantly expressed than CB1 under both proliferating and differentiating conditions. By incubating ST14A cells for 24 hrs with serial concentrations of 2-arachidonoylglycerol (2-AG), an increase in the number of cells was found at 5?M. A similar increase was found by incubating the cells with a CB2 specific agonist (300nM JWH133). Such effect was reverted by co-incubation with a CB2 specific antagonist (300 nM AM630), which had no effect when administered alone. A proliferation assay based on BrdU incorporation confirmed the above results. Changes in cell morphology and in the staining pattern of cytoskeletal components, such as the intermediate filament nestin, were observed in the various experimental conditions. Our data demonstrate the expression of a full eCBs and suggest its modulatory role in proliferating ST14A neural progenitors, setting the basis for future investigation of the intracellular mechanisms involved and possible crosstalks with other signaling systems. Differential modulations related to specific cell cycle and maturation stages are also important issues to be clarified.