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Figure 1. CB2 receptors control neurosphere generation and neural progenitor cell proliferation in vitro. A) Self-renewal of E17.5 neural progenitors derived from WT and CB2–/– mice. The number of neurospheres was quantified after 5 consecutive neurosphere passages. Inset) Primary neurosphere generation in the two mouse strains. B) Primary neurosphere generation was determined after 7 d of exposure of neural progenitors (black bars) to vehicle (C), the CB2-selective agonists HU-308 or JWH-133 (30 nM) and/or the CB2-selective antagonist SR144528 (2 µM; SR). CB2–/– progenitors (gray bars) were also employed. C) Self-renewal of WT neural progenitors (solid line) incubated as above for 5 consecutive passages. Self-renewal of CB2-deficient progenitors in the presence of vehicle is also shown (dashed line). D) Quantification of BrdU-positive cells from dissociated neurospheres incubated as above for 16 h. E) Quantification of BrdU-positive cells (upper panel) and neurosphere generation (lower panel) of progenitors treated with vehicle (C), HU-308 (30 nM) and/or PD98059 (10 µM; PD) and/or LY294,002 (5 µM; LY). F) ERK and Akt phosphorylation after progenitor challenge with vehicle (C) or HU-308 (alone or in the presence of SR144528) for 15 min (ERK) or 2 min (Akt). Results correspond to 3 (A, C, E, and F) or 4 (B and D) independent experiments. Significantly different from control WT cells: *P < 0.05, ** P < 0.01.
