FIGURE 7.

Antagonist interactions between CB₁ and CB₂ receptors on neurite outgrowth. SH-SY5Y neuroblastoma cells (A) or SH-SY5Y cell transfected with 3 μg of cDNA corresponding to CB₂R-YFP (B) were treated for 24 h with 10 μm retinoic acid (RA), 100 nm ACEA, or 50 nm JWH 133 or pretreated for 30 min with 500 nm AM630 or AM251 antagonist prior to agonist treatment. Neurite outgrowth was measured as indicated under “Materials and Methods.” Results are expressed as the percentage of differentiated cells versus the total cell number in non-transfected cells or versus CB₂R-YFP-expressing cells (detected by their own fluorescence) in transfected cells. Results are expressed as means ± S.E. (error bars) of 8–12 fields in three independent experiments. Significant differences between treated and non-treated cells (***, p < 0.001) or between antagonized cells compared with cells activated with JWH 133 (###, p < 0.001) or ACEA (&&&, p < 0.001) were determined by a one-way ANOVA followed by post hoc Bonferroni's tests.