Fig. 1.

Cannabinoids inhibit [³H]thymidine incorporation into EOC-20 microglia with no effect on cell cycle or MTT reduction. (A) [³H]Thymidine incorporation assay. Cannabinoids were present during the 4-h [³H]thymidine incubation. Results are expressed as a percent of control, and vertical lines represent SEM (n = 4); the single-site competition equation was used to determine IC₅₀. (B) PTx treatment during [³H]thymidine incorporation assay. Cells were treated with 100 ng/ml PTx during the 24-h stimulation with LMCM; THC or vehicle was added for the final 4 h. Indicated concentrations are in nM. Results are shown as a percentage of control proliferation; respective controls are shown. Treatment with PTx alone resulted in ≈70% of normal proliferation (n = 6). (C) MTT assay. EOC-20 microglia were treated for 24 or 48 h with vehicle, THC, or CBD before assaying for reduction of MTT tetrazolium salt. Indicated concentrations are in nM; shown are the means and SEM of the resulting absorbance at 562 nm. (D) Cell cycle analysis by FACS after 4 h of treatment with THC. To exclude fragmented or fused cells, cells per cell cycle stage were calculated as a percentage of total gated cells (n = 2).