Fig. 9.

CR8 potently attenuated up-regulation of cyclin D1 and cysteine–cysteine chemokine ligand 21 (CCL21) expression in cultured neurons stimulated by conditioned medium (CM) derived from lipopolysaccharide (LPS)-activated microglia, as well as microglial proliferation and activation in vitro. (a, b) CM from cultured microglia stimulated by LPS or saline were applied to primary neuronal culture. Protein expression of cyclin D1 and CCL21 was up-regulated when the neurons were co-cultured with LPS-treated CM compared with saline-treated CM (*p < 0.05 compared with control group, n = 4 from 3 independent cultures), and significantly attenuated with CM from CR8 treatment prior to incubation with LPS (#p < 0.05 compared with LPS group, n = 4 from 3 independent cultures). (c, d) Pre-treatment with CR8 in cultured microglia significantly attenuated LPS-induced both microglial proliferation and release of nitric oxide in a dose-dependent manner. The effect of CR8 was similar to that of flavopiridol, but 10–20-fold higher potency than roscovitine (*p < 0.05 compared with LPS alone-treated group, n = 4 from 4 independent cultures). GAPDH = glyceraldehyde 3-phosphate dehydrogenase