Psychosine regulates MMP-3 expression differently in CNS microglia and peripheral blood cells/macrophages. Mixed glial culture, purified microglia, whole blood white cells, and peritoneal macrophages were treated with psychosine (10 μM) or LPS (10 μg/mL) for 4 hr, and MMP-3 mRNA expression level was analyzed by qRT-PCR (A, C, E, G). Also, to ensure the cellular responsiveness to stimulus, TNF mRNA expression level was also quantified (B, D, F, H). Note that CNS cells with psychosine treatment had increased MMP-3 expression (A and C), but not peripheral cells (E and G), although peripheral cells had increased TNF expression in response to LPS (F and H). N = 3–4/treatment/cell type. Data represent mean ± SEM. *P < 0.05, **P < 0.01.