FIGURE 8.

GPR17 stimulation exclusively triggered short term ERK1/2 activation. A, kinetics of ERK1/2 phosphorylation in differentiating Oli-neu cells after treatment with 10 μm MDL29,951 (n = 6). B, phosphorylation ratio of ERK1/2 in Oli-neu cells after incubation with MDL29,951 for 10 min and 24 and 48 h compared with the phosphorylation peak detected upon 7 min treatment (n = 4). C, time-course of ERK1/2 phosphorylation triggered by 10 μm MDL29,951 in primary rat oligodendrocytes previously differentiated for 48 h in growth factor-free medium (n = 5). D, concentration-effect curve derived from the data (phosphorylation peak upon 5 min of treatment) of three separate experiments in oligodendrocytes. E, representative Western blot analysis of phosphorylated ERK1/2 (p-ERK1/2) reprobed for total ERK1/2 levels (t-ERK1/2) in differentiating primary rat oligodendrocytes after 24 and 48 h of incubation in the presence and absence of 10 μm MDL29,951. F, quantitative analysis of phosphorylated to total ERK1/2 ratios in oligodendrocytes from five independent experiments. G, MDL29,951-mediated short term phosphorylation (5 min) of ERK1/2 in oligodendrocytes is diminished after pretreatment with PTX (n = 5). H, PTX treatment does not affect phosphorylation of ERK1/2 triggered by 10% fetal calf serum (FCS) in oligodendrocytes (n = 3).