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. 2010 Jan 27;11(2):173–185. doi: 10.1007/s10162-009-0205-8

FIG. 4.

FIG. 4

Early activation of MAPK pathway is necessary for maximal response in FSK-induced BrdU incorporation. Cochlear explants were cultured for 72 h with 100 µM FSK in standard medium in the presence or absence of ERK MAPK inhibitors for three different time periods: all 72 h, last 48 h, or last 24 h. After 72 h in culture, cochleas were fixed and processed for immunocytochemistry, and the number of BrdU-labeled nuclei were counted. The standard media contained 10% fetal calf serum and 0.01% BrdU. A Bar graph showing the average number of FSK-induced BrdU-labeled nuclei per cochlea in the presence of 10 µM Radicicol for three different time periods. All three conditions tested significantly inhibited FSK-induced BrdU incorporation compared with FSK only cochleas (p < 0.001 for all 72 h cochleas; p < 0.005 for last 48 h cochleas; p < 0.05 for last 24 h cochleas). The average number of BrdU-labeled cells per cochlea was 234 ± 39.5 for FSK only, n = 5; 1.8 ± 0.7 for all 72 h, n = 6; 27 ± 21 for the last 48 h, n = 5; and 104.28.5 ± 4.9 for the last 24 h, n = 5. B Bar graph showing the average number of FSK-induced BrdU-labeled nuclei per cochlea in the presence of 10 µM U-126 for three different time periods. Two conditions, all 72 h and the last 48 h, significantly inhibited FSK-induced BrdU incorporation compared with FSK only cochleas (p < 0.001). The average number of BrdU-labeled cells per cochlea was 263 ± 30.5 for FSK only, n = 5; 19.5 ± 5.4 for all 72 h, n = 7; 39.6 ± 10.6 for the last 48 h, n = 6; and 184.2 ± 34.3 for the last 24 h, n = 5. C Bar graph showing the average number of FSK-induced BrdU-labeled nuclei per cochlea in the presence of 50 µM PD98059 for three different time periods. All three conditions tested significantly inhibited FSK-induced BrdU incorporation compared with FSK only cochleas (p < 0.001 for all 72 h cochleas and last 48 h cochleas; p < 0.005 for last 24 h cochleas). The average number of BrdU-labeled cells per cochlea was 294 ± 29.9 for FSK only, n = 6; 39.5 ± 15.9 for all 72 h, n = 6; 45.7 ± 5 for the last 48 h, n = 5; and 128.4 ± 18 for the last 24 h, n = 5.