Fig. 4.
Injury-induced upregulation of CP-AMPARs was dependent on protein synthesis. A: incubation with the protein synthesis inhibitor anisomycin (40 μM) prevented upregulation of CP-AMPARs at 4 h post-injury. The percent inhibition of [Ca2+]i oscillation amplitude by Naspm (50 μM) was significantly greater at 4 h post-injury for untreated injured neurons (47.8 ± 6.4%, n = 57 cells from 5 wells) compared with untreated control neurons (7.1 ± 5.6%, n = 50 cells from 5 wells, ***P < 0.001), anisomycin-treated injured neurons (8.5 ± 4.1%, n = 55 cells from 5 wells, ###P < 0.001), or anisomycin-treated controls (10.3 ± 6.3%, n = 30 cells from 3 wells, +++P < 0.001). Percent inhibition by Naspm did not differ between anisomycin-treated injured neurons, untreated control neurons, or anisomycin-treated control neurons (P > 0.05). B: [Ca2+]i oscillation amplitude was significantly decreased for anisomycin-treated injured neurons 4 h post-injury (0.18 ± 0.02) compared with control (0.25 ± 0.02, **P < 0.01) or untreated injured neurons (0.25 ± 0.01, ##P < 0.01). Recordings were made in the presence of BMI and APV. C: percentage of anisomycin-treated injured neurons displaying basal [Ca2+]i oscillations (23.6%) was significantly smaller than untreated control neurons (50.9%, **P < 0.01), anisomycin-treated control neurons (47.4%, ##P < 0.01), and untreated injured neurons (62.8%, n = 43, +++P < 0.001). D: [Ca2+]i oscillation frequency was significantly decreased for untreated injured neurons (0.038 ± 0.002 Hz) and anisomycin-treated injured neurons (0.037 ± 0.002 Hz) compared with untreated control (0.056 ± 0.004 Hz, ***P < 0.001) and anisomycin-treated control neurons (0.062 ± 0.006 Hz, ###P < 0.001).