Time course of the expression of FRA-like (Upper) and JunD-like (Lower) immunoreactivity after kainate administration as revealed by Western blot analysis. Representative photomicrographs from four separate experiments are shown. Immunostaining for a control rat from a 3-month (Control) time point is shown. There were no significant differences in the levels of FRA and JunD immunoreactivity from the control hippocampi at different time points. The kainate-injected groups were sacrificed after 3 hr (3 h), 3 days (3 d), 2 weeks (2 w), 4 weeks (4 w), 3 months (3 m), 7 months (7 m), and 1 year (1 y). Note that at least four bands of protein were recognized by the FRA antiserum at 3 hr after kainate treatment, but only one 35-kDa FRA was detected at 2 weeks after kainate treatment. JunD antiserum appears to recognize three bands of immunoreactivity at 43, 39, and 28 kDa.