Fig. 5

Microglial deramification is observed in Nrf2-KO mice after 90 dB SPL noise exposure, but not in WT mice. (a) Representative images of IBA1-stained microglia in the auditory cortex of Nrf2-KO and WT mice under control conditions and following noise exposure. In the control group, microglia displayed a ramified morphology, indicative of a resting state. After 5 and 14 days of noise exposure, some microglia in the Nrf2-KO group exhibited activated morphology (white arrows), whereas no morphological changes were observed in the WT group. (b-d) Microglial morphological alterations were quantified as indicators of activation. Five days post-exposure, the number of microglial branches significantly decreased in the Nrf2-KO group (b). At both 5 and 14 days after noise exposure, the total branch length of microglia in the Nrf2-KO group was significantly reduced (c), and the ratio of the cell body to total cell size increased (d), suggesting enhanced microglial activation. No significant differences were observed in the microglial activation index in the WT group (n = 4 or 5). Scale bars = 50 μm and 10 μm. Data are expressed as mean ± SEM. *, **, and *** denote P < 0.05, P < 0.01, and P < 0.001, respectively, for comparisons between Nrf2-KO and WT groups. ### indicates P < 0.001 compared to control groups, with color coding representing the group being compared. Nrf2-KO nuclear factor erythroid 2-related factor 2 knockout, WT wild-type, IBA1 ionized calcium-binding adapter molecule 1, SEM standard error of the mean.