Figure 2. Noise exposure induces rapid UPR upregulation in the cochlea in vivo.
(A–H) To investigate the temporal evolution of the UPR after acoustic overstimulation, we exposed 8-week-old male WT CBA/J mice to 8–16 kHz octave-band noise for 2 hours at 98 dB SPL (A–D), which induces TTS, or 106 dB SPL (E–H), which induces PTS. The 2 cochleae from each animal were harvested and pooled at the indicated time points after noise exposure for qPCR measurement of BiP, S-Xbp1, and Chop mRNA expression using the 2–ΔCt method relative to Gapdh expression and normalized against control (unexposed) levels. Data were cleaned by removing outliers (ROUT method, q = 1%; 9 of 312 (2.9%) data points removed) and compared with 1-way ANOVA with Dunnett’s test for multiple comparisons against control for each condition. Data are presented as means ± SEM, with individual animals shown as dots. *P < 0.05; **P < 0.01. n = 12 mice (CTL, 98 dB); 8 (CTL, 106 dB); 6 (0, 2, 12, 24 hours, 98 dB and 106 dB); 6 (2 weeks, 106 dB); 4 (2 weeks, 98 dB).