Fig. 6

Cortisol-mediated sensitization depends on the GR. (A) Representative images of fish treated for 1 or 24 h with cortisol with or without pharmacological inhibition of the GR or MR, prior to treatment with 50 μM neomycin. Scale bar = 400 μm and applies to all images. (B) 1 h cortisol treatment does not significantly sensitize hair cells to neomycin damage. Co-treatment with cortisol and either the GR inhibitor RU486, the MR inhibitor epleronone, or both inhibitors, however, does lead to slightly increased hair cell loss relative to fish treated with neomycin only (1-way ANOVA: F_(4,33) = 6.091, p = 0.0009). (C) 24 h treatment with the GR inhibitor RU486 in combination with cortisol prior to neomycin treatment attenuated cortisol-mediated sensitization to neomycin, but inhibition of the MR (with epleronone) was not sufficient to attenuate cortisol-mediated sensitization (1-way ANOVA, F_(4,46) = 16.49, p < 0.0001). Post-hoc analysis for 1 or 24 h treatments was performed using Tukey's HSD test, *p < 0.05, **p < 0.01. ***p < 0.001, where all comparisons are relative to treatment with neomycin only. N = 6–12. Error bars = ± 1 s.d.