Fig. 6.

Effect of acute glucocorticoid injection on noise stress-induced corticosterone secretion during the diurnal nadir. Single injection of methylprednisolone (PRED, 500 μg, n = 12, ▴) given 15 min before the onset of a 30-min white noise stress (104 dB, shaded area) caused a significant attenuation of the corticosterone response compared with saline-injected controls (n = 10, ■). Asterisks indicate time points that significantly differ between groups before injection of CRH (P < 0.05, repeated-measures ANOVA). Injection of CRH (1 μg, iv) at 100 min confirmed pituitary-adrenal responsiveness. Data are mean ± sem.