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. 2016 May 4;157(7):2785–2798. doi: 10.1210/en.2016-1123

Figure 4. Experiment 3: test of CORT fast feedback, silent period, and delayed feedback in adrenal-intact rats.

Figure 4.

CORT infusion (0.31 mg/kg) 60 minutes (delayed feedback test), 15 minutes (silent period test), or 30 seconds (fast feedback test) prior to restraint onset substantially suppressed restraint-induced ACTH levels compared with time-matched vehicle infusion. In contrast, CORT infusion 5 minutes after restraint onset (fast feedback test) had no significant effect on subsequent stress-induced ACTH levels for the time period examined, suggesting a stress-state fast feedback resistance. Note the substantial inhibition produced by the very short (30 sec) prestress treatment interval and the similarly effective inhibition produced by the 15-minute CORT prestress treatment, a pretreatment interval resulting in declining CORT levels at the time of stress onset (see Figure 2), suggesting an absence of a putative feedback silent period. *, Significantly different from vehicle-treated rats at same time point (P < .05; n = 8–9).