Figure 1. Increased plasma ACTH and corticosterone response to restraint stress, but not to ether exposure in GF mice.

A, mice were subjected to a 1 h period of restraint stress (GF, n = 6–11 for each time point, total of 52 animals; SPF, n = 6–11 for each time point, total of 50 animals). The baseline data were obtained by cardiac puncture from mice that were killed by cervical dislocation before stress exposure. The baseline ACTH and corticosterone levels in the GF and SPF mice were 49 ± 12 pg ml⁻¹ and 23 ± 4.2 ng ml⁻¹, in the GF mice, 46 ± 13 pg ml⁻¹ and 19 ± 5.6 ng ml⁻¹, respectively. P < 0.05, **P < 0.01, ***P < 0.001 in Dunnett's post hoc test between GF and SPF. B, GF and SPF mice failed to show any difference in HPA response to ether exposure (n = 6 for each time point, total of 30 animals per group).