Plasma corticosterone at expression.
Plasma corticosterone levels at the expression phase. All groups (n = 12) were habituated to the chamber for 30 min prior to receiving a challenge injection of MK-801 at T0. Corticosterone levels were unaltered by any prior treatment either at baseline (T-30) or 60min after MK-801 challenge (T60). Corticosterone levels did not significantly increase from baseline and were not affected by prior induction treatment of RU486 or MK-801. Data are presented as the mean ± SEM.