Fig 1. Experimental timeline.

Timeline of the study. Behavioural testing was completed on the first cohort of animals (a) and corticosterone analysis on the second cohort (b). During the induction phase (Days 1–7) rats were sensitised with injections of MK-801 (0.25mg/kg) or Saline. Thirty min prior to these injections either RU486 (20mg/kg) or Vehicle (DMSO) was administered. In the second cohort blood samples were collected from the saphenous vein on Days 1, 4 and 7. The time points are relative to the MK-801 or saline injection at T0. The first sample was collected at T-60 min prior to habituation to the test chamber. After 30 min habituation (T-30) rats were injected with RU486 or Vehicle and the next sample was taken after 30min at T0. Rats were then injected with MK-801 or Saline and the third blood sample was collected 60min later at T60. At day 13, all rats were administered MK-801 to test for the expression of sensitisation. The first blood sample was taken at T-30, prior to habitation to the test chamber. At T0 rats were administered with MK-801 and the second blood sample was collected 60min later at T60.