Figure 1. Timeline of the experimental design.

Animals were exposed to increasing doses of THC (2.5, 5 and 10 mg/kg or vehicle, i.p.) from pnd 28 to 45, and to MDMA (10 mg/kg or saline, s.c.) twice daily every 5 days from pnd 30 to 45 with an inter-dose interval of 4 h (n = 16 animals per experimental group, see text for details). One day after the last drug administration, on pnd 46, the holeboard test (HB) was performed, immediately followed by the elevated plus maze test (EPM). The novel object test (NOT) was performed on pnd 75, and open-field (OF) data obtained from the first day of habituation to the arena on pnd 71 was also used. The animals were submitted to the prepulse inhibition test (PPI) on pnd 84. Thereafter, around pnd 90 (pnd 89–92), the animals were sacrificed and their brain was collected for future analyses. In addition, blood samples were extracted from the tail vein on pnd 50 for endocrine measurements, and from the trunk at sacrifice.