Treating rat pups with MDMA during different preweaning periods (postnatal days 1–5, 6–10, 11–15, or 16–20) produced lasting effects. The three highest doses (15, 20, and 25 mg/kg) reduced spontaneous locomotor activity during the first 10 minutes of testing, especially when given on days 1–5 or 6–10. All MDMA-treated groups showed impaired allocentric learning in the Morris water maze during both acquisition and reversal phases; the two highest doses also impaired performance on the small platform phase. No effects were found on anxiety, novel object recognition, or egocentric learning, though a nonsignificant trend appeared. The results indicate that allocentric and egocentric learning have different exposure-duration sensitivities and that the stress hyporesponsive period is not critical for MDMA's effects on allocentric learning.
Treating young rats with either MDMA or the club drug 5-MeO-DIPT from postnatal days 11 to 20 caused lasting cognitive and behavioral changes, but the patterns differed between the two drugs. MDMA-treated animals showed increased anxiety, deficits in spatial and path integration learning, and memory problems. 5-MeO-DIPT-treated animals had spatial learning deficits but no impairments in spatial memory or path integration learning, and they were hyperactive when given a challenge dose of methamphetamine. The findings indicate that developmental exposure to either drug produces distinct behavioral effects.
In rats, treatment with the recreational drug MDMA during a developmental period equivalent to the human third trimester causes long-term spatial and egocentric learning and memory deficits, along with serotonin reductions. Pretreatment with the antidepressant citalopram, a selective serotonin reuptake inhibitor, did not prevent these cognitive deficits. Unexpectedly, citalopram alone produced learning deficits as severe as those caused by MDMA. These are the first findings showing cognitive impairments from developmental exposure to a selective serotonin reuptake inhibitor, suggesting the need for further research on the long-term safety of antidepressants during pregnancy.