Long-term effects of neonatal methamphetamine exposure on cognitive function in adolescent mice

Exposure to methamphetamine during brain development impairs cognition in children and adult rodents. In mice, these impairments are greater in females than males. Adult female, but not male, mice show impairments in novel location recognition following methamphetamine exposure during brain development. In contrast to adulthood, little is known about the potential effects of methamphetamine exposure on cognition in adolescent mice. As adolescence is an important time of development and is relatively understudied, the aim of the current study was to examine potential long-term effects of neonatal methamphetamine exposure on behavior and cognition during adolescence. Male and female mice were exposed to methamphetamine (5 mg/kg) or saline once a day from postnatal days 11 to 20, the period of rodent hippocampal development. Behavioral and cognitive function was assessed during adolescence beginning on postnatal day 30. During the injection period, methamphetamine-exposed mice gained less weight on average compared to saline-exposed mice. In both male and female mice, methamphetamine exposure significantly impaired novel object recognition and there was a trend toward impaired novel location recognition. Anxiety-like behavior, sensorimotor gating, and contextual and cued fear conditioning were not affected by methamphetamine exposure. Thus, neonatal methamphetamine exposure affects cognition in adolescence and unlike in adulthood equally affects male and female mice.