Methamphetamine exposure during the first, but not the second half of prenatal development, affects social play behavior.

Methamphetamine (MA), as a psychostimulant drug that crosses the placental barrier, may disrupt the development of social play. The present study aims to examine the effect of prenatal MA (5 mg/kg) exposure during the first (gestational day (GD) 1-11) or second (GD 12-22) halves of prenatal development of rats on social play behavior. To investigate an acute effect of MA on social play in adulthood, juvenile rats were exposed to a dose of 1 mg/kg MA or saline on the test day and tested for social play for 15 min. Prenatal exposure to MA during GD 1-11 increased social play behavior during 5-10 min interval of the test in males but not females. Prenatal MA during GD 12-22 did not influence social play in males nor females. However, social play occurred to a greater extent in GD 12-22 groups compared with GD 1-11. Acute exposure to MA eliminated playful behavior in all groups and decreased social exploration in GD 1-11. Our results suggest that manipulation of prenatal development during the first half of the gestational period has a greater impact on social play behavior than during the second half.