Psychostimulants, including methamphetamine (MA), haveneurotoxic effect,
especially, if they are targeting CNS during its critical periods of development. The present study was aimed to examine cognitive changes after prenatal and neonatal MAtreatment in combination with chronic MA
exposure in adulthoodof male rats. Eight groups of male rats were tested in adulthood:males whose mothers were exposed to MA (5 mg/kg) or saline(SA, 1 ml/kg) during the first half of gestation period (GD 1-11),the second half of gestation period (GD 12-22) and neonatalperiod (PD 1-11). In addition, we compared indirect neonatalapplication via the breast milk
with the group of rat pups that received MA or SA directly by injection
(PD 1-11). Males weretested in adulthood for cognitive changes in the
Morris WaterMaze (MWM). MWM experiment lasted for 12 days: Learning(Day 1-6), Probe test (Day 8) and Retrieval Memory test
(Day 12). Each day of the MWM animals were injected with MA(1 mg/kg)
or SA (1 ml/kg). Prenatal MA exposure did not inducechanges in learning abilities of male rats, but neonatal exposureto MA leads to an increase search errorsand latencies to find thehidden platform. Prenatal and also
neonatal MA exposureimpaired cognitive ability to remember the position of the platform in Retrieval Memory test in adulthood. Animals exposed to the
prenatal treatment within the second half of gestation(ED 12-22) swam longer, slower and spent more time to find the hidden platform in Retrieval Memory test than animals exposedthroughout other periods. The present
study demonstrated thatstage of development is crucial for determination
the cognitivedeficits induced by prenatal or neonatal MA exposure.