Impact of prenatal methamphetamine exposure on the sensitivity to the same drug in adult male rats.

There are only few studies that examine the effect of prenatal methamphetamine (MA) exposure on the sensitivity to the same drug and the drug-seeking behavior in adulthood. The aim of the present study was to examine the effect of prenatal MA exposure on exploratory behavior and nociception with respect to challenge dose of the same drug. Mothers of the tested offspring received a daily injection of MA (5 mg/kg) or saline throughout the gestation period. Adult male offspring (prenatally MA- or saline-exposed) were divided to groups with challenge dose of MA (1 mg/kg) or saline. A modified Open field test (Laboras) was used to examine behavior in unknown environment. Plantar test was used to measure nociception on forelimbs, hind limbs, and the tail. Conditioned place preference (CPP) test was used to examine drug-seeking behavior. Our results in Laboras demonstrated that prenatal MA exposure sensitized the animals to the challenge dose of MA. Specifically prenatally MA-exposed animals that received the challenge MA in adulthood displayed higher locomotion and rearing activity relative to all the other groups. The Plantar test data suggest analgesic effect of MA (1 mg/kg), which however, did not differ based on the prenatal drug exposure. The results of CPP test showed that MA (5 mg/kg) conditioning resulted in increased drug-seeking behavior, but this effect was not affected by prenatal drug exposure. Thus, our data demonstrate that the effects of prenatal MA exposure and the challenge dose of the same drug in adulthood depend on behavioral model used.