Methamphetamine administration during gestation impairs maternal behavior

Previous studies demonstrated that repeated drug exposure, such as opiates or cocaine, during the gestation period attenuates maternal behavior of rats; however, it is not known whether methamphetamine (MA), a drug whose usage has increased recently, negatively affects maternal behavior as well. Therefore, the present study tested the hypothesis that repeated subcutaneous administration of MA (5 mg/kg daily) throughout the entire gestation period alters maternal behavior. Dams (control, saline-, and MA-treated) were observed with their pups in two types of tests. In the observation test, 11 types of activities and three types of nursing positions of mothers were recorded 10 times during each 50-min session for the 22-day lactation period. A decrease in nursing and active maternal behavior was found in MA-treated mothers relative to control rats. In addition, stereotypic behavior such as rearing and sniffing was increased in MA- as well as in saline-treated mothers relative to controls. All mothers, regardless of the treatment, displayed significantly less maternal behavior and more nonmaternal activities as postpartum time progressed. In the retrieval test, mothers also were tested for pup retrieval from postpartum Days 1 through 12. MA-treated mothers were slower in retrieving the first pup, returning the first pup into the nest, and returning all pups into the nest relative to controls or saline-treated mothers. Interestingly, the latency to return all pups to the nest was longer in saline-treated mothers relative to controls. In conclusion, the present study demonstrates a novel finding that MA administered during the gestation period has a negative effect on maternal behavior.