Effect of methamphetamine exposure and cross-fostering on sensorimotor development of male and female rat pups.

The present study tested the hypothesis that cross-fostering influences the development of rat pups. Mothers were exposed daily to injection of methamphetamine (M) (5 mg/kg) or saline for 9 weeks: 3 weeks prior to impregnation, throughout gestation and lactation periods. Control females animals without any injections were used. On postnatal day (PD) 1, pups were cross-fostered so that each mother received four pups of her own and eight pups from the mothers with the other two treatments. Offspring were tested for sensorimotor development in preweaning period by using tests of: negative geotaxis, tail pull, righting reflexes, rotarod and bar-holding. Further, the pups were weighed daily. Our results showed that birth weight in prenatally M-exposed pups was lower than in control or saline-exposed pups. Prenatally M-exposed pups gained less weight than control or saline-exposed pups regardless of postnatal treatment and sex. Further, our data demonstrated that prenatal and postnatal M exposure impairs sensorimotor functions in most of the tests. On the other hand, the negative effect of prenatal M exposure was partially suppressed in prenatally M-exposed pups by cross-fostering to control dams. Our hypothesis that cross-fostering may affect postnatal development of pups was confirmed.