Cross-fostering effect on postnatal development of rat pups exposed to methamphetamine during gestation and preweaning periods Marie Pometlova ´ , Lenka Hruba ´, Romana S ˇ lamberova ´ *, Richard Rokyta Charles University in Prague, Third Faculty of Medicine, Department of Normal, Pathological and Clinical Physiology, Ke Karlovu 4, 120 00 Praha 2, Prague, Czech Republic 1. Introduction One of the most serious problems of the last and present centuries is drug-, alcohol-, and nicotine-abuse. The drug-abuse, especially, is getting more serious during the last few decades. Statistics show that the number of infants with drug-related birth defects has increased dramatically over the past several years (Marwick, 2000). Psychoactive drugs cross easily the placental barrier and therefore they may affect the development of the fetus (Cho et al., 2001). Furthermore, the newborns may receive these drugs also postnatally in mother’s breast milk (Cho et al., 2001). The drug abuse of pregnant women and mothers is therefore not only a serious social problem, but also serious health problem that is necessary to deal with. Beside the direct influence of the drug on morphological and functional development of offspring, drugs have also indirect effects. It was shown that drug-abusing women are less scrupulous in the prenatal as well as postnatal care of their children (Vavr ˇı ´nkova ´ et al., 2001). They are in 90% single mothers and deliver generally in younger ages than mothers, who do not abuse drugs (Vavr ˇı ´nkova ´ et al., 2001). They are often unemployed women with economic and social problems and do not take good care for their children. This usually results in judicial takeaway of the child from the drug-abusing mother. All this may lead to psychic deprivation and mental retardation of the child. Thus, not only the drug abuse by itself, but also worse maternal care may induce irreversible changes in the development of children. In agreement with clinical works, the experimental studies (Bridges and Grimm, 1982; S ˇ lamberova ´ et al., 2005b, 2006) demonstrated that rat mothers, who received drugs during pregnancy displayed decreased maternal behavior toward their pups that may alter healthy development of their pups. This impairing effect may affect even second generation that was not exposed to the drug at all (S ˇ lamberova ´ et al., 2007, 2005d). Moreover, it was shown (Peters, 1982; Schindler et al., 2004) that placebo injection of saline administered to pregnant mothers may induce mild stress for the rat and that way indirectly affect the development of her pups. There are studies demonstrating that prenatal stress may alter the healthy development of the pups similarly as prenatal drug exposure (Peters, 1982; Schindler et al., 2004). Int. J. Devl Neuroscience 27 (2009) 149–155 ARTICLE INFO Article history: Received 8 July 2008 Received in revised form 10 November 2008 Accepted 26 November 2008 Keywords: Methamphetamine Development Sensorimotor Homing test Maturation Cross-fostering Breeding ABSTRACT There are studies showing that drug abuse during pregnancy may have a long-term effect on progeny of drug-abusing mothers. Our previous work demonstrated that prenatal and/or postnatal methamphe- tamine injections impair maternal behavior. The purpose of the present study was to assess the effect of prenatal methamphetamine or stress exposure and postnatal breeding on postnatal development of rat pups. Female rats were injected with methamphetamine (5 mg/kg daily) or physiological saline prior, during and after gestation. Absolute controls did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received some of her own and some of the pups from the mothers with the other two treatments. Pups were weighted daily for the entire lactation period. Postural motor reaction development was examined daily by righting reflex between postnatal day 1 and 12. On postnatal day 15 homing test examining pups’ nest-seeking behavior was performed. On postnatal day 23 rotarod and bar-holding tests were used to investigate sensorimotor coordination of pups. We demonstrated that prenatal methamphetamine exposure impairs performance of sensorimotor tests (righting reflex on surface and rotarod test). Moreover, the effect of methamphe- tamine as well as the effect of prenatal stress induced by saline injections was affected by postnatal breeding conditions in sensorimotor tests as well as in the test of homing. Our results support the hypothesis that the variation in rat maternal care could serve as a mechanism for a nongenomic behavioral mode of transmission of traits. ß 2008 ISDN. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +420 224902713; fax: +420 224902750. E-mail address: rslamber@lf3.cuni.cz (R. S ˇ lamberova ´). Contents lists available at ScienceDirect International Journal of Developmental Neuroscience journal homepage: www.elsevier.com/locate/ijdevneu 0736-5748/$34.00 ß 2008 ISDN. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijdevneu.2008.11.006