Nicotine exposure during the neonatal brain growth spurt produces hyperactivity in preweanling rats

Despite warning labels and increases in evidence of the adverse effects of tobacco use, women continue to use tobacco products during pregnancy. Cigar ette smoking has been linked to increased prenatal mortality, increased inc idence of SIDS, reductions in birth weight, and disruptions in CNS and beha vioral development. Animal model systems have critically established the ca usal relationship between nicotine and adverse developmental outcome. The p resent study examines the behavioral effects of nicotine exposure in the ra t during the third trimester equivalent of the human brain growth spurt, a period of rapid development of the cholinergic systems and a period during which the CNS is particularly vulnerable to a number of insults. Sprague-Da wley rat pups were exposed to nicotine (6.0 mg/kg/day) from postnatal days (PD) 4-9 via an artificial rearing procedure. This procedure ensures that o bserved effects are not due to nutritional deficits. Two control groups wer e employed, an artificially reared control group and a normally reared cont rol group. Activity level was measured on PD 18-19. Nicotine-exposed subjec ts were significantly overactive compared to both control groups, which did not differ significantly from one another. This behavioral alteration was observed in the absence of nicotine-induced body weight deficits. These res ults suggest that women who use tobacco products during late gestation may place their fetuses at risk for hyperactivity later in life, particularly d uring early adolescence. (C) 2000 Elsevier Science Inc. All rights reserved .