Jd. Thomas et al., Nicotine exposure during the neonatal brain growth spurt produces hyperactivity in preweanling rats, NEUROTOX T, 22(5), 2000, pp. 695-701
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
.