Smoking during early pregnancy affects the expression pattern of both nicotinic and muscarinic acetylcholine receptors in human first trimester brainstem and cerebellum

Prenatal nicotine exposure is associated with an increased risk of complications during pregnancy and childhood. In this study the expression of nicotinic and muscarinic acetylcholine receptors in first trimester pons, medulla oblongata and cerebellum from abortus (5-12 weeks of gestation) of smoking and nonsmoking women was compared. A significant age-related increase in binding of nicotinic receptor subtype alpha 4 was found in both pons and cerebellum only in fetal tissue from non-smoking women, while a similar increase was observed in medulla oblongata from fetuses exposed to smoking. A significant age-related increase in binding of muscarinic receptor subtype m(2) was observed in pons from abortus of smoking compared with non-smoking women. The gene expression pattern of both alpha 4 and alpha 7 nicotinic receptor subunits was changed after smoking in all three regions investigated. Smoking also changed the expression of m(1) and m(2) muscarinic receptor mRNA in pons, m(1) mRNA in cerebellum and the m(3) mRNA in medulla oblongata. The findings indicate that early prenatal nicotine exposure affects the normal developmental pattern of the cholinergic system in human fetal brain. (c) 2005 IBRO. Published by Elsevier Ltd. All rights reserved.