Prenatal Nicotine Exposure Alters the Responses to Subsequent Nicotine Administration and Withdrawal in Adolescence: Serotonin Receptors and Cell Signaling

Abstract

Offspring of women who smoke during pregnancy are themselves more likely to take up smoking in adolescence, effects that are associated with a high rate of depression and increased sensitivity to withdrawal symptoms. To evaluate the biological basis for this relationship, we assessed effects on serotonin (5-hydroxytryptamine, 5HT) receptors and 5HT-mediated cellular responses in rats exposed to nicotine throughout prenatal development and then given nicotine in adolescence (postnatal days PN30-47.5), using regimens that reproduce plasma nicotine levels found in smokers. Evaluations were then made during the period of adolescent nicotine treatment and for up to one month after the end of treatment. Prenatal nicotine exposure, which elicits damage to 5HT projections in the cerebral cortex and striatum, produced sex-selective changes in the expression of 5HT(1A) and 5HT2 receptors, along with induction of adenylyl cyclase (AC), leading to sensitization of heterologous inputs operating through this signaling pathway. Superimposed on these effects, the AC response to 5HT was shifted toward inhibition. By itself, adolescent nicotine administration, which damages the same pathways, produced similar effects on receptors and the 5HT-mediated response, but a smaller overall induction of AC. Animals exposed to prenatal nicotine showed a reduced response to nicotine administered in adolescence, results in keeping with earlier findings of persistent desensitization. Our results indicate that prenatal nicotine exposure alters parameters of 5HT synaptic communication lasting into adolescence and changes the response to nicotine administration and withdrawal in adolescence, actions which may contribute to a subpopulation especially vulnerable to nicotine dependence.