Chronic nicotine causes functional upregulation of ionotropic glutamate receptors mediating hippocampal noradrenaline and striatal dopamine release

It has been proposed that (−)-nicotine can activate release-stimulating presynaptic nicotinic acetylcholine receptors (nAChRs) on glutamatergic nerve terminals to release glutamate, which in turn stimulates the release of noradrenaline (NA) and dopamine (DA) via presynaptic ionotropic glutamate receptors on catecholaminergic terminals. The objective of this study was to compare the function of N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazide-4-propionic acid (AMPA) glutamate receptors in synaptosomes of rat hippocampus and striatum following acute and chronic (−)-nicotine administration. In hippocampal synaptosomes, prelabeled with [<F>3H</F>]NA, both the NMDA- and AMPA-evoked releases were higher in (−)-nicotine-treated (10 days) than in (−)-nicotine-treated (1 day) or vehicle-treated (1 or 10 days) rats. In striatal synaptosomes prelabeled with [<F>3H</F>]DA, the NMDA-evoked, but not the AMPA-evoked, release of [<F>3H</F>]DA was higher in (−)-nicotine-treated (10 days) than in nicotine-treated (1 day) or vehicle-treated (1 or 10 days) animals. Chronic (−)-nicotine did not affect catecholamine uptake, basal release and release evoked by high-K+ depolarization. Thus, chronic exposure to nicotine enhances the function of ionotropic glutamate receptors mediating noradrenaline release in the hippocampus and dopamine release in the striatum. [Copyright &y& Elsevier]