Effects of nicotine on odor-induced increases in regional blood flow in the olfactory bulb in rats.

The present study examined the effects of nicotinic acetylcholine receptor activation on the odor-induced blood flow response in the olfactory bulb. In urethane-anesthetized rats, odor stimulation (5% amyl acetate, 30 s) produced an increase in olfactory bulb blood flow (reaching 107% ± 3% of the pre-stimulus basal values), without changes in frontal cortical blood flow or mean arterial pressure. Intravenous injection of nicotine (30 μg/kg), a nicotinic acetylcholine receptor agonist, significantly augmented the odor-induced increase response of olfactory bulb blood flow, without changes in the basal blood flow level. The nicotine-induced augmentation of the olfactory bulb blood flow response to odor was negated by dihydro-β-erythroidine, an α4β2-preferring nicotinic acetylcholine receptor antagonist. Our results suggest that the activation of α4β2-like neuronal nicotinic acetylcholine receptors in the brain potentiates an odor-induced blood flow response in the olfactory bulb.