[H-3]nicotine binding in peripheral blood cells of smokers is correlated with the number of cigarettes smoked per day

The principal sites for biological action of tobacco products are thought t o be the nicotinic acetylcholine receptors (nAChR). Nicotinic receptor subu nit genes, therefore, represent an important gene family for study in nicot ine addiction. They are localized in both brain and in the periphery. In br ain these receptors appear to function as modulators of synaptic transmissi on; the function of peripheral receptors is not known. Nicotinic receptor l evels in human brain are regulated by smoking in a dose-dependent manner. I n peripheral blood, nicotinic receptors are present on both lymphocytes and polymorphonuclear cells (PMN). We have compared [H-3]nicotine binding in P MN isolated from smokers and non-smokers. [H-3]nicotine binding was increas ed in smokers and was correlated, as in brain, with tobacco use. Expression of both mRNA and protein in lymphocytes and PMN, for a subset of nicotinic receptor subunits, suggests that these cell types contain both alpha4 beta 2 and alpha3 beta4 receptors. (C) 2000 Elsevier Science Ltd. All rights res erved.