Mesolimbic dopamine activation--the key to nicotine reinforcement?

The mesolimbic dopaminergic system appears to mediate the rewarding effects of certain stimulant drugs, such as (+)amphetamine. Autoradiographic mapping techniques have revealed that these neurons are potential targets for nicotine, since they possess nicotinic receptors located on their cell bodies and terminals in rat brain. Functional studies are consistent with this proposal: nicotine can increase the firing rate of these neurons, and nicotine-induced dopamine release has been demonstrated in vitro and in vivo. The locomotor stimulant effect resulting from the acute administration of nicotine is accompanied by, and appears to be dependent upon, activation of mesolimbic neurons. Likewise, destruction of this system appears to attenuate the acute rewarding effects of intravenous nicotine in rats. Thus, when administered intermittently, nicotine, like certain other stimulant drugs, may activate the mesolimbic dopamine system, and this action may contribute to the tobacco habit.