Influence of nicotine on brain reward systems: study of intracranial self-stimulation

We used the rate-frequency curve-shift procedure to evaluate the effects of nicotinic blockers, locally infused into the mesopontine tegmentum or ventral tegmentum, on the threshold of brain stimulation reward. Mecamylamine, the nicotinic acetylcholine receptor blocker, was infused one hour before the self-stimulation of the medial forebrain bundle. When injected into the mesopontine tegmentum, mecamylamine shifted rate-frequency curves to the right. Similar effects were also observed when the drug was injected into the ventral tegmentum. Thus, in both the mesopontine tegmentum and the ventral tegmentum, nicotinic receptors appear to facilitate the rewarding effect of the self-stimulation.