Upregulation of [3H]methyllycaconitine binding sites following continuous infusion of nicotine, without changes of alpha7 or alpha6 subunit mRNA: an autoradiography and in situ hybridization study in rat brain.

It is well established that exposure of experimental animals to nicotine results in upregulation of the alpha4beta2-subtype of neuronal nicotinic acetylcholine receptors (nAChRs). The aim of this study was to determine the effect of nicotine on the levels of alpha7-nAChRs in rat brain, for which only partial information is available. Rats were infused with nicotine (3 mg/kg/day) or saline for 2 weeks and their brains processed for receptor autoradiography with [3H]methyllycaconitine (MLA), a radioligand with nanomolar affinity for alpha7-nAChRs.