Ethanol consumption produces changes in behavior and on hippocampal alpha7 and alpha4beta2 nicotinic receptors

Ethanol consumption produces a wide range of effects on the central nervous system, most of them related to changes in neural receptors. In vitro studies have demonstrated that ethanol increases neural nicotinic acetylcholine receptor (nnAChR) affinity for ACh (Narahashi et al., 1991) and have also reported differences in sensitivity of nnAChRs for ethanol, depending on the subunit composition of the receptor (Cardoso et al., 1999). There is evidence that ethanol induces changes in density of nnAChRs in cellular cultures (Gorbounova et al., 1998). However, there are no clear results concerning the effects of chronic ethanol on nicotinic receptors and on behavior in rats nonselected by their preference to ethanol. A number of studies demonstrate that nnAChRs participate in a variety of functions, including memory and learning processes, neurodegeneration, and neuroprotection (Picciotto et al., 2000). In the present work, we found significant alterations in the Fixed-Interval Behavioral Test, as well as in density and affinity parameters of hippocampal main subtypes of nnAChRs: alpha7 homopentamers and alpha4beta2 heteropentamers of ethanol-drinking rats nonselected by their preference to ethanol.