RESUMO
Acute low doses of ethanol can produce reversible memory deficits, but it is unknown whether they persist upon chronic use. We investigated whether the chronic intake of a low dose of ethanol induces memory impairments in the ethanol-preferring C57BL/6J mouse strain. Because stress precipitates alcohol abuse and the stress hormone corticosterone contributes to memory processes, ethanol consumption and toxic effects, we also determined the impact of co-treatment with corticosterone on these effects. BDNF contributes to memory function and toxic effects of ethanol, therefore its levels were quantified in the hippocampus and frontal cortex. Ethanol (1% in drinking water) and corticosterone (250 µg/mL) were administered using the two-bottle choice test to monitor their appetitive properties. Spatial and non-spatial memory performance was assessed using the spontaneous alternation, object recognition and object location tests. The chronic exposure to a low dose of ethanol caused spatial and non-spatial memory deficits after withdrawal associated with a reduction in hippocampal BDNF levels, which were prevented by co-treatment with corticosterone (~21 mg/kg/day). The protective effect of corticosterone on memory was no longer observed at higher doses (~41 mg/kg/day), but persisted for hippocampal BDNF levels. C57BL/6J mice did not develop an appetence for 1% ethanol, but the addition of corticosterone increased voluntary consumption of and preference for the ethanol+corticosterone solutions. Although acute low doses of corticosterone (1 mg/kg) were found to rescue established memory impairments, this is the first report of a protective effect of chronic doses of corticosterone in the range of 20-32 mg/kg, and particularly against memory deficits induced by alcohol.
