RESUMO
Abstract Twenty-eight Wistar rats treated orally with 20% ethanol solution, were divided into two groups: adult group (n = 19) and aged group (n = 9) consisting of animals aged 4 and 12 months, respectively, at the beginning of the treatment. Neurons from the basal nucleus region were counted and the percentage of choline acetyltransferase-immunoreactive cholinergic neurons was determined in adjacent sections. Acetylcholine release and choline-acetyltransferase activity in the cerebral cortex were assessed in the same animals. Nutritional parameters of the ethanol treated animals were monitored and found to be normal. Chronic exposure to ethanol did not result in global neuronal loss or loss of cholinergic neurons in the basal nucleus region. However, a greater expression of ChAT-immunoreactivity in the basal nucleus region and a tendency toward increased ChAT activity in the cerebral cortex of the control and treated aged animals, compared respectively to adult ones, were observed. These findings suggest adaptive changes of the aged rats in response to the possible cholinergic hypofunction, manifested as a decreased release of acetylcholine under stimulated conditions.