LATE-ONSET CHRONIC ALCOHOL CONSUMPTION EFFECTS ON THE TOTAL NUMBER OF CHOLINERGIC NEURONS OF THE LATERODORSAL TEGMENTAL NUCLEUS OF THE RAT: AN UNBIASED STEREOLOGICAL STUDY

Aims: The brain cholinergic system comprises two main recognized subdivisions, the basal forebrain and the brainstem cholinergic nuclei. The effects of aging and chronic alcohol consumption on the former nuclei have been extensively investigated, but there are few studies that have examined those effects on the latter nuclei. Furthermore, to the best of our knowledge, no studies have addressed the cumulative effects of aging and late-onset chronic alcohol intake on the laterodorsal tegmental nucleus (LDT), a cell group that is part of the brainstem cholinergic system.
Methods: Using unbiased stereological methods, we analyzed the LDT cholinergic population in male Wistar rats. To compare different ages of onset, alcohol was administered for 6 months starting at either 2 or 18 months of age. The total number of LDT choline acetyltransferase (ChAT)-immunoreactive neurons was estimated in four groups: adult control, adult-ethanol treated, old control and old-ethanol treated animals (n=5 per group).
Results: We found that neither aging nor chronic alcohol intake induced alterations in the total number of LDT cholinergic neurons.
Conclusions: These results suggest a remarkable resistance of the LDT cholinergic neurons to aging and prolonged alcohol consumption compared to other brain cholinergic populations, and highlight the relevance of finding the factors that are putatively involved in this greater resistance. The present data are even more relevant as there is evidence that alcohol use disorder is a growing public health problem in the elderly population, and several elderly alcoholics had onset of alcohol use later on in their age.