EFFECTS OF CHRONIC ALCOHOL-CONSUMPTION ON THE CHOLINERGIC INNERVATIONOF THE RAT HIPPOCAMPAL-FORMATION AS REVEALED BY CHOLINE-ACETYLTRANSFERASE IMMUNOCYTOCHEMISTRY

The specific aim of this study was to evaluate whether the cholinergic innervation of the hippocampal formation is affected by chronic alcoh ol consumption in the rat. Choline acetyltransferase-immunoreactive fi bres and neurons were analysed in both alcohol-fed and control rats us ing a monoclonal antibody against choline acetyltransferase and quanti tative methods. We found a global reduction in the cholinergic plexus, which was more pronounced in the hippocampus proper than in the denta te gyrus. The areal density of choline acetyltransferase immunoreactiv e neurons was also reduced. Differences from controls in neuronal numb er were particularly striking in the stratum lacunosum moleculare of t he regio superior, which is precisely the zone of the hippocampal form ation where choline acetyltransferase immunoreactive neurons are more abundant in controls. In conclusion, our results show that prolonged e thanol consumption leads to a substantial reduction in the cholinergic innervation of the hippocampal formation, as there was a loss of chol inergic fibres and also an apparent loss of hippocampal cholinergic ne urons. These findings may help to explain the cognitive dysfunctions o bserved after chronic alcohol consumption.