Ethanol exposure following unilateral entorhinal deafferentation alters synaptic reorganization in the rat dentate gyrus: a quantitative analysis of acetylcholinesterase histochemistry.
The phenomenon of reactive synaptogenesis in the dentate gyrus following partial deafferentation was used to assess quantitatively the effects of ethanol exposure on neuronal plasticity. Adult male Long-Evans rats received unilateral lesions of the entorhinal cortex, followed by 40 days of dietary ethanol exposure. Synaptic reorganization of the commissural/associational (C/A) and cholinergic (primarily septal) afferents was evaluated in the dentate gyrus processed for acetylcholinesterase (AChE) histochemistry. The widths and optical densities of several laminae in the molecular layer were measured using a computer-based digital imaging system. The degree of reorganization was assessed by comparing the lesioned side to the unlesioned side in each animal (difference scores were calculated). In the exposed blade of the dentate gyrus, the lesion-induced expansion of the C/A width was reduced significantly in the ethanol group. However, in the buried blade, there was an actual shrinkage of the C/A zone in the ethanol group. There was also a tendency for less "clearing" or lightening of the AChE staining in the C/A zone of both blades. On the lesioned side, the ethanol group also displayed a significantly greater condensation or darkening of the AChE staining in the proximal outer molecular layer than the pair-fed control group. The supragranular layer of both blades ipsilateral to the lesion was reduced in width in the ethanol group. These results indicate that exposure to ethanol following partial deafferentation disrupts the normal pattern of synaptic reorganization in the dentate gyrus.
Orona
E
E
Gainesville Veterans Administration Medical Center, Florida.
Hunter
B E
BE
Walker
D W
DW
D000110:Acetylcholinesterase / Q000378:metabolism; D000344:Afferent Pathways / Q000502:physiology; D000428:Alcohol Drinking; D000818:Animals; D001835:Body Weight; D003714:Denervation; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D006624:Hippocampus / Q000201:enzymology / Q000502:physiology*; D006651:Histocytochemistry; D008032:Limbic System / Q000502:physiology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology*
D000431:Ethanol; D000110:Acetylcholinesterase