Morphological alterations in rat CA1 hippocampal pyramidal cell dendrites resulting from chronic ethanol consumption and withdrawal.

Hippocampal CA1 pyramidal cell dendrites were studied in rats after 5 months of consumption of an ethanol liquid diet and 5 months of ethanol diet followed by 2 months of withdrawal. Morphometric data were compared with those obtained from matched littermate, yoke -fed control animals. Dendritic branching in Golgi-Cox-stained tissues was assessed by standard and modified Sholl analysis techniques and basilar dendrites were analysed three-dimensionally by computer. Five months of chronic ethanol consumption caused a significant decrease in the number of second-order basilar dendrites, 60-90 micron from the apical border of the cell layer. No significant changes in the neuronal density of CA1 or CA3 cells were found; however, the thickness of the strata oriens and radiatum of the CA1 field was significantly decreased in the ethanol-fed group. After 5 months of chronic ethanol consumption and 2 months of withdrawal, the thickness of the strata returned to control sizes and the frequency of proximal basilar branching recovered. Evidence of lengthening and new branching of distal basilar dendrites occurred in the third-, fourth-, and fifth-order segments when control animals 6 and 8 months of age were compared. During the 2-month period of withdrawal, the number and length of third-, fourth-, and fifth-order segments of basilar dendrites increased when compared to the nonwithdrawn ethanol group while the number and length of second- and third-order segments decreased. This is comparable to the changes seen during normal aging and suggests that withdrawal may interact with aging to produce enhanced dendritic growth in "compensation" for the developmental retardation induced by chronic ethanol intake.