Effect of ethanol on the development and maturation of synapses in the rat hippocampus: a quantitative electron-microscopic study.

The effects of chronic ethanol administration on the development and maturation of synapses in the strata radiatum and lacunosum-moleculare of CA1 in the hippocampus were quantitatively examined in rats exposed to ethanol for the entire period of fetal life as well as the whole period of postnatal life. Synapse densities in the strata radiatum and lacunosum-moleculare of the ethanol-treated group were significantly lower than those of the control group at 2, 14, 21, and 70 days of age. However, the rates of density reduction did not change between either of the strata that receive different groups of afferent fibers. The ratio of axospinous to axoshaftic synapses also did not change between control and ethanol-treated groups. These data suggest that chronic administration of ethanol reduces the density of synapses in this area and that this effect is not specific to neither the type of afferent fibers nor the type of synapses.