The effect of chronic ethanol consumption on the fine structure of the CA1 stratum oriens in short-sleep and long-sleep mice: short-term and long-term exposure.

The effect of chronic ethanol administration on the fine structure of the hippocampal CA1 stratum oriens was examined in two lines of mice selectively bred for their differential sensitivity to acute ethanol exposure (long-sleep, LS and short-sleep, SS mice). Two experiments were performed. In the first experiment, mice received a liquid diet for 3 weeks with the final amount of ethanol being 35% ethanol-derived calories. In the second experiment, mice received 23.5% ethanol-derived calories for 3 months. Quantitative electron microscopy of the dendritic spines and synaptic appositions in the stratum oriens of CA1 revealed an interaction between diet and line of mice, but only in the 3-month exposure condition. This difference was due to a significant decrease in the density of spines and synaptic appositions in the LS mice receiving ethanol. Additionally, baseline differences between lines indicate that the lines are differing in the density of spine synapses in the absence of ethanol treatment. The possible interaction between acute sensitivity to ethanol and differences in fine structure are examined.