The threshold concentration of dietary ethanol necessary to produce toxic effects on hippocampal cells and synapses in the mouse.

A nutritionally complete liquid diet containing 0, 3, 5, or 7% ethanol was fed to C57 mice for 4 months and killed after a further 4 months on a standard food pellet diet. The number of pyramidal cells in Araldite sections of the hippocampus was not significantly reduced in any group relative to the zero alcohol intake group. Synaptic counts in the area occupied by the pyramidal cell basal dendrites showed the 7% alcohol group to have a reduced number of synaptic contacts, with no convincing differences between the other groups relative to the zero alcohol group. All measurements made collectively could not be used to distinguish 3 or 5% ethanol consuming animals from 0% ethanol consuming animals. Significant differences in body weight and dry brain weight were detected in the comparison of the group treated with 7% ethanol and 4-month recovery with the group receiving the 0% ethanol dose and 4-month recovery. It is concluded that maintaining mice on a diet containing not more than 5% ethanol has no adverse long-term structural effects on hippocampal pyramidal cells or synapses.