Membrane fluidity and alcohol dependence.

Rats were chronically intoxicated with alcohol by exposing them to increasing concentrations of ethanol vapor over a 4-week period. They were tested for alcohol consumption in a free choice situation of water and 10% (v/v) alcohol. On the basis of their intakes they were divided into alcohol-dependent and nondependent groups. Synaptosome membrane fluidity evaluated by fluorescence polarization was compared between the two groups and against nonintoxicated controls. The intoxicated animals had a lower membrane fluidity than controls, mainly because of a highly significant increase of rigidity in the alcohol-dependent group. Furthermore, membrane fluidity was found to be correlated with the degree of behavioral dependence (i.e., alcohol intake during the free choice period).