Synaptic membrane alterations in rats exposed to alcohol.

Synaptic membranes were isolated from 2 and 4-month-old rats, pair-fed controls (PF), prenatally (PAE) or pre + postnatally (PPAE) exposed to alcohol, and the activities of some membrane-bound enzymes were measured. We found a 22-36% reduction in the levels of the (Na + K)ATPase, Ca++ATPase, acetylcholinesterase and 5'-nucleotidase from PAE rats. This reduction was greater in PPAE animals. The transition temperature in Arrhenius plots of the synaptosomal (Na + K)ATPase activity from PPAE rats was lower than in control rat membranes, indicating an alteration of lipid-protein interactions. No change in transition temperature was noted in PAE animals. Also, there was a decreased cholesterol content in PPAE synaptic membranes, vs. controls, while there was no change in PAE membranes. Kinetic parameters of the synaptosomal (Na + K)ATPase from PPAE rats, revealed a decrease in the Km and Vmax for potassium. These findings indicate that prenatal alcohol exposure probably delays synaptic development, whereas continued alcohol exposure during lactation may, in addition, alter the physicochemical structure of synaptic membranes.