Membrane properties and aging: In vivo and in vitro effects of ethanol on synaptosomal γ-aminobutyric acid (GABA) release

It has been reported previously that biological membranes from aged mice are disordered less by ethanol as compared with membranes from younger animals. The purpose of this study was to determine whether those age differences would be associated with changes in membrane transport as measured by release of γ-aminobutyric acid (GABA). GABA release in the presence and absence of ethanol was measured in synaptosomes from young (4 months), middle (14 months) and aged (28 months) C57BL/6NNIA male mice. In addition, the effects of chronic ethanol administration on GABA release was examined in young and aged mice. GABA release was inhibited more by ethanol in synaptosomes from young mice as compared with older mice. The IC₅₀ for ethanol was significantly lower for the younger mice than for the older mice. GABA release in the presence of ethanol was affected by chronic ethanol administration. Inhibition of release was significantly less for young ethanol-tolerant as compared with young control animals. Release did not differ significantly between the old ethanol and old control groups. Inhibition of GABA release was found to be highly related to the membrane/buffer partition coefficient of n-alcohols. The results of the present study are consistent with our earlier finding that membranes from aged mice are disordered less by ethanol as compared with younger mice.