This proposal to study factors which influence differences in sensitivity to ethanol in mice is derived from the hypothesis that ethanol not only binds to the interior of neuronal membranes but also to the surface of the membrane. It is proposed that the interior bound ethanol exerts a disordering vector which is opposed by the ordering vector of the surface bound ethanol. These effects are dependent on both ethanol concentration and temperature. Preliminary results indicate that the degree of surface binding and hence its ordering effect is dependent on the nature of the membrane surface, in particular the ganglioside content. Delayed Fourier Transform 1H-NMR will be used to assess the degree of the ordering/disordering effects of ethanol simultaneously on the terminal methyl, methylene and choline methyl moieties of the membrane lipids. In these experiments, an increase in order results in a decrease in observed spectral intensity and vice versa. Deuterium-NMR will be used to determine the partition coefficients of the ethanol to the interior and the surface of the membrane. The thermodynamics of binding will be determined in all systems. The extent of the surface binding and the resulting order/disorder effects for diametric pairs of animals of differing ethanol sensitivity will be determined. These pairs include short sleep (SS) and long sleep (LS) mice and nonsensitive and ethanol sensitive mice culled from the HR strain. The question of whether surface effects are the primary differences in these pairs, will be addressed. One hypothesis to be tested is that the difference in ganglioside content between LS/SS mice is responsible for differences in the ethanol-induced surface effects. In this regard, preliminary evidence has shown that the addition of gangliosides to dipalmitylphosphatidylcholine liposomes has little effect on the amount of interior binding of the ethanol but the surface bound ethanol is much more mobile. Therefore, with the loss of the surface ordering vector, a marked increase in total ethanol-induced disordering is observed. We propose to initiate a systematic study of this """"""""ganglioside"""""""" effect. Although short sleep and long sleep mice show marked differences in their ethanol sensitivity, they are equally sensitive to butanol. Parallel studies with butanol will be conducted.
| Schroeder, F; Colles, S M; Kreishman, G P et al. (1994) Synaptic plasma membrane structure and polarity of long-sleep and short-sleep mice. Arch Biochem Biophys 309:369-76 |
