[Ganglioside-dependent factor inhibiting lipid peroxidation in synaptosomal membranes]

The inhibitory effect of exogenous monosialoganglioside GM1 on lipid peroxidation was studied in synaptosomal membranes from rat brain. When this effect was studied over a wide GM1 concentration range, the biphasic kinetics was observed, the highest per cent of inhibition (70%) was found at GM1 concentration of 10(-9)- 10(-8) M. In liposomes made from lipids isolated from rat synaptosomal membranes the inhibition of lipid peroxidation by exogenous GM1 was much less pronounced (25% at maximum) it reached the saturation at ganglioside concentration of 10(-8)-10(-6) M. The thermal denaturation (90 degrees C), storage at 0 degrees C, addition of polymyxin B result in considerable decrease of inhibitory effect of GM1 on lipid peroxidation in synaptosomal membranes. On the contrary phorbol-12-myristate-13-acetate (10(-6)M) or Ca2+ (2.10(-3)M) inhibit lipid peroxidation in synaptosomal membranes, the presence of exogenous GM1 in incubation medium having additional inhibitory effect. Possible mechanisms of ganglioside participation in regulation of functional activity of excitatory membranes are discussed.