[Mechanism of the stabilization of synaptosomes with alpha-tocopherol during activation of lipid peroxidation]

Abstract

Using the fluorescent probe technique, it was shown that activation of lipid peroxidation decreases the value of transmembrane potential of rat brain synaptosomes. Depolarization of synaptosomes may be due to the impairment of the "barrier" properties of synaptosomal membranes and the decrease in Na,K-ATPase activity. alpha-Tocopherol and its model derivative devoid of the phytol chain--2,2,5,7,8-pentamethyl-6-oxychromanol--stabilize the transmembrane potential value during inhibition of lipid peroxidation. alpha-Tocopherol acetate causes no stabilizing or inhibiting effects. Unlike 2,2,5,7,8-pentamethyl-6-oxychromanol, alpha-tocopherol exerts a structuralizing action which manifests itself in the stabilization of the synaptosomal membrane potential during incomplete inhibition of lipid peroxidation. The previously established ability of alpha-tocopherol to protect synaptosomes from the damaging action of phospholipases and the experimental results of this work permit to regard vitamin E as a universal stabilizer of brain synaptosomal membranes.