Stabilization of synaptic membranes by alpha-tocopherol against the damaging action of phospholipases. Possible mechanism of biological action of vitamin E.
Using fluorescent and ESR-spin probes, the effects of phospholipases A2, C and D on rat brain synaptosomal membranes were investigated. It was shown that the exposure of synaptosomal membranes to phospholipases A2, C and D results in their depolarization and an increase of the negative surface potential. In the case of phospholipases A2 and C, these changes are associated with a decrease of the microviscosity of the membrane lipid bilayer. alpha-Tocopherol stabilizes synaptosomal membranes against the damaging action of the phospholipases. This stabilization consists in the reconstitution of the transmembrane potential and an increase of microviscosity of the phospholipase-treated membranes. The stabilizing effect of alpha-tocopherol is due to the binding of phospholipid hydrolysis products, but not to the inhibition of phospholipases. The observed stabilization of synaptosomal membranes by alpha-tocopherol is regarded as a possible mechanism of biological action of vitamin E on biomembranes.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000648:ultrastructure*; D008563:Membrane Lipids / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D010739:Phospholipase D / Q000494:pharmacology; D010740:Phospholipases / Q000494:pharmacology*; D010741:Phospholipases A / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013570:Synaptic Membranes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013696:Temperature; D010738:Type C Phospholipases / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology*
D008563:Membrane Lipids; D014810:Vitamin E; D010740:Phospholipases; D010741:Phospholipases A; D010738:Type C Phospholipases; D010739:Phospholipase D