Age-related differences in synaptosomal membrane fluidity.

Fluidity of the lipid bilayer near the surface of the membranes and in the core of the lipid bilayer of synaptosomal membranes isolated from the cortex, hippocampus, striatum, hypothalamus, midbrain, pons-medulla oblongata and cerebellum of mice at 1, 2, 4, 12, and 18 months of age was examined using electron spin resonance spectrometry. Using the spin labels, 5- and 16-DS-stearic acid, the order parameter for 5-DS was found to be increased in all brain areas with aging and a much greater increase was found in the hippocampus and cerebellum at 18 months of age. The results demonstrated that there was a different pattern of the increase of the parameter between 15-DS and 16-DS in synaptosomal membranes of different brain regions with aging.