A comparative-evolutionary study of lipids in the aging brain of mice.

The lipids of aging brain were studied using a comparative-evolutionary model involving two species of mice, Mus Musculus (Mus) and Peromyscus leucopus (Peromyscus). Mus ages 2.5 times faster than does Peromyscus. Brain weight, water content, cholesterol, and ethanolamine plasmalogen decreased and phosphatidyl ethanolamine increased in both species with age. Differences between species included 12% more cholesterol/g total lipid extract in Peromyscus than in Mus throughout life, a linear increase with age in lipid phosphorus/g fresh weight at a faster rate in Peromyscus over Mus, and a linear increase in the total lipid extract weight throughout life in Mus but a decrease in Peromyscus. Cerebroside, sulfatide and GM1 ganglioside all increased during maturation and then decreased in old age in both mice. Lipid-bound sialic acid (ganglioside) increased linearly throughout life in Peromyscus but decreased slightly in Mus. These changes are interpreted to mean that the cellular membranes of Peromyscus may be inherently more stable than those of Mus, Peromyscus is better able to preserve its neuronal cell population with age than is Mus, proliferation of non-myelin membranes may occur in both species in advanced age, and both species of mice may experience some loss of myelin with age.