Neuronal perikarya and astroglia of rat brain: chemical composition during myelination.

Cells isolated by a new technique from 10-, 20-, and 30-day-old rat brains have been analyzed for total lipid, cholesterol, galactolipid, individual phospholipids, gangliosides, DNA, and RNA. The lipid composition does not vary appreciably in either neurons or astrocytes during this period of rapid myelination. Moreover, the lipid compositions of the two cell types are surprisingly similar, both having very low galactolipid concentrations, high phospholipid content, and cholesterol concentrations lower than whole brain. Astrocytes have a higher ganglioside content than neuronal perikarya, a finding ascribed to the higher ratio of surface membrane to mass in the astrocytes, and considered as evidence that gangliosides are normal glial constituents. Compared with an average astrocyte, the individual neuron soma has less mass, a lower total lipid content, and a much higher RNA content.