LIPID COMPOSITION AND METABOLISM OF CULTURED HAMSTER BRAIN ASTROCYTES

Abstract— The lipid composition and metabolism of confluent cultures of cells derived from newborn hamster brain and having morphology characteristic of immature astrocytes or spongioblasts was investigated and compared to that of newborn hamster brain dispersions and cloned glioma cells (C6). The cells displayed stable morphology for at least 30 subcultures; thereafter spontaneous transformation occurred. No appreciable changes were observed in either composition or metabolic characteristics of any major neutral lipid or phospholipid class in successive subcultures or following transformation. The overall lipid composition of the hamster astrocyte cultures closely resembled that of newborn hamster brain, but the phospholipid composition showed substantial differences. The cells contained as a percent of lipid P relatively more ethanolamine plasmalogen, choline plasmalogen and sphingomyelin and somewhat less phosphatidylcholine and phosphatidylethanolamine. The phospholipids of the hamster astrocyte and C6 cells were similar. Of the lipid precursors examined, [U-¹⁴C]glucose was incorporated best into all preparations. C6 glioma cells incorporated both [U-¹⁴C]glucose and [1-¹⁴C]acetate most actively. From 69–88% of ³²P incorporated into hamster astrocyte phospholipids was present in choline phosphoglycerides, whereas the corresonding figure for hamster brain dispersions was 53%. The ratio of specific activities of phosphatidylcholine to phosphatidylinositol was substantially higher in the cultured cells than in the brain preparations. The small pool of choline plasmalogen in the hamster astrocytes usually achieved the highest specific activity of any phospholipid. When [U-¹⁴C]glucose and [1-¹⁴C]acetate were precursors, the bulk of label in the astrocytes appeared in choline phosphoglycerides and triacyglycerol. Our results indicate that the hamster astrocyte cell line as grown expresses distinctive features of lipid composition and metabolism which are nearly constant through many generations.