Glycosphingolipids in the spleen of developing rats

Splenic cholesterol, and glucosyl, lactosyl, trihexosyl, and sialyl lactosyl ceramides were studied in developing normal rats from birth to 96 days of age. Total lipid, extracted from pooled organs for each age group in the study, were subjected to mild alkaline hydrolysis and separated into purified glycolipid fractions in high yield, by a series of silicic acid column and thin-layer chromatographic procedures. Enzymatic and colorimetric methods were applied to quantitative analysis of each splenic glycosphingolipid fraction, and the fatty acids were analyzed by gas-liquid chromatography. Glycosphingolipid content in the total spleen increased over the period of the study. The most rapid increase occurred during the third and fourth weeks. There was also a 2.5-fold change in the concentration (per gram of tissue) of glucosyl and sialyl lactosyl ceramides, the principal glycosphingolipids of rat spleen. In contrast, cholesterol concentration increased only slightly. A precisely equimolar ratio of glucosyl and sialyl lactosyl ceramide was observed throughout all stages of splenic development. Fatty acid compositions of these two lipid fractions were always significantly different.