CHOLESTEROL SULFATE IN RAT TISSUES - TISSUE DISTRIBUTION, DEVELOPMENTAL-CHANGE AND BRAIN SUBCELLULAR-LOCALIZATION

A reliable micromethod for the determination of the tissue level of cholesterol sulfate was developed. Cholesterol sulfate was separated from the bulk of the free cholesterol by silica gel column chromatography, and the cholesterol sulfate fraction subjected to benzoylation. A small amount of contaminating free cholesterol and other lipids remaining in this fraction were converted to benzoyl esters while the cholesterol sulfate remained unreacted. The cholesterol sulfate was then separated from the benzoylated contaminants by a 2nd silica gel chromatography column and subjected to solvolysis. The liberated cholesterol was determined by GLC. The cholesterol sulfate contents of the visceral organs [liver, thymus, lung, heart, spleen, kidney, brain, adrenal, eye, testis, prostate, uterus, ovaries] of 43 day old rats were determined. Every tissue examined contained small amounts of this sulfate. Kidney contained the highest concentration of cholesterol sulfate (250-300 .mu.g/g dry tissue weight) followed by spleen (77 .mu.g/g), adrenal gland (50-70 .mu.g/g) and lung (50-57 .mu.g/g). In brain, cholesterol sulfate level rises sharply from 17 .mu.g/g dry weight in 7 day old rats to more than 50 .mu.g/g in 15 day olds, then it declines rapidly to 15 .mu.g/g in the 40 day olds and this level is maintained to adulthood. The developmental pattern in the liver resembles that in the brain, except that the peak is somewhat flatter with the highest value (60 .mu.g/g dry weight) occurring in the 21 day old animal. In contrast to the above 2 tissues, the level of kidney cholesterol sulfate increases steadily from 15 .mu.g/g in 7 day olds and reaches the adult level of approximately 200 .mu.g/g in 50 day olds. The highest level of cholesterol sulfate in subcellular fractions of rat brain occurred in a fraction rich in nerve endings. The level here was 10 times higher than that in the mitochondrial fraction, which contained the lowest level of this steroid sulfate.