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FLOW OF GLUCOSE CARBON INTO BRAIN LIPIDS IN ADULT RATS FOLLOWING FOOD DEPRIVATION
Author(s) -
Barkai A.,
Rapport M. M.
Publication year - 1975
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1975.tb07693.x
Subject(s) - chemistry , endocrinology , medicine , cholesterol , metabolism , lipid metabolism , specific activity , carbohydrate metabolism , in vivo , biochemistry , biology , enzyme , microbiology and biotechnology
— Rates of flow of glucose carbon in vivo into brain cholesterol, phospholipids, cerebrosides and gangliosides and concentrations of these lipids in the brain, were determined in adult rats after various periods of food deprivation. The rates were calculated from two measurements, the curve representing the decrease of plasma [ 14 C]glucose specific activity with time and the specific activity of the brain lipid 180 min after intravenous injection of a tracer dose of d ‐[U‐ 14 C]glucose. Specific activities of brain lipids in rats deprived of food for 72h were significantly higher than in postabsorptive rats which were treated with the same dose of [ 14 C]glucose. These higher specific activities were interpreted as a result of more labelled glucose available to lipid synthesis in the brain of fasted rats due to the substantial decrease in the rate of irreversible disposal of glucose by the whole body, commonly observed in fasted animals. The possibility that the higher specific activity values resulted from enhanced synthesis of brain lipids from glucose was ruled out since no changes were observed in the rate of flow of glucose carbon into brain lipids after food deprivation. The rate of flow of glucose carbon into gangliosides (15.4 ng C/min/mg C) was more than twice as fast as into either phospholipids or cerebrosides and about 4 times as fast as into cholesterol. The rates of carbon flow were used to calculate half lives of glucose carbon in the different classes of brain lipids. These half life values were 31 days for gangliosides, 72 days for phospholipids, 82 days for cerebrosides and 133 days for cholesterol. The results suggest that the synthesis of brain lipids from glucose is not affected by prolonged starvation in the adult rat.