Inhibition of glycolysis in brain by a phospholipid effect on interconversion of fructose phosphates. A possible regulatory control on utilization of glucose 6-phosphate.

Glucose 6-phosphate accumulation in 10,000 X g supernatant of rat brain was enhanced up to 16-fold by the addition of phosphatidylcholine, other common phospholipids, or linoleate. This glucose 6-phosphate is of endogenous origin via UDP-glucose and glucose 1-phosphate but not glucose. The accumulation is the result of inhibition of glycolysis by an effect of phospholipid on the interconversion of fructose 6-phosphate and fructose 1,6-bisphosphate. Brain is therefore capable of gluconeogenesis from fructose 1,6-bisphosphate. A regulatory function for phospholipid which coordinates glycolysis and other major routes of utilization of glucose 6-phosphate in brain, e.g. inositol synthesis, is proposed.