Abstract— Synaptosomes isolated from rat cerebral cortex converted [l‐14C]glucose more rapidly than [6‐24C]glucose to ,14CO2. The ratio of C‐l: C‐6 in 14CO2 was 3‐9, thus suggesting that the hexose monophosphate shunt (HMP) pathway was functional in synapses in vitro. When changes in the ratio of C‐l: C‐6 in 14CO2 were used as an index of shunt activity, glucose oxidation by this route was stimulated by electron acceptors as well as by neurohormones, including norepinephrine, acetylcholine and serotonin. Brain mince also exhibited a C‐l: C‐6 ratio of 3‐2 when short (15 min) incubations were employed. Negative results previously reported are attributable to prolonged incubation during which depletion of NADP or randomization of the labelled carbons in radioactive glucose could have occurred. Our experiments excluded the incorporation of glucose into macromolecules as a specific role for the hexose monophosphate pathway. The generation of NADPH for numerous metabolic reactions including the maintenance of membrane SH groups and the oxidation and hydroxylation reactions may represent the functions of the hexose monophosphate in synaptosomes and account for its stimulation by neurohormones.

Original languageEnglish (US)
Pages (from-to)1619-1626
Number of pages8
JournalJournal of Neurochemistry
Issue number12
StatePublished - Jan 1 1970

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience


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