title: Synaptic vesicle-bound pyruvate kinase can support vesicular glutamate uptake.
abstract: Glucose metabolism is essential for normal brain function and plays a vital role in synaptic transmission. Recent evidence suggests that ATP synthesized locally by glycolysis, particularly via glyceraldehyde 3-phosphate dehydrogenase/3-phosphoglycerate kinase, is critical for synaptic transmission. We present evidence that ATP generated by synaptic vesicle-associated pyruvate kinase is harnessed to transport glutamate into synaptic vesicles. Isolated synaptic vesicles incorporated [(3)H]glutamate in the presence of phosphoenolpyruvate (PEP) and ADP. Pyruvate kinase activators and inhibitors stimulated and reduced PEP/ADP-dependent glutamate uptake, respectively. Membrane potential was also formed in the presence of pyruvate kinase activators. "ATP-trapping" experiments using hexokinase and glucose suggest that ATP produced by vesicle-associated pyruvate kinase is more readily used than exogenously added ATP. Other neurotransmitters such as GABA, dopamine, and serotonin were also taken up into crude synaptic vesicles in a PEP/ADP-dependent manner. The possibility that ATP locally generated by glycolysis supports vesicular accumulation of neurotransmitters is discussed.
authors.affiliation: Molecular and Behavioral Neuroscience Institute, University of Michigan Medical School, BSRB, Ann Arbor, MI 48109-2200, USA.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Ishida
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Noda
authors.forename: Tetsufumi
authors.initials: T
authors.lastname: Ueda