Prolonged depolarization of rat cerebral synaptosomes leads to an increase in vesicular glutamate content.
Glutamate accumulation into synaptic vesicles is a vital step in glutamate synaptic transmission. In this study, we have explored the possibility that vesicular glutamate storage may be subject to some regulation. Synaptosomes were depolarized and subjected to [3H] glutamate under non-depolarizing conditions, and vesicular [3H] glutamate content was determined by a filter-based assay. We present evidence here that prolonged depolarization of synaptosomes leads to an increase in vesicular glutamate content. Induction of this enhanced state is time- and temperature-dependent. The enhanced state has two components, one readily reversible and the other long-lasting. The up-regulation of glutamate storage capacity could lead to an increase in quantal size and play a role in modulation of glutamate transmission efficiency.
Bole
David G
DG
Mental Health Research Institute, University of Michigan Medical School, 205 Zina Pitcher Place, Ann Arbor, MI 48109-0720, USA.
Hirata
Koji
K
Ueda
Tetsufumi
T
D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D014316:Tritium; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
D014316:Tritium; D018698:Glutamic Acid; D011189:Potassium Chloride; D002122:Calcium Chloride