The role of GTP-binding protein activity in fast central synaptic transmission.
Guanosine 5'-triphosphate (GTP)-binding proteins (G proteins) are involved in exocytosis, endocytosis, and recycling of vesicles in yeast and mammalian secretory cells. However, little is known about their contribution to fast synaptic transmission. We loaded guanine nucleotide analogs directly into a giant nerve terminal in rat brainstem slices. Inhibition of G-protein activity had no effect on basal synaptic transmission, but augmented synaptic depression and significantly slowed recovery from depression. A nonhydrolyzable GTP analog blocked recovery of transmission from activity-dependent depression. Neither effect was accompanied by a change in presynaptic calcium currents. Thus, G proteins contribute to fast synaptic transmission by refilling synaptic vesicles depleted after massive exocytosis.
Takahashi
T
T
Department of Neurophysiology, University of Tokyo Faculty of Medicine, Tokyo 113-0033, Japan. ttakahas-tky@umin.ac.jp
Hori
T
T
Kajikawa
Y
Y
Tsujimoto
T
T
D000200:Action Potentials; D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials; D005089:Exocytosis; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D066298:In Vitro Techniques; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000378:metabolism*; D013873:Thionucleotides / Q000494:pharmacology
D013873:Thionucleotides; D006153:Guanosine Diphosphate; C032829:6-thioguanosine 5'-diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D002118:Calcium