Synaptic fusion pore structure and AMPA receptor activation according to Brownian simulation of glutamate diffusion.
The rising phase of fast, AMPA-mediated Excitatory Post Synaptic Currents (EPSCs) has a primary role in the computational ability of neurons. The structure and radial expansion velocity of the fusion pore between the vesicle and the presynaptic membrane could be important factors in determining the time course of the EPSC. We have used a Brownian simulation model for glutamate neurotransmitter diffusion to test two hypotheses on the fusion pore structure, namely, the proteinaceous pore and the purely lipidic pore. Three more hypotheses on the radial expansion velocity were also tested. The rising phases of the EPSC, computed under various conditions, were compared with experimental data from the literature. Our present results show that a proteinaceous fusion pore should produce a more marked foot at the beginning of the rising phase of the EPSC. They also confirm the hypothesis that the structure of the fusion pore and its radial expansion velocity play significant roles in shaping the fast EPSC time course.
Ventriglia
Francesco
F
Istituto di Cibernetica E.Caianiello del CNR, Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy. franco@biocib.cib.na.cnr.it
Maio
Vito Di
VD
D000818:Animals; D002490:Central Nervous System / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism / Q000502:physiology; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology*; D008959:Models, Neurological; D017729:Presynaptic Terminals / Q000502:physiology*; D018091:Receptors, AMPA / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013570:Synaptic Membranes / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000502:physiology*; D013997:Time Factors
D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid