Modulation of presynaptic store calcium induces release of glutamate and postsynaptic firing.
Action potential-independent transmitter release is random and produces small depolarizations in the postsynaptic neuron. This process is, therefore, not thought to play a significant role in impulse propagation across synapses. Here we show that calcium flux through presynaptic neuronal nicotinic receptors leads to mobilization of store calcium by calcium-induced calcium release. Recruitment of store calcium induces vesicular release of glutamate in a manner consistent with synchronization across multiple active zones in the CA3 region of the rat hippocampus. This modulation of action potential-independent release of glutamate is sufficient to drive the postsynaptic pyramidal cell above its firing threshold, thus providing a mechanism for impulse propagation.
Sharma
Geeta
G
Department of Physiology and Biophysics and The Neuroscience Program, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
Vijayaraghavan
Sukumar
S
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009538:Nicotine / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000502:physiology; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology; D017661:Receptors, Presynaptic / Q000502:physiology*
D011978:Receptors, Nicotinic; D017661:Receptors, Presynaptic; D018698:Glutamic Acid; D009538:Nicotine; D002118:Calcium