Glutamic acid (also known as Glutamate) is a negatively charged amino acid with an acidic side chain. It is a vital component in the excitatory pathways of the nervous system in mammals with it's gated ion channels being the most common ion channels found in the brain. Glutamate ion channels found in the hippocampus are responsible for most of the depolarizing currents of Excitatory PostSynaptic Potentials (EPSPs).
Furthermore, Glutamic acid (Glutamate) is involved in Long Term Potentiation (LTP). LTP is an example of synaptic plascitity. Glutamate is firstly released from the pre-synaptic neuron. Glutamate then binds to 2 inotropic receptors AMPA and NMDA (the NMDA at this point is currently blocked by magnesium ions though.)
The AMPA receptor is a Na+ channel so an EPSP is triggers. The EPSP is converted to an action potential is the threshold value (-55mV) is reached. The depolarization caused as a result trigges the Mg2+ to be ejected from the NMDA receptor. This causes the NMDA receptor to open. As a result, Ca2+ ions flow through the NMDA receptor.
The Ca2+ activates secondary messenger pathways, and so post-synaptic cell becomes more sensitive to glutamate. The release of Ca2+ causes enhanced neurotransmitter release (so enhanced glutatmate from the pre-synaptic cell.) For example, the Ca2+ can trigger a phorphorylation cascade, causing the phosphorylation of the glutamate receptor channels (AMPA and NMDA.)
LTP leads to an increase in the quality (and quantity) of synaptic transmission .
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