AMPA receptors are Ligand gated ion channels.The ligand (signalling molecule) they are complementary to is a Glutamate which is the main excitatory neurotransmitter in the CNS, this means there is a high proportion of these AMPA receptors on postsynaptic neurons in the brain.
When Glutamate binds to AMPA receptors it causes a conformational change and the ion channel opens allowing Na+ ions to flood into the postsynaptic cell. The increase in Na+ concentration causes depolarisation of the postsynaptic membrane generating an EPSP ( which if strong enough can go on to initiate an action potential at the axon hillock). Repetitive stimulation of these synapses in the brain can cause LTP (Long-term potentiation) , due to more Glutamate being released across the synaptic cleft binding to more AMPA receptors which leads to a higher influx of Na+ ions into the cell generating a stronger EPSP. This strong depolarisation of the post-synaptic member aids to the activation of NMDA receptors (along with glutamate binding) which allow Ca2+ ions to enter the post synaptic cell. This increase in Ca2+ concentration can cause new AMPA receptors to be inserted in to the post-synaptic membrane increasing the sensitivity of the post-synaptic cell to Glutamate .
- ↑ Bruce Alberts, e. a., 2008. Molecular Biology of the cell. 5th ed (pg 690). New York: Garland Science.