AMPA receptor

AMPA receptors are Ligand gated ion channels.The ligand (signalling molecule) they are complementary to is aGlutamate 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 .