AMPA receptor

<xmlns:texthelpns rwthpgen="1">AMPA receptors are </xmlns:texthelpns>Ligand gated ion channels<xmlns:texthelpns rwthpgen="1">.The ligand (signalling molecule) they are complementary to is a </xmlns:texthelpns>Glutamate<xmlns:texthelpns rwthpgen="1">which is the main excitatory </xmlns:texthelpns>neurotransmitter<xmlns:texthelpns rwthpgen="1">in the </xmlns:texthelpns>CNS<xmlns:texthelpns rwthpgen="1">, this means there is a high proportion of these AMPA receptors on postsynaptic neurons in the brain.</xmlns:texthelpns>
<xmlns:texthelpns rwthpgen="1">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.</xmlns:texthelpns><xmlns:texthelpns rwthpgen="1">The increase in Na+ concentration causes depolarisation of the postsynaptic membrane generating an</xmlns:texthelpns>EPSP<xmlns:texthelpns rwthpgen="1">( which if strong enough can go on to initiate an </xmlns:texthelpns>action potential<xmlns:texthelpns rwthpgen="1">at the axon hillock).</xmlns:texthelpns><xmlns:texthelpns rwthpgen="1">Repetitive stimulation of these synapses in the brain can cause LTP (</xmlns:texthelpns>Long-term potentiation<xmlns:texthelpns rwthpgen="1">) , 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.</xmlns:texthelpns><xmlns:texthelpns rwthpgen="1">This strong depolarisation of the post-synaptic member aids to the activation of </xmlns:texthelpns>NMDA receptors<xmlns:texthelpns rwthpgen="1">( along with glutamate binding) which allow Ca2+ ions to enter the post synaptic cell.</xmlns:texthelpns><xmlns:texthelpns rwthpgen="1">This increase in Ca 2+ 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.</xmlns:texthelpns>

References

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