Question

When glutamate binds to it's ionotropic receptors, including __, it can also cause an __ in the post-synaptic neuron by letting __ into the cell.

a) AMPA; excitatory post-synaptic potential (EPSP); Ca++

b) NMDA; inhibitory post-synaptic potential (IPSP); Cl-

c) G-protein coupled receptors; inhibitory post-synaptic potential (IPSP); K+

d) Kainate; excitatory post-synaptic potential (EPSP); Na+

e) NMDA; excitatory post-synaptic potential (EPSP); Ca++

Answer 1

Ionotropic receptors or Ionotropic glutamate receptors are ligand gated ion channels responsible for excitatory synaptic transmission throughout the central nervous system and are activated by Glutamate. Glutamate is a major excitatory neurotransmitter in the central nervous system and it acts by activating NMDA, AMPA and Kainate receptors and responsible for the influx of positively charged ions like calcium, sodium and potassium.

Excitatory postsynaptic potential is a temporary state of depolarization of post synaptic membrane which is caused by the inflow of positively charged ions into the postsynaptic neuron.

NMDA and AMPA both receptors act as an excitatory neurotransmitter by the influx of positively charged ions but the difference is that NMDA is responsible for the influx of mainly Calcium ions whereas the AMPA receptor is responsible for the influx of mainly Sodium and Potassium ions. Kainate receptor has a limited role in influx of cations in the post synaptic neuron.

Therefore the correct option is (e).

Option (a) is incorrect because AMPA is mainly resposible for the influx of Sodium and Potassium ions.

Option (b) is incorrect because NMDA receptors cause excitatory post synaptic potential and not inhibitory post synaptic potential.

Option (c) is incorrect because G- protein coupled receptors are not ionotropic receptors.

Option (d) is incorrect because Kainate receptors have a minimal role in cause influx of cations inside the post synaptic neuron.