Question

a new drug called Xaelenfal is on the market. Xaelenfal is an AMPA receptor antagonist, meaning that it binds onto AMPA receptors without activating them and prevents glutamate from binding.

i. If I take the drug Xaelenfal, how will this effect EPSPs recorded in the postsynaptic neuron when an excitatory presynaptic neuron fires an action potential? (1 point)

ii. How will the drug Xaelenfal effect IPSPs in the postsynaptic neuron when an inhibitory presynaptic neuron fires an action potential? (1 point)

iii. In a normal brain, synapses can get stronger when a presynaptic cell repeatedly causes a postsynaptic cell to depolarize (we call this long-term potentiation, or LTP). Explain how long term potentiation works including the following details. (3 points)
- Name the neurotransmitter that is released by the presynaptic cell.
- Name the receptor that this neurotransmitter binds to on the postsynaptic cell to mediate normal excitatory transmission.
- What other receptors are involved and how do they get recruited?
- List one way in which the presynaptic neuron changes and one way in which the postsynaptic neuron changes during LTP.

iv. Given what you know about plasticity, could Xaelenfal effect the ability of synapses to potentiate. Explain your answer. (2 points)

Answer 1

a. i) When excitatory presynaptic neuron fire an action potential, it releases glutamate that will bind to AMPA receptor but due to the presence of AMPA antagonist i.e Xaelenfal the glutamate can no longer bind to AMPA receptor on the post synaptic neuron and inhibiting the depolarisation of member following inhibition of action potential. Thus, EPSP doesn't recorded with any action potential.

ii) Inhibitory pre-synaptic neuron cause the hyperpolarisation of memberane by activating more k+ and Cl- channel and thereby inhibiting the action potential. So, if drug bing to an inhibitory post synaptic neuron (IPSP), the membrane no longer become hyperpolarise.

iii)-Glutamate is the neurotransmittor release from pre synaptic neuron.

-It will bind to AMPA receptor on the post synaptic membrane.

-The other receptor involve is kainate receptors. The recruitment of kainate receptor is thought to involve the Cadherin/Catenin Complexes that stabilize the receptor on the synaptic membrane.

-LTP causes persistent increase in synaptic strength following high-frequency stimulation of a chemical synapse. So, it lead to change both the presynaptic and post synaptic by continuously firing an action potential. By applying the multiple input pre synaptic neuron can changes during LTP.

iv) Synaptic plasticity is the process that result in changes in synaptic strength by changes its specific pattern and is thought to contribute to learning and memory. Thus, Xaelenfal affect the ability to potentiate as it inhibit the generation of action potential by binding to AMPA antagonist.