Which of the following is not a method by which the effects of neurotransmitters are terminated?​​


a. Reuptake into the presynaptic neuron
b. Diffusion away from the synaptic cleft and uptake by glial cells
c. Movement back to the cell body by retrograde axonal transport
d. Degradation by enzymes in the synaptic cleft

Verified step by step guidance

1. Identify the common methods by which neurotransmitter effects are terminated: reuptake, diffusion, and enzymatic degradation.
2. Understand that reuptake involves the neurotransmitter being absorbed back into the presynaptic neuron.
3. Recognize that diffusion involves the neurotransmitter moving away from the synaptic cleft, sometimes being taken up by glial cells.
4. Know that enzymatic degradation involves enzymes breaking down the neurotransmitter in the synaptic cleft.
5. Evaluate the option of retrograde axonal transport, which is not a typical method for terminating neurotransmitter effects, as it involves movement of substances back to the cell body, not neurotransmitter termination.

Key Concepts

Neurotransmitter Reuptake

Reuptake is a process where neurotransmitters are reabsorbed by the presynaptic neuron after they have transmitted a signal across the synapse. This mechanism helps to terminate the action of neurotransmitters, allowing the neuron to recycle them for future use. It is a key method for regulating neurotransmitter levels and ensuring that signals are not prolonged unnecessarily.

Diffusion and Glial Cell Uptake

After neurotransmitters are released into the synaptic cleft, they can diffuse away from the synapse. Glial cells, which support and protect neurons, can uptake these neurotransmitters, effectively removing them from the synaptic space. This process contributes to the termination of neurotransmitter action and helps maintain the balance of neurotransmitter levels in the brain.

Enzymatic Degradation

Enzymatic degradation involves specific enzymes breaking down neurotransmitters in the synaptic cleft, rendering them inactive. This method is crucial for terminating the effects of neurotransmitters quickly and efficiently, preventing overstimulation of the postsynaptic neuron. For example, acetylcholinesterase breaks down acetylcholine, a neurotransmitter, to stop its action at the synapse.