What is the role of cholinesterase in neuronal function?

• A. It synthesizes acetylcholine.
• B. It releases neurotransmitters.
• C. It deactivates acetylcholine.
• D. It transmits nerve impulses.

Answer: (C)

Cholinesterase plays a vital role in neuronal function by deactivating acetylcholine, which is a key neurotransmitter in the nervous system. Once acetylcholine is released into the synaptic cleft during neurotransmission, it binds to receptors on the postsynaptic neuron to facilitate communication between nerve cells. However, it is essential to terminate this signal promptly to prevent continuous stimulation of the postsynaptic neuron, which could lead to issues like muscle spasms or paralysis.

Cholinesterase achieves this by breaking down acetylcholine into its components, acetate and choline, effectively stopping its action at the synapse. This deactivation process ensures that nerve impulses are regulated and that communication between neurons occurs in a controlled manner.

The other roles mentioned in the answer choices are not functions of cholinesterase. For instance, cholinesterase does not synthesize acetylcholine; that task is performed by the enzyme acetyltransferase. It also does not release neurotransmitters or transmit nerve impulses directly; those functions are handled by different cellular mechanisms and proteins within the neuron. Thus, the critical function of cholinesterase is specifically to deactivate acetylcholine, allowing for precise control over neurotransmission.