Give an example of a neuropeptide.

Give an example of a neuropeptide.

• A. Met-enkephalin.
• B. Glutamate.
• C. Acetylcholine.
• D. Dopamine.

Answer: (A)

Neuropeptides are peptide-based signaling molecules produced in neurons as larger precursor proteins and released from dense-core vesicles to modulate neural circuits over longer timescales than classic neurotransmitters. They often act on G-protein–coupled receptors and can influence pain, mood, appetite, and stress responses, typically producing slower onset and longer-lasting effects. Met-enkephalin fits this pattern. It is an endogenous opioid peptide derived from the larger precursor proenkephalin and functions by binding opioid receptors to dampen pain signaling and influence emotional states. This makes it a quintessential example of a neuropeptide. The other options are not neuropeptides because they are small-molecule neurotransmitters: glutamate is the main excitatory amino acid transmitter, acetylcholine is a fast-acting cholinergic transmitter, and dopamine is a monoamine transmitter. They are not peptide-based signaling molecules.

Neuropeptides are peptide-based signaling molecules produced in neurons as larger precursor proteins and released from dense-core vesicles to modulate neural circuits over longer timescales than classic neurotransmitters. They often act on G-protein–coupled receptors and can influence pain, mood, appetite, and stress responses, typically producing slower onset and longer-lasting effects.

Met-enkephalin fits this pattern. It is an endogenous opioid peptide derived from the larger precursor proenkephalin and functions by binding opioid receptors to dampen pain signaling and influence emotional states. This makes it a quintessential example of a neuropeptide.

The other options are not neuropeptides because they are small-molecule neurotransmitters: glutamate is the main excitatory amino acid transmitter, acetylcholine is a fast-acting cholinergic transmitter, and dopamine is a monoamine transmitter. They are not peptide-based signaling molecules.