Which term describes a molecule that increases a neurotransmitter's action?

• A. Agonist
• B. Antagonist
• C. Partial agonist
• D. Inverse agonist

Answer: (A)

In neurotransmission, a molecule that increases the action of a neurotransmitter works by activating the receptor to produce a response similar to the natural signal. This is what an agonist does. By binding to the receptor, an agonist triggers the cellular response, effectively boosting signaling.

A full agonist delivers the maximal response the receptor can produce. A partial agonist also activates the receptor but yields a smaller, submaximal response. In contrast, an antagonist binds without activating, blocking the neurotransmitter from binding; an inverse agonist reduces the receptor’s baseline activity. For the description “increases a neurotransmitter’s action,” the best fit is agonist.