Which neurotransmitter group includes dopamine, norepinephrine, serotonin, and epinephrine?

• A. Monoamines
• B. Neurotrophins
• C. Amino acids
• D. Peptides

Answer: (A)

Grouping neurotransmitters by chemical structure helps you see how they’re produced and function. Dopamine, norepinephrine, epinephrine, and serotonin are all monoamines, a class of biogenic amines derived from single amino acids. Dopamine, norepinephrine, and epinephrine are catecholamines, a subset of monoamines, while serotonin is an indolamine, but all four share the monoamine designation. This means they’re synthesized through related decarboxylation and hydroxylation steps and are typically stored in vesicles, released by exocytosis, terminated by reuptake, and degraded by enzymes like MAO and COMT.

Neurotrophins are growth factors (not classic neurotransmitters), amino acids like glutamate and GABA are the primary fast-acting transmitters in their own category, and peptides are short chains such as substance P or endorphins. So the group that includes these four is monoamines.