A Chemical That Affects Neuronal Function but is Not Stored

Question

A chemical that affects neuronal function but is not stored in presynaptic vesicles is
A) acetylcholine.
B) epinephrine.
C) endorphin.
D) nitric oxide.
E) GABA.

Accepted Answer

Nitric oxide is a gas that is produced by neurons and diffuses out of the cell, rather than being stored in presynaptic vesicles. It is a signaling molecule that affects neuronal function. The other options (A, B, C, and E) are neurotransmitters that are stored in vesicles and released at the synapse to affect neuronal function.