Question

Which one of the following statements is not true regarding chemical signaling between neurons?

A. Neurotransmitter synthesis may be stimulated by influx of Ca2+
B. NE-releasing neurons have presynaptic α receptors, which are involved in a negative feedback system to stop NE release
C. Once dopamine is released into the synaptic cleft it works until it diffuses away or is removed by reuptake mechanisms
D. Exocytosis is the process by which neurotransmitter storage vesicles release their contents into the synaptic cleft
E. Monoamine oxidase type B (MAO-B) metabolizes NE and serotonin

Answer 1

The incorrect statement about chemical signaling between neurons is that MAO-B metabolizes NE and serotonin; in fact, MAO-A primarily metabolizes these neurotransmitters.

Step-by-step explanation:

The statement that is not true regarding chemical signaling between neurons is: E. Monoamine oxidase type B (MAO-B) metabolizes NE and serotonin. This is incorrect because MAO-B specifically metabolizes phenethylamine and benzylamine, and although it can oxidize dopamine, it does not typically metabolize norepinephrine (NE) or serotonin. NE and serotonin are mainly metabolized by monoamine oxidase type A (MAO-A).

The correct statements are:

• A. Neurotransmitter synthesis may be stimulated by influx of Ca2+.
• B. NE-releasing neurons have presynaptic α receptors, which are involved in a negative feedback system to stop NE release.
• C. Once dopamine is released into the synaptic cleft it works until it diffuses away or is removed by reuptake mechanisms.
• D. Exocytosis is the process by which neurotransmitter storage vesicles release their contents into the synaptic cleft.

Chemical signaling in neurons is essential for the transmission of signals across the synapses, involving complex feedback mechanisms, synaptic vesicle exocytosis, neurotransmitter actions, and inactivation processes.