Many Drugs Produce Their Effects by Facilitating or Interfering with Neurotransmitters

Multiple Choice

Many drugs produce their effects by facilitating or interfering with neurotransmitters at synapses. Which of the following drugs would most likely increase the effect of serotonin?

A) a drug that binds to directly coupled serotonin receptors but does not change membrane permeability to ions
B) a drug that prevents the activity of an enzyme that breaks down serotonin molecules in the synaptic cleft
C) a drug that blocks the effect of Ca²⁺ ions
D) a drug that blocks the effect of a conditional neurotransmitter that normally facilitates the effect of serotonin