Drugs that block transmitter reuptake have what effect on receptor activation?

A. Drugs that block neurotransmitter reuptake—for example, selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and some tricyclic antidepressants—increase the concentration of the neurotransmitter in the synaptic cleft. By preventing the presynaptic neuron from reabsorbing the neurotransmitter, these drugs allow more of the neurotransmitter to remain available to bind to postsynaptic receptors, resulting in enhanced receptor activation. For example, SSRIs increase serotonin availability, which improves mood and alleviates symptoms of depression or anxiety. This principle also applies to other CNS drugs targeting norepinephrine or dopamine reuptake. B. Reuptake inhibition directly affects receptor activation because the increased neurotransmitter availability leads to greater stimulation of postsynaptic receptors. Saying it has no effect ignores the mechanism of action. C. Reuptake inhibitors do not decrease receptor activation. Instead, by keeping neurotransmitters in the synapse longer, receptor activation is enhanced, not diminished. D. The effect of reuptake inhibition on receptor activation is well established in pharmacology. It is predictable and measurable, not unknown.