Desensitization is defined as which of the following descriptions?

Desensitization is defined as which of the following descriptions?

• A. An intrinsic pharmacological property of receptors where, in the presence of an agonist, the receptor becomes desensitized/inactivated (decrease or loss in response)
• B. A reversible increase in receptor numbers
• C. An irreversible receptor activation
• D. A rapid increase in ligand potency

Answer: (A)

Desensitization is a receptor-level decrease in response that happens during ongoing exposure to an agonist. It’s an intrinsic property of the receptor signaling system: even though the ligand is still present and bound, the receptor becomes less able to transmit the signal. This often involves processes like receptor phosphorylation, recruitment of β-arrestin, uncoupling from G proteins, and sometimes receptor internalization or downregulation. The net result is a reduced or lost response despite continued agonist presence. This is different from upregulation, which would mean more receptors appear on the surface; desensitization reduces responsiveness, not receptor numbers in the short term. It’s also not about irreversible activation, which would sustain signaling rather than dampen it. And it doesn’t describe a change in ligand potency; desensitization concerns how the receptor responds, not how strongly the ligand binds or how potent it is.

Desensitization is a receptor-level decrease in response that happens during ongoing exposure to an agonist. It’s an intrinsic property of the receptor signaling system: even though the ligand is still present and bound, the receptor becomes less able to transmit the signal. This often involves processes like receptor phosphorylation, recruitment of β-arrestin, uncoupling from G proteins, and sometimes receptor internalization or downregulation. The net result is a reduced or lost response despite continued agonist presence.

This is different from upregulation, which would mean more receptors appear on the surface; desensitization reduces responsiveness, not receptor numbers in the short term. It’s also not about irreversible activation, which would sustain signaling rather than dampen it. And it doesn’t describe a change in ligand potency; desensitization concerns how the receptor responds, not how strongly the ligand binds or how potent it is.