Is desensitization reversible?

• A. No, desensitization is permanent
• B. Desensitization requires receptor degradation
• C. Desensitization affects only non-receptor targets
• D. Yes, after removal of the drug for some time, the receptor can again be activated

Answer: (D)

Desensitization to a drug is usually reversible. When a receptor is chronically stimulated, the cell adjusts by processes like receptor phosphorylation and uncoupling from G proteins, and often receptor internalization. These changes reduce the response but don’t permanently destroy the receptor. Once the drug is removed for a period, those modifications can be reversed: receptors are dephosphorylated, recycled back to the membrane, and signaling can resume. So after withdrawal, the receptor can again be activated by the drug.

This is different from scenarios where receptor numbers are permanently reduced by degradation over very long exposure, which is a slower form of tolerance and not the typical desensitization pattern.