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Related to down-regulation: Upregulation, Up-regulation
Development of a refractory or tolerant state consequent on repeated administration of a pharmacologically or physiologically active substance; often accompanied by an initial decrease in affinity of receptors for the agent and a subsequent diminution in the number of receptors.
down-regulation/down-reg·u·la·tion/ (doun reg-u-la´shun) a decrease in the number of receptors for a chemical or drug on cell surfaces in a given area, usually due to long-term exposure to the agent.
a decrease in the number of receptors for a chemical or drug on cell surfaces in a given area, usually caused by long-term exposure to the agent. See also up-regulation.