Scientific Glossary

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When receptors are continuously exposed to high levels of an agonist, cells often compensate by reducing the number of receptors on the cell surface (downregulation) or making existing receptors less responsive (desensitization). This is why research studies often use pulsatile or cyclical administration rather than continuous exposure. For example, GHRH receptors downregulate with continuous GHRH stimulation — this is why pulse administration is studied more than continuous infusion for GH secretagogues.