receptorincrease

Receptor increase, or upregulation, is a process in which a cell increases the number or density of specific receptors on its surface or within its signaling system. This change enhances the cell’s sensitivity to a given ligand, such as a hormone, neurotransmitter, or drug, and can alter the strength and duration of a signal.

Upregulation typically arises as a compensatory response to reduced signaling. Mechanisms include increased gene transcription of the receptor, enhanced translation and trafficking of receptor proteins to the membrane, reduced receptor internalization, and slower receptor degradation. In some cases, changes in receptor affinity or signaling efficiency accompany density changes, contributing to altered cellular responses.

Triggers for receptor upregulation include chronic depletion of the ligand, prolonged receptor blockade by antagonists or certain drugs, and some physiological or pathological states that demand heightened cellular responsiveness. Receptor upregulation can occur across many receptor families, including G protein–coupled receptors and tyrosine kinase receptors. A common illustrative scenario is upregulation of certain receptors after long-term exposure to receptor antagonists, which can increase responsiveness to endogenous ligands when signaling resumes.

Clinical and research relevance includes potential withdrawal or rebound phenomena when antagonists are removed, altered drug sensitivity, and implications for tolerance and treatment strategies. Receptor upregulation is typically studied using binding assays, imaging, and molecular techniques to quantify receptor density and assess changes in signaling pathways.