What is the Origin of Receptor Site Desensitization?

This concept is fundamental to molecular endocrinology and pharmacology, emerging from the study of cellular communication and the mechanisms of tolerance to drugs and hormones. The term combines "receptor site," the specific binding location, with "desensitization," the loss of sensitivity. It explains why constant stimulation can lead to a diminished biological effect.

What is the Mechanism of Receptor Site Desensitization?

The mechanism often begins with receptor phosphorylation, which tags the receptor for internalization into the cell's interior, a process called endocytosis. Once internalized, the receptors may be dephosphorylated and recycled back to the membrane, or they may be degraded in the lysosome, leading to a net reduction in surface receptor density. This reduction requires a higher concentration of the hormone to elicit the same response, effectively dampening the signal transduction efficiency.

Receptor Site Desensitization ∞ Area

Receptor Site Desensitization

Meaning

A reversible or sometimes irreversible biological process where the continuous or excessive presence of a hormone or ligand causes a reduction in the target cell’s responsiveness to that signal, despite adequate circulating levels. This phenomenon, also known as downregulation, occurs due to biochemical modifications or a reduction in the number of functional receptors on the cell surface. Desensitization is a key mechanism of hormonal resistance and is a clinical challenge in both endogenous endocrine disorders and exogenous hormone therapy.