GLOSSARY

Hormone Receptor Upregulation
Hormone receptor upregulation is an increase in receptor expression or availability under specified conditions. It may involve greater gene expression, altered protein turnover or movement of receptors toward the functional cell-surface pool.

Availability has several meanings

More receptor RNA does not necessarily mean more receptor protein at the membrane. Total protein, cell-surface localization and ligand-binding capacity are distinct measurements.

Response can change

• An increased functional receptor pool can increase sensitivity when other signaling components remain effective.
• Downstream constraints, competing signals and ligand availability may limit the actual physiological effect.

Practical interpretation

A stronger response after training should not automatically be attributed to receptor upregulation. Changes in blood flow, transporters or post-receptor pathways can also contribute. Identifying the mechanism requires measurement of the receptor compartment relevant to the proposed effect.