Question about Anatomy and Physiology- Up and Down Receptors

Question

Please explain up-regulation and down-regulation as it applies to receptor sites. Describe how this impacts the system long term and give an example for both up and down.

Answer 1

Upregulation is the increase in the cellular components or increase in the number of receptors on the surface of target cells, making the cells more sensitive to a hormone or another agent. Upregulation may occur by increasing the synthesis of new receptors, decreasing the degradation of existing receptors or by activating receptors

For example,  During labor, a hormone called oxytocin is released that intensifies and speeds up contractions.

Down regulation is the mechanism in which a hormone decreases the number or affinity of its receptors in a target tissue.This process could either occur by increasing the degradation of existing receptors,decreasing the synthesis of new receptors or by deactivating receptors.

For example, prolong use of the asthma medication salbutamol down regulates the beta-2 adrenoceptors, which may be responsible for decreased effect of salbutamol seen in asthmatics.