What causes receptor upregulation?

Upregulation (i.e., increase in the number) of receptors occurs when the activity of the receptor is lower than usual (e.g., due to long-term administration of an antagonist). For example, administration of beta-blockers upregulates β adrenoreceptors.

What determines drug affinity?

Affinity can be defined as the extent or fraction to which a drug binds to receptors at any given drug concentration or the firmness with which the drug binds to the receptor. The strength of the binding (interaction) of a ligand and its receptor can be described by affinity.

What causes downregulate and upregulate receptors?

The more receptors a cell has that are tuned to the message, the more the cell will respond to it. Receptors are created, or expressed, from instructions in the DNA of the cell, and they can be increased, or upregulated, when the signal is weak, or decreased, or downregulated, when it is strong.

What causes downregulation of receptors?

Receptor desensitization refers to the decreased responsiveness that occurs with repeated or chronic exposure to agonist and is a general feature of most signaling membrane receptors.

What is upregulation receptors?

Upregulation: An increase in the number of receptors on the surface of target cells, making the cells more sensitive to a hormone or another agent. For example, there is an increase in uterine oxytocin receptors in the third trimester of pregnancy, promoting the contraction of the smooth muscle of the uterus.

What does upregulation mean in medicine?

In biology, the process by which a cell increases its response to a substance or signal from outside the cell to carry out a specific function. For example, a cell may increase the number or activity of protein receptors or other molecules on its surface to make it more sensitive to a hormone or drug.

What makes drugs physiologically active?

In order to exert their effects, drugs usually interact in a structurally specific way with a protein receptor or act on physiological processes within the body. This activates a secondary messenger system that produces a physiological effect.

What is selectivity of drug action?

Selectivity is the degree to which a drug acts on a given site relative to other sites. Relatively nonselective drugs affect many different tissues or organs.

When do receptors upregulate?

How do target cells become more or less sensitive to hormones?

In up-regulation, the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone, allowing for more cellular activity. When the number of receptors decreases in response to rising hormone levels, called down-regulation, cellular activity is reduced.

What happens when receptors are downregulated?

Downregulation: An decrease in the number of receptors on the surface of target cells, making the cells less sensitive to a hormone or another agent.

Can cause down-regulation of a target cell?

For example, the presence of a significant level of a hormone circulating in the bloodstream can cause its target cells to decrease their number of receptors for that hormone. This process is called downregulation, and it allows cells to become less reactive to the excessive hormone levels.