Cause of Receptor Down-Regulation
Down-regulation of receptors is caused by:
- Enzyme inhibition
- First-pass metabolism
- Continuous agonist exposure — Correct Answer
- Prolonged antagonist exposure
Explanation:
Correct Answer: Continuous exposure to an agonist
When tissues are continuously exposed to an agonist, the number of receptors decreases — this is called down-regulation. It is a reason for tachyphylaxis (decreased response on repeated administration).
Contrast: Up-Regulation
Prolonged contact with an antagonist leads to formation of new receptors — this is called up-regulation. This explains why sudden withdrawal of an antagonist (e.g. propranolol) can lead to rebound effects.
📚 About this Topic — Veterinary Pharmacology and Toxicology
This multiple choice question is from Veterinary Pharmacology and Toxicology, Veterinary Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Veterinary Pharmacology and Toxicology to strengthen your preparation.
