Which are the types of opioid receptors?

Which are the types of opioid receptors?

• A. Mu, Delta, Kappa, Nociceptin
• B. Alpha, Beta, Gamma, Delta
• C. Mu, Sigma, Theta, Nociceptin
• D. Epsilon, Zeta, Eta, Iota

Answer: (A)

Opioid receptors are a group of G-protein–coupled receptors that mediate analgesia and other opioid effects. The classical subtypes are mu, delta, and kappa, each with unique distributions and signaling outcomes. In addition, a fourth receptor, the nociceptin receptor (also called ORL1 or NOP), completes the commonly cited set and is activated by nociceptin/orphanin FQ rather than by most typical opiates. This combination—mu, delta, kappa, and nociceptin—reflects how pharmacology classifies the opioid receptor family. The other options mix in receptors that are not part of the standard opioid receptor family (or include receptors like sigma, which historically appear in opiate discussions but are not one of the main opioid receptor subtypes). Therefore, the grouping that includes mu, delta, kappa, and nociceptin best represents the types of opioid receptors.

Opioid receptors are a group of G-protein–coupled receptors that mediate analgesia and other opioid effects. The classical subtypes are mu, delta, and kappa, each with unique distributions and signaling outcomes. In addition, a fourth receptor, the nociceptin receptor (also called ORL1 or NOP), completes the commonly cited set and is activated by nociceptin/orphanin FQ rather than by most typical opiates. This combination—mu, delta, kappa, and nociceptin—reflects how pharmacology classifies the opioid receptor family.

The other options mix in receptors that are not part of the standard opioid receptor family (or include receptors like sigma, which historically appear in opiate discussions but are not one of the main opioid receptor subtypes). Therefore, the grouping that includes mu, delta, kappa, and nociceptin best represents the types of opioid receptors.