Little respiratory depression but dysphoria and diuresis are produced by which receptor subtype?

Little respiratory depression but dysphoria and diuresis are produced by which receptor subtype?

• A. mu, kappa, and delta opioid receptors
• B. mu1 opioid receptors
• C. mu2 opioid receptors
• D. kappa opioid receptors

Answer: (D)

Kappa opioid receptor activation produces analgesia with relatively little impact on respiration, but it causes dysphoria and a diuretic effect. The diuresis comes from inhibition of antidiuretic hormone release, and the dysphoria is a well-known psychotomimetic effect of kappa agonists. In contrast, mu receptor activation causes strong respiratory depression and euphoria, while delta receptors are less associated with these dysphoric and diuretic effects. So the combination of minimal respiratory depression with dysphoria and diuresis points to kappa receptors.

Kappa opioid receptor activation produces analgesia with relatively little impact on respiration, but it causes dysphoria and a diuretic effect. The diuresis comes from inhibition of antidiuretic hormone release, and the dysphoria is a well-known psychotomimetic effect of kappa agonists. In contrast, mu receptor activation causes strong respiratory depression and euphoria, while delta receptors are less associated with these dysphoric and diuretic effects. So the combination of minimal respiratory depression with dysphoria and diuresis points to kappa receptors.