Which statement best describes a kappa receptor’s systemic effects?

Which statement best describes a kappa receptor’s systemic effects?

• A. Sedation
• B. Dysphoria
• C. Miosis
• D. Pruritus

Answer: (D)

Kappa opioid receptor activation in the CNS gives analgesia with a distinctive, often unpleasant set of effects. The most telling systemic effect is dysphoria—a mood disturbance that can include unease, anxiety, or perceptual changes. This is a hallmark of kappa agonists and helps distinguish them from mu agonists, which more commonly produce euphoria and pruritus via histamine release. Sedation can occur with kappa activation, but it’s less specific to this receptor type than dysphoria. Miosis is typically linked to mu receptor activity, not a primary feature of kappa effects. Pruritus, on the other hand, is usually a mu-mediated consequence of histamine release, and kappa agonists are known to have antipruritic properties rather than itch-inducing effects. So the most characteristic systemic effect of activating kappa receptors is dysphoria, with sedation also possible, while miosis and pruritus are not typical hallmarks of kappa receptor actions.

Kappa opioid receptor activation in the CNS gives analgesia with a distinctive, often unpleasant set of effects. The most telling systemic effect is dysphoria—a mood disturbance that can include unease, anxiety, or perceptual changes. This is a hallmark of kappa agonists and helps distinguish them from mu agonists, which more commonly produce euphoria and pruritus via histamine release.

Sedation can occur with kappa activation, but it’s less specific to this receptor type than dysphoria. Miosis is typically linked to mu receptor activity, not a primary feature of kappa effects. Pruritus, on the other hand, is usually a mu-mediated consequence of histamine release, and kappa agonists are known to have antipruritic properties rather than itch-inducing effects.

So the most characteristic systemic effect of activating kappa receptors is dysphoria, with sedation also possible, while miosis and pruritus are not typical hallmarks of kappa receptor actions.