Salvinorin A is a naturally occurring, potent, and selective kappa opioid agonist. Kappa receptors are one of the canonical opioid receptors, often appreciated best for anti-opioid effects. Kappa receptors don’t interact well with morphine or other narcotics, and we’d thought that activation of kappa receptors produces a dysphoric state. For instance, kappa activation has been implicated in the miserable feelings associated with alcohol withdrawal.
