Immediate and Persistent Effects of Salvinorin A on the Kappa Opioid Receptor in Rodents, Monitored In Vivo with PET.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology December 1, 2015 Michael S Placzek, Genevieve C Van de Bittner, Hsiao-Ying Wey et al.
Kappa opioid receptor (KOR) binding availability in the brain was measured in living rats using positron emission tomography (PET) after administration of the KOR agonist salvinorin A. At lower doses, salvinorin A briefly competed for receptor binding but had no lasting effect. At a dose of 0.60 mg/kg, however, it induced a sustained decrease in KOR binding of 40–49% that persisted for up to 2.5 hours after the drug had left the brain, suggesting an adaptive response by the receptor not previously observed in vivo with PET.