Salvinorin A (SalA), a selective κ-opioid receptor (KOR) agonist, increases dopamine transporter (DAT) activity in cells and rat striatum, which reduces dopamine signaling. This effect is mediated by KOR activation and the ERK1/2 pathway, and involves physical interaction between KOR and DAT proteins. SalA also decreases serotonin transporter activity but does not affect norepinephrine transporter activity. The enhanced dopamine transport, combined with reduced dopamine release, may contribute to the dysphoric and pro-depressant effects of SalA and other KOR agonists.
Activating the κ opioid receptor with the salvinorin A analogue 2-methoxy-methyl salvinorin B (MOM Sal B) at 0.3 mg/kg reduced cocaine-seeking behavior in rats, but also reduced sucrose reinforcement. No sedation was observed—locomotion in cocaine-induced hyperactivity and open field tests was unchanged—yet the forced swim test showed increased immobility and decreased swimming times, indicating pro-depressive effects. The compound thus modulates cocaine-seeking non-selectively without sedation, but depressive side effects may limit its therapeutic use.