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Keywords:

  • κ-opioid receptor;
  • endocannabinoid system;
  • emotional response;
  • binding;
  • tricyclic antidepressant;
  • benzodiazepine;
  • Salvia divinorum

Background and purpose:  Drugs targeting brain κ-opioid receptors produce profound alterations in mood. In the present study we investigated the possible anxiolytic- and antidepressant-like effects of the κ-opioid receptor agonist salvinorin A, the main active ingredient of Salvia divinorum, in rats and mice.

Experimental approach:  Experiments were performed on male Sprague-Dawley rats or male Albino Swiss mice. The anxiolytic-like effects were tested by using the elevated plus maze, in rats. The antidepressant-like effect was estimated through the forced swim (rats) and the tail suspension (mice) test. κ-Opioid receptor involvement was investigated pretreating animals with the κ-opioid receptor antagonist, nor-binaltorphimine (1 or 10 mg·kg−1), while direct or indirect activity at CB1 cannabinoid receptors was evaluated with the CB1 cannabinoid receptor antagonist, N-(piperidin-1-yl) -5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251, 0.5 or 3 mg·kg−1), binding to striatal membranes of naïve rats and assay of fatty acid amide hydrolase in prefrontal cortex, hippocampus and amygdala.

Key results:  Salvinorin A, given s.c. (0.001–1000 µg·kg−1), exhibited both anxiolytic- and antidepressant-like effects that were prevented by nor-binaltorphimine or AM251 (0.5 or 3 mg·kg−1). Salvinorin A reduced fatty acid amide hydrolase activity in amygdala but had very weak affinity for cannabinoid CB1 receptors.

Conclusions and implications:  The anxiolytic- and antidepressant-like effects of Salvinorin A are mediated by both κ-opioid and endocannabinoid systems and may partly explain the subjective symptoms reported by recreational users of S. divinorum.