The hallucinogenic herbSalvia divinorumand its active ingredient salvinorin A inhibit enteric cholinergic transmission in the guinea‐pig ileum

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Abstract
Abstract Salvia divinorumis a widespread hallucinogenic herb traditionally employed for divination, as well as a medicament for several disorders including disturbances of gastrointestinal motility. In the present study we evaluated the effect of a standardized extract from the leaves ofS. divinorum(SDE) on enteric cholinergic transmission in the guinea‐pig ileum. SDE reduced electrically evoked contractions without modifying the contractions elicited by exogenous acetylcholine, thus suggesting a prejunctional site of action. The inhibitory effect of SDE on twitch response was abolished by the opioid receptor antagonist naloxone and by theκ‐opioid antagonist nor‐binaltorphimine, but not by naltrindole (aδ‐opioid receptor antagonist), CTOP (aμ‐opioid receptor antagonist), thioperamide (a H3receptor antagonist), yohimbine (anα2‐receptor antagonist), methysergide (a 5‐hydroxytryptamine receptor antagonist),NG‐nitro‐l‐arginine methyl ester (an inhibitor of NO synthase) orapamin (a blocker of Ca2+‐activated K+channels). Salvinorin A, the main active ingredient ofS. divinorum, inhibited in a nor‐binaltorphimine‐ and naloxone‐sensitive manner electrically induced contractions. It is concluded that SDE depressed enteric cholinergic transmission likely through activation ofκ‐opioid receptors and this may provide the pharmacological basis underlying its traditional antidiarrhoeal use. Salvinorin A might be the chemical ingredient responsible for this activity.