Ginseng root extract inhibits calcium channels in rat sensory neurons through a similar path, but different receptor, as mu-type opioids.
The effect of Panax ginseng root extract on Ca2+ current of adult rat trigeminal ganglion neurons was investigated using whole-cell patch-clamp methods. The application of P. ginseng root extract (100 micrograms/ml) produced rapid, reversible reduction of the Ca2+ current by 22 +/- 4%. Treatment with pertussis toxin (250 ng/ml) for 16 h reduced the inhibition to 4 +/- 1%. The continual presence of 1 microM DAGO, a selective mu-opioid agonist that inhibits Ca2+ channels, occluded further inhibition of Ca2+ current by P. ginseng root extract. Yohimbine, phaclofen, atropine, and naloxone--antagonists of alpha 2-adrenergic, GABAB, muscarinic, and opiate receptors, respectively--did not block the inhibitory effect on Ca2+ current of P. ginseng root extract. Thus, P. ginseng root extract acts on sensory neurons through a similar pathway as mu-type opioids: both inhibit Ca2+ channels through pertussis toxin-sensitive GTP-binding proteins. However, the receptor for P. ginseng root extract is not an alpha 2-adrenergic, GABAB, muscarinic, or opioid receptor.
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Department of Cell Biology and Physiology #8228, Washington University School of Medicine, St. Louis, MO 63110.
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D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D009294:Narcotics / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000187:drug effects*; D005894:Panax; D037342:Pertussis Toxin; D010936:Plant Extracts / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010946:Plants, Medicinal; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000166:cytology / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004745:Enkephalins; D009294:Narcotics; D010936:Plant Extracts; D011956:Receptors, Cell Surface; D017450:Receptors, Opioid, mu; D010566:Virulence Factors, Bordetella; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins