Effects of ginseng saponins on responses induced by various receptor stimuli.
We investigated the effects of four ginseng saponins, ginsenoside-Rb1, -Rg2, -Rg3 and -Ro, on the responses induced by receptor stimulation of various stimuli. Ginsenoside-Rg2 (1-100 microM) reduced the secretions of catecholamines from bovine adrenal chromaffin cells stimulated by acetylcholine and gamma-aminobutyric acid but not by angiotensin II, bradykinin, histamine and neurotensin. In guinea-pig, the ginsenoside also diminished the nicotine-induced secretion of catecholamines from the adrenal chromaffin cells, but it did not affect the muscarine- and the histamine-induced ileum contractions. On the other hand, ginsenoside-Rg3 (1-100 microM) reduced not only the acetylcholine-, the gamma-aminobutyric acid- and the neurotensin-induced secretions but also, at a higher concentration (100 microM), the angiotensin II-, the bradykinin- and the histamine-induced secretions from the bovine chromaffin cells. Furthermore, the saponin (3-100 microM) significantly inhibited the muscarine- and the histamine-induced ileum contractions of the guinea-pig. Ginsenoside-Rb1 and -Ro had no marked effect on their responses. These results strongly suggest that ginsenoside-Rg2 is a potent selective blocker of nicotinic acetylcholine and gamma-aminobutyric acid receptors (ionotropic receptors) and ginsenoside-Rg3 is not only a blocker of ionotropic receptors but also an antagonist of muscarinic or histamine receptors.
Tachikawa
E
E
Department of Pharmacology, School of Medicine, Iwate Medical University, Morioka, Japan. etachika@iwate-med.ac.jp
Kudo
K
K
Harada
K
K
Kashimoto
T
T
Miyate
Y
Y
Kakizaki
A
A
Takahashi
E
E
D000311:Adrenal Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002491:Central Nervous System Agents / Q000494:pharmacology; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D036145:Ginsenosides; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009116:Muscarine / Q000494:pharmacology; D018721:Muscarinic Agonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009496:Neurotensin / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D005894:Panax / Q000737:chemistry*; D010946:Plants, Medicinal; D011956:Receptors, Cell Surface / Q000187:drug effects*; D012503:Saponins / Q000737:chemistry / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D002395:Catecholamines; D002491:Central Nervous System Agents; D036145:Ginsenosides; D018721:Muscarinic Agonists; D018722:Nicotinic Agonists; D011956:Receptors, Cell Surface; D012503:Saponins; D000804:Angiotensin II; D009496:Neurotensin; D005680:gamma-Aminobutyric Acid; D009538:Nicotine; D009116:Muscarine; D006632:Histamine; D001920:Bradykinin