Inhibitory effect of schisandrin on spontaneous contraction of isolated rat colon

• Published in: Phytomedicine (Stuttgart) Vol. 18; no. 11; pp. 998 - 1005
• Main Authors: Yang, Jiaming, Ip, Paul S.P., Yeung, John H.K., Che, Chun-Tao
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 15.08.2011; Urban & Fischer Verlag
• Subjects: Adrenergic Antagonists - pharmacology; Animals; Atropine - pharmacology; Benzyl Compounds - pharmacology; Colon, Ascending - drug effects; Colon, Ascending - surgery; Colonic smooth muscle; Cyclic GMP - metabolism; Cyclooctanes - pharmacology; Enteric nervous system; Enzyme Inhibitors - metabolism; Health aspects; Imidazoles - pharmacology; In Vitro Techniques; Lignans - pharmacology; Male; Marine toxins; Muscle Contraction - drug effects; Muscle Relaxation; Nitric oxide; Nitric Oxide - metabolism; Non-adrenergic non-cholinergic relaxation; Phentolamine - pharmacology; Physiological aspects; Plant Extracts - pharmacology; Polycyclic Compounds - pharmacology; Propranolol - pharmacology; Purinergic Antagonists - pharmacology; Pyridoxal Phosphate - analogs & derivatives; Pyridoxal Phosphate - pharmacology; Rats; Rats, Sprague-Dawley; Receptors, Epoprostenol - antagonists & inhibitors; Schisandra; Schisandra - chemistry; Schisandra chinensis; Schisandrin; Tetrodotoxin - pharmacology; Xanthines - pharmacology; Hong Kong; United States; Enteric nervous system; Colonic smooth muscle; Schisandra chinensis; Nitric oxide; Schisandrin; Non-adrenergic non-cholinergic relaxation
• ISSN: 0944-7113; 1618-095X
• DOI: 10.1016/j.phymed.2011.02.014

This study examined the effect of schisandrin, one of the major lignans isolated from Schisandra chinensis, on spontaneous contraction in rat colon and its possible mechanisms. Schisandrin produced a concentration-dependent inhibition (EC 50 = 1.66 μM) on the colonic spontaneous contraction. The relaxant effect of schisandrin could be abolished by the neuronal Na + channel blocker tetrodotoxin (1 μM) but not affected by propranolol (1 μM), phentolamine (1 μM), atropine (1 μM) or nicotine desensitization, suggesting possible involvement of non-adrenergic non-cholinergic (NANC) transmitters released from enteric nerves. N ω-nitro- l-arginine methyl ester (100–300 μM), a nitric oxide synthase inhibitor, attenuated the schisandrin response. The role of nitric oxide (NO) was confirmed by an increase in colonic NO production after schisandrin incubation, and the inhibition on the schisandrin responses by soluble guanylyl cyclase inhibitor 1 H-[1,2,4] oxadiazolo[4,3-α]-quinoxalin-1-one (1–30 μM). Non-nitrergic NANC components may also be involved in the action of schisandrin, as suggested by the significant inhibition of apamin on the schisandrin-induced responses. Pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt hydrate (100 μM), a selective P2 purinoceptor antagonist, markedly attenuated the responses to schisandrin. In contrast, neither 8-cyclopentyl-1,3-dipropylxanthine, an antagonist for adenosine A 1 receptors, nor chymotrypsin, a serine endopeptidase, affected the responses. All available results have demonstrated that schisandrin produced NANC relaxation on the rat colon, with the involvement of NO and acting via cGMP-dependent pathways. ATP, but not adenosine and VIP, likely plays a role in the non-nitrergic, apamin-sensitive component of the response.