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Inhibitory Effect of Schisandrin on Spontaneous Contraction of Isolated Rat Colon

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journal contribution
posted on 27.05.2012 by Jiaming Yang, Paul S. P. Lp, John H. K. Yeung, Chun-Tao Che
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 (EC50 = 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. Nω-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 1H-[1,2,4] oxadiazolo[4,3-]-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 A1 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.

Funding

This study was partially supported by grant 1-U19-AT003266 (PI: Brian Berman, University of Maryland) from the National Center for Complementary and Alternative Medicine (NCCAM), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCCAM.

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Publisher Statement

This is the author’s version of a work that was accepted for publication in Phytomedicine. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Phytomedicine, Vol 18, Issue 11, (Aug. 15, 2011) DOI: 10.1016/j.phymed.2011.02.014

Publisher

Elsevier

Language

en_US

issn

1618-095X

Issue date

15/08/2011

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