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Ethanol Upregulates iNOS Expression in Colon Through Activation of Nuclear Factor‐kappa B in Rats
Author(s) -
Wang Chao,
Wang Shuanglian,
Qin Junfang,
Lv Yinglian,
Ma Xuelian,
Liu Chuanyong
Publication year - 2010
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2009.01066.x
Subject(s) - pyrrolidine dithiocarbamate , myenteric plexus , nitric oxide synthase , downregulation and upregulation , chemistry , western blot , contraction (grammar) , nf κb , endocrinology , medicine , biochemistry , immunohistochemistry , biology , signal transduction , enzyme , gene
Background: Alcohol inhibits colonic motility but the mechanism is unknown. The goal of this study was to test the possibility that nuclear factor‐kappa B (NF‐κB) is involved in the upregulation of inducible nitric oxide synthase (iNOS) expression induced by ethanol in colon. Methods: The isometric contraction of longitudinal muscle strips of proximal colon (LP) was monitored by polygraph. Western blot analysis was used to measure the amount of iNOS and I‐κB in the cytoplasm and P65 in the nucleus. Immunohistochemistry was applied to locate iNOS in colon. Results: Ethanol (87mM) inhibited the contraction of LP. Pretreatment of S‐methylisothioure (SMT) (1 mM), a specific iNOS inhibitor, Pyrrolidine dithiocarbamate (PDTC) (10 mM) and BAY11‐7082(10 mM), specific inhibitors of NF‐κB significantly reversed the inhibitory effect of ethanol on LP contraction. Ethanol increased the amount of iNOS and content of NO in colon, and these effects were attenuated by pretreatment of PDTC. Following ethanol administration, the amount of I‐κB in the cytoplasm decreased, but that of P65, the subunit of NF‐κB in the nucleus, increased. The iNOS was located in the cell body of myenteric plexus in colon. Conclusion: Ethanol inhibited the contraction of LP in colon mainly through activation of NF‐κB, the subsequent upregulation of iNOS expression and increase of NO release in myenteric plexus.