Yip Wai Nga. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 93-101). / Abstracts in English and Chinese. / Abstract (English version) --- p.i / Abstract (Chinese version) --- p.v / Acknowledgements --- p.viii / Table of contents --- p.ix / List of figures --- p.xii / List of abbreviation --- p.xv / Chapter Chapter I: --- Introduction --- p.1 / Chapter I.1 --- Transepithelial ion transport --- p.1 / Chapter I.1.1 --- Fluid secretion in colon --- p.1 / Chapter I.1.2. --- Cellular mechanism of chloride secretion --- p.3 / Chapter 1.2. --- Regulation of chloride secretion in T84 cells --- p.6 / Chapter I.2.1 --- Human colonic T84 cells as the study model --- p.6 / Chapter I.2.2 --- Signal transduction pathways of chloride secretion in T84 cells --- p.13 / Chapter I.3. --- Pharmacological actions of Scutellariae Radix --- p.13 / Chapter I.3.1. --- What is Scutellariae Radix? --- p.13 / Chapter I.3.2. --- Some biological and pharmacological actions of Scutellariae Radix --- p.13 / Chapter I.4. --- Effects of Scutellariae Radix and its major flavonoid baicalein on ion transport in T84 cells --- p.15 / Chapter I.4.1. --- Effects of Scutellariae Radix extract on ion transport in T84 cells --- p.15 / Chapter I.4.2. --- Biological effects of baicalein --- p.15 / Chapter I.5 --- "Relationship of Coptidis rhizoma and its active ingredient berberine, with Scutellariae radix in traditional remedies" --- p.18 / Chapter I.6 --- Aim of study --- p.20 / Chapter Chapter II: --- Methods and Materials --- p.21 / Chapter II.1. --- Culture technique of the T84 cells --- p.21 / Chapter II.2. --- Conventional short-circuit current (Isc) measurement --- p.24 / Chapter II.2.1. --- Experimental setup --- p.24 / Chapter II.2.2. --- Preparation of the permeable supports --- p.27 / Chapter II.2.3. --- Cell seeding --- p.27 / Chapter II.2.4. --- Short-circuit measurement --- p.29 / Chapter II.2.5 --- Short-circuit measurement in nystatin-permeabilized T84 monolayers --- p.30 / Chapter II.3. --- Measurement of protein kinase A activity --- p.31 / Chapter II.4. --- Solutions and chemicals --- p.32 / Chapter II.5. --- Statistical analysis --- p.33 / Chapter Chapter III: --- Result --- p.34 / Chapter III.1. --- Effect of SRE on transepithelial ion transport processes in T84 monolayers --- p.35 / Chapter III.1.1 --- Effect of SRE and baicalein on baseline Isc --- p.35 / Chapter III.1.2 --- Effect of ion channel blockers on SRE-stimulated Isc --- p.39 / Chapter III.1.3 --- Effect of K+ channel blockers on SRE-stimulated Isc --- p.42 / Chapter III.1.4 --- Effect of SRE in C1- free solution --- p.48 / Chapter III.2. --- Effect of SRE on apical C1- conductance and basolateral K+ conductance in nystatin-permeabilized T84 monolayers --- p.51 / Chapter III.2.1 --- Effect of SRE and baicalein on baseline IC1 --- p.51 / Chapter III.2.2 --- Study of apical C1- conductance in T84 monolayers --- p.54 / Chapter III.2.3 --- Interaction of SRE and forskolin --- p.61 / Chapter III.2.4 --- Study of basolateral K+ conductance in T84 monolayers --- p.62 / Chapter III.3 --- Effect of SRE and baicalein on PKA activities in T84 cells --- p.64 / Chapter III.3.1 --- Effect of Scutellariae Radix on PKA activity --- p.66 / Chapter III.3.2 --- Effect of baicalein on PKA activity --- p.69 / Chapter III.3.3. --- Effect of berberine on PKA activity --- p.69 / Chapter III.3.3. --- Interaction of baicalein and berberine on PKA activity --- p.74 / Chapter Chapter IV: --- Discussion --- p.77 / Chapter IV.1 --- "Scutellariae Radix，Coptidis Rhizoma, and gastrointestinal secretory function" --- p.77 / Chapter IV.2 --- SRE- and baicalein-induced increase in Isc --- p.79 / Chapter IV.3 --- Cellular signaling mechanisms underlying the effect of SRE and baicalein --- p.82 / Chapter IV.4 --- "Interaction between Scutellariae Radix and Coptidis Rhizoma - the ""ying and yang"" hypothesis" --- p.89 / Chapter IV.5 --- Summary --- p.91

Acute colitis was induced by exposing male SD rats to 4% DSS in drinking water for 8 days. Rats were divided into four groups as follows: DSS group---DSS-induced colitis; DSS + SRE group---SRE, 100 mg/kg/day in addition to DSS; Ctr + SRE group---SRE alone; and Ctr group---sham control group. The colon damage was elucidated by macroscopic, histological, electrophysiological and biochemical assessment. Orally administered SRE significantly reduced the colonic damage in all four aspects. However, baicalein did not show similar effect in the same experiment. / In summary, our finding indicated that both SRE and its major flavonoid, baicalein, could stimulate chloride secretion in human colonic T84 cells and mucosa freshly isolated from human colon. Although SRE was effective in treating acute DSS-induced ulcerative colitis, baicalein is unlikely the active anti-inflammatory component of SRE. Nevertheless, the results demonstrated that this TCM has a scientific basis for its effectiveness. Our data support further evaluation of the therapeutic potential of SRE for the treatment of IBD. / In TCM, Scutellariae radix and Coptidis Rhizoma (CR) derived compounds have been frequently used for gastroenteritis and secretory diarrhea. Our laboratory findings suggested that the major flavonoid component of SR, baicalein, stimulates chloride secretion in rat distal colon, probably via CFTR activation (Ko et al., 2002). In contrast, limited information about the cellular mechanism of chloride secretion induced by SR in human colonic epithelia is available. Therefore, the effect of Scutellariae radix extract (SRE) on electrolyte transport in a human colonic epithelial cell line, T84, was examined using the short-circuit current (ISC) technique. Results demonstrated that SRE stimulated a Cl--dependent secretion across T84 cells, probably via both Ca2+- and cAMP-mediated pathway. / On the other hand, the cellular mechanism of baicalein-induced Cl - secretion in T84 cells was further investigated. It was found that the secretory mechanisms involve protein kinase A (PKA)-, adenylate cyclase (AC)- and luminal cAMP-dependent Cl- channels, most likely cystic fibrosis transmembrane conductance regulator (CFTR) and serosal 293B-sensitive K + channels. However, the action of baicalein cannot be solely explained by its cAMP-elevating effect. In addition, the effect of baicalein could be potentiated by the inhibition of mitogen-activated protein kinase (MAPK) and phosphoinositide-3 kinase (PI3K). Furthermore, it was found that inhibition of protein kinase C (PKC) delta limited the baicalein-induced chloride secretion. / Our laboratory has found that baicalein (Ko et al., 2002 and Yue et al., 2003) stimulates chloride secretion in rat distal colon and human colonic T84 cells. As it is known that responses in the animal model or the cell line may not completely reflect the in vivo physiology, it is important to study the above responses in human colon. With scarce supply of freshly isolated human colonic mucosa, the results showed that the effect of SRE and baicalein on ion transport in human samples is similar to that obtained in T84 cell line and rat model. / Scutellariae radix (SR) is the dry root of Scutellariae baicalensis Georgi (Huangqin). SR has been employed for centuries as a traditional Chinese medicine (TCM) for various purposes. It contains a large amount of flavonoids such as baicalein, baicalin, and wogonin, which possess a number of beneficial bioactivities including anti-oxidant, anti-bacterial and anti-inflammatory, etc. / Ulcerative colitis (UC), an inflammatory bowel disease (IBD), has been known for more than half a century. Recent studies have shown that two flavonoids derived from SR, baicalein and wogonin, might alleviate the symptoms of IBD. Moreover, SR is the major component of Hange-shasshin-to (HST), one of the Chinese herbal formulas, which has been reported to suppress the pathogenesis of IBD. The above scientific background led us to examine the effect of SRE administration on DSS-induced colitis in rats in a way to evaluate new treatments potentially applicable to UC in humans. / Chung, Ho Lam. / "August 2007." / Adviser: W. H. Ko. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0925. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

University of Macau / Institute of Chinese Medical Sciences