Owen Rickford Carryl

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate.

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol‐induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high‐fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague‐Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(−1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high‐fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high‐fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high‐fat diet and ethanol increased superoxide anion production by 10.0‐, 4.3‐, 5.7‐ and 4.8‐fold, respectively, in the gastric mucosa, and by 10.4‐, 5.3‐, 7.0‐ and 5.5‐fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high‐fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3‐, 4.5‐, 3.5‐ and 4.8‐fold, respectively, in the gastric mucosa, and by 17.0‐, 4.8‐, 3.5‐ and 4.7‐fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high‐fat diet and ethanol increased lipid peroxidation by 3.6‐, 2.4‐, 2.6‐ and 2.0‐fold, respectively, in the gastric mucosa, and by 4.1‐, 3.5‐, 3.6‐ and 2.7‐fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high‐fat diet and ethanol‐induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0‐, 2.0‐, 2.4‐ and 2.0‐fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high‐fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6‐, 6.1‐, 7.3‐ and 5.4‐fold, respectively, in the gastric mucosa, and by 16.2‐, 7.9‐, 9.5‐ and 7.8‐fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Differential dietary effects on colonic and small bowel neoplasia in C57BL/6J Apc Min/+ mice.

The effects of fiber on colon cancer are controversial. Twenty 5-week old C57BL/6J Apc Min/+ mice were fed for 60 days with a commercial mouse diet (Teklad LM-485) and eight semidefined diets containing 5–10% various fibers and 20% soybean oil. Ten additional C57BL/6J congenic litter-mates were fed each diet to assay colonic SCFA. SCFA, stool bulk, and colonic tumor incidence differed only slightly among the semidefined diets despite variations in fiber content and source. However, food consumption, caloric intake, stool bulk, and SCFA were substantially increased by the Teklad diet compared with all other groups. The Teklad diet significantly increased the number of mice with colonic tumors, average number of tumors/mouse, total tumor burden, colonic atypical hyperplasia, and small bowel tumors. Mice fed high-fat, no-fiber diets had more small bowel tumors (29.8 ± 3.1) than mice fed diets with fiber (8.2 ± 2.1) or with low fat and no fiber (18.1 ± 3.4) (P < 0.05 for each group). These studies suggest that fat predisposes to and fiber protects against small bowel tumors but not colon tumors in these mice. Thus, diets high in fiber or yielding high colonic luminal SCFA may not necessarily protect against colonic cancer. Furthermore, the effects of dietary fiber in Teklad appear overshadowed by some other biologically active factors in this animal model.

Mechanism of gastroprotection by bismuth subsalicylate against chemically induced oxidative stress in cultured human gastric mucosal cells.

Reactive oxygen species (ROS) are implicated inthe pathogenesis of chemically induced gastric mucosalinjury. We have investigated the effects of ethanol,hydrochloric acid (HCl), and sodium hydroxide (NaOH) on: (1) enhanced production of ROSincluding superoxide anion and hydroxyl radicals, (2)modulation of intracellular oxidized states by laserscanning confocal microscopy, and (3) DNA fragmentation, indices of oxidative tissue, and DNA damage ina primary culture of normal human gastric mucosal cells(GC), which were isolated and cultured from Helicobacterpylori-negative endoscopic biopsies from human subjects. The induction of ROS and DNAdamage in these cells following exposure to ethanol(15%), HCl (150 mM) and NaOH (150 mM) were assessed bycytochrome c reduction (superoxide anion production), HPLC detection for enhanced production ofhydroxyl radicals, changes in intracellular oxidizedstates by laser scanning confocal microscopy, and DNAdamage by quantitating DNA fragmentation. Furthermore, the protective ability of bismuth subsalicylate(BSS) was assessed at concentrations of 25, 50, and 100mg/liter. Incubation of GC with ethanol, HCl, and NaOHincreased superoxide anion production by approximately 8.0-, 6.1- and 7.1-fold and increased hydroxylradical production by 13.3-, 9.6-, and 8.9-fold,respectively, compared to the untreated gastric cells.Incubation of GC with ethanol, HCl, and NaOH increased DNA fragmentation by approximately 6.7-, 4.3-,and 4.8-fold, respectively. Approximately 20.3-, 17.5-,and 13.1-fold increases in fluorescence intensities wereobserved following incubation of gastric cells with ethanol, HCl, and NaOH, respectively,demonstrating dramatic changes in the intracellularoxidized states of GC following exposure to thesenecrotizing agents. Preincubation of GC with 25, 50, and 100 mg/liter of BSS decreased ethanol-inducedincreases in intracellular oxidized states in thesecells by 36%, 56%, and 66%, respectively, demonstratinga concentration-dependent protective ability by BSS. Similar results were observed withrespect to BSS in terms of superoxide anion and hydroxylradical production, and DNA damage. The present studydemonstrates that ethanol, HCl, and NaOH induce oxidative stress and DNA damage in GC and thatBSS can significantly attenuate gastric injury byscavenging these ROS.

Cytoprotective effect of bismuth subsalicylate in indomethacin-treated rats is associated with enhanced mucus bismuth concentration

Bismuth compounds prevent gastric injury from the short‐term administration of nonsteroidal anti‐inflammatory drugs. We studied the mechanisms underlying the gastroprotective actions of bismuth subsalicylate against indomethacin‐induced injury in rats.

Effect of pepper and bismuth subsalicylate on gastric pain and surface hydrophobicity in the rat.

The mechanism by which dietary pepper causes dyspepsia and epigastric pain is poorly understood, as is the ability of bismuth subsalicylate (BSS) to relieve these symptoms.

Protection Against Chemically-Induced Oxidative Gastrointestinal Tissue Injury in Rats by Bismuth Salts

Oxygen free radicals (OFR) are implicated in thepathogenesis of stress, chemically induced gastriclesions, and gastrointestinal injury. Theconcentration-dependent scavenging abilities of bismuthsubsalicylate (SBS), colloidal bismuth subcitrate (CBS), andselected OFR scavengers, including superoxide dismutase(SOD), catalase, mannitol, and allopurinol were examinedagainst biochemically or chemically generated superoxide anion, hydroxyl radical, andhypochlorite radical plus hypochlorous acid based on achemiluminescence assay. Furthermore, both gastric (GM)and intestinal mucosa (IM) were individually exposed in vitro to these free radical generatingsystems, and the concentration-dependent protectiveabilities of SBS and CBS against lipid peroxidation (LP)were compared with selected OFR scavengers. In addition, 24-hr fasted rats were orally treated with thenecrotizing agents 0.6 M HCl, 0.2 M NaOH, 80% ethanol,and aspirin (200 mg/kg). The extent of tissue injury inthe GM and IM was determined by assessing LP, DNA fragmentation, and membrane microviscosity.Dose- and time-dependent in vivo protective abilities ofCBS (100 mg/kg) and SBS (15 mg/kg) were also assessed.Following incubations with superoxide anion and hydroxyl radical generating systems in thepresence of 125 mg SBS/liter, approximately 47% and 61%inhibitions were observed in the chemiluminescenceresponse, respectively, while 48% and 46% inhibitions were observed with 125 mg CBS/liter. SBS andCBS exerted similar abilities towards hypochloriteradical plus hypochlorous acid. Approx. 3.1- and3.7-fold increases in LP were observed in the GM and IMof rats following oral administration of 0.6 MHCl. Pretreatment of the rats with SBS and CBS decreased0.6 M HCl-induced LP in the GM by approx. 39% and 27%,respectively, with similar decreases in LP in the IM. SBS exhibited better protectiveabilities towards 0.6 M HCl and 0.2 m NaOH-induced GMand IM injury as compared to CBS. SBS and CBS providedsimilar protection towards 80% ethanol-induced gastric injury, while CBS exerted a superior protectiveability towards aspirin-induced gastric injury. Theresults demonstrate that both SBS and CBS can scavengereactive oxygen species and prevent tissue damage produced by OFR.