Degree Type

Dissertation

Date of Award

2005

Degree Name

Doctor of Philosophy

Department

Food Science and Human Nutrition

Major

Toxicology

First Advisor

Suzanne Hendrich

Abstract

Deoxynivalenol (DON) is a mycotoxin naturally occurring in worldwide grain supplies and has caused gastrointestinal disease, in humans and animals, and immunotoxicity in animals. Methods were optimized for analysis and screening of food samples for DON. Caffeine was a suitable internal standard for analytical detection of DON in wheat samples using high performance liquid chromatography (HPLC). This method will allow analysis of samples using a stable and inexpensive compound not likely to be found in most samples of interest. A bioassay was used to screen for DON in a variety of food samples. Human K-562 erythroleukemia cells, modeling immune stem cells, were incubated with wheat and corn extracts in media, cell proliferation assessed by the MTS dye reduction assay. Samples containing DON ranged in concentrations from 204 to 3792 ng DON/g food strongly correlating with HPLC analysis. This sensitive bioassay may serve as an inexpensive low-tech alternative for screening food samples or products of DON detoxification studies. We hypothesized that acute exercise stress would exacerbate immunosuppressive effects of dietary DON. Male BALB/c mice were fed 0 or 2 mg DON/kg diet for 14 days (n = 12 per dose), then half of each dose were exercised to fatigue. Non-exercised DON-fed mice showed significant splenocyte proliferation suppression and increased IL-4 expression. Antibody response to sheep red blood cells was significantly less for exercised DON-fed mice with increased IL-2 expression. Exercise caused elevated serum corticosterone levels. Exercise stress protected against DON-mediated suppression of splenocyte proliferation, perhaps mediated by stress hormone effects on differential cytokine expression. This interaction was investigated further with BALB/c male mice fed 0, 1 or 2 ppm DON for 28 days then half of each dose was exercised to fatigue. Exercise was inhibitory for IL-4, NK cytotoxicity, spleen: body weight ratio, blood lymphocytes, hemoglobin, hematocrit but caused elevated blood neutrophils. Dietary DON at 2 ppm inhibited weight gain, red blood cell numbers and hematocrit but increased feed intake. DON fed at 1 ppm stimulated NK cytotoxicity, PFCs, and spontaneous IFN-gamma secretion. This is the first report of in vivo immunostimulatory effects of sub-chronic low dose DON feeding.

DOI

https://doi.org/10.31274/rtd-180813-379

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Cindy A. Landgren

Language

en

Proquest ID

AAI3184629

File Format

application/pdf

File Size

174 pages

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