Identifier

etd-11022015-134700

Degree

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

Document Type

Dissertation

Abstract

Overweight and obesity have been imposing $147 billion a year to the health care system in the United States. Limited medications are available in the market with side effects. Surgical treatments are second-line obesity treatments. Short chain fatty acids (SCFAs) produced from the fermentable resistant starch improves the secretion of satiety hormones peptide YY (PYY) and glucagon-like peptide 1 (GLP-1) from L-endocrine cells of cecum and colon. We hypothesized that consumption of fermentable non-digestible dietary fiber and bioactive compounds will increase insulin sensitivity, reduce body fat, and improve healthspan in Caenorhabditis elegans (C. elegans), and hyperglycemia (2% glucose) that may cause insulin resistance and impair lipid metabolism will attenuate these effects. Wild type C. elegans N2 or sir-2.1(ok434)IV, daf-16(mgDf50)I, and daf-16(mgDf50)I;daf-2(m65)III mutants were used. The control animals were fed with E. coli OP50. Experimental groups were fed with additional treatments: butyrate (0.3mM, 0.6mM), sodium acetate (5mM, 50mM), sodium propionate (7mM), or tributyrin (0.5mM, 3mM); PWB, oats or wheat bran (0.5%, 1.0%, or 3.0% w/v) with or without additional 2% glucose. SCFAs increased the lifespan of N2 and daf-16(mgDf50)I, but reduced lifespan in the daf-16/daf-2 deficient and sir-2.1(ok434)IV mutants. PWB or wheat bran sustained the pharyngeal pumping rate (PPR) in N2, sir-2.1(ok434)IV, daf-16(mgDf50)I, and daf-16(mgDf50)I;daf-2(m65)III. The N2, daf-16, or sir-2.1 mutant increased the PPR following oat consumption. This increase persisted in the presence of glucose at a low dose in daf-16 or daf-16/daf-2 mutant. The Nile red stained intestinal fat deposition (IFD) was reduced by butyrate (0.3, 0.6mM), acetate (100mM), propionate (0.3mM), and tributyrin (0.1, 1mM) in N2; and was increased in sir-2.1 mutant. PWB reduced IFD in N2, sir-2.1 or daf-16 mutants. Hyperglycaemia attenuated the effects on IFD in N2 or daf-16/daf-2 mutant. Oat-feeding decreased IFD in N2, and daf-16 or daf-16/daf-2 mutant with or without hyperglycaemia. Wheat bran reduced IFD in N2, and in daf-16 or daf-16/daf-2 mutants without hyperglycemia, while hyperglycemia increased IFD in sir-2.1(ok434)IV. In summary, PWB, oats, wheat bran, and SCFAs reduced the IFD and improved the healthspan in C. elegans, and these effects were mediated by the sir-2.1, daf-2, or daf-2/daf-16 pathways.

Date

2015

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Zheng, Jolene, M.D., Ph.D.

DOI

10.31390/gradschool_dissertations.2424

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