Browsing by Author "Haynie, Kimberly Rebekah"

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    The Role of High Saturated Fatty Acid Diets on Skeletal Muscle Metabolism and Inflammation
    Haynie, Kimberly Rebekah (Virginia Tech, 2011-10-31)
    The purpose of this study was to examine the relationship between metabolic adaptive response to 5 days of high SFA feeding, independent of positive energy balance, and diet-induced agonism of pro-inflammatory pathways. A secondary aim was to determine if the metabolic adaptive response in skeletal muscle to a single, high fat meal was altered by 5 days of high saturated fat feeding. Twelve college-age, non-obese males were studied and skeletal muscle samples were obtained prior to and concluding the consumption of a high SFA diet. In a subset of volunteers (N=6), we fed participants a high fat meal after the initial skeletal muscle biopsy and measured changes in postprandial endotoxin concentrations for four hours following the meal challenge. A second biopsy was obtained four hours after the meal challenge. Skeletal muscle samples were used to measure fatty acid oxidation, glucose oxidation, oxidative enzyme activities, mRNA expression of metabolic targets, and phosphorylation and total content of inflammatory proteins. In response to five days of high SFA feeding, skeletal muscle glucose and complete palmitate oxidation were significantly reduced as was the ratio of complete to incomplete fatty acid oxidation. Five days of high SFA feeding also attenuated the meal challenge-induced up-regulation of oxidative genes while augmenting postprandial increases in plasma endotoxin concentrations. To assess the relationship between metabolic adaptability and diet-induced inflammatory response we categorized volunteers by the diet induced percent change in fatty acid oxidation. Volunteers who were the least capable to adapt to high SFA feeding displayed the most robust increases in phosphorylation of inflammatory proteins. Lastly, we measured the correlation between the meal challenge associated percent change in oxidative and inflammatory markers in samples obtained prior to and following five days of high SFA feeding. We observed positive associations between the percent change in oxidative and inflammatory markers in samples obtained prior to the high SFA diet that were not observed following five days of high SFA feeding. These findings suggest that diet induced inflammatory response is involved in the regulation of adaptive response to high SFA feeding and that this relationship becomes dysregulated with chronic high SFA intake.
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    The Role of Neuropeptide Y Y1R in Skeletal Muscle Lipid Metabolism
    Haynie, Kimberly Rebekah (Virginia Tech, 2009-04-28)
    The Hulver laboratory has recently found that the neuropeptide Y Y1 receptor (NPY Y1R) mRNA expression is elevated in skeletal muscle of obese humans (Hulver, unpublished). The goal of this research is to study the role of the NPY Y1R in skeletal muscle lipid metabolism. Rat L6, mouse C2C12, and human primary myotubes were incubated in 14C palmitate labeled fatty acid oxidation medium containing 80ng/mL, 250ng/mL, and 500ng/mL of NPY and for a three hour period. Experiments were repeated with the addition of 17mg/mL diprotin A to each NPY treatment. Fatty acid oxidation (FAO) and the percentage of lipids stored within the myotubes as diacylglyceride (DAG) and triaclyglyceride (TAG) were measured. Analyses were repeated in rat L6 and mouse C2C12 following a three hour incubation in 14C palmitate labeled fatty acid oxidation medium containing 1µg/mL, 10µg/mL, and 50µg/mL of the NPY Y1R ligand, [Leu31, Pro34] neuropeptide Y (Bachem, Torrance, CA). Incubation of human primary myotubes in NPY treatments with the addition of diprotin A significantly increased TAG accumulation (p< 0.05). Mouse C2C12 mytoube incubation in 500ng/mL NPY with diprotin A increased FAO (p 0.05). All other NPY and NPY Y1R ligand treatments in had no significant effect on FAO or the accumulation of TAG and DAG.