Matching Items (2)
Description
High fat diets (HFD) are known to cause hepatic non-alcoholic steatosis in rats in as few as four weeks. Accumulation of triglycerides in liver and skeletal muscle is associated with insulin resistance and obesity. However, studies of fat accumulation in cardiac muscle are not as prevalent. Therefore, the first hypothesis of this study was that HFD would lead to hepatic steatosis as well as lipid accumulation in pectoralis and cardiac muscles, tissues responsible for the majority of postprandial glucose disposal. Prior studies also indicated that HFD leads to increased inflammation and oxidative stress within the vasculature resulting in impaired endothelium-dependent vasodilation, however biomarkers of immune system reactivity were not assessed. Therefore, the second aim of this study was to explore additional pathways of immune system reactivity and stress (natural antibodies; heat shock protein 60 (HSP60)) in rats fed either a control (chow) or high fat (HFD) diet. HSP60 has also recently been recognized as an early marker of vascular dysfunction in humans. The hypothesis was that immune system reactivity and early vascular dysfunction would be heightened in rats fed a HFD compared to chow-fed controls. Young male Sprague-Dawley rats (140-160g) were maintained on a chow diet (5% fat, 57.33% carbohydrate, 3.4kcal/g) or HFD (60% fat, 20% carbohydrate, 5.24 kcal/g) for 6 weeks. HFD rats developed hepatic steatosis with significantly elevated liver triglyceride concentrations compared to chow-fed controls (20.73±2.09 vs.9.75±0.52 mg triglycerides/g tissue, respectively; p=0.001). While lipid accumulation appeared to be evident in the pectoralis muscle from HFD rats, triglyceride concentrations were not significantly different from controls. Likewise, there was no evidence of lipid infiltration in cardiac muscles of HFD rats. Lipid accumulation in the liver of overweight HFD rats may contribute to the observed insulin resistance in these animals. Contrary to the second hypothesis, there were no significant differences in plasma HSP60 expression between HFD and chow rats (p>0.05). Likewise, hemagglutination and hemolysis responses were similar between HFD and chow-fed rats (p>0.05). These findings suggest that immune system responses may not be affected by 6 weeks of high fat intake and that HSP60 is not an early marker of vascular dysfunction in this rodent model.
ContributorsLiss, Tyler Jessee (Author) / Sweazea, Karen (Thesis director) / Shaibi, Gabriel (Committee member) / Johnston, Carol (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2013-05
Description
The prevalence of cardiovascular diseases, closely associated with elevated cholesterol levels, remains a significant public health concern worldwide. Dietary interventions, particularly the consumption of whole grains, have been advocated for their potential in reducing cholesterol levels and mitigating cardiovascular risk. However, the specific impact of corn flour, a staple in many diets, on cholesterol modulation remains underexplored. This thesis aims to address this gap by exploring how three varieties of corn flour (refined, whole grain, and excellent fiber mixture) provided by the North American Millers Association Corn Division (NAMA) affect both LDL cholesterol levels and triglycerides. This study was conducted using a randomized-single blinded crossover design. There were three treatment periods that were each 4-weeks long, each treatment period consisting of a different flour treatment. There was a 2-week washout period in between each treatment making the study a total of 16 weeks. During each treatment period, blood samples were collected from each participant to analyze LDL and triglyceride levels. At the beginning and end of each treatment period, two blood samples were taken to account for day-to-day variability. Pre-intervention LDL cholesterol levels were compared to post-intervention LDL cholesterol levels using a general linear model. This study found that LDL cholesterol levels were significantly reduced by the excellent fiber mixture by ~10 mg/dL. Whole grains and refined grains, however, had no significant effect on LDL cholesterol levels. None of the corn flour treatments had a significant effect on triglyceride levels. The overall results of the study indicated that implementing the excellent fiber mixture into the diet could be effective in reducing risk for cardiovascular disease.
ContributorsProbst, Amanda Grace (Author) / Whisner, Corrie (Thesis advisor) / Grant, Shauna (Committee member) / Mayol-Kreiser, Sandra (Committee member) / Arizona State University (Publisher)
Created2024