Nutrition and Exercise Physiology electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Nutrition and Exercise Physiology. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Impact of dietary supplementation of glycocalyx precursors on vascular function in type 2 diabetes(University of Missouri--Columbia, 2024) Smith, James Alexander; Padilla, Jaume; Manrique-Acevedo, CamilaDegradation of the endothelial glycocalyx in type 2 diabetes (T2D) is thought to contribute to impaired shear stress mechanotransduction, leading to endothelial dysfunction and the development of cardiovascular disease. Herein, it was hypothesized that restoration of the endothelial glycocalyx with dietary supplementation of glycocalyx precursors (DSGP, containing glucosamine sulfate, fucoidan, superoxide dismutase, and high molecular weight hyaluronan) improves endothelial function and other indices of vascular function in T2D. First, in db/db mice, treatment with DSGP (100 mg/kg/day) for four weeks restored endothelial glycocalyx length, as assessed via atomic force microscopy in aortic explants. Restoration of the glycocalyx with DSGP was accompanied by improved flow-mediated dilation (FMD) and reduced arterial stiffness in isolated mesenteric arteries. Further corroborating these findings, treatment of cultured endothelial cells with that same mixture of glycocalyx precursors promoted glycocalyx growth. Next, as an initial step to investigate the translatability of these findings, a pilot (n=22) double-blinded randomized placebo-controlled clinical trial was conducted to assess the effects of DSGP (3,712.5 mg/day) for eight weeks on endothelial glycocalyx integrity and indices of vascular function, including FMD, in Veterans with T2D. Contrary to the hypothesis, DSGP neither enhanced endothelial glycocalyx integrity nor improved vascular function indices relative to placebo. Together, these findings conceptually support the notion that restoration of the endothelial glycocalyx can lead to improvements in vascular function in a mouse model of T2D; however, DSGP as a therapeutic strategy to enhance vascular function in individuals with T2D does not appear to be efficacious.Item Estrogen in the nucleus accumbens : impacts on metabolism, wheel-running, and cocaine preference(University of Missouri--Columbia, 2024) Shay, Dusti; Vieira-Potter, Victoria J.Estrogen (E2) signaling in the reward circuit of the brain (e.g. nucleus accumbens (NAc)) is known to modulate rewarding behaviors, such as exercise, palatable food intake, and drug use. Women, given constantly fluctuating levels of E2 throughout the menstrual cycle, are at particular risk for development of substance use disorder (SUD) pre-menopause and metabolic dysfunction due to obesity post-menopause. This highlights a need for greater understanding of how E2 signaling in the reward regions of the brain impacts behaviors contributing to disease risk throughout the lifespan of women. This dissertation reports findings detailing the effect of systemic administration of a novel-selective estrogen receptor beta (ER[beta]) ligand in mice following ovariectomy (OVX) on adiposity and metabolism, as well as physical activity and gene expression in the NAc. In addition, two aims of this dissertation report the effects of direct NAc microinjection of E2 on voluntary wheel-running (VWR) and conditioned place preference (CPP) for cocaine. Results demonstrate a possible role for ER[beta] in lean mass preservation with weight loss, given a longer course of treatment with ER[beta] ligand than the 2 weeks given here. Regarding E2 in NAc, 0.75µg of E2 partially rescued VWR after OVX-induced reductions. However, the same dose of E2 unexpectedly contributed to the development of a cocaine conditioned place aversion (CPA). These findings suggest an important role for E2 in the NAc (possibly via ER[beta]) for increasing physical activity, which mitigates cardiometabolic disease risk associated with obesity. In addition, E2 in the NAc plays a critical role in cocaine conditioning and elucidation of these mechanisms may provide understanding for the treatment of SUD in young women.Item Glucose and lipid metabolism : the role of sleep, exercise, and adipose tissue(University of Missouri--Columbia, 2024) Maloney, Alan Christopher; Kanaley, Jill AHabitual sleep restriction (SR) (<7 h/night) is widespread in modern society and may be contributing to the development of type 2 diabetes by inducing insulin resistance (IR) in skeletal muscle (SM) and adipose tissue (AT). A lack of sleep also likely contributes to IR development indirectly by affecting behavior (i.e., physical activity and energy intake). Whether the way sleep is restricted, or prior exercise engagement, impact these outcomes is not fully understood. As SM and AT are particularly susceptible to the ramifications of SR, mechanistically investigating the nuances of their dysfunction in disease states (i.e., obesity and gestational diabetes mellitus) may provide insight into SR-induced metabolic impairments. Given the above, a series of experiments were performed that determined: 1) during modest SR, advancing wake time tends to increase physical activity while delaying sleep time tends to increase energy intake, particularly through high fat and sodium foods; 2) prior evening exercise reduces morning postprandial lipemia in the latter half of a 4-h oral fat tolerance test, but this effect is abolished during SR; 3) gestational diabetes mellitus affects AT in a depot- specific manner, predominantly affecting visceral AT metabolism and inflammation; and 4) in of obese mice, a beta-3 adrenergic receptor agonist has therapeutic effects similar to exercise as it increases lean mass during weight loss, improves glucose tolerance, and alters markers of lipid metabolism in SM. Collectively, these data advance our understanding of the metabolic and behavioral consequences of SR, evaluate the efficacy of therapeutics on these consequences, and mechanistically provide tissue-specific insight into disease states that could hypothetically develop from chronic SR.Item The vascular response to hypoxia and sympathetic activation : sex differences and the role of [beta]-adrenergic receptors and nitric oxide(University of Missouri--Columbia, 2024) Jacob, Dain Ward; Limberg, Jacqueline KDuring hypoxia, systemic sympathetic vasoconstrictor activity is increased but peripheral vasodilation prevails -- suggesting vasodilatory factors outweigh sympathetically-mediated vasoconstrictor influences in the healthy state. Prior data from our lab show when the sympathetic vasoconstrictor activity is increased with exogenous stimulation, the vasoconstrictor response during hypoxia is blunted in females but not males. [beta]-adrenergic receptors both contribute to hypoxic vasodilation and have been reported to blunt sympathetically mediated vasoconstriction. [beta]-adrenergic receptors have also been shown to mediate greater dilation in females and arteries from females have greater vascular expression relative to males. We hypothesized pharmacological blockade of [beta]-adrenergic receptors would blunt hypoxic dilation and augment the vasoconstrictor response to acute sympathetic activation during hypoxia and this effect would be greater in females relative to males. Participants were studied twice in a randomized, placebo-controlled fashion undergoing two trials per visit: 1) steady state hypoxia and 2) steady state hypoxia and concomitant cold pressor test to stimulate the sympathetic nervous system. In agreement with our hypothesis, under [beta]-adrenergic blockade, we observed a significantly greater attenuation of hypoxic dilation in females, with no effect in males. In contrast to our hypothesis, [beta]-adrenergic blockade during hypoxia had no effect on sympathetically mediated vasoconstriction, in males or females. These data advance our understanding of sympathetic vascular regulation in the context of hypoxia and may have clinical implications in conditions where hypoxia is observed (i.e., sleep apnea, COVID-19, heart failure).Item The effects of 6-weeks of resistance training on the gut microbiome in young adults with overweight and obesity(University of Missouri--Columbia, 2022) Cullen, John; Dhillon, JaapnaINTRODUCTION: Obesity is a known risk factor for the development of insulin resistance, type 2 diabetes, and other cardiometabolic outcomes. Recently, the gut microbiome had been identified as a possible contributor to the onset of obesity and subsequent health complications. Exercise has been regularly utilized as a therapeutic intervention to treat obesity and its associated comorbidities and has also recently been shown to have an effect on the gut microbiome. Various modalities of exercise and their effects on the gut microbiome have been studied to differing degrees, with aerobic exercise being the most commonly studied exercise modality and resistance training (RT) being the least studied modality. AIMS: Hence, we sought to examine the effects of RT on the gut microbiome (Aim 1), hypothesizing that RT would have an effect on the diversity, composition, and metabolic pathways of the gut microbiome. We additionally sought to study the effects of RT on cardiometabolic outcomes and the associations of the gut microbiome with cardiometabolic outcomes (Aim 2), hypothesizing that beneficial changes in the gut microbiome would be positively associated with changes in cardiometabolic outcomes. METHODS: Sedentary young adults (age 18-35 years) with overweight and obesity (BMI 25-45 kg/m2) were recruited to participate in this randomized controlled trial. Participants were randomized into 1 of 2 groups: RT (n=17) which participated in a 6-week resistance training program (3 days/week), or control (CT) (n=16) which continued normal patterns of daily living and served as a non-exercising control. Main outcomes of the study included gut microbiome measures (composition, diversity, and pathways) and cardiometabolic measures (glucoregulatory and cardiovascular outcomes). Data was collected at baseline (BL) and at the end of the 6-week study (W6). RESULTS: Notable findings include an increase in Roseburia genus abundance, a SCFA producer, and microbial starch and sucrose metabolism pathway abundance over 6 weeks with RT in comparison to CT (group x week, p[less than]0.05, q[less than]0.25). Moreover, RT resulted in higher QUICKI and lower diastolic blood pressure at W6 compared to CT (BL-adjusted p[less than]0.05). Correlation analyses demonstrate a trend for a moderately positive correlation of Roseburia with QUICKI (r=0.48, p[less than]0.1) and negative correlation with HOMA-IR (r=-0.46, p[less than]0.1) in the RT group at W6 which was not observed in the CT group. CONCLUSION: This study provides preliminary evidence that resistance training induces positive changes in the gut microbiome and cardiometabolic health. Additionally, the microbiome-glucoregulation associations indicate that SCFA producers may be potentially associated with glucoregulatory improvements which could have important clinical implications and should be examined in future studies with larger sample sizes.