Matching Items (3)
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- All Subjects: Obesity
- Creators: Sweazea, Karen
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
Birds have unusually high plasma glucose concentrations compared to mammals of similar size despite their high metabolic rate. While birds use lipids as their main source of energy, it is still unclear how and why they maintain high plasma glucose concentrations. To investigate a potential underlying mechanism, this study looks at the role of lipolysis in glucose homeostasis. The purpose of this study is to examine the effects of decreased glycerol availability (through inhibition of lipolysis) on plasma glucose concentrations in mourning doves. The hypothesis is that decreased availability of glycerol will result in decreased production of glucose through gluconeogenesis leading to reduced plasma glucose concentrations. In the morning of each experiment, mourning doves were collected at the Arizona State University Tempe campus, and randomized into either a control group (0.9% saline) or experimental group (acipimox, 50mg/kg BM). Blood samples were collected prior to treatment, and at 1, 2, and 3 hours post-treatment. At 3 hours, doves were euthanized, and tissue samples were collected for analysis. Acipimox treatment resulted in significant increases in blood glucose concentrations at 1 and 2 hours post- treatment as well as renal triglyceride concentrations at 3 hours post-treatment. Change in plasma free glycerol between 0h and 3h followed an increasing trend for the acipimox treated animals, and a decreasing trend in the saline treated animals. These results do not support the hypothesis that inhibition of lipolysis should decrease blood glycerol and blood glucose levels. Rather, the effects of acipimox in glucose homeostasis appear to differ significantly between birds and mammals suggesting differing mechanisms for glucose homeostasis.
ContributorsKouteib, Soukaina (Author) / Sweazea, Karen (Thesis director) / Deviche, Pierre (Committee member) / Chandler, Douglas (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
It is presently believed that brown adipose tissue (BAT) is an important tissue in the control of obesity because it has the propensity to increase energy expenditure. The purpose of this study was to attempt to quantify the thermogenesis of BAT when four rats were exposed to a progression of low-fat to high-fat diet. Exogenous norepinephrine (NE) injections (dose of 0.25 mg/kg i.p.) were administered in order to elicit a temperature response, where increases in temperature indicate increased activity. Temperatures were measured via temperature sensing transponders that had been inserted at the following three sites: interscapular BAT (iBAT), the abdomen (core), and lower back (reference). Data showed increased BAT activity during acute (2-3 weeks) high fat diet (HFD) in comparison to low fat diet (LFD), but a moderate to marked decrease in BAT activity during chronic HFD (6-8 weeks) when compared to acute HFD. This suggests that while a HFD may initially stimulate BAT in the short-term, a long-term HFD diet may have negative effects on BAT activation.
ContributorsSivak, Hanna (Author) / Sweazea, Karen (Thesis director) / Herman, Richard (Committee member) / Caplan, Michael (Committee member) / School of Life Sciences (Contributor) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The prevalence of excessive weight gain (obesity) has steadily increased since about 1980. Excessive weight gain is associated with many comorbidities; thus, a successful treatment is needed. The most common form of non-surgical treatment for excessive weight gain is caloric restriction with the intent to reduce body weight by 10%. Though this treatment is successful at reducing body weight, it often fails at maintaining the weight loss. Dietary menthol has been suggested as a possible treatment for excessive weight gain and has produced promising results as a preventative method for excessive weight gain. Our studies aimed at reducing weight regain and maintaining caloric restriction by feeding male Sprague-Dawley rats 0.5% dietary menthol during a period of caloric restriction, aimed at reducing their body weight by 10%, following an experimental period where the rats were fed a high-fat diet (HFD) or low-fat diet (LFD). The effects of the dietary menthol were observed during the weight regain period following the caloric restriction period. Two studies were conducted, and both were unable to achieve a maintenance of weight loss following caloric restriction, although our first study was able to produce a delay in weight regain and did not show any evidence of increased thermogenesis in menthol-treated rats. Our findings differ from the findings of previous studies on dietary menthol which could possibly be due to species effects, differences in procedures, age effects, or effects of different fatty acid compositions. The contrasting results in our studies could be due to genetic differences between litters used or a difference in manufacturing of the menthol diet between studies. Given the partial response to menthol in the first study, it can be suggested that the concentration of 0.5% may be below the threshold of menthol sensitivity for some rats. Future research should focus on increasing the concentration of dietary menthol from 0.5% to 1%, since the current concentration did not yield a reduction in weight regain or maintenance of caloric restriction.
ContributorsRascon, Kasandra (Author) / Herman, Richard (Thesis director) / Sweazea, Karen (Committee member) / Kim, Minjoo (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05