Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
We determined the influence of thermonuetrality on the oxygen consumption (VO2) and heart rate (HR) responses to short-term moderate fat feeding in male C57BL/6J (B6; obesity-prone) mice and A/J (obesity-resistant) mice. Mice were adapted to either Ta=23°C or Ta=30°C for at least 5 weeks, implanted with telemetry devices, and housed in metabolic chambers for measurement of food intake, VO2, HR, mean arterial pressure (MAP), and locomotor activity. Access to moderate fat diet resulted in similar increases in normalized VO2 at both Ta=23°C (B6 Δ: 2.7±0.4 ml/min/kg0.75; A/J Δ: 3.8±0.5 ml/min/kg0.75) and Ta=30°C (B6 Δ: 2.4±0.4 ml/min/kg0.75; A/J Δ: 4.4±0.6 ml/min/kg0.75) within each respective strain. However, the A/J mice (Δ: 4.1±0.4 ml/min/kg0.75) had an enhanced metabolic response compared to the B6 mice (Δ: 2.5±0.3 ml/min/kg0.75). Tachycardia following the nutritional intervention occurred at Ta=30°C, and was similar in magnitude in B6 mice (Δ: 55±10 beats/min at Ta=30°C vs. 12±8 beats/min at Ta=23°C) and A/J mice (Δ: 61 ± 15 beats/min at Ta=30°C vs. 25±18 beats/min at Ta=23°C). By the third day of access to moderate fat diet, caloric intake for A/J mice returned to baseline chow levels. However, the B6 mice remained hyperphagic throughout the 7 days of moderate fat feeding. The results demonstrate that an enhanced ability to engage adaptive thermogenesis is one mechanism utilized by the A/J mice to prevent obesity. Because the thermogenic response was observed in mice chronically adapted to thermoneutrality, we conclude it is not likely mediated by brown adipose tissue. Finally, the observation that the cardiovascular responses to short term moderate fat feeding in mice were more evident at thermoneutrality suggests that rodent studies examining the role of obesity on cardiovascular disease should be performed at thermoneutral temperatures.
A Thesis Submitted to the Department of Nutrition, Food and Exercise Sciences in Partial Fulfillment of the Requirements for the Degree of Master of Science.
Includes bibliographical references.
Florida State University
Use and Reproduction
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them.