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Life and death: thermogenesis, metabolism and membranes

Abstract
Currently, research on maximum sustained metabolic rate concentrates on the importance of heat dissipation in lactating females. It has been shown that due to the exothermic process of milk production and because they digest very large quantities of food, females raising young are constrained by hyperthermia in their energy intake. Reportedly, females allow their body temperature to increase by 1.2° and the unanswered question in this context is what determines the upper limit of body temperature. We intend to test the hypothesis that oxidative stress might determine this limit. Therefore we propose to perform a series of experiments in lactating mice from the MF1 strain which involve manipulations of body temperature while assessing oxidative stress, antioxidant activity and gene expression of uncoupling proteins. At the end of our study we will be able to identify the physiological importance of oxidative damage in response to sustained energy intake, a topic which will be of interest for many scientific groups working in the fields of metabolism and aging. Another newly generated hypothesis in context with body temperature regulation in mammals suggests that certain membrane constituents, n-3 polyunsaturated fatty acids, may modulate thermogenic capacity in mammals. Thus, we hypothesise that in parallel with changes in core body temperature, membrane fatty acid composition is adjusted accordingly, with n-3 polyunsaturated fatty acids having a particular role for thermogenesis. To test our hypothesis we will use lactating mice from the MF1 strain in addition to the model system of the long-lived Ames dwarf mouse. Importantly, Ames dwarf mice also have lower body temperatures and presumably impaired thermoregulation while at the same time possessing muscle membrane phospholipids rich in n-3 polyunsaturated fatty acids. We will keep animals on diets enriched with both n-3 or n-6 fatty acids and will establish a control on an isocaloric saturated diet. In all experimental animals we will measure body temperature with implanted transmitters and tissue fatty acid composition. In another group of animals we will assess proton leak in isolated liver mitochondria. This part of the project will identify the role of membrane bound fatty acids for modulation of body temperature in mammals.
Keywords
biochemistry
experimental zoology
animal physiology
Project Leader
Valencak Teresa,
Duration
01.03.11-28.02.14
Subprogramme
Elise Richter
Type of Research
Basic Research
Staff
Valencak T., Project Leader
Vetmed Research Units
Research Institute of Wildlife Ecology,
Funded by
FWF Fonds zur Förderung der wissenschaftlichen Forschung, Sensengasse 1, 1090 Wien, Austria
Publications
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