| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術研究所 === 89 === The maintenance of an adequate body weight is a major determinant of survival of higher organisms including mammals. Homeostasis of body weight is dependent on balance in energy intake and energy expenditure. Obesity is one of a severe health problem throughout developed countries including Taiwan. For instance, 80% of type II diabetic patients are obese. However, it remains unclear how obesity can bring about resistance to insulin.
Adipocytes is the key tissue responsible for energy balance. In the status of positive energy balance, adipocytes synthesize and store fat. Fatty acid sythase (FAS) is the rate-limiting enzyme in fatty acid synthesis. Adipocytes also have an energy-dissipating capacity. White adipocytes generate heat via uncoupling protein (especially UCP-2) in mitochondria. In this thesis, I try to establish a sensitive and accurate method for measuring the levels of mRNA of FAS and UCP-2 by real-time multiplex quantitative RT-PCR. The up- or down-regulation of FAS and UCP-2 in adipocytes induced by diet or drugs can thus be monitored. It was found that (1) FAS and UCP-2 were up-regulated when 3T3-L1 were differentiated to adipocyte; (2) leptin down-regulated FAS and up-regulated UCP-2 in 3T3-L1 and ex vivo adipocyte cells isolated from mouse; (3) Troglitazone (TZD) up-regulated both FAS and UCP-2 in 3T3-L1 and ex vivo adipocyte cells; (4) TNF-a down-regulated both FAS and UCP-2 in 3T3-L1 and ex vivo adipocyte cells isolated from mouse; (5) fasting caused down-regulation of FAS and UCP-2 in fat cells in vivo; (6) fructose diet induced up-regulation of FAS more than UCP-2 in fat cells in vivo. Taken together, FAS and UCP-2 can be indices reflecting energy balance in adipocytes and our developed method may be useful for screening drugs which affecting energy balance changes in adipocytes.
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