Type of Document Master's Thesis Author Shen, Li Author's Email Address Shenl@pbrc.edu URN etd-07092008-100712 Title Dietary Resistant Starch Increases Hypothalamic POMC Expression Independent of Capsaicin-Sensitive Neurons in Rats Degree Master of Science (M.S.) Department Human Ecology Advisory Committee
Advisor Name Title Roy J Martin Committee Chair jun zhou Committee Member Michael Keenan Committee Member Keywords
- Dietary Fiber
- GI Hormones
- Hypothalamic Arcuate Nucleus
- Vagus Nerve
Date of Defense 2008-07-07 Availability unrestricted AbstractResistant starch (RS) is fermentable dietary fiber. It has been shown that inclusion of resistant starch in the diet causes decreased body fat accumulation and altered gut hormone profile. Gut hormone has complex effect on neuropeptidesí expression in the brain hypothalamic area which is regarded as key factors in regulation of energy homeostasis. In this project, thereby, it is proposed that 1) the hypothalamic neuropeptide Y (NPY), agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) mRNA expression may be altered by RS feeding; 2) afferent vagal nerves might be involved in this process.
Animal experiment was conducted to investigate the hypothesis. The rats were injected intraperitoneally with capsaicin to destroy unmyelinated small vagal afferent nerve fibers. The cholecystokinin food suppression test was performed to validate the effectiveness of the capsaicin treatment. Then, capsaicin treated rats and vehicle treated rats were subdivided into a control diet or a resistant starch diet group, and fed the corresponding diet for 65 days. At the end of study, body fat, food intake, plasma peptide YY (PYY) and glucagon-like peptide -1 (GLP-1), and hypothalamic pro-opiomelanocortin, neuropeptide Y, agouti-related peptide gene expressions were measured.
Resistant starch fed rats had decreased body fat, increased POMC expression in the hypothalamic arcuate nucleus, and elevated plasma PYY and GLP-1 in both the capsaicin and vehicle treated rats. Hypothalamic NPY, AgRP gene expressions and food intake were not changed by resistant starch or capsaicin. Therefore, destruction of the capsaicin sensitive afferent nerves did not alter the response to resistant starch in rats. The conclusion is that dietary resistant starch might reduce body fat through increasing the hypothalamic POMC expression and vagal afferent nerves are not involved in this process.
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