糙米有助抵御高脂肪食物诱惑
时间： 2012-07-27 点击次数：次 作者：admin
日本的一个研究小组发现，糙米成分有助于减少高脂肪食物对实验鼠的吸引力，这一发现可能有助于肥胖和糖尿病预防研究。
糙米在加工时只脱去稻壳，成为含有一层红褐色米糖层、胚芽和胚乳的米，其营养成分高于精米。琉球大学教授益崎裕章和同事给实验鼠提供两种食物，一种是高脂肪食物，其中脂质占45%，其余是碳水化合物和蛋白质。另一种食物是脂肪含量较低的普通食物，其中脂质占10%，其余是碳水化合物和蛋白质。结果发现，在自由摄取的情况下，实验鼠只吃高脂肪食物，变得非常肥胖。
研究人员将高脂肪食物中约50%的碳水化合物由玉米淀粉更换为糙米，结果实验鼠就开始选择普通食物，增加的体重只及此前的一半。而用精米替代玉米淀粉却没有这种效果。
研究人员发现，实验鼠吃高脂肪食物后，控制食欲的丘脑下部会出现应激反应，陷入更加喜欢吃高脂肪食物的恶性循环，而糙米能够遏制这种应激反应。进一步的实验确认，糙米中含量丰富的γ－谷维素起到重要作用。
研究小组还准备就γ－谷维素对人体的作用开展进一步研究，以期开发出预防肥胖和糖尿病的营养辅助食品。相关论文将刊登在美国学术期刊《糖尿病》上。
Brown Rice and Its Component, γ-Oryzanol, Attenuate the Preference for High-Fat Diet by Decreasing Hypothalamic Endoplasmic Reticulum Stress in Mice
Brown rice is known to improve glucose intolerance and prevent the onset of diabetes. However, the underlying mechanisms remain obscure. In the current study, we investigated the effect of brown rice and its major component, γ-oryzanol (Orz), on feeding behavior and fuel homeostasis in mice. When mice were allowed free access to a brown rice-containing chow diet (CD) and a high-fat diet (HFD), they significantly preferred CD to HFD. To reduce hypothalamic endoplasmic reticulum (ER) stress on an HFD, mice were administered with 4-phenylbutyric acid, a chemical chaperone, which caused them to prefer the CD. Notably, oral administration of Orz, a mixture of major bioactive components in brown rice, also improved glucose intolerance and attenuated hypothalamic ER stress in mice fed the HFD. In murine primary neuronal cells, Orz attenuated the tunicamycin-induced ER stress. In luciferase reporter assays in human embryonic kidney 293 cells, Orz suppressed the activation of ER stress-responsive cis-acting elements and unfolded protein response element, suggesting that Orz acts as a chemical chaperone in viable cells. Collectively, the current study is the first demonstration that brown rice and Orz improve glucose metabolism, reduce hypothalamic ER stress, and consequently, attenuate the preference for dietary fat in mice fed an HFD.