Lyou Sunok, Tujioka Kazuyo, Hirano Emi, Mawatari Yuka, Hayase Kazutoshi, Okuyama Satoshi, Yokogoshi Hidehiko
Laboratory of Nutritional Biochemistry, School of Nutritional Sciences, The University of Shizuoka, Yada, Shizuoka 422-8526, Japan.
Nutr Neurosci. 2004 Jun;7(3):185-90. doi: 10.1080/10284150412331279818.
A deficiency of sex hormones affects brain function in mammals, including the decrease of protein synthesis. Recently, we have shown that the protein synthesis in the brain depended on the quality of dietary protein in ovariectomized female rats. The methionine is the first limiting amino acid for the recommended dietary allowance of amino acids in soy protein. The purpose of this study was to determine whether the addition of dietary methionine affected the rate of brain protein synthesis in ovariectomized female rats fed on the soy protein diet. Experiments were conducted on two groups of ovariectomized female rats (24 week) given the diets containing 5% soy protein or 5% soy protein + 0.2% methionine for 10 d. The fractional rates of protein synthesis in cerebral cortex and cerebellum significantly increased with an addition of dietary methionine. In the brain, the RNA activity [g protein synthesized/((g RNA) x d)] was significantly correlated with the fractional rate of protein synthesis. The RNA concentration (mg of RNA/g of protein) was not related to the fractional rate of protein synthesis in any organ. The results suggest that the addition of limiting amino acid for the low soy protein elevates the rate of protein synthesis in the brain of ovariectomized female rats, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis.
性激素缺乏会影响哺乳动物的大脑功能，包括蛋白质合成的减少。最近，我们发现大脑中的蛋白质合成取决于去卵巢雌性大鼠饮食蛋白质的质量。蛋氨酸是大豆蛋白中氨基酸推荐膳食摄入量的第一限制氨基酸。本研究的目的是确定添加膳食蛋氨酸是否会影响以大豆蛋白饮食喂养的去卵巢雌性大鼠大脑蛋白质合成的速率。对两组24周龄的去卵巢雌性大鼠进行实验，分别给予含5%大豆蛋白或5%大豆蛋白+0.2%蛋氨酸的饮食，持续10天。添加膳食蛋氨酸后，大脑皮层和小脑的蛋白质合成分数速率显著增加。在大脑中，RNA活性[合成的蛋白质克数/（（克RNA）×天）]与蛋白质合成分数速率显著相关。RNA浓度（RNA毫克数/蛋白质克数）与任何器官中的蛋白质合成分数速率均无关。结果表明，添加低大豆蛋白的限制氨基酸可提高去卵巢雌性大鼠大脑中的蛋白质合成速率，并且RNA活性至少部分与大脑蛋白质合成分数速率相关。
