Rodriguez B, Torres N, Rincon A R, Bourges H, Panduro A, Tovar A R
Dept. Physiology of Nutrition, Instituto Nacional de la Nutrición Salvador Zubirán, Mexico City, Mexico.
Rev Invest Clin. 1996 Nov-Dec;48(6):413-9.
The effect of dietary protein concentrations on the hepatic expression of phenylalanine hydroxylase (PAH) and tyrosine aminotransferase (TAT) mRNA concentrations was studied in rats adapted to consume diets (18 or 50% casein) in a restricted schedule of 7 h (0900 to 1600) for 5 days. After 6 hours of feeding, TAT mRNA concentrations of rats adapted to 18% casein diet and fed acutely 6, 18 and 50% casein diet were 0.15, 0.84 and 5.08 fold respectively higher than mRNA concentrations of rats before feeding. After 17 hours of fasting, TAT mRNA concentrations of rats previously fed 6, 18 or 50% casein diet were -0.45, 1.76 and 9.11 fold respectively higher than mRNA concentrations of rats before they were fed. PAH mRNA concentrations showed a similar pattern. There was a -0.68, 1.63 and 2.5 fold rise of PAH mRNA concentrations in rats fed 6,18 and 50% casein diet during the feeding period, and -0.86, 2.32 and 9.33 fold rise after 17 hours of fasting. TAT and PAH mRNA concentrations of rats adapted to consume 50% casein diet and then changed to 6% or kept on the 50% casein diet showed a maximum peak 6 hours after the rats began to consume the diet; however, they decreased 5 hours after fasting. These results suggest that increasing concentrations of protein in the diet were able to increase the concentration of TAT and PAH mRNA, possibly in order to eliminate the excess of amino acids consumed. The concentration of TAT and PAH mRNA depended more on the protein content of the diet to which the rats were previously adapted.
研究了膳食蛋白质浓度对适应按7小时（09:00至16:00）限制时间表进食5天（18%或50%酪蛋白）的大鼠肝脏中苯丙氨酸羟化酶（PAH）和酪氨酸转氨酶（TAT）mRNA浓度表达的影响。喂食6小时后，适应18%酪蛋白饮食并急性喂食6%、18%和50%酪蛋白饮食的大鼠的TAT mRNA浓度分别比喂食前大鼠的mRNA浓度高0.15倍、0.84倍和5.08倍。禁食17小时后，先前喂食6%、18%或50%酪蛋白饮食的大鼠的TAT mRNA浓度分别比喂食前大鼠的mRNA浓度高-0.45倍、1.76倍和9.11倍。PAH mRNA浓度呈现类似模式。在喂食期间，喂食6%、18%和50%酪蛋白饮食的大鼠的PAH mRNA浓度分别升高-0.68倍、1.63倍和2.5倍，禁食17小时后分别升高-0.86倍、2.32倍和9.33倍。适应食用50%酪蛋白饮食然后改为6%或继续食用50%酪蛋白饮食的大鼠的TAT和PAH mRNA浓度在开始进食后6小时出现最大峰值；然而，禁食5小时后它们下降。这些结果表明，饮食中蛋白质浓度的增加能够增加TAT和PAH mRNA的浓度，可能是为了消除摄入的过量氨基酸。TAT和PAH mRNA的浓度更多地取决于大鼠先前适应的饮食中的蛋白质含量。
