支链氨基酸与酰胺类氨基酸对大鼠胱硫醚-β-合成酶活性的影响

EFFECTS OF BRANCHED CHAIN AMINO ACIDS AND AMIDE AMINO ACIDS ON CYSTATHIONINE-β-SYNTHASE ACTIVITY

目的探讨支链氨基酸与酰胺类氨基酸对胱硫醚-β-合成酶活性的影响。方法 40只Wistar大鼠随机分为10%酪蛋白(10C)对照组, 10C+0.75%L-蛋氨酸+0.15%L-苏氨酸(10CMT)组,10CMT+12%支链氨基酸(10CMT+BCAA)组,10CMT+12%酰胺类氨基酸(10CMT+AmideAA)组,10CMT+12%支链氨基酸+12%酰胺类氨基酸(10CMT+BCAA+AmideAA)组。实验饲料喂养10d后处死动物,采集血液、肝脏样品,用于测定血液同型半胱氨酸以及肝脏中蛋氨酸代谢物和相应的酶学以及mRNA指标。结果蛋氨酸的添加使血浆同型半胱氨酸的浓度显著升高,而支链氨基酸与酰胺类氨基酸的添加明显抑制了由蛋氨酸的摄入导致的高同型半胱氨酸血症的发生(P<0.05),10CMT+BCAA+AmideAA组同型半胱氨酸水平接近10C组的水平。10CMT+BCAA+AmideAA组明显的降低了血中葡萄糖的水平(P<0.05),10CMT+BCAA组显著增加了血中胰岛素的浓度(P<0.05)。与10C组比较,各氨基酸添加组均显著增加了肝脏S-腺苷甲硫氨酸(SAM)浓度(P<0.05)。10CMT、10CMT+BCAA、10CMT+AmideAA、10CMT+BCAA+AmideAA组的肝脏胱硫醚-β-合成酶(CBS)活性均明显升高(P<0.05), 10CMT+BCAA组效果强于10CMT+AmideAA组,10CMT+BCAA+AmideAA组升高幅度最大。结论高膳食蛋白引起的胱硫醚-β-合成酶活性增强可能与膳食蛋白中支链氨基酸与酰胺类氨基酸有关。

Objective To investigate the effects of branched chain amino acids and amide amino acids on the activity of cystathionine-β-synthase. Methods 40 Wistar rats were fed diets with different amino acid mixtures for 10 days. The rats were randomly divided into 10% of casein group(10 C),10 C+0.75% L-methionine +0.15% L-threonine(10 CMT),10 CMT+12% branched chain amino acids group(10 CMT+BCAA), 10 CMT+12% amide amino acid group( 10 CMT+ AmideAA),10 CMT+12% BCAA +12% amide amino acid group(10 CMT+BCAA+AmideAA). They were sacrificed by decapitation to obtain blood and livers for biochemical analysis. Results The plasma homocysteine concentration significantly increased with the addition of methionine. The addition of branched chain amino acids and amide amino acid could significantly suppress hyperhomocysteinemia induced by the intake of methionine(P<0.05), and homocysteine levels were similar in 10 CMT+BCAA+AmideAA group and 10 C group. The level of blood glucose was significantly decreased in 10 CMT+ BCAA+AmideAA group(P<0.05), and the level of blood insulin was significantly increased in 10 CMT+BCAA group(P<0.05). Compared with 10 C group, the concentration of SAM in the liver was significantly increased in each amino acid addition group(P<0.05). The activity of CBS in the liver was significantly increased in 10 CMT, 10 CMT+BCAA,10 CMT+AmideAA, 10 CMT+BCAA+AmideAA groups(P<0.05), and the effect of 10 CMT+BCAA diet was stronger than that of 10 CMT+ AmideAA diet. The diet of 10 CMT+BCAA+AmideAA increased the activity of CBS most. Conclusion The increased activity of CBS induced by high dietary protein is mainly due to the effects of branched chain amino acids and amide amino acids in dietary protein.