摘要
目的探讨蛋氨酸对胱硫醚-β-合成酶的影响。方法 56只SPF级6周龄Wistar雄性大鼠随机分为7组:10%酪蛋白(10C)组、40%酪蛋白(40C)组、10C+0.75%L-蛋氨酸(10CM)组、10C+氨基酸混合物(10CAA)组、10CAA-蛋氨酸(10CAA-Met)组、10C+必需氨基酸(10C+EAA)组和10C+非必需氨基酸(10C+NEAA)组,每组8只。实验饲料喂养10 d后处死大鼠,测定血浆同型半胱氨酸水平、肝脏中蛋氨酸代谢产物和相应酶学指标。结果蛋氨酸与必需氨基酸的添加使血浆同型半胱氨酸浓度从(17.1±0.3)μmol/L(10C)分别显著升高至(50.7±4.8)μmol/L(10CM)和(40.5±3.9)μmol/L(10C+EAA)(P<0.01),说明蛋氨酸摄入导致高同型半胱氨酸血症发生。与10C对照组相比,除10CM组外,其他各实验组肝脏胱硫醚-β-合成酶活性均显著升高(P<0.05),其中40C组增幅最大,10C+NEAA组升幅最小。与10C对照组相比,除10CAA-Met与10C+NEAA组外,其余各组肝脏同型半胱氨酸甜菜碱甲基转移酶活性均显著升高(P<0.05)。结论高膳食蛋白引起的胱硫醚-β-合成酶活性增强由高氨基酸摄入量决定,而非蛋氨酸。
OBJECTIVE To investigate the effects of methionine on the activity of cystathionine-β-synthase. METHODS A total of 56 male rats of the Wistar were randomly divided into 7 groups: 10% casein(10 C) group, 40% casein(40 C) group, 10 C+0.75% L-methionine(10 CM) group, 10 C+amino acid mixture(10 CAA) group, 10 CAA-methionine(10 CAA-Met) group, 10 C+ essential amino acid(10 C+EAA) group, and 10 C+ non-essential amino acid(10 C+NEAA) group, with 8 rats in each group for 10 days.RESULTS The plasma homocysteine concentration significantly increased from(17.1±0.3)μmol/L to(50.7±4.8)μmol/L and(40.5±3.9)μmol/L in rats fed 10 CM and 10 C+EAA diets(P<0.01). Supplementation with methionine induced hyperhomocysteinemia. Compared to 10 C, the activity of hepatic cystathionine-β-synthase(CBS) were significantly increased in the experimental group except for 10 CM(P<0.05). The activity of hepatic CBS was the largest increases in diets with 40 C and the smallest increases in 10 C+NEAA. The activity of hepatic betaine-homocysteine S-methyltransferase(BHMT) were increased in the experimental group except for 10 CAA-Met and 10 C+NEAA(P<0.05). CONCLUSION The increased CBS activity induced by high protein diets is determined by high amino acid intake rather than methionine supplemention.
引文
[1] HAORAN Z,SHAUN B,KEEFE T C.Cystathionine β-synthase in physiology and cancer [J].Biomed Res Int,2018,2018:3205125.
[2] WARREN D K.Cystathionine β-synthase deficiency:of mice and men[J].Mol Genet Metab,2017,121(3):199-205.
[3] 郭东豪,刘慧,苗雅,等.老年患者颈动脉粥样硬化和血浆同型半胱氨酸水平关系的研究[J].上海交通大学学报(医学版),2018,38(11):1318-1321.
[4] 朱烨,吴雅利,李宝香.阿尔茨海默病患者同型半胱氨酸的表达水平及认知功能减退的危险因素[J].中国老年学杂志,2018,38(10):2406-2408.
[5] BEHERA J,BALA J,NURU M,et al.Homocysteine as a pathological biomarker for bone disease [J].J Cell Physiol,2017,232 (10):2704-2709.
[6] OHUCHI S,MORITA T,MORI M,et al.Hepatic cystathionine betasynthase activity does not increase in response to methionine supplementation in rats fed a low casein diet:association with plasma homocysteine concentrations[J].J Nutr Sci Vitaminol,2009,55(2):178-185.
[7] 毛宏梅,张琳,韩超,等.甜菜碱对蛋氨酸诱导大鼠高同型半胱氨酸血症的抑制作用[J].营养学报,2016,38(2):172-176.
[8] LOWRY O H,ROSEBROUGH N J,FARR A L,et al.Protein measurement with the Folin phenol reagent[J].J Biol Chem,1951,193:265-275.
[9] HANAFY A M,SASANAMI T,MORI M.Sensitivity of expression of perivitelline membrane glycoprotein ZP1 mRNA in the liver of Japanese quail (Coturnix japonica) to estrogenic compounds[J].Biochem Physiol C Toxicol Pharmacol,2007,144(4):356-362.
[10] RATNAM S,MACLEAN K N,JACOBS R L,et al.Hormonal regulation of cystathionine β-synthase expression in liver [J].Biol Chem,2002,277(45):42912-42918.
[11] INGENBLEEK Y,HARDILLIER E,JUNG L.Subclinical protein malnutrition is a determinant of hyperhomocysteinemia[J].Nutrition,2002,18(1):40-46.
[12] FINKELSTEIN J D,KYLE W E,HARRIS B J.Methionine metabolism in mammals:regulation of homocysteine methyltransferases in rat tissue [J].Arch Biochem Biophys,1971,146:84-92.