Effects of oxidative stress on homocysteine metabolism in methionine loading rat hepatocytes

Abstract

Objective To investigate the effects of oxidative stress on homocysteine and related amino acids metabolism in methionine-loading BRL rat hepatocytes.Methods Cultured BRL rat hepatocytes were divided into control and oxidatively stressed group(100 μmol/L H2O2 was added in culture medium for 2 hours),methionine group(50 mmol/L methionine was added in culture medium for 1 hour),and oxidatively stressed + methionine group(100 μmol/L H2O2 was added in culture medium for 2 hours + 50 mmol/L methionine was added in culture medium for 1 hour).At the end of the experiment,culture fluid was collected.Homocysteine,cysteine,and glutathione were measured by high-performance liquid chromatography,and amino acids were assayed by amino acids analyzer.Results Compared with the control group,the contents of homocysteine[(3.76 ± 0.22)vs.(1.54±0.05)μmol/L,P=0.000]and cysteine[(199.80 ±8.75)vs.(99.11 ±2.47)μmol/L,P=0.000]significantly increased in methionine group,and the contents of homocysteine[(3.84 ± 0.34)vs.(1.54 ±0.05)μmol/L,P=0.000]and cysteine[(200.66±8.60)vs.(99.11 ±2.47)μ mol/L,P=0.000]also increased in oxidatively stressed + methionine group.Compared with oxidatively stressed group,the concentrations of homocysteine[(3.76 ± 0.22)vs.(1.67 ± 0.13)μmol/L,P =0.000],cysteine[(199.80 ± 8.75)vs.(82.64±15.88)μmol/L,P=0.000],and glutathione[(1.50 ±0.14)vs.(1.00 ±0.11)μ mol/L,P=0.011)]significantly increased in methionine group,and the concentrations of homocysteine[(3.84 ± 0.34)vs.(1.67±0.13)μmol/L,P=0.000],cysteine[(200.66±8.60)vs.(82.64±15.88)μmol/L,P=0.000]and glutathione[(1.40 ± 0.30)vs.(1.00 ± 0.11)μmol/L,P =0.028]significantly increased in oxidatively stressed + methionine groups.Compared with the control group,the contents of serine[(12.41 ± 1.51)vs.(24.00 ±2.54)mg/L,P =0.000],glutamate[(33.31 ±0.17)vs.(43.10 ±0.52)mg/L,P =0.000]and glycine[(6.23 ± 0.18)vs.(24.66 ± 10.87)mg/L,P =0.000]significantly decreased,while taurine [(7.99 ±0.16)vs.(6.17 ±0.15)mg/L,P =0.000]increased significantly in oxidatively stressed group.Compared with the oxidatively stressed group,the concentrations of serine[(16.98 ± 0.39)vs.(12.41 ± 1.51)mg/L,P=0.006)]and glutamate[(35.44 ±0.82)vs.(33.31 ±0.17)mg/L,P =0.002]in methionine group significantly increased,while taurine[(3.77 ±0.16)vs.(7.99 ±0.16)mg/L,P =0.000]significantly decreased in methionine group.Compared with the methionine group,the contents of serine[(12.59 ± 0.66)vs.(16.98±0.39)mg/L,P=0.008],glutamate[(30.87±0.60)vs.(35.44±0.82)mg/L,P=0.000]significantly decreased while taurine[(4.37 ± 0.12)vs.(3.77 ± 0.16)mg/L,P =0.001]in oxidatively stressed + methionine group significantly increased.Conclusion Oxidative stress can somehow promote homocysteine production in methionine loading BRL rat hepatocytes,but it is not the main effects. Key words: Methionine loading; Homocysteine ; Oxidative stress