酪氨酸对心理应激大鼠中枢多巴胺含量及其更新率的影响

目的 探讨酪氨酸(Tyr)干预对心理应激大鼠中枢多巴胺(DA)含量及其更新率的影响.方法 40只SD大鼠按数字表法随机分为5组:对照组、心理应激组和3个剂量Tyr干预组(分别经饲料每天给予Tyr 250、500、1000 mg/kg),每组8只.建立大鼠Communication Box心理应激模型,采用高效液相色谱-电化学(HPLC-ECD)法测定各组大鼠前额皮质(mPFC)、伏隔核(Nac)和中脑腹侧被盖区(VTA)的DA与3,4-二羟基苯乙酸(DOPAC)含量.结果 与对照组mPFC、Nac、VTA区的DA含量[(0.36±0.15)、(3.47±0.52)、(1.35±0.31)μg/g]相比,心理应激组相应区的DA含量[(0.08±0.05)、(1.88±0.27)、(1.01±0.26)μg/g]降低(P＜0.05),DOPAC/DA升高(P＜0.01).与心理应激组相比,Tyr 500 mg/kg干预组和1000 mg/kg干预组mPFC、Nac、VTA区的DA含量增加(P＜0.05),mPFC、VTA区的DOPAC/DA降低(P＜0.05).结论 心理应激导致大鼠mPFC、Nac、VTA区的DA含量下降和DA更新率升高；Tyr干预能提高心理应激大鼠VTA-Nac-mPFC脑区的DA含量,降低DA更新率.

Effects of central tyrosine on the dopamine content and its turnover rate in rats with psychological stress

Objective To investigate the effects of central tyrosine on the dopamine content and its turnover rate in rats with psychological stress.Methods Forty SD rats were randomly divided into 5 groups:the control group,the psychological stress group,and 3-dose tyrosine intervention groups( fed with tyrosine with doses of 250 mg/kg,500 mg/kg and 1000 mg/kg respectively),each consisting of 8 rats.The psychological stress model was developed with the Communication Box.Contents of dopamine (DA) and dihydroxy-phenyl acetic acid (DOPAC) in the mesoprefrontal cortex (mPFC),nucleus accumbens (Nac) and ventral tegmental area(VTA) were determined by HPLC-ECD.Results The content of DA declined and that of DOPAC/DA increased significantly in mPFC,Nac and VTA area in the animals of psychological stress treatment group [ (0.08 ± 0.05 )、( 1.88 ± 0.27 )、( 1.01 ± 0.26 ) μg/g ]( P ＜ 0.05 ),when a comparison was made with the animals of the control group[(0.36 ± 0.15 )、(3.47 ± 0.52 )、( 1.35 ± 0.31 ) μg/g ].As compared with those of the psychological stress treatment group,the content of DA increased significantly in mPFC,Nac and VTA area (P ＜ 0.05 ) and DOPAC/DA declined significantly in mPFC and VTA area (P ＜ 0.05 ) in the 500 mg/kg and 1 000 mg/kg tyrosine intervention groups( P ＜0.05 ).Conclusions The content of DA could be depressed and the turnover rate of DA could be increased by psychological stress in the mPFC,Nac and VTA area,while tyrosine intervention could increase the content of DA and depress the turnover rate of DA in rats with psychological stress.