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

Abstract

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. Key words: Tyrosine; Psychological stress; Dopamine; Turnover rate