心理应激对大鼠多巴胺受体功能的影响及酪氨酸的干预作用

目的 探讨心理应激对大鼠中枢多巴胺受体功能的影响以及酪氨酸的干预作用。方法 用Communication Box模型对大鼠进行连续14天、每天30min的心理应激，并经饲料给予250、500、1000mg／kg三个剂量的酪氨酸干预。采用放射性配基结合分析法测定不同应激时间的中脑腹侧被盖区（VTA）、伏隔核（Nac）、前额皮质（mPFC）等脑区多巴胺D1、D2受体的最大结合容量（Bmax）和平衡解离常数（Kd）。结果 心理应激组mPFC、Nac区D2受体最大结合容量较对照组有明显下降（P〈O．05），mPFC区D2受体最大结合容量也有明显的下降（P〈O.05）。与心理应激组相比，酪氨酸500mg／kg干预组mPFC区D2受体最大结合容量升高（P〈0．05），1000mg／kg干预组VTA、mPFC区D2受体最大结合容量升高（P〈0．05）。心理应激及酪氨酸干预组D1、D2受体平衡解离常数无明显差别。结论 心理应激能够降低mPFC、Nac区D2受体最大结合容量，酪氨酸干预能够提高心理应激时mPFC、VTA区的D1，受体最大结合容量。心理应激对不同脑区D2受体功能的影响可能不同。

Effects of psychological stress on the function of dopamine receptor in rat: the effect of intervention with tyrosine

Objective To investigate the effect of psychological stress on the function of dopamine receptor in the central nervous system in rats and the intervention effect of tyrosine. Methods Rats were continuously subjected to psychological stress by communication box model 30min a day for 14 days. They were fed with tyrosine 250mg/kg, 500mg/kg, or 1000mg/kg, respectively. The maximal bonding capacity (Bmax) and the balance dissociation constant (Kd) of D1, D2 receptor of DA at the site of ventral tegmental area (VTA), nucleus accumbens (Nac), mesoprefrontal cortex (mPFC) were determined by radioactive ligand bonding analysis. Results Bmax of the D1 receptors declined significantly in mPFC and Nac area of psychological stress treated group compared with that of control group (P<0.05). Intervention with tyrosine 500mg/kg remarkably increased Bmax in mPFC area (P<0.05), while intervention with tyrosine 1000mg/kg significantly increased Bmax in VTA and mPFC area. Bmax of D2 receptor in mPFC area of psychological stress treated group was lower than that of control (P<0.05). Psychological stress treatment and tyrosine intervention showed no significant effects on the Kd of D1, D2 receptor. Conclusion Psychological stress could depress the Bmax of D1 receptor in mPFC and Nac area, while intervention with tyrosine would improve the Bmax of D1 receptor in mPFC and VTA area against the influence of psychological stress. Psychological stress rendered different effects on the D2 receptor function of the different cerebral area.