心理应激对大鼠工作记忆影响及酪氨酸干预作用

目的探讨心理应激对工作记忆(working memory)的影响及中枢递质多巴胺(dopamine，DA)的前体酪氨酸(tyrosine)的干预作用。方法先用八臂放射状迷宫训练大鼠(1次／d、6d／周、连续10周)至学习记忆形成，再以Communication Box模型对大鼠进行连续14d、30min／d的心理应激，并从0d起经饲料给予250，500和1000mg／kg 3个剂量的酪氨酸干预，观察第1，4，7，10，13天的工作记忆错误(working memory error)及参考记忆错误(reference memory error)。结果与对照组相比，心理应激组在第1，7，10，13天的工作记忆错误及所有时间测定的参考记忆错误皆高于对照组。与心理应激组相比，酪氨酸1000mg／kg组在第7天及第13天出现工作记忆错误降低，在第4天及第10天出现参考记忆错误降低，酪氨酸500mg／kg组在第10天时也出现了工作记忆错误、参考记忆错误的降低，酪氨酸250mg／kg组均未出现具有显著性统计学意义的变化。结论急性和反复的心理应激能够损害大鼠的工作记忆，高剂量酪氨酸能在较早期降低心理应激对工作记忆的损害，500mg／kg酪氨酸干预对降低较长期的心理应激造成的工作记忆损害也有一定的作用。

The effect of psychological stress on working memory in rats and the intervention effect of tyrosine

Objective To study the effects of psychological stress on working memory in rats, as well as the intervention effects of tyrosine, the precursor of central neurotransmitter dopamine. Methods SD rats trained by eight-arms maze (1 time/d, 6 d/w, continuously for 10 weeks) and formed the model of working memory, were exposed to stress continuously for 14 days (30 min/d) by Communication Box, and fed with tyrosine 250, 500 and 1000 mg/ kg respectively. Working memory error (WME) and reference memory error (RME) were observed.Results WME of stress treated group determined in 1, 7, 10 and 13 d were higher than that of control group, and RME of stress treated group determined in each time were obviously higher too.Compared with psychological stress group, WME of tyrosine 1000 mg/kg treated group was decreased in 7 and 13 d (P<0.05), and RME decreased in 4 and 10 d(P<0.05), WME and RME of tyrosine 500 mg/kg treated group determined in 10 d were lower than that of psychological stress group (P<0.05). No significant difference was found in tyrosine 250 mg/kg treated group. Conclusions The acute and repeated psychological stress could impair the performance of working memory, while high dose tyrosine obtained remarkable protection in early part of time. Mid-dose tyrosine also had protective effects to the injury of the performance of working memory induced by a long time and repeated psychological stress conditions.