烧伤并发抑郁大鼠学习记忆能力与海马N-甲基天冬氨酸表达的关系

Relationship between learning and memory ability and expression of hippocampal N-methyl-D-aspar- tic acid （NMDA） in burn rats with depression

目的了解烧伤大鼠并发抑郁后的学习汜忆能力变化，探讨与海马N-甲基天冬氨酸（NMDA）表达的关系。方法按照简单随机化法将36只大鼠分为烧伤组、抑郁组、烧伤并发抑郁组，其中烧伤并发抑郁组采用30％TBSA深Ⅱ度烧伤及慢性不町预见中度刺激制作模型。观察各组大鼠在水迷宫实验训练5d中逃避潜伏期变化情况，利用免疫组织化学法分析海马CA1、CA3区及齿状回NMDA表达。另取10只大鼠作为健康对照组，检测指标同上。结果训练第2天，健康对照组大鼠水迷宫逃避潜伏期时间为（22±20）S，与烧伤组（38±31）S、抑郁组（41±36）S、烧伤并发抑郁组（42±33）s比较，差异有统计学意义（P〈0．05或P〈0．01）；训练至第4天时，烧伤并发抑郁组大鼠潜伏期时间与其他3组比较，差异均有统计学意义（P〈0．01）。大鼠海马CA1、CA3区NMDA表达在4个组之间比较，差异无统计学意义（P〉0．05）。健康埘照组大鼠齿状回NMDA阳性细胞为（224±23）个，烧伤组（219±25）个，抑郁组（198±14）个，烧伤并发抑郁组（191±6）个；与健康对照组比较，后2组差异有统计学意义（P〈0．05或P〈0．01）。结论烧伤大鼠并发抑郁后学习记忆能力降低，可能与海马齿状回NMDA减少有关。

Objective To observe changes of learning and memory ability （LMA） in burn rats with depression, and study the relationship between LMA and expression of hippocampal NMDA. Methods According to simple random method, 46 Wistar rats were divided into burn group （ B, with 30% TBSA deep partial-thickness burn, n=10） , depression group （D, with moderate stress stimulation in chronic and unpredictable, n=12）, B ＋ D group （with the same stress stimulation inflicted to B group after burn, n=12）, healthy control group（ HC, without treatment, n=12）. Changes in escape latency was examined in water maze test. Expression of hippocampal NMDA in CA1, CA2 regions and dentate gyms were observed with im- munohistochemistry. Results Compared with that of HC group （22±20 s） , water maze escape latency in B, D, B ＋ D groups on 2 day after training prolonged （38±31 , 41±36, 42±33 s, respectively, P 〈0.05 or P 〈 0.01）. Water maze escape latency in B ＋ D group on 4^th day after training was longer than that of other groups（ P 〈0.01）. There was no obvious difference in positive expression of NMDA in CA1, CA2 regions among groups （ P 〉0.05）. The positive count of NMDA in dentate gyms in D group （198±14） and B＋D group（ 191 ±6） were lower than that of HC group （224±23, P 〈0.05 or P〈0.01）, but there was no obvious difference between HC group and B group （219±25, P〉0.05）. Conclusions Burn complicated with depression can reduce LMA, whieh may be due to a decrease in NMDA in dentate gyrus.