[老年大鼠海马中学习能力、记忆与自由基的关系]
[Relationship between learning ability and memory and free radical in hippocampus of old rats].
作者信息
Jia Jian-min, Jia Jian-ping, Jia Li, Shen Yu, Jia Lin, Pollock M
机构信息
Department of Neurology, First Hospital of Handan City, Handan, Hebei province 056002, China.
出版信息
Zhonghua Yi Xue Za Zhi. 2003 May 10;83(9):796-8.
OBJECTIVE
To study the relationship between the amount of free radical in hippocampus and the learning ability and memory in old rats.
METHODS
Morris water maze was used for 10 days to examine the learning scores, latency scores, and the loci of movement in the maze among 46 old rats (aged 20 months), 36 young rats (aged 6 months), and 34 adult rats (aged 12 months). Salicylate was injected intraperitoneally and hippocampus dialysis was performed. Chromatography was used to measure the basic values of 2,3DHBA and 2,5DHBA in dialysis fluid chemiluminometry was used to measure the superoxide dismutrase (SOD) in the sample. The rats were killed and their brains were taken out. Histological examination was conducted to calculate the number of neurons in CA1, CA4, and PM regions in hippocampus.
RESULTS
The learning scores on the first, fifth, and tenth days were 36.5 +/- 5.9 sec, 38.6 +/- 5.9 sec, and 39.4 +/- 6.9 sec (P > 0.05) in the old rats; 60.2 +/- 5.4 sec, 156.8 +/- 5.8 sec, and 165.1 +/- 6.8 sec in the young rats; and 61.7 +/- 5.8 sec, 152.3 +/- 6.9 sec, and 168.7 +/- 6.5 sec in adult rats. The learning scores at any time point of old rats were significantly lower than those of the young and adults rats (all P < 0.01). The latency scores of the first, fifth, and tenth days were 25.7 +/- 1.2 sec, 27.5 +/- 1.9 sec, and 27.7 +/- 1.9 sec in the old rats without significant difference between any two of these values (P > 0.05), however, the 3 latency scores of the old rats were all significantly larger than those of the young and adult rats (21.8 +/- 1.7 sec, 5.9 +/- 1.0 sec, and 3.6 +/- 0.6 sec, and 21.8 +/- 1.6 sec, 5.0 +/- 0.9 sec, and 4.8 +/- 0.7 sec respectively, all P < 0.01). The basic value of 2,3DHBA after intraperitoneal injection of salicylate was 20.7 +/- 0.3 pmol/ml in the old rats, 5 times that of the young rats and 6 times that of the adult rats (P < 0.01). The basic value of 2,5DHBA after intraperitoneal injection of salicylate was 60.12 pmol/ml in the old rats, 6 times that of the young rats and 5.8 times that of the adult rats (P < 0.01). The SOD activity was 410 U x g(-1) x min(-1) +/- 50 U x g(-1) x min(-1), significantly lower than those in the young and adult rats (880 U x g(-1) x min(-1) +/- 62 U x g(-1) x min(-1) and 860 U x g(-1) x min(-1) +/- 60 U x g(-1) x min(-1) (both P < 0.01). The values of neuron density in CA1, CA4, and PM regions of the old rats were all significantly lower than those of the young and adult rats (all P < 0.01).
CONCLUSION
The decrease of learning ability in old rat is positively correlated with the increase of free radicals and loss of neurons in hippocampus.
目的
研究老年大鼠海马中自由基含量与学习能力及记忆的关系。
方法
对46只老年大鼠（20月龄）、36只青年大鼠（6月龄）和34只成年大鼠（12月龄）进行为期10天的Morris水迷宫实验，检测其学习成绩、潜伏期成绩及在迷宫中的运动轨迹。腹腔注射水杨酸盐后进行海马透析。采用色谱法测量透析液中2,3 - 二羟基苯甲酸（2,3DHBA）和2,5 - 二羟基苯甲酸（2,5DHBA）的基础值，用化学发光法测量样本中的超氧化物歧化酶（SOD）。处死大鼠并取出大脑，进行组织学检查以计算海马CA1、CA4和PM区的神经元数量。
结果
老年大鼠第1天、第5天和第10天的学习成绩分别为36.5±5.9秒、38.6±5.9秒和39.4±6.9秒（P>0.05）；青年大鼠分别为60.2±5.4秒、156.8±5.8秒和165.1±6.8秒；成年大鼠分别为61.7±5.8秒、152.3±6.9秒和168.7±6.5秒。老年大鼠在任何时间点的学习成绩均显著低于青年和成年大鼠（均P<0.01）。老年大鼠第1天、第5天和第10天的潜伏期成绩分别为25.7±1.2秒、27.5±1.9秒和27.7±1.9秒，两两之间无显著差异（P>0.05），然而，老年大鼠的这3个潜伏期成绩均显著高于青年和成年大鼠（青年大鼠分别为21.8±1.7秒、5.9±1.0秒和3.6±0.6秒，成年大鼠分别为21.8±1.6秒、5.0±0.9秒和4.8±0.7秒，均P<0.01）。腹腔注射水杨酸盐后，老年大鼠2,3DHBA的基础值为20.7±0.3 pmol/ml，是青年大鼠的5倍，成年大鼠的6倍（P<0.01）。腹腔注射水杨酸盐后，老年大鼠2,5DHBA的基础值为60.12 pmol/ml，是青年大鼠的6倍，成年大鼠的5.8倍（P<0.01）。SOD活性为410 U·g⁻¹·min⁻¹±50 U·g⁻¹·min⁻¹，显著低于青年和成年大鼠（分别为880 U·g⁻¹·min⁻¹±62 U·g⁻¹·min⁻¹和860 U·g⁻¹·min⁻¹±60 U·g⁻¹·min⁻¹，均P<0.01）。老年大鼠海马CA1、CA4和PM区的神经元密度值均显著低于青年和成年大鼠（均P<0.01）。
结论
老年大鼠学习能力下降与海马中自由基增加及神经元丢失呈正相关。
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