谷氨酸和谷氨酰胺对大鼠学习记忆的影响

Effects of glutamate and glutamine on learning and memory of rats

为了观察谷氨酸(Glu)和谷氨酰胺(Gln)对大鼠学习记忆的影响并探讨其机理,选用Wistar大鼠36只,随机分为3组:对照组、Glu 组和Gln 组,分别给予普遍饲料、补充2% Glu 和2% Gln 的饲料喂养2周后,以穿梭箱实验作为学习记忆的行为模型对大鼠进行训练,记录主动回避反应次数和被动逃避时间,并用氨基酸自动分析仪、双波长比色法、放射性配基结合法分别测定了脑中游离氨基酸含量、一氧化氮合酶(NOS)活性和海马N-甲基-D-天冬氨酸受体(NMDA-R)的数目及亲和力。结果显示补充Gln 后,大鼠的主动回避反应率显著增加,被动逃避时间缩短,脑中Glu、天门冬氨酸Gln、精氨酸含量显著增高,NOS活性和海马NMDA-R数目亦增加,而补充Glu 组未观察到上述作用。结果提示:Gln 对大鼠的学习记忆具有促进作用,而Glu 则无此作用,推测其机理可能与脑中兴奋性氨基酸含量。

The effects of glutamate(Glu)and glutamine(Gln)on learning and memory of rats and the mechanism involved were examined.Three groups of rats were fed with stock diet(control group),and the diets supplemented with 2% Glu(Glu group)or 2% Gln (Gln group)respectively.Compared with control group,the active avoidance response rats of Gln group in shuttle box test was significantly elevated while the time of passive avoidance response shortened.The contents of brain free amino acids,such as Gln,Glu,aspartic acid and arginine,activity of brain nitric oxide synthase(NOS),Bmax of N methyl D aspartate(NMDA) receptors in hippocampus of Gln group were all increased significantly.Such changes were not observed in Glu group.The results suggested that Gln could improve the learning ability and memory of rats,which might be related to the change of amino acids composition of brain,the synthesis of messenger nitric oxide and the binding capacity of NMDA receptor in hippocampus.