老年记忆减退大鼠NO-2含量和NOS活性的变化

目的：同时测定老年性记忆减退大鼠一氧化氮合酶（ＮＯＳ）活性和一氧化氮（ＮＯ）的终末代谢产物亚硝酸盐含量（ＮＯ－２），研究ＮＯ与老年记减退发生的关系，为探讨老年性记忆减退发生的机制及寻找新的治疗方法提供理论依据。方法：用Ｍｏｒｉｓ水迷宫将老年大鼠（２４月龄）筛选为记忆正常和记忆减退两组，以老年记忆减退大鼠作为老年记忆减退模型；用双波长分光光度法测定一氧化氮合酶（ＮＯＳ）比活性；用改良硝酸还原酶法测定亚硝酸盐含量。结果：①海马组织中老年记忆正常组和老年记忆减退组较青年组ＮＯＳ比活性和亚硝酸盐含量均下降，记忆减退组下降更为显著。②小脑组织中ＮＯＳ比活性和亚硝酸盐含量，老年记忆正常组和老年记忆减退组较青年组下降，但老年记忆正常组和老年记忆减退组间无差异。③额叶组织的结果与小脑相同。结论：海马、小脑和额叶等脑区衰老时ＮＯ生成下降，海马脑区老年记忆减退大鼠较老年记忆正常鼠下降更为显著；提示ＮＯ生成减少可能与老年记忆减退的发生有关

Changes of Nitric Oxide Synthase Activity and Nitrite in the Brain of Senile Memory Deficit Rats

Objective: Study the relationship between nitric oxide(NO) and senile memory deficits, in order to explore the mechanism of senile memory deficits and find out a new method for the treatment. Methods: Aged rats (24 month old) were divided into aged memory impaired group and aged memory non impaired group using Morris water maze. NOS specific activity were measured by a method in which the oxidation of oxyhaemoglobin to methaemoglobin by NO is monitored spectrophotometrically. Using modified nitrate reductase method to measure the concentration of nitrite.Results: In hippocampus, NOS specific activity and nitrite in aged rats were decreased in comparison to young rats; aged memory impaired rats reduced more significantly than aged memory non impaired rats. In cerebellum, NOS activity and nitrite also were lower in aged rats; but no difference between memory non impaired rats and impaired rats. In frontal cortex, the result is similar to that in cerebellum. Conclusions:Generation of NO is decreased in hippocampus, cerebellum and frontal cortex of aged rats, aged memory impaired rats reduced more significantly in hippocampus. It suggested that decreased NO generation may have close relationship with occurrence of senile memory deficits.