目的：研究S－腺苷甲硫氨酸（SAM）对β－淀粉样蛋白（Aβ）诱导大鼠脑组织胆碱能系统损伤和活性氧产生的影响。方法将大鼠随机分为对照组、模型组和SAM 治疗组，采用Aβ双侧海马注射方法建立Aβ损伤大鼠模型，采用比色法检测3组大鼠大脑皮层顶叶乙酰胆碱（ACh）含量和乙酰胆碱酯酶（AChE）活性，化学荧光法检测活性氧（ROS）含量。结果 Aβ损伤6周后，大鼠大脑皮层顶叶ACh含量明显下降，为对照组的69％（P ＜0．05），AChE活力明显升高，为对照组的1．27倍（P ＜0.05），ROS含量显著升高，为对照组的1．37倍（P ＜0．01）；SAM治疗后，大鼠大脑皮层顶叶ACh含量较模型组明显升高，为模型组的1．42倍（P＜0．05），AChE活性显著降低，仅为模型组的64％（P＜0.01），ROS含量显著降低，为模型组的66％（P＜0．01）。结论 SAM可减轻Aβ诱导大鼠大脑皮层胆碱能系统损伤，减少活性氧的产生，对Aβ引起的脑组织损伤有保护作用。%Objective To investigate the effect of S -adenosylmethionine (SAM ) on Aβ-induced cholinergic system damage and the production of reactive oxygen species (ROS) in the cerebral cortex of rats .Methods Rats were randomly divided into control group ,model group and SAM treatment group The bilateral hippocampal Aβ injection was used to establish Aβ damaged rat model . Acetylcholine (ACh) level and Acetylcholine esterase (AChE) activity in parietal cortex of rats were measured by col‐orimetric method .The level of ROS was measured by chemistry fluorescence method .Results After Aβinjection for 6 weeks ,the Ach level in the cortex of model group decreased to 69% of the control group (P < 0 .05) ,while the AChE activity was increased to 1 .27 times as compared with the control group (P < 0 .05) .The ROS level was significantly increased to 1 .37 times as compared with the control group (P < 0 .01) .After the treatment of SAM ,the Ach level was increased to 1 .42 times as compared with model group (P< 0 .05)and the AChE activity and ROS level decreased significantly to 64% and 66% of the model group respectively (P< 0 .01) .Conclusions SAM may protect the rat cortex against Aβinju‐ry through alleviation cholinergic system damage and reduction of ROS generation .
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