磷酸肌酸钠对VaD老年大鼠的学习记忆能力影响及机制

Effect of sodium phosphocreatine on learning,memory,and cognitive impairment in aged rats with VaD and its mechanism

目的探讨磷酸肌酸钠对血管性痴呆(VaD)大鼠的学习记忆功能的影响及机制。方法72只SD雄性老年大鼠(>20周龄)随机均分为假手术组、模型组及磷酸肌酸钠低(20 mg/kg)、高剂量(40 mg/kg)组,后3组建立VaD大鼠模型,造模后两组大鼠分别腹腔注射相应浓度的磷酸肌酸钠,假手术组和模型组给予等体积生理盐水腹腔注射,连续给药28 d;实验期间观察大鼠体质量和生长趋势,造模第24天时通过Morris水迷宫实验记录各组大鼠逃避潜伏期、穿越平台次数和平台象限活动时间;实验结束时,取各组大鼠海马组织,检测三磷酸腺苷(ATP)、丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)的含量,ELISA法检测海马组织中炎症因子白细胞介素-1β(IL-1β)、IL-6、IL-10及肿瘤坏死因子(TNF-α)的含量;苏木素-伊红(HE)染色观察海马组织结构。结果与模型组比较,磷酸肌酸钠组大鼠的体质量和生长趋势无明显差异;与模型组比较,磷酸肌酸钠高剂量组大鼠的逃逸潜伏期缩短、穿越平台的次数和平台象限活动时间增加,所在目标象限轨迹更长(P<0.05);与模型组比较,磷酸肌酸钠高剂量组大鼠海马区ATP水平以及SOD、GSH-PX活力升高(P<0.05),MDA水平降低(P<0.05);与模型组比较,磷酸肌酸钠高剂量组大鼠IL-1β、IL-6、TNF-α水平下降,IL-10水平升高(P<0.05);与模型组比较,磷酸肌酸钠低剂量组大鼠HE染色的海马区细胞形态较为完整、规则,磷酸肌酸钠高剂量组神经元染色均匀,细胞形态规则,边界清晰且数量增多。结论磷酸肌酸钠腹腔注射,可改善老年VaD模型大鼠的学习记忆能力,其机制可能与提高大鼠海马区ATP的产生,保护VaD老年大鼠海马神经元,减少病理损伤有关。

Objective To explore the effect of sodium phosphocreatine on learning,memory and cognitive function in aged rats with vascular dementia(VaD)and its mechanism.Methods Seventy-two SD male aged rats(>20 weeks old)were randomly divided into sham,model,low dose(20 mg/kg)-and high dose(40 mg/kg)-sodium phosphocreatine groups.The latter three groups were used to establish rat VaD model.After the model was successfully established,rats in each dose group were injected intraperitoneally with corresponding concentration of sodium phosphocreatine for 28 d.Sham and model groups were intraperitoneallygiven an equal volume of saline for 28 d.Rat body weights and growth trends were observed.On the 24 th day after modeling,Morris water maze was used to assess escape latency,platform crossover number and staying time at the platform quadrant in each group.At the end of the experiment,hippocampal tissues were collected in each group.Adenosine triphosphate(ATP),malondialdehyde(MDA),superoxide dismutase(SOD),and glutathione peroxidase(GSH-PX)were measured.ELISA assay was used to detect the levels of inflammatory factors including interleukin-1β(IL-1β),IL-6,IL-10,and TNF-αin rat hippocampal tissues.Hematoxylin-eosin(HE)staining was applied to observe hippocampal histology.Results When compared with model group,rat body weight and growth trend in sodium phosphocreatine groups were not significantly affected.High dose-sodium phosphocreatine group shortened rat escape latency,increased the platform crossover number and staying time at the platform quadrant,had long trajectory in the target quadrant relative to model group(P<0.05).When compared with model group,ATP levels,SOD,and GSH-PX activities in rat hippocampi in high dose-sodium phosphocreatine group were increased(P<0.05).When compared with model group,IL-1β,IL-6,and TNF-αwere decreased,while IL-10 was increased in high dose-sodium phosphocreatine group(P<0.05).HE staining results showed that cell morphology in rat hippocampi in low dose-odium phosphocreatine group was more intact and regular than those in model group.Neuronal staining in high dose-sodium phosphocreatine group was uniform with regular cell morphology,clear borders and increased number.Conclusions Intraperitoneal injection with sodium phosphocreatine improved the learning memory ability of aged rats with VaD,and its mechanism may be related to increasing ATP production in rat hippocampal region,protecting hippocampal neurons,and reducing pathological damage in aged rats with VaD.