腹腔注射内毒素对成年和老年大鼠记忆功能的影响

Effects of intraperitoneal injection of endotoxin on memory function in adult and aged rats

目的探讨腹腔注射内毒素对成年和老年大鼠记忆功能的影响。方法将成年和老年雄性SD大鼠各16只随机分为4组:成年大鼠生理盐水组(A组)、成年大鼠内毒素组(B组)、老年大鼠生理盐水组(C组)和老年大鼠内毒素组(D组),每组8只。经腹腔注射内毒素250μg/kg或等体积的生理盐水,24 h后记录大鼠从明室进入暗室的潜伏期作为记忆成绩。取海马组织,应用酶联免疫吸附法测定白细胞介素1β(interleukin-1β,IL-1β)蛋白的表达,并检测其中半胱氨酸天冬氨酸酶1(caspase-1)的活性。结果 D组大鼠进入暗室的潜伏期明显短于C组,差异有统计学意义(P<0.01),而B组与A组大鼠进入暗室的潜伏期差异无统计学意义(P>0.05);D组大鼠海马组织caspase-1活性较B组明显升高(P<0.05);B组大鼠海马IL-1β蛋白表达较A组明显增加,差异有统计学意义(P<0.05),D组大鼠海马IL-1β蛋白表达明显高于B组和C组,差异有统计学意义(P<0.01)。结论腹腔注射内毒素后老年大鼠记忆功能受损,但并不影响成年大鼠的记忆功能,这可能与衰老加重内毒素诱导的海马IL-1β蛋白表达升高有关。

Objective To explore the effects of intraperitoneal lipopolysaccharide（LPS） on memory function in adult and aged rats. Methods Adult and aged male rats were randomly assigned to four groups：adult rats and saline group（group A） ,adult rats and LPS group（group B） ,aged rats and saline group（group C）,aged rats and LPS group（group D）. The rats were injected intraperitoneally with LPS（250 μg/kg） or sterile saline immediately after the rats were trained to acquire passive avoidance. The latency period of entering the dark compartment was recorded as memory performance 24 h after training. The hippocampus was removed for determination of IL-1β protein expression using ELISA and analysis of caspase-1 activity. Results The latency period in group D was significantly shorter than that in group C （P 〈 0.01）. The caspase-1 activity in hippocampus in group D was significantly higher than that in group B （P 〈 0.05）. IL-1β level in hippoeampus in group B was significantly higher than that in group A （P 〈 0.05）. The expression of IL-1β in hippocampus in group D was significantly enhanced compared with that in groups B and C （P 0.01）. Conclusion Intraperitoneal LPS impairs memory function in aged rats but not in adult rats,probably because aging enhances LPS-induced increase in hippocampal IL-1β protein levels.