吡格列酮对脂多糖引起的大鼠学习记忆障碍及海马炎症反应的影响

Effects of pioglitazone on LPS-induced learning and memory disorders and inflammatory reaction in rat hippocampus

目的研究吡格列酮(pioglitazone,Pio)能否对抗脂多糖(lipopolysaccharide,LPS)所致的大鼠学习记忆障碍及海马炎症反应。方法取SD大鼠40只,随机分为4组:生理盐水对照组,LPS损伤组,LPS+Pio 40和80 mg.kg-1组。灌胃给予Pio 2 d后,脑室注射LPS 5μl(1.0 mmol·L-1),生理盐水对照组注射等量生理盐水。脑室注射后d 2进行Morris定位航行实验,连续5 d,在d 6进行空间探索实验,训练期间继续给药。d 7,快速取海马CA1区,Western blot方法观察白介素-1β(Interleukin-1β,IL-1β),诱导型一氧化氮合酶(Inducible Nitric Oxide Synthase,iNOS),半胱氨酸天冬氨酸蛋白酶(caspase)3,caspase-9及多聚ADP-核糖聚合酶(PARP)蛋白表达水平的变化。RT-PCR检测IL-1β和iNOS的mRNA表达水平。结果脑室内注射LPS,大鼠出现明显的空间学习记忆障碍,表现为逃避潜伏期较生理盐水对照组明显延长(P<0.05),在原平台象限游泳时间占总游泳时间的百分比明显降低(P<0.01)。Western蛋白印迹及RT-PCR结果显示注射LPS后,与对照组相比海马CA1区IL-1β、iNOS蛋白及mRNA表达水平明显增加(P<0.01),活化的caspase-3,caspase-9蛋白表达水平明显增高,分子质量116 ku PARP表达明显减少,而分子质量89 ku劈切PARP表达明显增加(P<0.01)。Pio(40和80 mg.kg-1)能改善大鼠学习记忆功能,对抗LPS引起的海马CA1区IL-1β、iN-OS、活化的caspase-3、活化的caspase-9表达增加,也可明显抑制LPS所致的PARP表达的改变(P<0.01)。结论吡格列酮能够改善大鼠学习记忆功能,抑制LPS引起的海马炎症反应。

Aim To observe the improving effects of pioglitazone on learning and memory ability after in- tracerebroventricular injection of lipopolysaccharide （LPS）. Methods Fourty Sprague-Dawley rats were randomly divided into four groups （ll） rats for each） ： control ; LPS ; LPS ＋ pioglitazone 40 mg·kg-1 ; LPS ＋ pioglitazone 80 mg· kg-1. Rats were intracerebrov- entricularly injected LPS 5 μl （ 1.0 mmol·L-1） after given pioglitazone 24 h. The contral group were injected with saline of the same volume. Two days later, Morris water maze was used to measure the spatial learning and memory ability. The rats were trained in Morris water maze test for 5 consecutive days, on the sixth day, probe tests were given. Seven days after in- jection, the levels of iNOS,IL-1β ,caspase-3, caspase-9 and peroxisome poly ADP-ribose polymerase （PARP） in hippocampal CA1 region were determined by Western blot method. The changes in IL-1β, iNOS mRNA level were determined by RT-PCR method. Results Intracerebroventricular injection of LPS in rats resulted in learning and memory impairments shown by longer escape latency and decreased percentage of time spent in the target quadrant. These behavioral dysfunctions were accompanied by the increased levels of IL-113 ,iN- OS, cleaved-caspase-3, cleaved-caspase-9, the elevated IL-I[3,iNOS mRNA levels, and the caspase-3 substrate PARP cleavage. These changes were inhibited by Pio （40,80 mg · kg-1）. Conclusion Pioglitazone can improve the learning and memory ability of rats im- paired by LPS through the suppressions of inflammatory response in hippocampus.