PI3K/Akt 信号通路对新生大鼠缺氧缺血性脑损伤后学习记忆能力的影响

Effects of PI3K/Akt signaling pathway on learning and memory abilities in neonatal rats with hypoxic-ischemic brain damage

摘要:

目的：研究PI3K/Akt 信号通路抑制剂 wortmannin 对新生大鼠缺氧缺血性脑损伤（HIBD）后远期学习记忆及认知功能的影响。方法：于制备新生大鼠左脑 HIBD 模型前 30 min，应用脑立体定位仪定位大鼠左侧海马区，注射wortmannin 2 μL，同时建立 HIBD+DMSO 组、HIBD模型组、假手术组及空白对照组。于大鼠 28 日龄时用 Morris水迷宫试验检测各组大鼠的学习记忆能力。结果：随游泳次数增加各组大鼠逃避潜伏期（EL）时间均有不同程度缩短；从第 2 天开始，HIBD+wortmannin 组EL明显长于假手术组和空白对照组 (t=2.637，P=0.023；t=3.585，P=0.003)，且随着时间的延长差距逐渐扩大。到第 4 天和第8天时，HIBD+wortmannin 组EL值明显长于其他4组(P<0.05； P<0.01)。而在空间探索试验撤去平台后 120 s 内，HIBD+DMSO组和 HIBD 组的穿越平台次数低于假手术组和空白对照组（P<0.05），HIBD+wortmannin组的穿越平台次数低于 DMSO+HIBD 组和 HIBD组（P<0.05）, 同时亦明显低于假手术组和空白对照组（P<0.01）。结论：抑制PI3K/Akt信号通路可加重大鼠认知功能障碍，从而影响远期的学习记忆及认知功能。

Abstract:

OBJECTIVE: To study the effects of PI3K/Akt signaling pathway inhibitor wortmannin on long-term learning and memory abilities in neonatal rats with hypoxic-ischemic brain damage (HIBD). METHODS: Forty-eight neonatal rats were randomly assigned to blank control (n=8), sham-operated (n=8), HIBD model (n=10), HIBD+DMSO (dimethyl sulfoxide, n=8) and HIBD+wortmannin groups (n=8). Wortmannin (2 μL) was injected to the left hippocampus 30 minutes before HIBD inducement in the HIBD+wortmannin group. The Morris water maze test was used to examine the long-term learning and memory abilities at the age of 28 days. RESULTS: With the increased number of swimming, the escape latency was shortened in various groups. From the second day, the escape latency in the HIBD+wortmannin group was significantly longer than that in the sham-operated and the blank control groups (P<0.05), and the differences increased with the time. On the fourth day, there were significant differences in the escape latency between the HIBD+wortmannin group and the HIBD+DMSO group as well as the HIBD model group (P<0.05). On the eighth day (retention trial), there were the most obvious differences in the escape latency between the HIBD+wortmannin group with the other four groups. In the space exploration test, the number of times crossing the former platform location within 120 seconds after removing the platform in the HIBD+DMSO and the HIBD model group was lower than the sham-operated and the blank control groups (P<0.05). The HIBD+wortmannin group showed lower number of times crossing the former platform location compared with the HIBD+DMSO and the HIBD model groups (P<0.05), as well as the sham-operated and the blank control groups (P<0.01). CONCLUSIONS: P13K/Akt signaling pathway inhibitor wortmannin can aggravate the cognitive impairments, thus affecting adversely long-term learning and memory abilities in neonatal rats with HIBD.