外源性胰岛素样生长因子-1对老年小鼠认知功能的影响

摘要：目的  探讨胰岛素样生长因子-1（IGF-1）对老年小鼠认知功能的影响机制。方法  给予老年C57/BL6小鼠侧脑室注射IGF-1,Western blot检测胰岛素样生长因子-1受体（IGF-1R）蛋白的表达,5-溴脱氧尿嘧啶核苷（BrdU）荧光染色标记海马齿状回增殖的细胞,尼氏染色标记海马齿状回神经元,用Morris水迷宫实验和跳台实验评定老年小鼠学习记忆能力。结果  Western blot检测显示,IGF-1组老年小鼠海马中IGF-1R表达与对照组比较,差异有统计学意义（P <0.05）。BrdU染色结果显示,IGF-1组海马BrdU阳性细胞数与对照组比较,差异有统计学意义（P <0.05）。尼氏染色结果显示,IGF-1组神经元细胞数与对照组比较,差异有统计学意义（P <0.05）。水迷宫实验结果显示,经过训练后,IGF-1组老年小鼠的逃避潜伏期短于对照组,穿过平台的次数与对照组比较,差异有统计学意义（P <0.05）。跳台实验结果显示,与对照组比较,IGF-1组老年小鼠的基础错误次数减少,而潜伏期延长（P <0.05）。结论  老年小鼠注射IGF-1后,其认知功能有一定改善,IGF-1可以提高老年小鼠认知功能。

Effect of exogenous insulin-like growth factors 1 on cognitive function in aged mice

Abstract: Objective To investigate the the effects of insulin-like growth factor 1 (IGF-1) on cognitive function in aged mice after microinjection of IGF-1. Methods IGF-1 was injected into the lateral ventricles of aged C57/BL6 mice. The expression of IGF-1R was assayed by Western Blot. The proliferative cells of the hippocampal dentate gyrus were marked by 5-bromodeoxyuridine (BrdU) immunofluorescence. The neurons of the hippocampal dentate gyrus were determined by Nissl staining. Morris water maze and step-down test were performed to evaluate the cognitive function of the aged mice. Results Western blot results showed that the protein level of IGF-1R increased in the IGF-1 treated group compared with the control group (P < 0.05). BrdU immunofluorescent results revealed BrdU-positive cells were obviously increased in the IGF-1 treated group compared to the control group (P < 0.05). Nissl staining revealed the increased number of neurons in the IGF-1 treated group compared with the control group (P < 0.05). Morris water maze test showed that escape latency of the IGF-1 treated group was significantly shorter than that of the control group after training, and the number of times through the platform was significantly larger than that of the control group (P < 0.05). Step-down test showed that the number of times of basal errors was dramatically smaller, and the latency was significantly longer in the IGF-1 treated group compared with the control group (P < 0.05). Conclusions After injection of IGF-1, the neurocognitive functions of aged mice were improved, so we may indicate that IGF-1 may improve the cognitive function in aged mice.