Effects of enriched environment on immature neurons in piriform cortex of a rat model of vascular dementia

doi:10.3969/j.issn.2095-4344.2016.27.008

Abstract

Abstract:

BACKGROUND: Researches showed that the enriched environment could improve the cognitive dysfunction of rats with vascular dementia. However, there are few reports regarding its mechanism of action.
OBJECTIVE: To explore the effect of enriched environment on the cognitive dysfunction of rats with vascular dementia from the behavioral level.
METHODS: Vascular dementia models were made by permanent ligation of bilateral common carotid arteries and were divided into vascular dementia group (n=8) and enriched environment group (n=12). Vascular dementia group was taken care under conventional breeding environment for 30 days, while the enriched environment group was subjected to the enriched environment for 30 days. Morris water maze test was adapted to test the cognitive function of rats between two groups. Immunohistochemistry and immunoblotting were applied to observe the number of DCX⁺ cells and DCX protein level in both groups. The number of DCX^-labeled cells co-expressing NeuN was observed using immunofluorescence technique.
RESULTS AND CONCLUSION: (1) The escape latency in the vascular dementia group was longer than that in the enriched environment group (P < 0.05). The times across the platform was less in the vascular dementia group than that in the enriched environment group (P < 0.05). (2) In comparison with the enriched environment group, the number of DCX-positive cells and its protein level in the piriform cortex were significantly decreased in the vascular dementia group (P < 0.05). (3) The number of DCX/NeuN co-labeled cells in the piriform cortex was significantly less in the vascular dementia group than in the enriched environment group (P < 0.05). (4) These findings suggested that enriched environment could improve the cognitive dysfunction of rats with vascular dementia through promoting the expression and differentiation of the immature neurons.

中国组织工程研究杂志出版内容重点：肾移植；肝移植；移植；心脏移植；组织移植；皮肤移植；皮瓣移植；血管移植；器官移植；组织工程

Key words: Models, Animal, Dementia, Vascular, Environmental Medicine, Tissue Engineering

CLC Number:

R318

Huang Jun, Wu Fan-fan, He Xu, Li Jian-ping, Yan Xiao-xin, Pan Ai-hua, Li Zhi-yuan. Effects of enriched environment on immature neurons in piriform cortex of a rat model of vascular dementia[J]. Chinese Journal of Tissue Engineering Research, 2016, 20(27): 4006-4012.

Figures/Tables 1

2.1 造模成功动物数量共造模26只大鼠，由于术后感染及其他不明原因，死亡6只，最后进入结果分析的大鼠为20只。 2.2 材料、方法的改进考虑到同时结扎两侧颈总动脉动物的存活率低[9]，借鉴黄文革等[10]报道，作者先结扎一侧颈总动脉，1周后再结扎另外一侧。 2.3 模型稳定性血管性痴呆主要由缺血性脑血管疾病引起，采用二血管法制作痴呆模型后引起学习记忆功能逐步下降，能较好模拟由缺血性脑卒中而引起的血管性痴呆。 2.4 丰富环境减少血管痴呆大鼠的逃避潜伏期，增加其跨越平台的次数 Morris水迷宫行为学实验结果显示，血管性痴呆组大鼠第2，3，4，5天的逃避潜伏期分别为(84.4±4.1)，(73.6±6.7)，(65.0±4.5)，(58.6± 6.5) s；丰富环境组依次为(74.6±3.8)，(61.6±4.9)，(49.2±5.1)，(35.8±4.0) s。两组逃避潜伏期在同一时间点比较，差异有显著性意义(P < 0.05)，见图1A。空间探索实验结果表明血管性痴呆大鼠的游泳轨迹混乱，路线较长，而丰富环境组游泳轨迹相对简单和路程较短，见图1C，D。血管性痴呆组跨越平台次数与丰富环境组相比(4.2±0.9 vs. 5.8±1.1)，差异有显著性意义(P < 0.05)，见图1B。 2.5 丰富环境增加血管性痴呆大鼠梨状皮质DCX+细胞数目及其蛋白含量两组大鼠DCX+细胞的胞体明显，发出许多突起，突起相互交织且伸向梨状皮质第Ⅰ层，见图2A(a，b)。血管性痴呆组梨状皮质DCX+细胞数目为(31.0±3.8)个，给予丰富环境干预后，梨状皮质 DCX+细胞数目显著增加，为(39.8±4.8)个，两组细胞数目相比，差异有显著性意义(P < 0.05)，见图2B。免疫印迹实验结果显示：与血管性痴呆组相比，丰富环境组DCX蛋白条带相对较粗，见图3A。丰富环境组与血管性痴呆组梨状皮质DCX蛋白含量分别为0.51± 0.01，0.32±0.02，两组大鼠梨状皮质DCX蛋白水平差异有显著性意义(P < 0.01)，见图3B。 2.6 丰富环境增加血管性痴呆大鼠梨状皮质DCX与NeuN共表达细胞实验结果显示丰富环境增加了血管性痴呆大鼠梨状皮质DCX+细胞数目，因此作者想探讨丰富环境是否能增加血管性痴呆大鼠梨状皮质 DCX+细胞转化成NeuN+细胞。结果显示DCX与NeuN的共表达细胞在梨状皮质有少量分布，且主要是DCX+细胞的胞浆存在共表达，见图4A。血管性痴呆组大鼠梨状皮质DCX/NeuN细胞为(5.5±1.1)个，丰富环境组为(8.8±1.5)个，两组大鼠梨状皮质DCX与NeuN的共表达细胞差异有显著性意义(P < 0.01)，图4B。"

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