Objectives: To investigate the effect of inhibiting miR-204 expression on the learning and memory abilities of neonatal rats with intrauterine growth restriction (IUGR) and related mechanism.
Methods: A rat model of IUGR was prepared by low-protein diet. The 3-day-old IUGR rats were divided into three groups: model, miRNA antagonist control and miR-204 antagonist, with 10 rats in each group. Ten normal neonatal rats served as the control group. Morris water maze test was used to measure the learning and memory abilities of the rats. Quantitative real-time PCR was used to measure the mRNA expression levels of miR-204 and brain-derived neurotrophic factor (BDNF) in the hippocampus. Nissl staining and TUNEL staining were used to observe the number of Nissl bodies and the apoptosis of cells in the hippocampus. Western blot was used to measure the expression levels of BDNF/TrkB signaling pathway-related proteins in the hippocampus.
Results: Compared with the control group, the model group had a significant increase in the escape latency and a significant reduction in the number of platform crossings (P<0.001). The model group also had significant increases in the apoptosis rate of cells and the expression level of miR-204 in hippocampal tissue (P<0.001), while the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB in the model group were significantly reduced compared with the control group (P<0.001). After inhibition of the expression of miR-204, the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB significantly increased, while the cell apoptosis rate and the expression level of miR-204 in the hippocampus significantly decreased. The escape latency was also reduced, while the number of platform crossings increased after inhibition of the expression of miR-204 (P<0.001).
Conclusions: Inhibiting miR-204 can improve the learning and memory functions of neonatal rats with IUGR, possibly by targeted activation of the BDNF/TrkB signaling pathway.
目的: 探讨抑制miR-204表达对宫内发育迟缓（intrauterine growth restriction，IUGR）新生大鼠学习记忆能力的影响及机制。方法: 采用低蛋白饮食法建立IUGR大鼠模型，将3日龄IUGR幼鼠设为模型组、miRNA拮抗剂对照组（antagomir-NC组）和miR-204拮抗剂组（antagomir组），另取正常幼鼠设为对照组，每组10只。Morris水迷宫实验测定大鼠学习与记忆能力；qRT-PCR检测各组大鼠海马组织中miR-204和脑源性神经营养因子（brain-derived neurotrophic factor，BDNF）mRNA表达水平；尼氏染色、Tunel法观察海马组织尼氏小体数量和细胞凋亡水平；Western blot检测海马组织中BDNF/TrkB信号通路相关蛋白表达水平。结果: 与对照组比较，模型组大鼠逃避潜伏期增加，跨台次数减少；海马组织中细胞凋亡率和miR-204表达水平升高，而尼氏小体数量、BDNF mRNA，以及BDNF、p-TrkB和p-CREB蛋白表达水平降低（P<0.001）。抑制miR-204表达后，IUGR大鼠海马组织中尼氏小体数量、BDNF mRNA，以及BDNF、p-TrkB和p-CREB 蛋白表达水平升高，细胞凋亡率和miR-204表达水平降低，逃避潜伏期减少，跨台次数增加（P<0.001）。结论: 抑制miR-204可改善IUGR新生大鼠学习及记忆功能，其作用机制可能与靶向激活BDNF/TrkB信号通路有关。.
Keywords: BDNF/TrkB signaling pathway; Intrauterine growth restriction; Learning and memory ability; Neonatal rat; miR-204.