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| Objectives To descript the changes in expression of microRNAs in the hippocampus of rats at 1 day, 3 days and 5 days following traumatic brain injury (TBI) by microarray technique, and investigate the possible cellular activities that are regulated by microRNAs which differentially expressed in the hippocampus, that may contribute to TBI-induced cognitive impairment. Methods Adult SD rats received a single controlled cortical impact (CCI) injury using an electromagnetic piston at a velocity of 4 m/sec, duration of 150 ms and depth of 3 mm. The ipsilateral hippocampus was harvested for the subsequent microarray assays at three time points post-injury: 1 day, 3 days and 5 days, respectively. We characterize the microRNA expression profile in rat hippocampus compared with sham group using the Significance Analysis of Microarrays analysis. Results We got a dendrogram of a Hierarchical Clustering analysis of the result. Totally 205 microRNAs were identified which were up-/down-regulated more than 1.5 times. At 1 d post-injury, 41 microRNAs were up-regulated more than 1.5 times, and 31 microRNAs were down-regulated more than 1.5 times; at 3 d post-injury, 81 microRNAs were up-regulated more than 1.5 times, and 11 microRNA s were down-regulated more than 1.5 times; at 5 d post-injury, 52 microRNAs were up-regulated more than 1.5 times, and 41 microRNAs were down-regulated more than 1.5 times. Furthermore, we revealed 17 microRNAs which were changed at all three time points post-injury, the notable two microRNAs were miR-142-3p and miR-221, which could involve in many pathophysiological processes. Conclusions Our microarray-based bioinformatics analysis has showed that microRNAs in rat hippocampus have different expression levels at various time points post-injury, suggesting it is likely an active approach for cells to cope with injury through modulating microRNA expression, and microRNAs play key roles in the pathological courses after injury and work collaboratively like a complicated gene expression network. MiR-142-3p and miR-221 may be used as potentially biological markers for TBI assessment, and thus make some improvements in exploratory research for TBI-related cognitive disorder. |
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| Keywords:forensic clinical medicine; microRNA; microarray; hippocampus; traumatic brain injury |
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