Abnormal expression of miR-122-5p in brain tissues and its effects on neurological functions after traumatic brain injury in rats

DIAO Bo; YANG Qian; WANG Gang; YUAN Zilin; CHEN Li; WANG Fang

doi:10.13798/j.issn.1009-153X.2018.04.009

Abstract：Objective To study the effects of the changes in miR-122-5p expression in brain tissues on the neurological functions after traumatic brain injury(TBI).Method Forty rats were randomly divided into 4 groups,i.e.group A,in which 10 animals received sham operation,group B,in which 10 animals underwent TBI,group C,in which 10 animals were treated by scrambled miRNA after IBI, and group D,in which 10 animals were treated by miR-122-5p mimics after TBI.The changes in memory were determined by Water Maze method in all the rats.The expression of miR-122-5p in the injured brain tissues was detected by qRT-PCR.The expression of p53 protein in the injured brain tissues was determined by Western Blot method. Cells apoptosis in the injured brain tissues and the change in brain cell mitochondrial membrane potential (MMP) were determined respectively by TUNEL method and Flow cytometry. Results The level of miR-122-5p expression in the injured brain tissues was significantly lower and the level of p53 protein expression was significantly higher in groups B and C than those in group A(P<0.05).The number of cells of apoptosis was significantly more and brain cell MMP was significantly lower in the injured brain tissues in groups B and C than those in group A(P<0.05).The time needed to find hidden platform was significantly longer in group B and C than that in group A(P<0.05).In the injured brain tissues the levels of miR-122-5p expression was significantly enhanced and the level of p53 protein expression and the number of cells apoptosis was significantly decreased and the time needed to find the hidden platform was significantly shortened in group D compared to those in group B (P<0.05). Conclusions The decrease in level of miR-122-5p expression might promote the expression of p53 protein in the injured brain tissues, in which the upregulation of p53 protein expression might cause the increase in the level of apoptosis of the cerebral cells after TBI.The miR-122-5p mimics can inhibit the expression of p53 protein,reducing the apoptosis of the cerebral cells and effectively relieve the damaged neurological function in the rats with TBI.