MiR-124-3p In The Mechanism Of Postoperative Cognitive Dysfunction Induced By Cardiopulmonary Bypass In Old Rats

Objective: This study aims to study the molecular mechanism of postoperative cognitive impairment after cardiopulmonary bypass,and to explore the mechanism of microRNAs in the development of postoperative cognitive dysfunction in rats,so as to provide the oretical basis for the diagnosis and treatment of POCD.Methods: We chose 72 healthy male rats,aged 18-20 month,which were randomly divided into Sham group(n=36)and CPB group(n=36)through the coin toss method.Rats in CPB group accepted cardiopulmonary bypass after anesthesia,whereas rats in Sham group only accepted anesthesia.The cognitive function of rats were tested by Morris Water Maze and Open-Field experiment,PCR method was used to determine the expression of miR-124-3p,miR-214-5p,miR-132-3p and LPIN1 in the prefrontal cortex and hippocampus.The downstream target genes of miR-124-3p were predicted by bioinformatics technology.The expression levels of lipin-1and Aβ 1-42 in prefrontal cortex and hippocampus were respectively detected by Western Blot,and the contents of cholesterol in the prefrontal cortex and hippocampal were determined by enzyme-linked immunoassay.Immunohistochemical staining was used to detect the protein content of lipin-1and Aβ 1-42 in prefrontal cortex and hippocampus.Besides,the targeted regulation of LPIN1 by miR-124-3p was verified using dual luciferase reporter assay.Results: 1.Morris water maze test: there was no significant differencebetween the escape latency and the number of crossing the platform between two groups before CPB surgery(P>0.05).Compared with Sham group,the escape latency of rats in CPB group was prolonged after surgery(P<0.05),and the number of crossing was less in CPB group after surgery(P<0.05).2.Open field experiment: there was no significant difference in Open field trail between two groups before CPB surgery(P>0.05).Compared with Sham group,the number of vertical standing times and center entry times were less in CPB group(P<0.05),while the total distance and the number of grooming were not significantly different(P>0.05).3.PCR results: Compared with Sham group,miR-124-3p was significantly decreased in the prefrontal cortex and hippocampus of rats in CPB group(P<0.05),but miR-214-5p and miR-132-3p showed no significant difference(P>0.05),and the expression level of LPIN1 in the prefrontal cortex and hippocampus of rats with CPB significantly increased(P<0.05).4.WB results showed that compared with Sham group,the expression level of lipin-1and Aβ 1-42 in the prefrontal cortex and hippocampus of CPB group significantly increased(P<0.05).5.Immunohistochemical staining results:compared with Sham group,and the IDO of LPIN1 and Aβ 1-42 protein increased in the prefrontal cortex and hippocampus of rats in CPB group(P<0.05).6.Cholesterol determination results: compared with Sham group,the prefrontal cortex and hippocampus of cholesterol in CPB group obviously increased(P<0.05).7.Dual-luciferase reporterassay results: mir-124-3p directly regulated the target gene LPIN1 in 293 Tcell.Conclusion:1.Short-term cognitive impairment can be caused after cardiopulmonary bypass in old rats;2.MiR-124-3p was down-regulated in the prefrontal cortex and hippocampus of rats with POCD after CPB surgery,while LPIN1,cholesterol and Aβ 1-42 were up-regulated in the prefrontal cortex and hippocampus of rats with POCD after CPB surgery.3.Short-term cognitive impairment in rats after cardiopulmonary bypass may be related to the regulation of LPIN1 expression by miR-124-3p,and the abnormal metabolism of lipid and Aβ metabolism.