To Explore The Mechanism Of Nerve Injury And Protective Measures After Deep Hypothermic Circulatory Arres

Aim:To investigate the transcriptomic profiling of circular ribonucleic acid（circRNA）in hippocampal tissue of rats suffered deep hypothermic circulatory arrest（DHCA）,the highthroughput sequencing technology was conducted.The specific circRNA and signaling pathways involved in cerebral injury and repair were screened by cluster analysis and enrichment analysis.Methods:Rats were randomly divided into two groups:DHCA group and SHAM group.Rats in DHCA group underwent the procedure of cooling（30 minutes）,circulatory arrest（45 minutes,body temperature<20℃）,rewarming（60 minutes）,and rats in the SHAM group did not experienced cooling and circulatory arrest.The fresh hippocampal tissues were harvested and used for high-throughput sequencing.Quantitative analysis,differential expression analysis and functional enrichment analysis were carried out.The sequencing results were verified by quantitative real-time polymerase chain reaction（qRTPCR）.Results:10 rats（5 in each group）were evaluated.A total of 31315 circRNAs were identified,among them 339 circRNAs were differentially expressed between the two groups,including 145 up-regulated circRNAs and 194 down-regulated circRNAs in DHCA rats.After Kyoto Encyclopedia of Genes and Genomes（KEGG）enrichment analysis on the different expression circRNA（DEC）,there were 26 signal pathways that might be related to DEC,including T cell signaling pathway,autophagy,mammalian target of rapamycin（mTOR）signaling pathway and cyclic adenosine monophosphate（cAMP）signaling pathway.qRT-PCR results verified that the expression of 4 circRNAs in DHCA group was significantly different from that of SHAM group.Rno_circ₀028462 and rno_circ₀037165 were upregulated while rno_circ₀045161 and rno_circ₀019047 were downregulated.Conclusion:DHCA can change the expression of circRNA in rat hippocampus.This study screened and verified 4 DEC after DHCA,which were rno_circ₀028462,rno_circ₀037165,rno_circ₀045161 and rno_circ₀019047.This study revealed the specific effects of DHCA on circRNA in hippocampus and provided some new targets for further research on the mechanism of cerebral injury.Aim:To identify,quantify and analysis of the proteins in hippocampal tissue of rats suffered deep hypothermic circulatory arrest（DHCA）.Then the different expression proteins（DEP）between groups were calculated to investigate the potential mechanism of cerebral injury after DHCA.Methods:Rats were randomly divided into two groups:DHCA group and SHAM group.Rats in DHCA group underwent hypothermia（<20℃）and circulatory arrest（45 minutes）,and rats in SHAM group did not experience the cooling and circulatory arrest.The hippocampal tissues were harvested and used for proteomics analysis.Quantitative analysis,differential expression analysis and functional enrichment analysis were carried out after that.Finally,the hippocampal tissue proteins were extracted and the western blot（WB）and immunofluorescence staining（IF）were conducted to verify the proteomics results.Results:10 rats（5 in each group）were evaluated.Totally,8432 proteins were identified,among which 8412 proteins could be quantified.There were 19 DEP between the two groups,of which 5 proteins were up-regulated and 14 proteins were down-regulated in DHCA rats.The DEP were involved in the adipocytokine signaling pathway and adenosine monophosphate activated protein kinase（AMPK）signaling pathway.The results of WB and IF indicated that the expression of adiponectin receptor 1 in DHCA group was significantly higher than that of SHAM group.Conclusion:DHCA can increase the expression of adiponectin receptor 1 in rats hippocampus.This study provided new directions to further explore the mechanism of DHCA-related cerebral injury or protection.Aim:Neuroinflammation after deep hypothermic circulatory arrest（DHCA）is one of the main reasons for postoperative cerebral complications.This study investigated whether a new adiponectin receptor agonist,AdipoRon,has the ability to inhibit neuroinflammation after DHCA.Methods:The DHCA rat model was established firstly.The rats in AdipoRon group were given AdipoRon（12.5 mg/kg）before cooling and 45 minutes after circulatory arrest,while rats in DHCA group were given equal dose of solvent at the above two time points.The rats in SHAM group did not suffer cooling and circulatory arrest.Vital signs were recorded periodically during the cardiopulmonary bypass（CPB）.Enzyme linked immunosorbent assay（ELISA）and quantitative real-time polymerase chain reaction（qRT-PCR）were used to test the plasma level of proinflammatory cytokines,including interleukin-1β（IL-1β）,interleukin-6（TL-6）,and tumor necrosis factor-α(TNF-α,and the messenger RNA（mRNA）expression levels of the 3 cytokines in brain.Immunofluorescent staining（IF）was used to test the expression of ionized calcium-binding adaptor molec-1（1ba-1）and mannose receptor C type 1（CD206）in rat hippocampus.The expression of phosphorylated adenosine monophosphate activated protein kinase（p-AMPK）and nuclear factor kappa B（NF-κB）in the hippocampus were detected using immunohistochemistry（IHC）.Western blot（WB）was used to quantify the expression of AMPK,p-AMPK and NF-κB in rat hippocampus.BV2 cells were cultured and the in vitro inflammatory model was built using lipopolysaccharide（1μg/mL）.Then AdipoRon（1-50 μM）was used to pre-treat the BV2 cells.The concentration of proinflammatory cytokines in the supernatant was evaluated via ELISA.Also,the concentration of NO was measured.The mRNA level of cytokines in BV2 cells was tested using qRT-PCR.The expressions of AMPK,p-AMPK and NF-κB were determined by WB.Results:There was no significant difference in vital signs among the 3 groups at the beginning of the CPB.After 45 minutes of DHCA,the concentration of lactic acid in DHCA group was significantly increased than SHAM group,while it was much lower in AdipoRon group than DHCA group.During the rewarming phase,the mean arterial pressure（MAP）and temperature of AdipoRon group rats were higher than those of DHCA group rats.ELISA demonstrated that the plasma level of IL-6,IL-1β,and TNF-α in DHCA group were significantly increased compared with the SHAM group（P<0.001）,while they were significantly decreased in AdipoRon group（P<0.001）.The qRT-PCR results showed that the relative expression of IL-6,IL-1β and TNF-α mRNA in brain tissue were significantly increased in DHCA group（P<0.05）.After applying AdipoRon,they were decreased（P<0.05）.The Iba-1 was increased in DHCA group rats（P<0.05）,while it was significantly decreased in AdipoRon group（P<0.05）.The expression of CD206 in Iba-1 positive microglia cells of SHAM group and DHCA group was similar,but increased in AdipoRon group（P<0.05）.The IHC and WB results demonstrated that the p-AMPK and NF-κB increased in DHCA group,while in the AdipoRon group,the p-AMPK was increased more significantly（P<0.05）and the NF-κB was decreased（P<0.05）.Consistently,we used LPS-treated BV2 cells to mimic the neuroinflammatory condition and found that AdipoRon dose-dependently decreased cytokines and NO,along with upregulated p-AMPK and downregulated NF-κB.Conclusion:AdipoRon can promote the recovery of cardiovascular function after DHCA.AdipoRon inhibits acute neuroinflammation induced by DHCA involving the AMPK/NFκB pathway.This study revealed the inhibitory effect of adiponectin receptor agonists on neuroinflammation induced by DHCA firstly and laid a foundation for the development of new compounds that can be used in clinical practice.Deep hypothermic circulatory arrest（DHCA）is a risk factor for postoperative cerebral complications in cardiovascular surgeries.Reducing the incidence of cerebral complications after DHCA and maintain the normal neurocognitive function are hot issues that cardiac surgeons are dedicated to solve.In order to provide references for a comprehensive understanding of DHCA-related cerebral injury,finding potential problems,selecting research directions,and formulating research protocols in the future,this review summarized the DHCA-related clinical studies,the mechanism of cerebral injury and interventions.