Objective:To evaluate the relationship between hippocampal miR-3065-5p and insulin-like growth factor-1/phosphatidylinositol 3-kinase/protein kinase B(IGF-1/PI3K/Akt)signaling pathway in a mouse model of perioperative neurocognitive disorder (PND).Methods:Eighty clean-grade healthy male C75BL/6 mice, aged 12-14 weeks, weighing 20-30 g, were divided them into 4 groups ( n=20 each) using the random number table method: control group (C group), PND group, miR-3065-5p agonist group (Ag group) and miR-3065-5p agonist negative control group (Ag-NC group). PND model was prepared by internal fixation of tibial fracture under anesthesia with 1.5% isoflurane. Two days before developing the model, miR-3065-5p agomir 2 μl was injected into the lateral ventricle in Ag group, miR-3065-5p agomir negative control 2 μl was injected into the lateral ventricle in Ag-NC group. Morris water maze test and open field test were performed at 7 days after surgery. The mice were sacrificed after the end of test, and hippocampal tissues were obtained for determination of the expression of miR-3065-5p, IGF-1 mRNA and Bcl-2 mRNA (by quantitative real-time polymerase chain reaction) and expression of IGF-1, phosphorylated Akt (p-Akt), phosphorylated glycogen synthase kinase-3β (p-GSK3β) and Bcl-2 (by Western blot). Results:There was no significant difference in each parameter in the open field test among the four groups ( P>0.05). Compared with group C, the postoperative escape latency was significantly prolonged, the percentage of time of stay at the target quadrant was decreased, the number of crossing the original platform was reduced, the expression of miR-3065-5p was up-regulated, and the expression of IGF-1 mRNA, Bcl-2 mRNA, IGF-1, p-Akt, p-GSK3β and Bcl-2 was down-regulated in the other three groups ( P<0.05). Compared with PND group and Ag-NC group, the postoperative escape latency was significantly prolonged, the percentage of time of stay at the target quadrant was decreased, the number of crossing the original platform was reduced, the expression of miR-3065-5p was up-regulated, and the expression of IGF-1 mRNA, Bcl-2 mRNA, IGF-1, p-Akt, p-GSK3β and Bcl-2 was down-regulated in Ag group ( P<0.05). Conclusions:Up-regulation of miR-3065-5p can inhibit the activation of IGF-1/PI3K/Akt signaling pathway, which might be one of the mechanisms of PND developed in mice.

Objective:To investigate the effects of mild hypothermia on microglia polarization and janus kinase 2/signal transduction and transcriptional activation factor 3 (JAK2/STAT3) signaling pathway during cerebral ischemia-reperfusion (I/R) in rats.Methods:Forty-five clean-grade healthy male Sprague-Dawley rats, aged 8 weeks, weighing 260-280 g, were divided into 3 groups ( n=15 each) by the random number table method: sham operation group (S group), cerebral I/R group (I/R) and mild hypothermia group (H group). In I/R group and H group, cerebral I/R was induced by middle cerebral artery occlusion using a nylon thread in anesthetized animals, the nylon thread was removed to restore the perfusion after 2 h of occlusion, and the rectal temperature was maintained at 36-37 ℃ during the period. Group H was wiped with 75% alcohol for 3 h starting from the time point immediately after reperfusion, and the rectal temperature was maintained at 32-33℃. Modified neurological severity score (mNSS) was evaluated at 24 h of reperfusion. Animals were then sacrificed for determination of the cerebral infarct size (using TTC staining), expression of M1 marker inducible nitric oxide synthase (iNOS), M2 marker arginase 1(Arg-1), phosphorylated JAK2(p-JAK2)and phosphorylated STAT3(p-STAT3)(by Western blot), expression of iNOS mRNA and Arg-1 mRNA (by quantitative polymerase chain reaction), and contents of interleukin-6 (IL-6) and IL-10 (by enzyme-linked immunosorbent assay). Results:Compared with group S, mNSS and cerebral infarct size were significantly increased, the expression of iNOS, Arg-1 protein and mRNA in cerebral ischemic penumbral zone was up-regulated, and the p-JAK2/JAK2 ratio, p-STAT3/STAT3 ratio, and contents of IL-6 and IL-10 were increased in the other two groups ( P<0.05). Compared with I/R group, mNSS and cerebral infarct size were significantly decreased, the expression of iNOS protein and mRNA in cerebral ischemic penumbral zone was down-regulated, the expression of Arg-1 and mRNA was up-regulated, and the p-JAK2/JAK2 ratio, p-STAT3/STAT3 ratio and IL-6 content were decreased, and the IL-10 content was increased in group H ( P<0.05). Conclusions:Mild hypothermia can promote the polarization shift of microglia from M1 to M2 phenotype during cerebral I/R and inhibit the central inflammatory responses, and the mechanism may be related to inhibition of JAK2/STAT3 signaling pathway in rats.

Objective:To evaluate the role of miR-124-3p in reduction of oxygen-glucose deprivation and restoration (OGD/R) injury by electrostimulation preconditioning in microglia and its relationship with microglial polarization.Methods:The well-growing BV2 cells were divided into 4 groups ( n=30 each) by the random number table method: control group (group C), OGD/R group, electrostimulation preconditioning group (group E) and miR-124-3p inhibitor group (group I). Group C was cultured under normal conditions, and group OGD/R was deprived of oxygen and glucose for 2 h followed by restoration of oxygen and glucose supply for 24 h to develop the OGD/R injury model. In group E, cells were stimulated with 100 mV/mm direct current for 4 h before oxygen-glucose deprivation, and the other treatments were similar to those previously described in group OGD/R. Group I was transfected with micrOFF? mmu-miR-124-3p inhibitor at 48 h before oxygen-glucose deprivation, and the other treatments were similar to those previously described in group E. The cell survival rate was determined by CCK-8 assay, the concentrations of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and IL-10 in the cell supernatant were measured by enzyme-linked immunosorbent assay. The expression of a surface marker of M1 microglia inducible nitric oxide synthase (iNOS) and a surface marker of M2 microglia arginase 1 (Arg-1) was detected by immunofluorescence and Western blot, respectively. The expression of iNOS and Arg-1 mRNA and miR-124-3p was detected by quantitative polymerase chain reaction. Results:Compared with group C, the cell survival rate was significantly decreased, the concentrations of TNF-α, IL-1β and IL-10 in the supernatant were increased, and the expression of iNOS and Arg-1 protein and mRNA and miR-124-3p was up-regulated in the remaining three groups ( P<0.05). Compared with group OGD/R, the cell survival rate was significantly increased, the concentrations of TNF-α and IL-1β in the supernatant were decreased, the IL-10 concentration was increased, the expression of iNOS protein and mRNA was down-regulated, and the expression of Arg-1 protein and mRNA and miR-124-3p was up-regulated in E and I groups ( P<0.05). Compared with group E, the cell survival rate was significantly decreased, the concentrations of TNF-α and IL-1β in the supernatant were increased, the IL-10 concentration was decreased, the expression of iNOS protein and mRNA was up-regulated, and the expression of Arg-1 protein and mRNA and miR-124-3p was down-regulated in group I ( P<0.05). Conclusions:The mechanism by which electrostimulation preconditioning reduces OGD/R injury in microglia is related to up-regulation of the expression of miR-124-3p, promotion of M2 microglia polarization, inhibition of M1 microglia polarization, and thus inhibiting the inflammatory responses.

Objective:To evaluate the role of glutathione S-transferase μ1 (GSTM1) expression in mild hypothermia-induced mitigation of cerebral ischemia-reperfusion (I/R) injury and the relationship with microglial polarization.Methods:Eighty clean-grade healthy male Sprague-Dawley rats, aged 8 weeks, weighing 260-280 g, were divided into 4 groups ( n=20 each) using a random number table method: sham operation group (S group), cerebral I/R group (I/R group), mild hypothermia group (H group), and GSTM1 inhibitor + mild hypothermia group (IH group). The rat model of cerebral I/R injury was prepared using the filament occlusion method. The filament was removed to restore blood flow after the left middle cerebral artery was blocked for 2 h, and the rats′ brain and rectal temperature were maintained at 36-37 ℃ during the period. The vessels were only isolated and ligated without occlusion in S group. In H group, the entire body was wiped with 75% ethanol immediately after removing the filament, and the brain and rectal temperatures were maintained at 32-33 ℃ for 3 h, and the other procedures were the same as those previously described in I/R group. In IH group, GSTM1 inhibitor itaconic acid 8.6 mg/kg was intraperitoneally injected at 24 and 1 h before developing the model, and the other procedures were the same as those previously described in H group. Neurological deficits were evaluated using a modified neurological severity score (mNSS) at 24 h of reperfusion, and then the animals were sacrificed and the brains were removed for observation of cerebral infarction (by TTC staining) and for determination of the expression of GSTM1, M1-type microglial marker inducible nitric oxide synthase (iNOS), and M2-type microglial marker arginase-1 (Arg-1) (by Western blot), expression of GSTM1, iNOS and Arg-1 mRNA (quantitative real-time polymerase chain reaction) and contents of interleukin-6 (IL-6), IL-10, tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) (by enzyme-linked immunosorbent assay). Results:Compared with S group, the mNSS and percentage of cerebral infarct size were significantly increased, and the expression of iNOS and Arg-1 protein and mRNA was up-regulated, the expression of GSTM1 and mRNA was down-regulated, and the contents of IL-6, TNF-α, IL-10 and TGF-β were increased in the other three groups ( P<0.05). Compared with I/R group and IH group, the mNSS and percentage of cerebral infarct size were significantly decreased, and the expression of iNOS protein and mRNA was down-regulated, the expression of Arg-1 protein and mRNA and GSTM1 was up-regulated, the contents of TNF-α and IL-6 were decreased, and the contents of TGF-β and IL-10 were increased in H group ( P<0.05). Conclusions:Up-regulated expression of GSTM1 is involved in mild hypothermia-induced mitigation of cerebral I/R injury, which is associated with inhibition of microglial polarization toward the M1 phenotype and promotion of polarization toward the M2 phenotype.

Microglia are widely present in the central nervous system and participate in various pathophysiological processes.They play an important role in degenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease.In recent years, the study of exosomes produced by microglia activation involved in the pathophysiological processes of various diseases has attracted extensive attention, but the role of exosomes has not been fully clarified.This article reviewed the characteristics and functions of microglia, the characteristics and functions of microglia-derived exosomes and their roles in central neurodegenerative diseases.

Objective:To evaluate the relationship between microRNA-93-5p and mitochondrial fusion protein-2 (Mfn2) in mouse nerve cells subjected to oxygen-glucose deprivation and reoxygenation (OGD/R).Methods:Mouse neuroblastoma cells were cultured in vitro to logarithmic growth phase.Experiment Ⅰ Cells were divided into 5 groups ( n=20 each) by the random number table method: control group (group C), group OGD/R, miR-93-5p inhibitor group (group I), siRNA-mfn2 plus miR-93-5p group (group siMfn2+ I) and miR-93-5p negative control group (group NC). Oxygen-glucose deprivation: the cells were cultured for 3 h in a low-glucose balanced salt solution at 37 ℃ in an environment of 5% CO 2-95% N 2.Restoration of oxygen and glucose: the cells were cultured in normal medium at 37℃ in 5% CO 2-95% air for 24 h. Group I, group siMfn2+ I and group NC were transfected with miR-93-5p inhibitor, miR-93-5p inhibitor plus siRNA-mfn2 and negative control miRNA, respectively, at 48 h before the OGD/R model was developed.Cell viability was measured by CCK-8 assay.Cell apoptosis rate was measured by flow cytometry.Quantitative real-time polymerase chain reaction was used to detect the expression of miR-93-5p and Mfn2 mRNA.Western blot was used to detect Mfn2 protein expression.Experiment Ⅱ The wild-type (WT)-Mfn2 and mutant (MUT)-Mfn2 were constructed and transfected into neuroblastoma cells with miR-93-5p mimic and miR-93-5p blank control (miR-93-5pNC), respectively.The cells were divided into 4 groups ( n=5 each) after 48 h of transfection by the random number table method: miR-93-5p NC-WT-Mfn2 co-transfection group, miR-93-5p mimic-WT-Mfn2 co-transfection group, miR-93-5p NC-MUT-Mfn2 co-transfection group, and miR-93-5p mimic-MUT-Mfn2 co-transfection group.The activity of luciferases was measured by double luciferase assay. Results:Experiment Ⅰ Compared with group C, the cell viability was significantly decreased, the apoptosis rate of cells was increased, the expression of miR-93-5p was up-regulated, and the expression of Mfn2 protein and mRNA was down-regulated in the other gorups ( P<0.05). Compared with group OGD/R or group NC, the cell viability was significantly increased, the apoptosis rate of cells was decreased, miR-93-5p expression was down-regulated, and the expression of Mfn2 protein and mRNA was up-regulated in group I ( P<0.05). Compared with group I, the cell viability was significantly decreased, the apoptosis rate of cells was increased, and the expression of Mfn2 protein and mRNA was down-regulated in group siMfn2+ I ( P<0.05). Experiment Ⅱ Compared with miR-93-5p NC-WT-Mfn2 co-transfection group, the luciferase activity was significantly decreased in miR-93-5p mimic-WT-Mfn2 co-transfection group ( P<0.05). There was no significant difference in luciferase activity between miR-93-5p NC-MUT-Mfn2 co-transfection group and miR-93-5p mimic-MUT-Mfn2 co-transfection group ( P>0.05). Conclusions:The miR-93-5p expression is up-regulated, which further targetedly down-regulates the expression of Mfn2, and this may be a mechanism of OGD/R in mouse nerve cells.

Objective:To evaluate the role of exosomes in neuronal injury induced by M1 microglia.Methods:Liposolysaccharide 100 ng/ml and interferon-γ (IFN-γ)20 ng/ml were added to well-growing BV2 microglia to induce the polarization of microglia into M1 phenotype.Cell supernatant of M1 microglia was collected and M1 microglia exosomes (M1-exo) were extracted with exosome kit.The well-growing N2a cells were divided into 4 groups ( n=24 each) using a random number table method: control group (group C), M1 microglia group (group M), exosome group (group E), and exosome inhibitor+ M1 microglia group (group G+ M). The cells in group C were conventionally cultured, the cells in group M were cultured with the supernatant of M1 microglia for 24 h, and the cells in group E were cultured with M1 microglia-derived exosomes for 24 h. In G+ M group, exosome inhibitor GW4869 was added, M1 microglia were incubated for 24 h, then the supernatant was collected and added to N2a cells, and the cells were incubated for 24 h. Cell viability of N2a cells was measured by the cell counting kit 8 assay, cell apoptosis rate was determined by flow cytometry.The expression of apoptosis-related genes Bcl-2 and Bax mRNA was detected by quantitative real-time-polymerase chain reaction, and the expression of apoptosis-related genes Bcl-2 and Bax protein was detected by Western blot. Results:Compared with group C, the cell viability was significantly decreased, the apoptosis rate was increased, the expression of Bcl-2 protein and mRNA was down-regulated, and the expression of Bax protein and mRNA was up-regulated in the other three groups ( P<0.05). Compared with group M, the cell viability was significantly increased, the apoptosis rate was decreased, the expression of Bcl-2 protein and mRNA was up-regulated, and the expression of Bax protein and mRNA was down-regulated in group G+ M ( P<0.05). There was no significant difference in the above indexes between group E and group M ( P>0.05). Conclusions:M1 microglia can mediate neuronal injury via exosomes.

Objective:To evaluate the role of miR-205-3p in oncosis in astrocytes subjected to oxygen-glucose deprivation and restoration (OGD/R) and the relationship with aquaporin4 (AQP4).Methods:Primary astrocytes were cultured in vitro to the logarithmic growth phase and divided into 5 groups ( n=16 each) using a random number table method: control group (C group), OGD/R group (O group), OGD/R+ miR-205-3p mimic group (M group), OGD/R+ miR-205-3p inhibitor group (I group), and OGD/R+ negative control group (NC group). Cells were cultured routinely in C group.Cells were subjected to 4 h of oxygen-glucose deprivation in a 37℃ anaerobic incubator (containing 94% N 2, 1% O 2 and 5% CO 2) followed by restoration of O 2-glucose supply for 24 h in O group.Cells in M, I and NC groups were transfected with miR-205-3p mimic, miR-205-3p inhibitor and miR-205-3p negative control for 48 h, respectively, and then cells were subjected to 4 h of oxygen-glucose deprivation followed by restoration of O 2-glucose supply for 24 h. The cell viability was evaluated by CCK-8 assay, the cell injury and oncosis were analyzed by flow cytometry, the expression of AQP4 mRNA was detected by quantitative reverse transcription-polymerase chain reaction, and the expression of AQP4 and porimin was detected by Western blot. Results:Compared with C group, the expression of miR-205-3p was significantly down-regulated, the cell viability was decreased, the rates of cell injury and oncosis were increased, and the expression of AQP4 protein and mRNA and porimin was up-regulated in O group ( P<0.05). Compared with O group, the expression of miR-205-3p was significantly up-regulated, the cell viability was increased, the rates of cell injury and oncosis were decreased, and the expression of AQP4 protein and mRNA and porimin was down-regulated in M group, the expression of miR-205-3p was significantly down-regulated, the cell viability was decreased, the rates of cell injury and oncosis were increased, and the expression of AQP4 protein and mRNA and porimin was up-regulated in I group ( P<0.05), and no significant changes were found in NC group( P>0.05). Conclusions:miR-205-3p is involved in oncosis in astrocytes subjected to OGD/R, which is associated with regulation of AQP4 expression.

Objective:To evaluate the role of miR-20a-5p in M1 microglia aggravating oxygen-glucose deprivation and restoration (OGD/R)-induced injury to neurons and the relationship with mitofusin2 (MFN2).Methods:The well-growing BV2 microglia (M0 type) were polarized into M1 phenotype by lipopolysaccharide (100 ng/ml) and IFN-γ (20 ng/ml) and identified by quantitative real-time polymerase chain reaction and immunofluorescence.The well-growing N2a cells were divided into 6 groups ( n=6 each) by the random number table method: control group (group C), OGD/R group, M0 microglia co-culture group (group M0), M1 microglia co-culture group (group M1), miR-20a-5p inhibitor transfection group (group I) and negative control group (group NC). The cells were routinely cultured in group C, and the cells were subjected to OGD for 3 h followed by restoration of oxygen-glucose supply to develop the model of OGD/R injury in group OGD/R.The cells were subjected to OGD for 3 h and were co-cultured with M0 microglia for 24 h during restoration of oxygen-glucose supply in group M0.The cells were subjected to OGD for 3 h and were co-cultured with M1 microglia for 24 h during restoration of oxygen-glucose supply in group M1.In group I and group NC, cells were transfected with miR-20a-5p inhibitor and negative control miRNA into M1 microglia, respectively, and N2a cells were subjected to OGD for 3 h and co-cultured with M1 microglia for 24 h during restoration of oxygen-glucose supply.The cell viability was determined by cell counting kit-8 assay, amount of lactate dehydrogenase (LDH) released was determined, the expression of miR-20a-5p and MFN2 mRNA was detected by quantitative real-time polymerase chain reaction, and MFN2 expression was detected by Western blot. Results:Compared with group C, the cell viability was significantly decreased, the amount of LDH released was increased, and the expression of MFN2 protein and mRNA was down-regulated in the other five groups, miR-20a-5p expression was significantly up-regulated in OGD/R, M0 and M1 groups, and miR-20a-5p expression was significantly down-regulated in group I ( P<0.05). There were no significant differences in the cell viability, amount of LDH released, and expression of miR-20a-5p, MFN2 protein and mRNA between group OGD/R and group M0 ( P>0.05). Compared with group OGD/R and group M0, the cell viability was significantly decreased, the amount of LDH released was increased, and the expression of MFN2 protein and mRNA was down-regulated, and miR-20a-5p expression was up-regulated in group M1 ( P<0.05). Compared with group M1, the cell viability was significantly increased, the amount of LDH released was decreased, the expression of MFN2 protein and mRNA was up-regulated, and miR-20a-5p expression was down-regulated in group I ( P<0.05). Conclusions:The mechanism by which M1 microglia aggravates OGD/R-induced damage to N2a cells may be related to the up-regulation of miR-20a-5p expression in M1 microglia and the inhibition of MFN2 expression in N2a cells.

Objective:To evaluate the role of exosomes in M2 microglia-induced reduction of oxygen-glucose deprivation and restoration (OGD/R) injury to astrocytes.Methods:The primary astrocytes were cultured in vitro to the logarithmic growth phase and divided into 5 groups ( n=14 each) using a random number table method: control group (group C), OGD/R group (group O), OGD/R+ M2 microglia group (O+ M2 group), OGD/R+ M2 microglia+ GW4869 group (O+ M2+ G group) and OGD/R+ M2 microglia-derived exosome group (O+ M2-E group). Cells in group C were cultured routinely.Cells in group O were subjected to 4 h of oxygen-glucose deprivation (OGD) and 24 h of restoration of O 2-glucose supply.In group O+ M2, cells were subjected to 4 h of OGD, and the supernatant of M2 microglia 2 ml was added to the medium during restoration of O 2-glucose supply, and the cells were cultured for 24 h. In group O+ M2+ G, cells were subjected to 4 h of OGD, and the supernatant of M2 microglia 2 ml treated with the exosome inhibitor GW4869 10 μmol/L was added to the medium during restoration of O 2-glucose supply, and the cells were cultured for 24 h. In group O+ M2-E, cells were subjected to 4 h of OGD, and the M2 microglia-derived exosome 10 μg/ml was added to the medium during restoration of O 2-glucose supply, and the cells were cultured for 24 h. The morphological changes of cells were observed with a light microscope, the cell viability was detected by CCK-8 assay, the expression of aquaporin 4 (AQP4) mRNA was detected by quantitative real-time polymerase chain reaction, and the expression of AQP4 and porimin was detected by Western blot. Results:Compared with group C, the cell viability was significantly decreased, the expression of AQP4 protein and mRNA and porimin was up-regulated ( P<0.05), and cell swelling occurred in the other four groups.Compared with group O, the cell viability was significantly increased, and the expression of AQP4 protein and mRNA and porimin was down-regulated in O+ M2 and O+ M2-E groups ( P<0.05), and no significant change was found in the parameters mentioned above ( P>0.05), and the cell viability was significantly attenuated in group O+ M2+ G.Compared with group O+ M2, the cell viability was significantly decreased, and the expression of AQP4 protein and mRNA and porimin was up-regulated in group O+ M2+ G ( P<0.05), and no significant change was found in the parameters mentioned above ( P>0.05), and the degree of cell swelling was increased in group O+ M2-E. Conclusions:M2 microglia can mitigate OGD/R injury to astrocytes through exosomes.