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Objective:To study the crosstalk between the activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1 (IRE1) - X-box binding protein 1 (XBP1) pathway in oxygen-glucose deprivation/reoxygenation (OGD/R)-injured mouse hippocampal neuronal cell line HT22.Methods:The OGD/R-injured HT22 cell model was used to observe the changes of the indicators of endoplasmic reticulum stress (ERS), cell viability, and apoptosis at different OGD/R time points (0, 3, 6, 12, and 24 hours). HT22 cells in the logarithmic growth phase were randomized into blank control group, control+ATF6 activator (AA147) group, control+IRE1 inhibitor (4μ8c) group, OGD/R model group, OGD/R+AA147 group and OGD/R+4μ8c group (10 μmol/L AA147 or 16 μmol/L 4μ8c was given during the whole process in the AA147 group and 4μ8c group). Western blotting was used to detect the expression of ERS-related proteins [glucose-regulated protein 78 (GRP78), phosphorylated-inositol-requiring enzyme 1 (p-IRE1), and phosphorylated-eukaryotic translation initiation factor-2α (p-eIF2α)], and apoptosis-related proteins (Bcl-2, Bax, caspase-3, and cleaved caspase-3). The mRNA of ERS-related genes, and ATF6 [homocysteine-inducible, endoplasmic reticulum stress-inducible, ubiquitin-like domain member 1 (Herpud1), protein disulfide isomerase associated 4 (Pdia4) and Sel-1 suppressor of lin-12-like (Sel1L)] and spliced XBP1 [XBP1s, include DnaJ heat shock protein family member B9 (Erdj4), Sec24 related gene family, member D (Sec24d) and signal sequence receptor, gamma (Ssr3)] induced transcriptional response-related genes were measured by real-time quantitative polymerase chain reaction (RT-qPCR). A cell counting kit-8 (CCK-8) assay was used to detect the viability of HT22 cells. Immunofluorescence was utilized to test the expression of cleaved caspase-3.Results:Compared with the blank control group, the expression of ERS-related proteins p-IRE1 and p-eIF2α were significantly increased at 12 hours and 3 hours following OGD/R, respectively (p-IRE1/β-actin: 2.09±0.10 vs. 1.00±0.00, p-eIF2α/β-actin: 1.39±0.11 vs. 1.00±0.00, both P < 0.01). The mRNA expressions of ERS-related genes [ATF6, XBP1s, unspliced XBP1 (XBP1u), activating transcription factor 4 (ATF4), CCAAT/EBP homologous protein (CHOP)] were also upregulated in different OGD/R timepoint in HT22 cells, which indicated ERS was activated in OGD/R-stimulated HT22 cells. Compared with the OGD/R model group, the expression of protein p-IRE1 was not changed, but the mRNA of XBP1s and XBP1u were obviously downregulated in the OGD/R+AA147 group [XBP1s (2 -ΔΔCt): 0.76 (0.71, 0.92) vs. 1.13 (1.03, 1.29), XBP1u (2 -ΔΔCt): 0.29±0.05 vs. 0.52±0.04, both P < 0.01], whereas the expressions of XBP1s-induced transcriptional response downstream genes did not change significantly. Compared with the OGD/R model group, the protein of short-form ATF6 (sATF6) and GRP78 were not changed after administration of 4μ8c, neither was the mRNA expression of ATF6-induced transcriptional response-related genes. These results showed that the mRNA expression of XBP1s and XBP1u were inhibited by AA147-induced activation of ATF6, but no crosstalk was observed between the transcriptional response induced by ATF6 and XBP1s. Compared with the blank control group, the cell viability decreased significantly at OGD/R 3 hours [(44.64±5.12) % vs. (99.13±5.76) %, P < 0.01], the ratios of apoptosis-related proteins Bax/Bcl-2 and cleaved caspase-3/caspase-3 were significantly increased at OGD/R 3 hours and OGD 0 hour, respectively (Bax/Bcl-2: 6.15±1.65 vs. 1.00±0.00, cleaved caspase-3/caspase-3: 17.48±2.75 vs. 1.00±0.00, both P < 0.01), which indicated that apoptosis was activated in OGD/R-treated HT22 cells. Compared with the OGD/R model group, the cell viability decreased significantly [(36.52±17.78)% vs. (69.90±9.43)%, P < 0.01], and the ratios of Bax/Bcl-2 and cleaved caspase-3/caspase-3 were significantly upregulated in the OGD/R+AA147 group in HT22 cells (Bax/Bcl-2: 2.06±0.31 vs. 1.10±0.25, cleaved caspase-3/caspase-3: 3.35±0.59 vs. 0.55±0.09, both P < 0.01). Conclusion:Under our experimental conditions, no obvious crosstalk between the transcriptional response induced by ATF6 and XBP1s was observed, while ATF6 activation induced by AA147 suppressed mRNA expression of XBP1s and XBP1u and promoted cell death in OGD/R-treated HT22 cells.
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Objective:To compare the severity of brain injury between asphyxia and electrical stimulation induced cardiac arrest in rats.Methods:Forty-two healthy male Sprague-Dawley (SD) rats were randomized into sham group ( n = 6), asphyxia group ( n = 18) and electrical stimulation group ( n = 18). Rats in each group were given invasive mechanical ventilation and femoral blood vessels catheterization for monitoring blood pressure and fluid infusion. In the asphyxia group, the tracheal tube was clamped to induce cardiac arrest, and in the electrical stimulation group, the esophageal electrical stimulation was used to induce cardiac arrest, and cardiopulmonary resuscitation (CPR) was performed 4 minutes after cardiac arrest. In the sham group, only tracheal intubation and femoral artery intubation were performed after anesthesia, but cardiac arrest was not induced. Animals were allowed to survive until 72 hours after resuscitation, and survival analysis was performed using Kaplan-Meier curves. At 24 hours and 72 hours after resuscitation, the neurological deficit score (NDS) was measured. The vena cava blood was collected, and the brain injury associated serum biomarkers, neuron-specific enolase (NSE) and S100B, were detected by enzyme-linked immunosorbent assay (ELISA). The brain tissues were then harvested to perform hematoxylin-eosin (HE) staining for observing pathological changes in the hippocampal CA1 area with light microscopy. Results:Cardiac arrest was successfully induced in both the asphyxia group and the electrical stimulation group, 94.4% (17/18) and 88.9% (16/18) animals were resuscitated successfully in the two groups respectively. Kaplan-Meier curves analysis showed that 72-hour cumulative survival rate was similar in the asphyxia group and the electrical stimulation group (Log-Rank test: χ2 = 0.040, P = 0.841). Both asphyxia group and electrical stimulation group had higher NDS score than sham group at 24 hours after resuscitation (37.50±4.26, 32.17±4.02 vs. 8.33±2.33, both P < 0.01). NDS score showed a downwards trend at 72 hours after resuscitation in both model groups, and the decline was more significant in the electrical stimulation group, which was significantly different as compared with asphyxia group (14.00±2.89 vs. 26.33±4.84, P < 0.05). ELISA results showed that the levels of serum NSE at 24 hours after resuscitation in the asphyxia and electrical stimulation groups were significantly higher than those in the sham group (μg/L: 1.02±0.07, 1.02±0.02 vs. 0.87±0.02, both P < 0.05). NSE kept increasing at 72 hours after resuscitation in the asphyxia group, which showed significant difference as compared with sham group (μg/L: 1.03±0.05 vs. 0.87±0.02, P < 0.01). But it had almost recovered to the normal level in the electrical stimulation group without significant difference as compared with sham group (μg/L: 0.96±0.04 vs. 0.87±0.02, P > 0.05). There was no significant difference in S100B level at different time points after resuscitation among three groups. It was displayed under light microscope that there was no significant neuronal damage in the hippocampal CA1 area in the two model groups at 24 hours after resuscitation as compared with the sham group. At 72 hours, there were certain damages in the hippocampal CA1 area in both model groups, which were more obvious in the asphyxia group. Conclusions:Both cardiac arrest models induced by asphyxia and electrical stimulation show a certain degree of brain injuries after resuscitation. Brain injuries are more severe in asphyxia-induced cardiac arrest compared with trans-esophageal electrical stimulation method.
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Objective To compare the differences in cardiac functions and myocardial injury between asphyxia and trans-oesophageal pacing induced rat cardiac arrest models.Methods Healthy adult male Sprague-Dawley (SD) rats were randomly divided into sham group,asphyxia group and electrical stimulation group by random number table.The rats in the latter two groups were randomly divided into two subgroups (24 hours and 72 hours)according to the sampling time after successful resuscitation,with 6 rats in each group.All rats were mechanically ventilated for 20 minutes,in electrical stimulation group,cardiac arrest was induced by trans-oesophageal cardiac pacing for about 3 minutes (intensity 30 V,frequency 50 Hz,pulse duration 2 ms),and in asphyxia group,cardiac arrest was induced by clipping trachea for about 3 minutes.Cardiopulmonary resuscitation (CPR) was initiated 4 minutes after cardiac arrest.Echocardiographic examination was performed at 2 hours after return of spontaneous circulation (ROSC) with cardiac color ultrasound apparatus.Cardiac tissues were harvested at 24 hours and 72 hours after ROSC,hematoxylin-eosin (HE) staining was performed,and myocardial damage was observed under light microscope.The levels of cardiac troponin I (cTnI) and B-type natriuretic peptide (BNP) in serum were determined by enzyme-linked immunosorbent assay (ELISA).Results There was no significant difference in ROSC rate between the asphyxia group and electrical stimulation group [94.4％ (17/18) vs.88.9％ (16/18),P ＞ 0.05].The heart rate (HR),mean arterial pressure (MAP),left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) at 2 hours after ROSC in asphyxia group and electrical stimulation group were significantly lower than those in sham group [HR (bpm):401.50± 19.76,370.67± 18.63 vs.430.17± 18.38,MAP (mmHg,1 mmHg =0.133 kPa):107.17± 12.92,92.50±9.35 vs.125.67±5.72,LVEF:0.60±0.02,0.54±0.03 vs.0.63±0.01,LVFS:(48.40±2.52)％,(40.33±3.32)％ vs.(55.47 ± 2.38)％,all P ＜ 0.05],and the decrease in electrical stimulation group was more significant (all P ＜ 0.05).Compared with sham group,the levels of cTnI and BNP in serum of electrical stimulation group were significantly increased at 24 hours after ROSC [cTnI (ng/L):51.57±13.04 vs.38.23±5.57,BNP (ng/L):1 919.61±823.22 vs.977.47 ±445.18,both P ＜ 0.05],but there was no significant difference in cTnI or BNP of serum between asphyxia group and sham group [cTnI (ng/L):46.84 ± 11.04 vs.38.23 ± 5.57,BNP (ng/L):1 144.13±390.05 vs.977.47 ± 445.18,both P ＞ 0.05].There was no significant difference in cTnI or BNP of serum at 72 hours after ROSC among all the groups.The results of HE stain showed that the pathological injury of myocardium in electrical stimulation group was more serious than that in asphyxia group,characterized by more severe myocardial edema and partial myocardial cell lysis.Conclusion The cardiac function after cardiac arrest-CPR was decreased in both asphyxia group and electrical stimulation group,but electrical stimulation had a heavier cardiac function injury than asphyxia.
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With the popularization of cardiopulmonary resuscitation (CPR) technology, the success rate of restoration of spontaneous circulation (ROSC) is gradually improved, and the survival rate and neurological outcome of patients with cardiac arrest are improved. Currently, therapeutic methods for cerebral resuscitation after cardiac arrest are limited. In addition to mild hypothermia for clinical application, the majority of drugs remain in the animal experimental stage. Finding effective brain protection drugs has become a hot spot in the field of brain resuscitation research. This article will review the pharmaceutical progress of research for cerebral resuscitation after cardiac arrest, so that we can study the brain protection mechanism of these drugs better and more targeted.
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With the popularization of cardiopulmonary resuscitation (CPR) technology, the success rate of restoration of spontaneous circulation (ROSC) is gradually improved, and the survival rate and neurological outcome of patients with cardiac arrest are improved. Currently, therapeutic methods for cerebral resuscitation after cardiac arrest are limited. In addition to mild hypothermia for clinical application, the majority of drugs remain in the animal experimental stage. Finding effective brain protection drugs has become a hot spot in the field of brain resuscitation research. This article will review the pharmaceutical progress of research for cerebral resuscitation after cardiac arrest, so that we can study the brain protection mechanism of these drugs better and more targeted.