The regulation of retinoid X receptor-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury / 生理学报

The aim of this study was to investigate the regulatory role of retinoid X receptor (RXR)-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury (PIRI) and the underlying mechanism. Seventy-seven male Sprague-Dawley (SD) rats were randomly divided into 7 groups (n = 11): control group, sham group, sham+9-cis-retinoid acid (9-cRA, RXR agonist) group, sham+HX531 (RXR inhibitor) group, ischemia/reperfusion (I/R) group, I/R+9-cRA group, and I/R+HX531 group. The unilateral lung I/R model was established by obstruction of left lung hilus for 30 min and reperfusion for 180 min in vivo. The rats in I/R+9-cRA and I/R+HX531 groups were given intraperitoneal injection of 9-cRA and HX531 before thoracotomy. After reperfusion, the left lung tissue was taken to evaluate the lung tissue injury, and the oxidative stress-related indexes of the lung tissue were detected by the corresponding kits. The lung tissue morphology and the ultrastructure of the alveolar epithelial cells were observed by HE staining and transmission electron microscope, respectively. The protein expression of RXR in lung tissue was observed by immunofluorescence labeling method, and the expression level of nuclear factor E2-related factor (Nrf2) protein was detected by Western blot. The results showed that, compared with the sham group, the I/R group exhibited obviously injured lung tissue, decreased SOD activity, increased MDA content and MPO activity, and down-regulated expression level of Nrf2 protein. Compared with the I/R group, the I/R+9-cRA group showed alleviated lung tissue injury, increased activity of SOD, decreased MDA content and MPO activity, and up-regulated expression levels of RXR and Nrf2 protein. The above-mentioned improvement effects of 9-cRA were reversed by HX531 treatment. These results suggest that RXR activation can effectively protect the lung tissue against I/R injury, and the mechanism may involve the activation of Nrf2 signaling pathway, the enhancement of antioxidant level and the reduction of oxidative stress response.

Effects of excessive endoplasmic reticulum stress on lung ischemia/reperfusion induced myocardial injury in mice / 中国应用生理学杂志

OBJECTIVE@#To investigate the effects of excessive endoplasmic reticulum stress on lung ischemia/reperfusion (I/R) induced myocardial injury in mice.@*METHODS@#Forty healthy SPF male C57BL/6J mice were divided into 4 groups randomly (=10):sham operation group (Sham group), lung I/R group (I/R group), endoplasmic reticulum stress (ERS) pathway agonist Tunicamycin group (TM) and ERS inhibitor 4-phenyl butyric acid group (4-PBA). The model of lung I/R injury was established by clamping the left hilum of lung for 30 min followed by 180 min of reperfusion. In sham group, only sternotomy was performed, the hilum of lung was not clamped, and the mice were mechanically ventilated for 210 min. In TM and 4-PBA groups, TM 1mg/kg and 4-PBA 400 mg/kg were injected intraperitoneally, respectively, at 30 min before establishment of the model. At 180 min of reperfusion, blood samples were collected from the orbit for determination of myocardial enzyme. The animals were then sacrificed, and hearts were removed for determination of light microscope, TUNEL, Caspase 3 enzymatic activity, real-time polymerase chain reaction and Western blot.@*RESULTS@#Compared with sham group, the cardiomyocytes had obvious damage under light microscope, and the serum creatine kinase-MB (CK-MB) and lactic dehydrogenase (LDH) activities, apoptosis index and Caspase 3 enzymatic activity were increased significantly, the expressions of p-Jun N-terminalkinase(p-JNK), Caspase 12, CCAAT/enhancer-binding protein homologous protein (CHOP) and glucose regulated protein 78(GRP78) protein and mRNA were up-regulated in I/R, TM and 4-PBA groups (<0.01). Compared with I/R group, the cardiomyocytes damage was obvious under light microscope, and the serum CK-MB and LDH activities, apoptosis index and Caspase 3 enzymatic activity were increased significantly, the expressions of p-JNK, Caspase 12, CHOP and GRP78 protein and mRNA were up-regulated in group TM; while all above changes were relieved in group 4-PBA (<0.01). Compared with TM group, the cardiomyocytes damage was relieved under light microscope, and the serum CK-MB and LDH activities, apoptosis index and Caspase 3 enzymatic activity were decreased significantly, the expressions of p-JNK, Caspase 12,CHOP and GRP78 protein and mRNA were down-regulated in group 4-PBA.@*CONCLUSIONS@#The excessive endoplasmic reticulum stress participates in myocardial injury induced by lung ischemia/reperfusion (I/R) and inhibit excessive endoplasmic reticulum stress response can relieved myocardial injury.

Effect of dexmedetomidine on apoptosis and CHOP in hypoxia/reoxygenation injury A549 cell / 中国应用生理学杂志

OBJECTIVES@#To investigate the effects of dexmedetomidine (Dex) on injury of A549 cells induced by hypoxia/reoxygenation(H/R)and the influence of C/EBP homologous protein (CHOP) expression.@*METHODS@#Logarithmic growth phase A549 cells(it originated from alveolar type Ⅱ epithelial cell line) were randomly divided into 4 groups (=10):normoxic control group (N), Dex group (D), hypoxia/reoxygenation group (H), hypoxia/reoxygenation + Dex group(HD). At the beginning of modeling, 1 nmol/L Dex was puted into D and HD groups. N and D groups were cultured in the normoxic incubator for 30 h. H and HD group were incubated in the anoxic cultivation for 6 h, fo llowed by normoxic culture for 24 h. Then A549 cells were observed under the inverted microscope to observe the morphological changes. Cell activity was detected by cell counting Kit-8(CCK-8) and the apoptosis index(AI) was detected by in situ end labeling (TUNEL) method. The expression of CHOP、glucose-regulated protein of molecular weight 78 kDa (Grp78)、cysteinyl aspirate-specificprotease-3 (caspase-3) protein and CHOP、Grp78 mRNA were detected by Western blot and RT-PCR.@*RESULTS@#Compared with N group, the number of adherent cells in H group decreased significantly, and cell morphology changed. The absorbance value in H group decreased obviously (<0. 01). The AI value and expression of CHOP, Grp78, caspase-3 proteins and CHOP, Grp78 mRNA were significantly increased (<0.01). Compared with H group, the cell damage in HD group was decreased, the absorbance value increased (<0.01), the number of apoptosis cells decreased relatively (<0.01), the expression of CHOP, caspase-3 protein and CHOP mRNA decreased (<0. 01).@*CONCLUSIONS@#Dex has notable effects against H/R injury, which may be related to effective inhibition of apoptosis mediated by the CHOP's signal path.

Excessive endoplasmic reticulum stress mediates brain damage in hypoxia hypercapnia induced pulmonary hypertension rats / 生理学报

The purpose of the present study was to investigate the effect of excessive endoplasmic reticulum stress (ERS) on the brain damage in hypoxia hypercapnia induced pulmonary hypertension (HHPH) rats. Forty healthy SPF male SD rats were randomly divided into four groups (n = 10 for each): control group, hypoxia hypercapnia group, ERS pathway agonist tunicamycin (TM) group and ERS pathway inhibitor 4-phenylbutyric acid (4-PBA) group. The rats of control group lived in normal environment, while the rats of other three groups were raised for four weeks in the tank with 8.5%-11% Oand 5%-6% CO. TM (0.08 mg/kg, twice a week) and 4-PBA (80 mg/kg, daily) were respectively intraperitoneally injected into the rats of TM and 4-PBA groups, and the hypoxia hypercapnia group was given the same volume of normal saline. The mean pulmonary artery pressure and heart perfusion of the rats were determined and recorded after four-week raising. Then the brain tissue of the rats were quickly taken out for the brain water content measuring and morphological changes observing. The Caspase-3 activity and the apoptotic index of the brain cells were also determined. The protein and mRNA expressions of p-JNK, Caspase-12, CHOP and GRP78 in brain tissues were detected by Western blot and RT-PCR. The results showed that compared with the control group, the mean pulmonary artery pressure, brain water content and brain cells apoptotic index, Caspase-3 activity, the protein and mRNA levels of p-JNK, Caspase-12, CHOP and GRP78 were increased (P < 0.05), and the brain tissues of the rats were obviously damaged in the rats raised in the hypoxia hypercapnia environment; compared with hypoxia hypercapnia group, the mean pulmonary artery pressure, brain water content, brain apoptotic index and Caspase-3 activity, p-JNK, Caspase-12, CHOP, GRP78 protein and mRNA expressions in TM group were increased (P < 0.05), and the brain tissues of the rats were obviously damaged, while all above changes were relieved in 4-PBA group (P < 0.05). These results suggest that excessive ERS may participate in the brain injury induced by HHPH in rats and inhibition of excessive ERS can relieve the brain injury in the rats with HHPH.

Effects of dexmedetomidine on hypoxia/reoxygenation injury-induced cell apoptosis and caspase-12 expression in A549 cells / 生理学报

To investigate the effects of dexmedetomidine (DEX) on hypoxia/reoxygenation (H/R) injury-induced cell apoptosis and caspase-12 expression, A549 cells were randomly divided into 4 groups: control group, DEX group, H/R group and DEX+H/R group. Cells of control and DEX groups were cultured in the normoxic incubator for 30 h. Cells of H/R and DEX+ H/R groups were incubated in the anoxic cultivation for 6 h, followed by normoxic culture for 24 h, and DEX (1 nmol/L) was added into the culture medium in DEX and DEX+H/R groups. Morphological changes were observed under the inverted microscope. Cell viability was detected by CCK-8. The apoptosis index (AI) of A549 cells was detected by TUNEL method. The activity of caspase-3 enzyme in cells was detected by using caspase-3 kit. The expressions of GRP78, caspase-12 protein and mRNA were determined by Western blot and RT-PCR respectively. Compared with control group, the morphological changes of the cultured cells were observed: some of the cell fusion occurred and the shape of the cells was multilateral; the cell viability was decreased significantly (P < 0.01), the number of apoptotic cells and the AI value, caspase-3 activity, and the expressions of GRP78, caspase-12 protein/mRNA were significantly increased (P < 0.01) in H/R group. While the administration of DEX alleviated the H/R injury-induced cell damage, obviously increased the cell viability (P < 0.01), significantly decreased the increment of apoptotic cells and the AI value induced by H/R injury (P < 0.01), and also dramatically decreased the H/R injury-induced high level of caspase-3 activity (P < 0.01) as well as high expression of caspase-12 protein and mRNA (P < 0.01). Taken together, the results suggest that DEX can effectively protect A549 cells from the H/R injury, which may be mediated by down-regulating the expression of caspase-12 and inhibiting cell apoptosis.