Effect of hypoxia-inducible factor-1α knockdown by siRNA on viability and CEACAM1 expression in oral squamous cell carcinoma

AIM: To investigate the relationship between hypoxia-inducible factor-1α (HIF-1α) and viability and apoptosis of oral squamous cell carcinoma and its mechanism. METHODS: The expression of HIF-1α and carcinoembryonic antigen-related cell adhesion molecular 1 (CEACAM1) at mRNA and protein levels in oral squamous cell carcinoma cell lines Tca8113 and CAL27 and normal epithelial cell line NOK was determined by RT-PCR and Western blot. The expression of HIF-1α in CAL27 cells was silenced by RNA interference (RNAi) technique. The cells were divided into blank control group, non-sense control group and siRNA-HIF-1α group. The viability of CAL27 cells was measured by MTT assay and the apoptotic rate was analyzed by flow cytometry. The protein levels of HIF-1α, P21, vascular endothelial growth factor (VEGF), Bcl-2 and Bax were examined by Western blot. RESULTS: The expression of HIF-1α and CEACAM1 in oral squamous cell carcinoma cells was significantly higher than that in normal cells (P<0.05), and the expression of HIF-1α and CEACAM1 was positively correlated. The protein expression of HIF-1α in siRNA-HIF-1α group was significantly lower than that in blank control group (P<0.05). Knockdown of HIF-1α significantly inhibited CAL27 cell viability (P<0.05), promoted apoptosis (P<0.05), increased the protein levels of P21 and Bax (P<0.05), and significantly decreased the levels of VEGF and Bcl-2 (P<0.05). CONCLUSION: HIF-1α is over-expressed in oral squamous cell carcinoma. Knockdown of HIF-1α significantly inhibits cell viability and promotes apoptosis possibly through regulating the expression of HIF-1α downstream target genes and tumor angiogenesis.     

H IF-1αm ediates effect of interm ittent hypoxia on biological behavior of A 549 cells in vitro

ATM: To investigate whether hypoxia-inducible factor 1α (HIF-1α) mediates the effect of intermittent hypoxia on A549 cell viability, apoptosis and invasive ability METHODS: A549 cells were transfected with HIF-1α-siRNA and cultured under intermittent hypoxia. The expression of HIF-1α and its downstream genes, such as Bcl-2, Bax, P53, P21 and VEGF at mRNA and protein levels was determined by real-time PCR and Western blot. The viability of the A549 cells was measured by MTT assay. The apoptosis and cell cycle distribution of the A549 cells were examined by flow cytometry. The invasive ability of the A549 cells was detected by transwell test. RESULTS: The expression levels of HIF-1α, Bcl-2 and VEGF in non-HIF-1α-siRNA transfected A549 cells cultured in intermittent hypoxia environment[blank controlgroup(IH C),empty vector control group (IH E) and negative control group (IH N)] were higher than those in the A549 cells in normoxia group (RA), but the expression levels of Bax and P21 were lower than those in RA group (P<0.05). The siRNA-mediated HIF-1α gene silencing[intermittent hypoxia silenced group (IHS)] resulted in obvious down-regulation of HIF-1α, Bcl-2 and VEGF, and significant increase in the protein expression of P21 and Bax(P<0.05). The expression level of P53 in intermittent hypoxia groups was significantly higher than that in RA group, and no significant difference of P53 expression in different intermittent hypoxia groups was observed. Compared with normoxia, intermittent hypoxia resulted in significantly enhanced cell viability, decreased apoptosis, and enhanced invasive ability of non-HIF-1α-siRNA transfected A549 cells (P<0.05). The siRNA-mediated HIF-1α gene silencing resulted in significant cell viability inhibition, elevated apoptotic rate and decreased invasive ability under hypoxic condition (P<0.05).CONCLUSION: Intermittent hypoxia promotes the viability and invasion of A549 cells by HIF-1α-mediated downstream gene expression. HIF-1α gene silencing inhibits A549 cell growth and invasion under intermittent hypoxia by inhibition of HIF-1α signal pathways in vitro.     

Fluorocitrate inhibits regulatory effect of ischemic postconditioning on HIF-1α/iNOS signaling pathway after cerebral ischemia in tree shrews with brain injury

AIM: To investigate the regulatory effect of HIF-1α/iNOS signaling pathway on the neuroprotection of ischemic postconditioning (PC) in tree shrews, and to explore the mechanisms of deteriorated cerebral injury after inhibiting astrocyte (AS) metabolism. METHODS: Thrombotic cerebral ischemia was induced by photochemical reaction in tree shrews. Fluorocitrate (FC) was used to inhibit AS metabolism and the ischemic PC was established at 4 h after ischemia followed by clipped ipsilateral common carotid artery on the ischemia side for 3 times, 5 min/time. A total of 67 male tree shrews were randomly divided into 7 groups:control (n=9), ischemia (4 h and 24 h, n=9 for each group), ischemia with PC (4 h and 24 h, n=9 for each group), and FC pretreatment (4 h and 24 h, n=11 for each group). The cerebral infarction size was detected by TTC staining, and the histological changes of hippocampal neurons were observed under light microscope. The regional cerebral blood flow (rCBF) in ischemic cortex was monitored by laser Doppler brain flowmetry. The protein expression of iNOS in hippocampus was detected both by immunohistochemistry and Western blot. The production of NO detected by spectrophotometer. The level of HIF-1α in hippocampus analyzed by ELISA. RESULTS: The cerebral infarct volume was increased with prolonged duration of ischemia, and the changes of ischemia at 24 h were significant (P<0.05). The cortical rCBF was progressively decreased, and it was decreased at 4 h and 24 h after ischemia (P<0.05). The expression of HIF-1α and iNOS in hippocampus was enhanced, and the production of NO was increased significantly (P<0.05). Ischemic PC restored the cortical rCBF (P<0.05), reduced cerebral infarction volume (P<0.05), down-regulated iNOS expression and reduced NO production in the hippocampus (P<0.05). However, the cortical rCBF in FC pretreatment group was significantly lower than that in ischemic group (P<0.05), the neuronal damage was aggravated, and the infarction volume was increased after pretreatment with FC (P<0.05). CONCLUSION: Ischemic PC may reduce cerebral injury by regulating the expression of HIF-1α and iNOS. Inhibition of AS function may attenuate the protective effect mediated by ischemic PC and aggravate brain injury.     

Effects of fucoidan on angiogenesis of human multiple myeloma RPMI 8226 cells

AIM: To investigate the effects of fucoidan on the angiogenesis of multiple myeloma cells in vitro, and its related mechanisms. METHODS: The human multiple myeloma RPMI 8226 cells and human endothelial cells were cultured in vitro. The growth inhibition rate of RPMI 8226 cells was examined by MTT assay. The cell cycle and apoptosis rate were measured by flow cytometry. RPMI 8226 cells were treated with fucoidan for 72 h, and the cell culture supernatant was collected. The VEGF concentration was examined by ELISA, and the tube formation assay was applied to assess the angiogenic activity. After treatment with fucoidan for 72 h at different concentrations, the protein levels of HIF-1α, VEGF, p-AKT and p-ERK1/2 were detected by Western blot. RESULTS: Fucoidan inhibited the growth of RPMI 8226 cells in a dose- and time-dependent manner. After treatment with fucoidan for 72 h, the cell cycle was arrested at G₁ phase, and the apoptotic rate of RPMI 8226 cells was increased with the increasing concentration of fucoidan, which was much higher than that in control group (P<0.05). The VEGF concentration was significantly decreased with the increa-sing concentration of fucoidan. The numbers and areas of the capillary-like structures decreased while the concentration of fucoidan increased, and those at 100 mg/L were less than those in the control (P<0.05). The protein levels of HIF-1α, VEGF, p-AKT and p-ERK1/2 in fucoidan group were significantly lower than those in control group (P<0.05). CONCLUSION: Fucoidan inhibits the secretion of VEGF in multiple myeloma cells, and reduces angiogenesis induced by multiple myeloma cells. It inhibits the protein expression of HIF-1α and VEGF, which may be related to inhibiting the phosphorylation of AKT and ERK1/2.     

Tetramethylpyrazine combined with bone marrow mesenchymal stem cell transplantation inhibits neuronal apoptosis in rats with cerebral ischemia

ATM: To investigate the effects of tetramethylpyrazine (TMP) combined with bone marrow mesenchymal stem cells (BMSCs) on neuronal apoptosis, and Bcl-2 and Bax expression in rats with cerebral ischemia. METHODS: The BMSCs were isolated by the whole bone marrow adherent method and cultured, and those in the 3rd passage were used for tail-vein transplantation. The rats were subjected to right middle cerebral artery occlusion (MCAO) using suture method, and the rats except sham group were randomly divided into model group, BMSCs (1×10⁹ cells/L) group, TMP (40 mg/kg) group and combination (TMP+BMSCs) group with 12 rats in each group. Neurological function was evaluated by modified neurological severity scoring (mNSS) on 1 d, 7 d and 14 d after cerebral ischemia. Toluidine blue staining was performed to detect cerebral infarct volume, HE staining was used to observe brain histopathological change, neuronal apoptosis was observed by TUNEL staining, and the mRNA and protein expression of Bcl-2 and Bax was detected by real-time fluorescence quantitative PCR and Western blot at 14 d after cerebral ischemia. RESULTS: Compared with BMSCs group and TMP group, TMP combined with BMSCs significantly reduced the score of mNSS (P<0.01) and the infarct volume (P<0.01), alleviated the pathological damage in the peripheral area of cerebral ischemia, decreased the number of TUNEL positive cells (P<0.01), increased the expression of Bcl-2 and decreased the expression of Bax at mRNA and protein levels (P<0.01).CONCLUSION: Tetramethylpyrazine combined with transplantation of BMSCs improves the functional recovery, reduces the infarct volume, relieves the ischemic injury of the brain tissue, and attenuates neuronal apoptosis in the rats with cerebral ischemia. The mechanism may be related to regulating the expression of Bcl-2 and Bax.     

Angiogenic effect of HIF-1α on extranodal nasal-type NK/T-cell lymphoma

AIM: To study the angiogenic effect of hypoxia inducible factor 1α(HIF-1α) and its significance on human extranodal nasal-type NK/T-cell lymphoma. METHODS: The protein levels of HIF-1α, vascular endothelial growth factor(VEGF) and VEGF receptor 2(VEGFR2) in human extranodal nasal-type NK/T-cell lymphoma were detected by immunohistochemistry. Microvessel density (MVD) of the tumor tissues was determined by labeling of microvessel endothelium with CD34 antibody. The correlation between the expression of HIF-1α, VEGF and VEGFR2 and MVD was analyzed with SPSS 13.0 statistical software. RESULTS: The positive expression of HIF-1α was observed in 39 cases (39/50, 78%) and the positive expression of VEGFR2 was 27 cases (27/50, 54%) of human extranodal nasal-type NK/T-cell lymphoma. A statistical difference of HIF-1α and VEGFR2 expression between tumor tissues and normal lymphocytes in lymph node was observed (P<0.05). In the tumor tissues, the co-expression of VEGF or VEGFR2 with HIF-1α was 72% and 64%, respectively, significantly higher than that without HIF-1α co-expression (P<0.05). The expression of HIF-1α, VEGFR and VEGFR2 was positively correlated with MVD of the tumor tissues (P<0.01). HIF-1α was expressed in all 15 cases of extranodal nasal-type NK/T-cell lymphoma with angiocentric infiltration.CONCLUSION: HIF-1α may promote angiogenesis of extranodal nasal-type NK/T-cell lymphoma through VEGF/VEGFR2 signaling pathway.     

Effects of stachydrine hydrochloride on experimental acute cerebral infarction in rats

AIM: To observe the therapeutic effect of stachydrine hydrochloride on experimental acute cerebral infarction in rats and to explore the underlying mechanisms. METHODS: SD rats (n=75) were randomly divided into 5 groups: sham group, cerebral infarction model group, and stachydrine hydrochloride (10 mg/kg, 20 mg/kg and 40 mg/kg) treatment groups. After the establishment of cerebral infarction model, the rats were given stachydrine hydrochloride at dose of 10 mg/kg, 20 mg/kg or 40 mg/kg by gavage daily for 14 d. The impairment of neurological function in each group was scored. The cerebral infarction volume and brain water content were measured. Moreover, the protein levels of β-catenin, cyclin D1, glycogen synthase kinase 3β (GSK-3β) and p-GSK-3β in the brain tissues were detected by Western blot. RESULTS: Compared with cerebral infarction group, the score of neurological function impairment, cerebral infarction volume and brain water content were significantly decreased in stachydrine hydrochloride treatment groups. In addition, the protein levels of β-catenin, cyclin D1 and p-GSK-3β were markedly increased after stachydrine hydrochloride treatment. CONCLUSION: Stachydrine hydrochloride protects against experimental acute cerebral infarction through activation of Wnt/β-catenin signaling pathway.     

Effect of SAPK/JNK signal pathway on neuronal apoptosis in cerebral infarction rats

AIM: To investigate the molecular mechanism of neuronal apoptosis by observing the changes of key proteins in SAPK/JNK and Bcl-2/Bax signal pathways after brain infarction. METHODS: The cortical infarction was induced by photochemistry, namely photothrombotic cortical injury (PCI). Thirty-six Sprague-Dawley rats were randomly divided into 2 groups: PCI group and sham-operated group. The ipsilesional cortex was harvested for histomorphometry and transmission electron microscopy 7 days after PCI. Some key proteins including p-JNK1, p-JNK2, p-c-Jun, p-ATF-2, total JNK1, total JNK2, Bcl-2 and Bax were detected by Western blotting analysis.RESULTS: The cortical infarction in rats was successfully induced by photochemistry. The apoptosis of neurons in cortex was more obvious in PCI group than that in sham-operated group 7 days after PCI. The levels of p-JNK1, p-JNK2, p-c-Jun and p-ATF-2 in PCI group were significantly higher than those in sham-operated group, whereas the ratio of Bcl-2/Bax was significantly lower(P<0.05). CONCLUSION: Apoptosis is a major contributor to neuronal loss induced by cerebral hypoxia-ischemia for a long period after cortical infarction. The process is related to some apoptotic proteins such as Bcl-2/Bax and the SAPK/JNK signal pathways activated by ischemic injury.     

Effect of AG490 on expression of VEGF and HIF-1α in HEL cells

AIM: To investigate the effect of AG490 on the expression of VEGF and HIF-1α, and the capacity of invasion in human erythroleukemia (HEL) cells. METHODS: The HEL cells were treated with AG490 at different concentrations. The cell viability was detected by CCK-8 assay. The apoptosis was detected by Hoechst staining. The apoptosis and the cell cycle were analyzed by flow cytometry. The capacity of migration was evaluated by Transwell assay. The mRNA expression level of JAK2 was measured by RT-PCR. The protein levels of p-JAK2, VEGF and HIF-1α were determined by Western blot. RESULTS: The HEL cell viabilities were 88%, 75%, 48%, 10% and 0.12% after treated with AG490 at 20, 40, 60, 80 and 100 μmol/L for 48 h, respectively. The results of Hoechst staining showed that brilliant blue cells in 80 μmol/L AG490 group was significantly increased compared with control group for 48 h. The apoptosis rate of 80 μmol/L AG490 group was significantly increased compared with control group at 48 h after AG490 treatment. The number of membrane-permeating HEL cells in 20 μmol/L AG490 group at 24 h after AG490 treatment was significantly lower than that in control group (P<0.05). The mRNA level of JAK2 decreased in a concentration-dependent manner after the HEL cells were treated with different concentrations of AG490 for 48 h. The protein levels of p-JAK2, VEGF and HIF-1α were lower in AG490 treatment groups than those in control group (P<0.05). CONCLUSION: AG490 inhibits the expression of VEGF and HIF-1α in HEL cells by inhibiting JAK2 pathway.     

Effects of HIF-1α silencing on proliferation of rat hepatoma cells

AIM：To study the effect of hypoxia-inducible factor 1α (HIF-1α) silencing on the proliferation of hepatoma cells under hypoxia. METHODS：Rat hepatoma cell line CBRH-7919 was used in this study. Hypoxia model was established by treating the cells with cobalt chloride (CoCl2). The expression of HIF-1α was silenced by small interfe-rence RNA. Real-time RT-PCR and Western blotting were used to detect the mRNA and/or protein expression of HIF-1α, vascular endothelial growth factor (VEGF), p21 and cyclin D1 in CBRH-7919 cells under hypoxia. The proliferation of CBRH-7919 cells was measured by the technique of 5-bromo-2’-deoxyuridine (BrdU) incorporation. RESULTS：The expression of HIF-1α and VEGF at mRNA and protein levels was significantly increased under hypoxia (P<0.05). Silencing of HIF-1α significantly inhibited the expression of HIF-1α, VEGF and cyclin D1 at mRNA and/or protein levels, while increased the protein expression of p21 (P<0.05). The BrdU-positive cells in HIF-1α siRNA transfection group were significantly less than those in control group. CONCLUSION：HIF-1α silencing significantly inhibits the proliferation of hepatoma cells under hypoxia.     

Effects of tanshinone IIA on proliferation,apoptosis and expression of HIF-1α, VEGF and wild-type P53 in human hepatoma HepG2 cells under hypoxia

AIM:To investigate the effects of tanshinone IIA (Tan IIA) on proliferation, apoptosis and its molecular mechanism in human hepatoma HepG2 cells under hypoxic condition. METHODS:Hypoxia model was established by treatment with cobalt chloride (CoCl2). The cells were divided into normoxia control group, hypoxia control group and hypoxia combined at different concentrations of Tan IIA groups. After HepG2 cells were incubated with different concentrations of Tan IIA (0.5, 1.0, 2.0, 5.0 and 10.0 mg/L) for 24 h, 48 h and 72 h under hypoxic condition, the cell proliferation was determined by MTT assay. After Tan IIA was added to the media at different concentrations for 24 h and 48 h, the apoptotic cells were observed by Hoechst 33258 staining. The protein levels of hypoxia-inducible factor 1 alpha (HIF-1α), vascular endothelial growth factor (VEGF) and wild-type P53 were detected by Western blotting after cultured with different concentrations of Tan IIA for 48 h. RESULTS:Tan IIA inhibited the proliferation of HepG2 cells in a dose- and time-dependent manner. Tan IIA induced the typical morphology of apoptotic cells and increased the apoptotic rate in a dose- and time-dependent manner after treatment with 1.0 mg/L~5.0 mg/L for 24 h and 48 h under hypoxic condition. The protein levels of HIF-1α and VEGF were weakly expressed in HepG2 cells under normoxia but up-regulated after incubated under hypoxia for 48 h. The protein expression of HIF-1α and VEGF were decreased with the increase in the concentration of Tan IIA under hypoxia. The protein expression of wild-type P53 was increased with the increase in the concentrations of Tan IIA under hypoxia. CONCLUSION: Tan IIA significantly inhibits the proliferation and induces the apoptosis of human hepatoma HepG2 cells under hypoxia, which may be related to the down-regulation of HIF-1α and VEGF and up-regulation of wild-type P53.     

Effect of Scutellaria barbata flavonoids on abnormal changes of Bcl-2, Bax,Bcl-xL and Bak protein expression in mitochondrial membrane induced by composite Aβ25-35

AIM：To study the abnormalities of Bcl-2, Bax, Bcl-xL and Bax in the cell mitochondrial membrane of cerebral cortex in the rats injected with β-amyloid beta protein 25-35 (Aβ25-35) in combination with aluminum trichloride (AlCl3) and recombinant human transforming growth factor β1 (rhTGF-β1) (composite Aβ25-35) into lateral cerebral ventricle, and to explore the intervention of Scutellaria Barbata flavonoids (SBF). METHODS：The male SD rats were used to establish the neuronal damaged model by receiving injection of RhTGF-β1 1 μL (10 ng) on day 1 of operation, and then from day 2 of operation, intracerebroventricular injection of Aβ25-35 (4 μg/d, consecutive 14 d) in the morning and 1% AlCl3 in the afternoon (3 μL/d, consecutive 5 d). On the day 49 of operation, the successful model rats were randomly divided into model control and 3 doses of SBF groupss. The rats in SBF groups were daily orally administered with SBF at doses of 35, 70 and 140 mg/kg for 36 d. All the rats were decapitated 60 min after the last administration. The protein expression of Bcl-2, Bax, Bcl-xL and Bak in rat cerebral cortex cell mitochondrial membrane was detected by Western blotting. RESULTS：The composite Aβ25-35 dramatically caused decreases in Bcl-2 and Bcl-xL (P<0.05), and increases in Bax and Bak (P<0.01) in rat cerebral cortex cell mitochondrial membrane. However, oral treatment with SBF for 36 d reversed the above disorders induced by composite Aβ25-35. CONCLUSION：The composite Aβ25-35 induces the expression abnormalities of Bcl-2, Bax, Bcl-xL and Bak in mitochondrial membrane and SBF reverses the above disturbances of apoptotic factors.     

Lactulose preconditioning protects against intestinal ischemia-reperfusion injury in rats

AIM: To investigate the protective effect of lactulose preconditioning on intestinal ischemia-reperfusion (IR) injury in rats. METHODS: Thirty Sprague-Dawley rats were randomly divided into 3 groups: sham operation group, IR group and IR plus lactulose preconditioning group. Lactulose was intragastrically administered in lactulose group 7 days prior to operation, and the equal volume of saline was administered in the other 2 groups. The intestinal IR injury was induced in IR group and IR+lactulose group using bulldog clamps on superior mesenteric artery by 30 min of ischemia followed by 60 min of reperfusion. Following reperfusion, the serum samples were collected for estimating the levels of interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and IL-1β. Segments of terminal jejunum were rapidly fixed in 4% paraformaldehyde, and HE staining was applied to assess the histopathology. Apoptosis in intestinal epithelium was determined by the technique of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The samples of terminal jejunum were also taken for measuring malondialdehyde,superoxide dismutase and the expression of cleaved caspase-3. RESULTS: Lactulose preconditioning significantly attenuated the severity of intestinal IR injury, with inhibition of IR-induced apoptosis. Moreover, lactulose preconditioning significantly limited the release of cytokines and lipid oxidation. CONCLUSION: Lactulose preconditioning has a protective effect on intestinal ischemia reperfusion by inhibiting IR-induced apoptosis and oxidative stress.     

Hypoxia-inducible factor-1α attenuates myocardial inflammatory injury induced by ischemia and reperfusion in rats

AIM:To investigate the role of hypoxia-inducible factor-1α (HIF-1α) stable expression in myocardial inflammatory injury induced by ischemia and reperfusion (I/R) in rats. METHODS:Male Wistar rats were randomly divided into 4 groups:sham operation (sham) group, I/R group, HIF-1α stabilizer dimethyloxalyl glycine (DMOG)+I/R group and HIF-1α inhibitor YC-1+I/R group. The protein expression of myocardial Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) was determined by Western blot. The mRNA levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, TLR4 and NF-κB were detected by real-time PCR. The myeloperoxidase (MPO) activity in the myocardial tissues was measured. HE staining was used to observe the infiltration of inflammatory cells. RESULTS:HIF-1α decreased the infiltration of inflammatory cells, the MPO activity, and the mRNA levels of inflammatory factors IL-1β, IL-6 and TNF-α in the myocardial tissues. HIF-1α also reduced the expression of TLR4 and NF-κB at mRNA and protein levels (P<0.05). CONCLUSION:The stable expression of HIF-1α has an anti-inflammatory effect on the myocardial tissues after I/R injury in rats. The mechanism may be related to the inhibition of TLR4/NF-κB signaling pathway.     

Effect of bFGF on promoting angiogenesis in infarct area and improving myocardial fibrosis in mouse myocardial infarction model

AIM: To investigate the protective effect of basic fibroblast growth factor (bFGF) on the heart of mice with myocardial infarction and its mechanism. METHODS: The model of myocardial infarction was established by the ligation of left anterior descending artery of C57/B6 mice (8~12 weeks old) after lateral thoracotomy. The mice were divided into sham operation group, myocardial infarction group and bFGF administration group. bFGF at 0.5 μg was intraperitoneally injected on alternate days after myocardial infarction for 7 d. Cardiac Doppler ultrasonography was used to detect cardiac function after myocardial infarction for 28 d, and left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left ventricular ejection fraction and left ventricular shortening fraction (LVFS) were used to evaluate cardiac function. After myocardial infarction for 28 d, the mice were sacrificed and the hearts were collected for preparing pathological sections. The degrees of myocardial fibrosis and angiogenesis in the myocardial infarction area were observed. Western blot was used to detect the indicators of angiogenesis. RESULTS: The results of Masson staining showed that bFGF administration significantly reduced myocardial fibrosis at 28 d after myocardial infarction. Cardiac ultrasound data showed that cardiac functions in myocardial infarction group were poorer than those in sham group, and bFGF administration significantly improved cardiac functions. Immunofluorescence staining showed that neovascularization in myocardial infarction area of bFGF administration group was more than that in myocardial infarction group. The results of Western blot showed that bFGF activated AKT/HIF-1α/VEGF signaling pathway. CONCLUSION: Intraperitoneal injection of bFGF reduces myocardial fibrosis and improves cardiac function in myocardial infarction mice. bFGF may promote angiogenesis by activating AKT/HIF-1α/VEGF signaling pathway.     

Effect of psychological stress on development of periodontitis and expression of periodontal hypoxia-inducible factor 1α in rats

AIM: To investigate the effect of psychological stress on the development of periodontitis and the expression of periodontal hypoxia-inducible factor 1α(HIF-1α) in rats.METHODS: Forty-eight male Wistar rats(SPF grade) were randomly divided into 4 groups:(1) normal control group, i.e. naive rats;(2) experimental periodontitis group: the periodontitis model was induced by wrapping 3-0 silk ligature inoculated with putative periodontopathic bacteria around the left maxillary second molar of the rats;(3) stress group: the rats were treated with stress alone;(4) periodontits with stress group, the periodontitis model was induced as above,and the rats were treated with stress. The rats were sacrificed at week 1, 4, 6 and 8 after the ligature. The attachment losses(AL) were measured by home-made probe. The histological changes of periodontal tissues stained with hematoxylin and eosin(HE) were observed under microscope. The HIF-1α expression level in the periodontal epithelium was determined by immunohistochemistry that was used to evaluate the severity of hypoxia by measuring the average rate of HIF-1α-positive cells.RESULTS: No significant difference of AL between stress group and normal control group was observed(P>0.05).The AL and the average rate of HIF-1α-positive cells in periodontitis with stress group were significantly higher than those in experimental periodontitis group at time points of week 4,6 and 8 after ligature(both P<0.01).CONCLUSION: Psychological stress is one of the periodontitis inducing factors in the animal model. Psychological stress may aggravate periodontitis by decreasing tissue oxygenation in rats.     

Protective effect of delayed ischemic preconditioning on renal ischemia/reperfusion injury via induction of hypoxia inducible factor

AIM: To investigate the effects of delayed ischemic preconditioning on renal ischemia-reperfusion injury in mice and to study the role of hypoxia inducible factor 1α(HIF-1α). METHODS: Male C57/BL6N mice were randomly divided into 3 groups: sham operation group(sham), ischemia/reperfusion group(IR) and ischemic preconditioning group(IPC). Thirty-minute ischemia was induced by clamping renal bilateral pedicles followed by reperfusion in IR group. Fifteen-minute pre-ischemia was performed 4 days before IR in IPC group. Serum creatinine(Scr), blood urea nitrogen(BUN), kidney morphology and apoptosis were observed at different time points following reperfusion. The expression of HIF-1α in the renal tissues was evaluated by the methods of immunohistochemistry and Western blotting analysis. The mRNA expression of vascular endothelial growth factor(VEGF) and glucose transporter-1(Glut-1) was detected by real-time quantitative RT-PCR.RESULTS: Compared with IR group at 24 h following reperfusion, acute tubulointerstitial injury was significantly relieved in IPC group. The levels of Scr and BUN, and apoptosis of tubular epithelial cells were also decreased in IPC group. Nuclear expression of HIF-1α was higher in IPC group than that in IR group. The mRNA expression of VEGF and Glut-1, the target genes of HIF-1, was also increased significantly in IPC group. CONCLUSION: Delayed ischemic preconditioning attenuates both morphologic and functional injuries induced by renal ischemia/reperfusion. This protective effect may be related to the increased expression of hypoxia inducible factor.