The miR-9-5p/CXCL11 pathway is a key target of hydrogen sulfide-mediated inhibition of neuroinflammation in hypoxic ischemic brain injury

We previously showed that hydrogen sulfide(H2S)has a neuroprotective effect in the context of hypoxic ischemic brain injury in neonatal mice.However,the precise mechanism underlying the role of H2S in this situation remains unclear.In this study,we used a neonatal mouse model of hypoxic ischemic brain injury and a lipopolysaccharide-stimulated BV2 cell model and found that treatment with L-cysteine,a H2S precursor,attenuated the cerebral infarction and cerebral atrophy induced by hypoxia and ischemia and increased the expression of miR-9-5p and cystathionineβsynthase(a major H2S synthetase in the brain)in the prefrontal cortex.We also found that an miR-9-5p inhibitor blocked the expression of cystathionineβsynthase in the prefrontal cortex in mice with brain injury caused by hypoxia and ischemia.Furthermore,miR-9-5p overexpression increased cystathionine-β-synthase and H2S expression in the injured prefrontal cortex of mice with hypoxic ischemic brain injury.L-cysteine decreased the expression of CXCL11,an miR-9-5p target gene,in the prefrontal cortex of the mouse model and in lipopolysaccharide-stimulated BV-2 cells and increased the levels of proinflammatory cytokines BNIP3,FSTL1,SOCS2 and SOCS5,while treatment with an miR-9-5p inhibitor reversed these changes.These findings suggest that H2S can reduce neuroinflammation in a neonatal mouse model of hypoxic ischemic brain injury through regulating the miR-9-5p/CXCL11 axis and restoringβ-synthase expression,thereby playing a role in reducing neuroinflammation in hypoxic ischemic brain injury.

Vascular endothelial growth factor: an attractive target in the treatment of hypoxic/ischemic brain injury

Cerebral hypoxia or ischemia results in cell death and cerebral edema, as well as other cellular reactions such as angiogenesis and the reestablishment of functional microvasculature to promote recovery from brain injury. Vascular endothelial growth factor is expressed in the central nervous system after hypoxic/ischemic brain injury, and is involved in the process of brain repair via the regulation of angiogenesis, neurogenesis, neurite outgrowth, and cerebral edema, which all require vascular endothelial growth factor signaling. In this review, we focus on the role of the vascular endothelial growth factor signaling pathway in the response to hypoxic/ischemic brain injury, and discuss potential therapeutic interventions.

Interventional effect of laser acupoint radiation on the expression of Nissl body and brain-derived neurotrophic factor in newborn rat models with ischemic/hypoxic cerebral injury

BACKGROUND： Some researches report that He-Ne laser can activate function of erythrocytes and increase content of blood and oxygen via bio-stimulating effect; therefore, it suspects that laser radiation at Baihui and Dazhui can partially increase blood circulation for oxygen-supplying content of brain and improve functional status of neurons. OBJECTIVE： To verify the effects of laser radiation at Baihui and Dazhui on the expression of Nissl body of brain tissue neurons and brain-derived neurotrophic factor （BDNF） in newborn rats with ischemic/hypoxic cerebral injury. DESIGN： Randomized controlled animal study. SETTING： Department of Neurological Histochemistry, Xianning University. MATERIALS： Forty Wistar rats of 7 - 8 days old, weighing 15 - 20 g and of both genders, were selected from Wuhan Experimental Animal Center. All the rats were randomly divided into sham operation group （n =8）, model group （n =16） and radiation group （n = 16）. The experimental animals were disposed according to ethical criteria. BDNF kit was provided by Wuhan Boster Bioengineering Co., Ltd. METHODS： The experiment was carried out in the Department of Neurological Histochemistry, Xianning University from April 2005 to October 2006. Rats in the radiation group and model group were performed with ligation of left common carotid artery, recovered at room temperature for 1 - 6 days, maintained in self-made hypoxic cabin under normal pressure and injected mixture gas （0.05 volume fraction of 02 and 0.92 volume fraction of N2） for 2 hours. In addition, rats in the sham operation group were treated with separation of left common carotid artery but not ligation and hypoxia. Rats in the model group were not given any treatment; while, rats in the radiation group were exposed with He-Ne laser of 63.28 nm in the wave length at Baihui and Dazhui acupoints on the second day after ischemia-hypoxia. The radiation was given for 10 minutes per day and once a day. Ten days were regarded as a course and the rats were exposed for 2 courses in total. At 20 days after routine breeding, left hemisphere tissues of rats in the three groups were collected for staining of Nissl body and immunohistochemistry of BDNF. MAIN OUTCOME MEASURES： Nissl body staining in left hemisphere tissue and expression of immune positive cells of BDNF. RESULTS： All 40 rats were involved in the final analysis. （1） Nissl body staining： Neuronal cytoplasm of brain tissue was full of blue granule Nissl bodies in the sham operation group; while, Nissl body in neuronal cytoplasm in the model group was stained slightly and had a certain degree of degeneration; meanwhile, there were a lot of blank area in ischemic region. Nissl body in neuron cytoplasm was gradually recovered in the radiation group and relieved as compared with that in the model group. （2） Positive cells of BDNF： Number of immune positive cells of BDNF which were ligated in lateral cerebral hemisphere of rats in the model group was higher than that in the sham operation group （P 〈 0.05）; while, BDNF expression in the radiation group was increased as compared with that in the model group （P 〈 0.05）. CONCLUSION： After laser acupoint radiation, Nissl body is increased and BDNF expression is also increased. This suggests that laser acupoint radiation has neuroprotective effect on brain tissue after ischemia-hypoxia injury.

Altered seizure susceptibility and vesicular glutamate transporter subtype 1 immunoreactivity in a rat model of hypoxic brain injury

BACKGROUND：To the best of our knowledge, few studies have analyzed the effects of hypoxic brain injury on seizure susceptibility and pathophysiological mechanisms underlying seizure susceptibility following hypoxic brain injury. OBJECTIVE： To investigate changes in seizure susceptibility and neuronal loss, as well as expression of vesicular glutamate transporter subtype 1（VGluT1）, following hypoxic cerebral insult. DESIGN, TIME AND SETTING： A randomized controlled animal experiment was performed in the Department of Neurology, The Second Affiliated Hospital, Chongqing Medical University, between May 2006 and September 2007. MATERIALS： Seventy, male, Sprague Dawley rats, weighing 230–270 g, were used in the present study. Pentylenetetrazol （PTZ） was purchased from Sigma. Mouse NeuN monoclonal antibody and rabbit VGluT-1 polyclonal antibody were purchased from Chemicon and Gene Tex, respectively. METHODS： Rats were randomly assigned to control and hypoxia groups （n = 35 for each group）. Hypoxia was induced in rats using 8% oxygen-nitrogen gas mixture. Control rats were subjected to the same procedures, but with exposure to room air. MAIN OUTCOME MEASURES： Rats （n = 15 for each group） received intraperitoneal injections of PTZ, a sub-convulsive dose of 35 mg/kg/2 d for 20 days. The success of model establishment, as well as seizure scales, was measured. Rats from both groups, which were successfully kindled with PTZ, were divided into simple kindling and post-hypoxic kindling, respectively. A separate group, including rats from simple kindling and post-hypoxic kindling, was studied for neuronal loss and VGluT1 expression in the temporal cortex, midbrain, and hippocampal CA1 subfield using immunohistochemistry and western blot techniques, respectively. RESULTS： Seventy rats were included in the final analysis. （1）Compared with control animals （n = 7）, seizure scales were greater in hypoxic rats （n = 11）, which indicates that post-hypoxic rats reacted more sensitive to kindling. （2）The average number of neurons within the temporal cortex, midbrain, and hippocampal CA1 subfield was less in hypoxic rats than in control rats. After comparing post-hypoxia kindling with simple kindling, both the temporal cortex and hippocampal CA1 subfield exhibited obvious neuronal loss in the post-hypoxic kindling group （P 〈 0.05）. （3）Compared with hypoxia and simple kindling, the number of VGluT1 immunopositive cells was greater in the post-hypoxic kindling group （P 〈 0.05）. CONCLUSION： Hypoxic brain injury leads to increased seizure susceptibility, neuronal loss, and enhanced of VGluT1 expression.

Exploring the mechanism of neuronal apoptosis and brain developmental damage in the hippocampus of hypoxicischemic neonatal rats based on BDNF/TrkB/CREB pathway

Objective:Based on the BDNF/TrkB/CREB pathway,to explore the mechanism of neuronal apoptosis and brain developmental injury in the hippocampus of hypoxic-ischemic neonatal rats.Methods:Wistar young rats were ligated on one side of the common carotid artery and placed in an 8%oxygen and 92%nitrogen hypoxia box for 2 h to prepare hypoxic-ischemic brain injury models.Healthy rats were used as the control group.Control group and model group were selected,with 10 rats in each group,and the learning and memory ability was tested by Y-maze;2,3,5-triphenyltetrazolium chloride(TTC)staining was used to detect brain tissue damage;Western blot was performed to determine the expression of brain-derived neurotrophic factor(BDNF),tyrosine protein kinase B(TrKB)and cAMP-response element binding protein(CREB)in hippocampal tissue.Another 15 mice in the control group and 60 mice in the model group were divided into negative control group(NC),BDNF overexpression group(LV-BDNF),TrkB overexpression group(LV-TrkB),and CREB overexpression group(LV-CREB),blank vector,BDNF,TrkB,CREB adenovirus overexpression vector was injected into the tail vein.Y-maze test for learning and memory ability;TTC staining method to detect brain tissue damage;neuronal apoptosis in the hippocampus were detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling;Western blot to detect the level of neuronal apoptosis in the hippocampus.Apoptosis-related protein B-cell lymphoma-2(Bcl-2),BCL2associated X protein(Bcl-2 Assaciated X,Bax)and nuclear factor kappaB(NFκB)expression.Results:The learning and memory ability of the young mice in the model group was significantly reduced,the brain infarct volume was significantly increased,the expressions of BDNF and TrkB proteins in the hippocampus were significantly increased,and the expression of CREB proteins was significantly decreased;After overexpression of BDNF and TrkB CREB,in the LVBDNF,LVTrkB,and LVCREB group,the learning and memory ability of young mice were significantly improved,the brain infarct volume were significantly reduced,the hippocampal neuronal apoptosis were significantly reduced,The protein expression of Bax and NFκB were significantly decreased and the protein expression of Bcl2 were significantly enhanced.Conclusion:The expression of BDNF/TrkB/CREB is abnormal in HIBI model young mice.Overexpression of BDNF/TrkB/CREB can improve the learning and memory ability of young mice,repair brain tissue damage,and inhibit neuronal apoptosis.Therefore,the mechanism of HIBI may be related to BDNF/TrkB/CREB pathways.

Gender difference in the neuroprotective effect of rat bone marrow mesenchymal cells against hypoxiainduced apoptosis of retinal ganglion cells

Bone marrow mesenchymal stem cells can reduce retinal ganglion cell death and effectively prevent vision loss. Previously, we found that during differentiation, female rhesus monkey bone marrow mesenchymal stem cells acquire a higher neurogenic potential compared with male rhesus monkey bone marrow mesenchymal stem cells. This suggests that female bone marrow mesenchymal stem cells have a stronger neuroprotective effect than male bone marrow mesenchymal stem cells. Here, we first isolated and cultured bone marrow mesenchymal stem cells from female and male rats by density gradient centrifugation. Retinal tissue from newborn rats was prepared by enzymatic digestion to obtain primary retinal ganglion cells. Using the transwell system, retinal ganglion cells were co-cultured with bone marrow mesenchymal stem cells under hypoxia. Cell apoptosis was detected by flow cytometry and caspase-3 activity assay. We found a marked increase in apoptotic rate and caspase-3 activity of retinal ganglion cells after 24 hours of hypoxia compared with normoxia. Moreover, apoptotic rate and caspase-3 activity of retinal ganglion cells significantly decreased with both female and male bone marrow mesenchymal stem cell co-culture under hypoxia compared with culture alone, with more significant effects from female bone marrow mesenchymal stem cells. Our results indicate that bone marrow mesenchymal stem cells exert a neuroprotective effect against hypoxia-induced apoptosis of retinal ganglion cells, and also that female cells have greater neuroprotective ability compared with male cells.

The expression of SIRT3 signaling in hypoxia-induced endothelial injury

Background Oxidative injury to the endothelial cells plays an important role in development of atherosclerosis.Investigation of the mechanisms of oxidative endothelial injury is of great importance.Our previous report has demonstrated that Sirtuin 3(SIRT3)protect cardiomyocytes from oxidative stress-mediated cell death via activating the nuclear factor kappa-B(NF-κB)signaling pathway.However,the role and exact mechanisms of SIRT3 signaling in endothelial hypoxia injury are largely unknown.The present study aimed to investigate the expression of SIRT3,hypoxia-inducible factor 1α(HIF-1α),and NF-κB/TNF-α(tumor necrosis factor-α)in human umbilical vein endothelial cells(HUVECs)treated by hypoxia.Methods Hypoxia model was established by anoxic tank and randomly divided into 3 groups:control group,1 h hypoxia group,and 3 h hypoxia group.3-(4,5-dimetrylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)detected the cell viability under hypoxia condition,and the intracellular reactive oxygen species(ROS)generation was determined by 2′,7′-Dichlorodihydrofluorescein diacetate(DCFH-DA).The expression of m RNA and protein of the SIRT3 signaling were detected by real-time quantitative polymerase chain reaction(q PCR)and western blot analysis,respectively.Results Hypoxia treatment time-dependently decreased the cell viability,especially in the first hour.ROS production significantly increased in the first hour of hypoxia compared with those in the second and the third hour.Hypoxic stimuli significantly elevated SIRT3 m RNA and protein expression.Furthermore,real-time q PCR results showed that elevated SIRT3 significantly increased the m RNA expression of HIF-1αand NF-κB/TNF-αin 1 h hypoxia group.Western blot results also showed that elevated SIRT3 significantly increased the protein expression of NF-κB in the 1 h hypoxia group.Conclusions The present study indicated that hypoxic stimuli promoted the expression of SIRT3,HIF-1α,and NF-κB/TNF-α,and suggested that SIRT3 signaling pathway may participate in the physiological process of acute ischemic hypoxia stress in human endothelial cells.