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.

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.

EFFECT OF MILD HYPOTHERMIA ON ACTIVITY NITRIC OXIDE SYNTHASE IN CORTICAL NEURONS AND GLYCEMIA LEVELS OF NEONATAL RATS WITH HYPOXIC ISCHEMIC BRAIN DAMAGE

Through investigating the effect of mild hypothermia on activity of nitric oxide snythase (NOS) in cortical neurons and glycemia levels of neonatal rats with hypoxic ischemic brain damage (HIBD). We studied the mechanism of protecting hypoxic ischemic neurons of mild hypothermia. We established neonatal rat HIBD models, used NOS immunohistochemistry and glycemia determination by micromethod. The number of cortical NOS positive neurons after hypoxic ischemia was significantly decreased as compared with controls. The glycemia levels was significantly increased than that controls. No significant difference was found in number of cortical NOS positive neurons and glycemia levels between 31℃ and 34℃ mild hypothemia. The results imply that hypothermia can decrease overproduction of NO through inhibiting the increase of the activity of NOS, and increase the glycemia levels, thus protect the hypoxic ischemic neurons.