ABSTRACT
In the central nervous system (CNS), three types of myelin-associated inhibitors (MAIs) have major inhibitory effects on nerve regeneration. They include Nogo-A, myelin-associated glycoprotein, and oligodendrocyte-myelin glycoprotein. MAIs possess two co-receptors, Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Previous studies have confirmed that the inhibition of NgR only results in a modest increase in regeneration in the CNS; however, the inhibitory effects of PirB with regard to nerve regeneration after binding to MAIs remain controversial. In this study, we demonstrated that PirB is expressed in primary cultures of retinal ganglion cells (RGCs), and the inhibitory effects of the three MAIs on the growth of RGC neurites are not significantly decreased after direct PirB knockdown using adenovirus PirB shRNA. Interestingly, we found that retinal Müller cells expressed PirB and that its knockdown enhanced the regeneration of co-cultured RGC neurites. PirB knockdown also activated the JAK/Stat3 signaling pathway in Müller cells and upregulated ciliary neurotrophic factor levels. These findings indicate that PirB plays a novel role in retinal Müller cells and that its action in these cells may indirectly affect the growth of RGC neurites. The results also reveal that PirB in Müller cells affects RGC neurite regeneration. Our findings provide a novel basis for the use of PirB as a target molecule to promote nerve regeneration.
ABSTRACT
Neurons, especially axons, are metabolically demanding and energetically vulnerable during injury. However, the exact energy budget alterations that occur early after axon injury and the effects of these changes on neuronal survival remain unknown. Using a classic mouse model of optic nerve-crush injury, we found that traumatized optic nerves and retinas harbor the potential to mobilize two primary energetic machineries, glycolysis and oxidative phosphorylation, to satisfy the robustly increased adenosine triphosphate (ATP) demand. Further exploration of metabolic activation showed that mitochondrial oxidative phosphorylation was amplified over other pathways, which may lead to decreased retinal ganglion cell (RGC) survival despite its supplement to ATP production. Gene set enrichment analysis of a microarray (GSE32309) identified significant activation of oxidative phosphorylation in injured retinas from wild-type mice compared to those from mice with deletion of phosphatase and tensin homolog (PTEN), while PTEN-/- mice had more robust RGC survival. Therefore, we speculated that the oxidation-favoring metabolic pattern after optic nerve-crush injury could be adverse for RGC survival. After redirecting metabolic flux toward glycolysis (magnifying the Warburg effect) using the drug meclizine, we successfully increased RGC survival. Thus, we provide novel insights into a potential bioenergetics-based strategy for neuroprotection.
ABSTRACT
In the central nervous system (CNS), three types of myelin-associated inhibitors (MAIs) have major inhibitory effects on nerve regeneration. They include Nogo-A, myelin-associated glycoprotein, and oligodendrocyte-myelin glycoprotein. MAIs possess two co-receptors, Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Previous studies have confirmed that the inhibition of NgR only results in a modest increase in regeneration in the CNS; however, the inhibitory effects of PirB with regard to nerve regeneration after binding to MAIs remain controversial. In this study, we demonstrated that PirB is expressed in primary cultures of retinal ganglion cells (RGCs), and the inhibitory effects of the three MAIs on the growth of RGC neurites are not significantly decreased after direct PirB knockdown using adenovirus PirB shRNA. Interestingly, we found that retinal Müller cells expressed PirB and that its knockdown enhanced the regeneration of co-cultured RGC neurites. PirB knockdown also activated the JAK/Stat3 signaling pathway in Müller cells and upregulated ciliary neurotrophic factor levels. These findings indicate that PirB plays a novel role in retinal Müller cells and that its action in these cells may indirectly affect the growth of RGC neurites. The results also reveal that PirB in Müller cells affects RGC neurite regeneration. Our findings provide a novel basis for the use of PirB as a target molecule to promote nerve regeneration.
ABSTRACT
Explosive blast injury has become the most prevalent injury in recent military conflicts and terrorist attacks. The magnitude of this kind of polytrauma is complex due to the basic physics of blast and the surrounding environments. Therefore, development of stable, reproducible and controllable animal model using an ideal blast simulation device is the key of blast injury research. The present review addresses the modeling of blast injury and applications of shock tubes.
Subject(s)
Animals , Blast Injuries , Disease Models, Animal , High-Energy Shock Waves , ResearchABSTRACT
With the increasing incidence of blast injury, the research on its mechanisms and protective measures draws more and more attention. Blast injury has many characteristics different from general war injuries or trauma. For example, soldiers often have various degrees of visceral injury without significant surface damage, combined injuries and arterial air embolism. Researchers in China began to investigate blast injury later than the United States and Sweden, but the development is so fast that lots of achievements have been gained, including the development of biological shock tube, the mechanisms and characteristics of blast injury in various organs, as well as protective measures under special environments. This article reviews the past and current situation of blast injury research in China.
Subject(s)
Animals , Humans , Blast Injuries , Diagnosis , Therapeutics , Brain Injuries, Traumatic , China , Disease Models, Animal , Ear , Wounds and Injuries , Eye Injuries , High-Energy Shock Waves , Lung Injury , ResearchABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of three different ways of chronic caffeine administration on blast- induced memory dysfunction and to explore the underlying mechanisms.</p><p><b>METHODS</b>Adult male C57BL/6 mice were used and randomly divided into five groups: control: without blast exposure, con-water: administrated with water continuously before and after blast-induced traumatic brain injury (bTBI), con-caffeine: administrated with caffeine continuously for 1 month before and after bTBI, pre-caffeine: chronically administrated with caffeine for 1 month before bTBI and withdrawal after bTBI, post-caffeine: chronically administrated with caffeine after bTBI. After being subjected to moderate intensity of blast injury, mice were recorded for learning and memory performance using Morris water maze (MWM) paradigms at 1, 4, and 8 weeks post-blast injury. Neurological deficit scoring, glutamate concentration, proinflammatory cytokines production, and neuropathological changes at 24 h, 1, 4, and 8 weeks post-bTBI were examined to evaluate the brain injury in early and prolonged stages. Adenosine A1 receptor expression was detected using qPCR.</p><p><b>RESULTS</b>All of the three ways of chronic caffeine exposure ameliorated blast-induced memory deficit, which is correlated with the neuroprotective effects against excitotoxicity, inflammation, astrogliosis and neuronal loss at different stages of injury. Continuous caffeine treatment played positive roles in both early and prolonged stages of bTBI; pre-bTBI and post-bTBI treatment of caffeine tended to exert neuroprotective effects at early and prolonged stages of bTBI respectively. Up-regulation of adenosine A1 receptor expression might contribute to the favorable effects of chronic caffeine consumption.</p><p><b>CONCLUSION</b>Since caffeinated beverages are widely consumed in both civilian and military personnel and are convenient to get, the results may provide a promising prophylactic strategy for blast-induced neurotrauma and the consequent cognitive impairment.</p>
Subject(s)
Animals , Male , Mice , Blast Injuries , Brain Injuries, Traumatic , Caffeine , Pharmacology , Cerebral Cortex , Pathology , Hippocampus , Pathology , Memory Disorders , Mice, Inbred C57BL , RNA, Messenger , Receptor, Adenosine A1 , GeneticsABSTRACT
Rho-associated coiled-coil protein kinase (ROCK) is a serine/threonine kinase that belongs to AGC family of kinases. By inducing the formation of stress fibers and reorganizing the cytoskeleton, it is involved in many biological behaviors of cells including cell contraction, cell migration, cell division, and morphological changes, and thus exerts important roles in regulating the multiple functions of cells.
Subject(s)
Humans , Cell Division , Cell Movement , Cytoskeleton , Metabolism , rho-Associated Kinases , Metabolism , PhysiologyABSTRACT
<p><b>OBJECTIVE</b>Radiation is an important cause of delayed wound healing, and there still exist many questions regarding the patterns and mechanisms of wound healing. This study investigated the characteristics of wound healing after varying doses of local radiation and explored possible causes of the delay in healing caused by radiation.</p><p><b>METHODS</b>A full-thickness dorsal longitudinal skin tissue, 2 cm in diameter, was excised after local irradiation on one side of the back of swine, and the other side was wounded as a control. The size of the wound area was recorded every two days after injury. Pathological changes, proliferating cell nuclear antigen (PCNA, immunohisto- chemistry) and apoptosis levels (TUNEL assay) were measured at different time points after wounding.</p><p><b>RESULTS</b>The course of wound healing can be divided into four phases, namely: the arresting phase, the healing priming phase, the fast healing phase, and the healed phase. Although the total wound healing time was closely correlated to the dose of irradiation (R(2) equal to 0.9758), it was more dependent on the length of the arresting phase (R(2) equal to 0.9903) because once the arresting phase ended, the wound healed at a similar speed regardless of radiation doses. Pathological analysis showed that compared with the control side there were more necrotic tissues, slower epithelial crawling, as well as fewer blood vessels and cellular components in the irradiated side at the arresting phase, while other phases revealed no significant difference concerning these measurements. Immunohistochemistry showed that the irradiated wounds had significantly less PCNA-positive and more TUNEL-positive labeling of cells in the arresting phase than in other phases. Moreover, the changes were positively related to the radiation doses, but there was no obvious difference in cell proliferation or apoptosis among the healing priming phase, fast healing phase or healed phase, whether on the control side or on the irradiated side.</p><p><b>CONCLUSIONS</b>After local irradiation, the length of the arresting phase determines the wound healing time. Increased apoptosis and decreased cell proliferation might be an important reason for the formation of the arresting phase.</p>
Subject(s)
Animals , Apoptosis , Cell Proliferation , Skin , Soft Tissue Injuries , Swine , Wound HealingABSTRACT
<p><b>OBJECTIVE</b>To study the role of Smad3 in transforming growth factor-beta1 (TGF-beta1)-induced bi-directional effects on skin fibroblast proliferation.</p><p><b>METHODS</b>The Smad3 small interfering (siRNA) plasmid was constructed using a pSUPER vector. The efficiency of cell transfection was detected by fluorescence microscopy, and the inhibitory effect of the plasmid was assessed by real-time quantitative RT-PCR and immunohistochemistry. The effect of the plasmid on the fibroblast proliferation and Smad3 binding activity was analyzed by BRDU ELISA and EMSA, respectively.</p><p><b>RESULTS</b>The transfection efficiency of the plasmid into the cells was 41.2%. The Smad3 siRNA plasmid produced efficient and specific inhibition of the expression of Smad3, and promoted the cell proliferation in a dose-dependent manner and abrogated the bi-directional effect of TGF-beta1 on the cell proliferation and Smad3 binding activity.</p><p><b>CONCLUSION</b>The siRNA targeting Smad3 gene can inhibit the protein expression and RNA transcription of Smad3, and TGF-beta1 exerts bi-directional regulation on fibroblast proliferation by modulating Smad3 activity.</p>
Subject(s)
Animals , Rats , Cell Proliferation , Cells, Cultured , Fibroblasts , Cell Biology , RNA Interference , RNA, Small Interfering , Genetics , Rats, Wistar , Skin , Cell Biology , Smad3 Protein , Genetics , Transfection , Transforming Growth Factor beta1 , PharmacologyABSTRACT
The aim of this study is to investigate the effect of (S)-4-carboxy-3-hydroxy-phenylglycine [(S)-4C3HPG], a mixed group I glutamate metabotropic receptor antagonist and a group II agonist, on impairment in a cortical impact model of traumatic brain injury (TBI) in mice and to elucidate the possible mechanisms. Mice were injected (i.p.) with saline, 1 mg/kg (S)-4C3HPG, 5 mg/kg (S)-4C3HPG and 10 mg/kg (S)-4C3HPG (n=10 per group), respectively, at 30 min before moderate TBI. Neurological deficit scores, water content in injured brain and glutamate concentration in cerebral spinal fluid (CSF) were detected at 24 h after TBI. The expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) mRNA in injured cortex were also detected by real-time RT-PCR. The results showed that the neurological deficits and cerebral edema were significantly attenuated in mice pretreated with (S)-4C3HPG (5 and 10 mg/kg respectively) compared with those in mice pretreated with saline. Furthermore, (S)-4C3HPG treatment also decreased the glutamate concentration in CSF and the expressions of TNF-α and IL-1β mRNA remarkably in a dose-dependent manner. These results suggest that (S)-4C3HPG treatment attenuates cortical impact-induced brain injury possibly via suppression of glutamate release and inhibition of excessive inflammatory cytokine production. These findings highlight the potential benefit of glutamate metabotropic receptor ligand for preventing TBI.
Subject(s)
Animals , Male , Mice , Brain Injuries , Drug Therapy , Metabolism , Cytokines , Metabolism , Glutamic Acid , Cerebrospinal Fluid , Glycine , Therapeutic Uses , Mice, Inbred C57BL , Receptors, Metabotropic GlutamateABSTRACT
Recently, activation of the adenosine A2A receptors has been shown to exert protection against peripheral tissue injuries but aggravation in the central nervous system (CNS) injuries. To explore the different effects of adenosine A2A receptors and try to perform some new treatment strategies for peripheral tissue and CNS traumas, we constructed the mouse models of skin trauma, skin combined radiation-impaired wound and traumatic brain injury (TBI), respectively. Wild type mice and A2A receptor gene knockout mice were both used in the experiments. In skin trauma and combined radiation-impaired wound models, the time of wound healing was observed, while in TBI model, neurological deficit scores, water content in injured brain and glutamate concentration in cerebral spinal fluid (CSF) were detected at 24 h after TBI. The results showed that in skin trauma and combined radiation-impaired wound models, CGS21680 (an agonist of the A2A receptors) promoted while A2A receptor gene knockout delayed the course of skin wound healing. On the contrary, in TBI model, A2A receptor gene knockout, not CGS21680, showed a protective role by inhibition of glutamate release. These data further indicate that promoting glutamate release may account for the different effects of A2A receptor activation in CNS injury and peripheral tissue injury models. These findings may provide some experimental evidence and a new strategy for clinical treatment of peripheral tissue damages by agonists of A2A receptors, while treatment of CNS injuries by antagonists of A2A receptors.
Subject(s)
Animals , Mice , Adenosine , Pharmacology , Brain , Pathology , Brain Injuries , Disease Models, Animal , Glutamic Acid , Cerebrospinal Fluid , Mice, Knockout , Phenethylamines , Pharmacology , Receptor, Adenosine A2A , Genetics , Physiology , Wound HealingABSTRACT
<p><b>OBJECTIVE</b>To study the association between decreased ligand binding activity of glucocoid receptor (GR) and heat shock protein 90 (Hsp90), the molecular chaperone of GR, after acute lung injury (ALI) in mice.</p><p><b>METHODS</b>In mouse models of oleic acid-induced ALI, the levels of GR, Hsp90 and Hsp70 were dynamically observed using Western blotting, and the binding capacity and binding affinity of GR assessed with radioligand binding assay.</p><p><b>RESULTS</b>After ALI, pulmonary edema was significantly aggravated in the mice with significantly increased lung body index and lung water ratio. GR increased within 1 h after the injury, but then decreased significantly to the lowest level at 12 h after the injury, and the levels of Hsp90 and Hsp70 was increased obviously and reached the highest at 12 h. Radioligand binding assay showed that the Bmax decreased gradually and Kd value increased, and these changes were consistent with the changes of Hsp90/GR.</p><p><b>CONCLUSION</b>The ligand binding activity of GR is related to the changes of Hsp90 after ALI.</p>
Subject(s)
Animals , Female , Male , Mice , Acute Lung Injury , Metabolism , Binding Sites , HSP70 Heat-Shock Proteins , Metabolism , HSP90 Heat-Shock Proteins , Metabolism , Oleic Acid , Radioligand Assay , Random Allocation , Receptors, Glucocorticoid , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To study the effect of imbalance between lysosomal enzymes and their inhibitors in blood on disturbance of the local and whole body after trauma.</p><p><b>METHODS</b>The dynamic changes of lysosomal enzymes and proteinase inhibitors were studied in 12 pigs with femoral comminuted fractures in both hind limbs caused by high velocity missiles. Four normal pigs served as controls.</p><p><b>RESULTS</b>After injury, the activity of Cathepsin D in arterial plasma increased gradually and reached the highest level at 8 hours, acid phosphatase in serum began to increase at 12 hours and the value of serum elastase did not change significantly. The level of alpha1-antitrypsin, a proteinase inhibitor in plasma, decreased significantly in the early stage after injury [73.5%+/-6.4% and 81.0%+/-5.1% of the baseline value (1.67 micromol x ml(-1) x min(-1)+/- 0.29 micromol x ml(-1) x min(-1)) at l and 2 hours after injury, respectively, P<0.05], then increased gradually and was higher than the baseline value at 12 hours after injury.</p><p><b>CONCLUSIONS</b>Imbalance between lysosomal enzymes and proteinase inhibitors occurs soon after injury, which might result in continuous tissue damage and play an important role in the disturbance of general reaction after injury.</p>