Sevoflurane post-conditioning attenuates traumatic brain injury-induced neuronal apoptosis by promoting autophagy via the PI3K/AKT signaling pathway

The Relationship Between Autophagy and Brain Plasticity in Neurological Diseases

Autophagy, a catabolic degradation system, is utilized for destroying and recycling the damaged or unnecessary cellular components. Brain plasticity refers to the remarkable characteristics of brain neurons that change their structure and function according to previous experience. This review was performed by searching the relevant articles in databases of SCIENCEDIRECT, PUBMED, and Web of Science, from respective inception to January 2019. Here, we review the neuroprotective effect of autophagy in neurological diseases and the mechanism of autophagy in brain plasticity. Moreover, the mechanism of autophagy in the process of brain plasticity can provide the possibility for the development of new treatment methods in the future, thus benefiting patients with neurological diseases. In summary, autophagy and brain plasticity play important roles in neurological diseases.

Multi-Dimensional Mapping of Brain-Derived Extracellular Vesicle MicroRNA Biomarker for Traumatic Brain Injury Diagnostics

The diagnosis and prognosis of traumatic brain injury (TBI) is complicated by variability in the type and severity of injuries and the multiple endophenotypes that describe each patient's response and recovery to the injury. It has been challenging to capture the multiple dimensions that describe an injury and its recovery to provide clinically useful information. To address this challenge, we have performed an open-ended search for panels of microRNA (miRNA) biomarkers, packaged inside of brain-derived extracellular vesicles (EVs), that can be combined algorithmically to accurately classify various states of injury. We mapped GluR2+ EV miRNA across a variety of injury types, injury intensities, history of injuries, and time elapsed after injury, and sham controls in a pre-clinical murine model (n = 116), as well as in clinical samples (n = 36). We combined next-generation sequencing with a technology recently developed by our lab, Track Etched Magnetic Nanopore (TENPO) sorting, to enrich for GluR2+ EVs and profile their miRNA. By mapping and comparing brain-derived EV miRNA between various injuries, we have identified signaling pathways in the packaged miRNA that connect these biomarkers to underlying mechanisms of TBI. Many of these pathways are shared between the pre-clinical model and the clinical samples, and present distinct signatures across different injury models and times elapsed after injury. Using this map of EV miRNA, we applied machine learning to define a panel of biomarkers to successfully classify specific states of injury, paving the way for a prognostic blood test for TBI. We generated a panel of eight miRNAs (miR-150-5p, miR-669c-5p, miR-488-3p, miR-22-5p, miR-9-5p, miR-6236, miR-219a.2-3p, miR-351-3p) for injured mice versus sham mice and four miRNAs (miR-203b-5p, miR-203a-3p, miR-206, miR-185-5p) for TBI patients versus healthy controls.

Potential Roles of NIX/BNIP3L Pathway in Rat Traumatic Brain Injury

NIX/BNIP3L is known as a proapoptotic protein that is also related to mitophagy. Previous reports have shown that NIX could be involved in neuronal apoptosis after intracerebral hemorrhage, but it also plays a protective role in mitophagy in ischemic brain injury. How NIX works in traumatic brain injury (TBI) is unclear. Thus, this study was designed to observe the expression of NIX and perform a preliminary exploration of the possible effects of NIX in a rat TBI model. The results showed that NIX expression decreased after damage, and colocalized with neuronal cells in cortical areas. Moreover, when we induced upregulation of NIX, autophagy was increased, while neuronal apoptosis and brain water content decreased along with neurological deficits. These findings remind us that NIX probably plays a neuroprotective role in TBI through autophagy and apoptosis pathways.

A standardized rat burr hole defect model to study maxillofacial bone regeneration

With high incidence rate and unique regeneration features, maxillofacial burr hole bone defects require a specially designed bone defect animal model for the evaluation of related bone regenerative approaches. Although some burr hole defect models have been developed in long bones or calvarial bones, the mandible has unique tissue development origins and regenerative environments. This suggests that the defect model should be prepared in the maxillofacial bone area. After dissecting the anatomic structures of rat mandibles, we found that creating defects in the anterior tooth area avoided damaging important organs and improved animal welfare. Furthermore, the available bone volume at the anterior tooth area was superior to that of the posterior tooth and ascending ramus areas. We then managed to standardize the model by controlling the age, weight and gender of the animal, creating standardized measurement instruments and reducing the variations derived from various operators. We also succeeded in deterring the self-rehabilitation of the proposed model by increasing the defect size. The 6 × 2 mm and 8 × 2 mm defects were found to meet the requirements of bone regenerative studies. This study provided a step-by-step standardized burr hole bone defect model with minimal tissue damage in small animals. The evaluations resulting from this model testify to the in vitro outcomes of the proposed regenerative approaches and provide preliminary screening data for further large animal and clinical trials. Therefore, the inclusion of this model may optimize the evaluation systems for maxillofacial burr hole bone defect regenerative approaches. STATEMENT OF SIGNIFICANCE: Unremitting effort has been devoted to the development of bone regenerative materials to restore maxillofacial burr hole bone defects because of their high clinical incidence rate. In the development of these biomaterials, in vivo testing in small animals is necessary to evaluate the effects of candidate biomaterials. However, little has been done to develop such defect models in small animals. In this study, we developed a standardized rat mandible burr hole bone defect model with minimal injury to the animals. A detailed description and supplementary video were provided to guide the preparation. The development of this model optimizes the maxillofacial bone regenerative approach evaluation system.

Metformin protects against sevoflurane-induced neuronal apoptosis through the S1P1 and ERK signaling pathways

The aim of the current study was to investigate whether metformin could counteract sevoflurane-induced neurotoxicity. In vitro experiments on the sevoflurane-induced nerve injury were performed using hippocampal neurons. Neuronal apoptosis was detected by an MTT assay. Protein expression levels of apoptosis-associated genes, including cleaved-caspase-3, apoptosis regulator BAX and apoptosis regulator Bcl-2 were detected by western blot analysis. The mechanism of the effect of metformin on sevoflurane-induced neuronal apoptosis was investigated using a sphingosine 1-phosphate receptor 1 (S1P1) antagonist (VPC23019) and mitogen-activated protein kinase kinase inhibitor (U0126). The current study revealed that metformin may reduce sevoflurane-induced neuronal apoptosis via activating mitogen-activated protein kinase (ERK)1/2 phosphorylation. VPC23019 and U0126 eliminated the neuroprotective effects of metformin on neuronal apoptosis, which suggests that metformin is able to protect against sevoflurane-induced neurotoxicity via activation of the S1P1-dependent ERK1/2 signaling pathway.

Benificial Effect of Stachydrine on the Traumatic Brain Injury Induced Neurodegeneration by Attenuating the Expressions of Akt/mTOR/PI3K and TLR4/NFκ-B Pathway

Present investigation aims to explore the protective effect of stachydrine against traumatic brain injury (TBI) and also investigate the molecular mechanism of its action. TBI was induced by the fall a hammer (450 g) from the height of 1.5 m. and later stachydrine was administered for 2 weeks starting 2 hr after the induction of TBI. Effect of stachydrine was determined by estimating modified neurological severity score (mNSS), percentage of water content in the brain and cognitive dysfunction in TBI rats. Moreover western blot assay, histopathology and enzyme linked immunosorbent assay (ELISA) tests were used to determine the effect of stachydrine on TBI injured rats. Result of the report suggests that stachydrine reduces the mNSS and percentage of water content in the brain and also attenuates the cognitive dysfunction in TBI injured rats. However data of western blot assay reports that stachydrine reduces the expression of PI3K/m-TOR/Akt pathway in the brain tissues of TBI rats. Concentration of interleukin (IL-1β), tumor necrosis factor-α (TNF-α) and interferon gamma (INF-γ) was reduces in stachydrine treated group than TBI group. Moreover expression of Nuclear factor-κB/Toll-like receptor 4 (NF-κB/TLR-4) protein was also decreased in stachydrine treated group than TBI group. Histopathology study on brain tissue reveals that the percentage of apoptotic cells was also reduced in stachydrine treated group than TBI group. Data of this investigation concludes that stachydrine protects the neuronal injury by attenuating the phosphatidylinositide 3-kinases/mammalian target of rapamycin/Protein kinase B (PI3K/m-TOR/Akt) and NF-κB/TLR-4 pathway in TBI injured rats.

Andrographolide Alleviates Acute Brain Injury in a Rat Model of Traumatic Brain Injury: Possible Involvement of Inflammatory Signaling

Neuroinflammation plays an important role in secondary injury after traumatic brain injury (TBI). Andrographolide (Andro), a diterpenoid lactone isolated from Andrographis paniculata, has been demonstrated to exhibit anti-inflammatory activity in neurodegenerative disorders. This study therefore aimed to investigate the potential neuroprotective effects of Andro after TBI and explore the underlying mechanisms. In our study, we used a weight-dropped model to induce TBI in Sprague–Dawley rats, the neurological deficits were assessed using modified neurological severity scores, Fluoro-Jade B (FJB) and terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining were employed to examine neuronal degeneration and apoptosis after TBI, immunofluorescence was designed to investigate microglial activation. Quantitative Real-time PCR and ELISA were conducted to detect the expression levels of pro-inflammatory cytokines, Western blot was used to examine the expression level of proteins of relative signaling pathway. Our results showed that after Andro administration, the neurological deficit was attenuated, and the cerebral edema and apoptosis in brain tissues were also decreased following TBI. Both microglial activation and the expression of pro-inflammatory cytokines were significantly inhibited by Andro after TBI. Moreover, Andro inhibited NF-κB p65 subunit translocation and decreased the expression levels of phosphorylated extracellular signal regulated kinase (ERK) and p38 MAPK after TBI. Altogether, this study suggests that Andro could improve neurobehavioral function by inhibiting NF-κB and MAPK signaling pathway in TBI, which might provide a new approach for treating brain injury.