Experimental Brain Injury Research Articles

The silent information regulator 1 agonist SRT1720 reduces experimental intracerebral hemorrhagic brain injury by regulating the blood-brain barrier integrity.

Intracerebral hemorrhage (ICH) is a significant public health matter that has no effective treatment. ICH-induced destruction of the blood-brain barrier (BBB) leads to neurological deterioration. Astrocytic sonic hedgehog (SHH) alleviates brain injury by maintaining the integrity of the BBB after ICH. Silent information regulator 1 (SIRT1) is neuroprotective in several central nervous system diseases via BBB regulation. It is also a possible influential factor of the SHH signaling pathway. Nevertheless, the role of SIRT1 on BBB and the underlying pathological process associated with the SHH signaling pathway after ICH remain unclear. We established an intracerebral hemorrhagic mouse model by collagenase injection. SRT1720 (a selective agonist of SIRT1) was used to evaluate the effect of SIRT1 on BBB integrity after ICH. SIRT1 expression was reduced in the mouse brain after ICH. SRT1720 attenuated neurobehavioral impairments and brain edema of ICH mouse. After ICH induction, SRT1720 improved BBB integrity and tight junction expressions in the mouse brain. The SHH signaling pathway-related factors smoothened and glioma-associated oncogene homolog-1 were increased with the intervention of SRT1720, while cyclopamine (a specific inhibitor of the SHH signaling pathway) reversed these effects. These findings suggest that SIRT1 protects from ICH by altering BBB permeability and tight junction expression levels. This process is associated with the SHH signaling pathway, suggesting that SIRT1 may be a potential therapeutic target for ICH.

Bi-directional neuro-immune dysfunction after chronic experimental brain injury

BackgroundIt is well established that traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function and that systemic immune changes contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined.MethodsTo further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham (i.e., 90 days post-surgery) congenic donor mice into otherwise healthy, age-matched, irradiated CD45.2 C57BL/6 (WT) hosts. Immune changes were evaluated by flow cytometry, multiplex ELISA, and NanoString technology. Moderate-to-severe TBI was induced by controlled cortical impact injury and neurological function was measured using a battery of behavioral tests.ResultsTBI induced chronic alterations in the transcriptome of BM lineage−c-Kit+Sca1+ (LSK+) cells in C57BL/6 mice, including modified epigenetic and senescence pathways. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI at 8 weeks and 8 months post-reconstitution showed that longer reconstitution periods (i.e., time post-injury) were associated with increased microgliosis and leukocyte infiltration. Pre-treatment with a senolytic agent, ABT-263, significantly improved behavioral performance of aged C57BL/6 mice at baseline, although it did not attenuate neuroinflammation in the acutely injured brain.ConclusionsTBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in hematopoiesis, innate immunity, and neurological function, as well as altered sensitivity to subsequent brain injury.

The Cerebral Protective Effect of Novel Erinacines from Hericium erinaceus Mycelium on In Vivo Mild Traumatic Brain Injury Animal Model and Primary Mixed Glial Cells via Nrf2-Dependent Pathways.

Hericium erinaceus, a consumable mushroom, has shown a potential to enhance the production of neuroprotective bioactive metabolites. Traumatic brain injury (TBI) often leads to cognitive, physical, and psychosocial impairments, resulting in neuroinflammation and the loss of cortical neurons. In this research, the effects of H. erinaceus mycelium, its derivative erinacine C, along with the underlying mechanisms, were examined in terms of oxidative stress modulation and neurological improvement in a rat model of mild traumatic brain injury (mTBI). Male Sprague-Dawley rats were administered diets containing H. erinaceus mycelium and erinacine C following experimental brain injury; these supplements were continued throughout the recovery phase. The binding activity of NF-E2-related factor 2 (Nrf2) near antioxidant genes in mixed glial cells was measured by chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR). The motor beam walking test revealed that dietary supplementation of H. erinaceus mycelium resulted in modest improvements in spatial memory while inhibiting neuron cell death and microglial activation according to brain histological examination. These findings were further corroborated by the upregulation of several antioxidant enzymes (catalase, glutathione reductase, thioredoxin reductase, and superoxide dismutase) and phospho-CAMP-response element-binding (p-CREB) levels in the mTBI model treated with H. erinaceus mycelium. Erinacine C treatment led to significantly reduced brain inflammation and normalization of mTBI-induced deficits through the modulation of the Nrf2 activation pathway and upregulated expression of numerous Nrf2-binding antioxidant genes such as catalase, thioredoxin reductase, superoxide dismutase, and brain-derived neurotrophic factor. This study demonstrates the potential of H. erinaceus mycelium and erinacine C in facilitating recovery following mTBI, including the prevention of neuronal injury and inactivation of microglia through the Nrf2-mediated antioxidant pathway in vivo.

DNA Methylation in Experimental Ischemic Brain Injury

DNA Methylation in Experimental Ischemic Brain Injury

The Role of Inhaled Estradiol and Myrtenol, Alone and in Combination, in Modulating Behavioral and Functional Outcomes Following Traumatic Experimental Brain Injury: Hemodynamic, Molecular, Histological and Behavioral Study.

Traumatic brain injury (TBI) is an important and growing cause of disability worldwide, and its cognitive consequences may be particularly significant. This study assessed the neuroprotective impacts of estradiol (E2), myrtenol (Myr), and the combination of the two on the neurological outcome, hemodynamic parameters, learning and memory, brain-derived neurotrophic factor (BDNF) level, phosphoinositide 3-kinases (PI3K/AKT) signaling, and inflammatory and oxidative factors in the hippocampus after TBI. Eighty-four adult male Wistar rats were randomly divided into 12 groups with seven rats in each (six groups to measure intracranial pressure, cerebral perfusion pressure, brain water content, and veterinary coma scale, and six groups for behavioral and molecular studies): sham, TBI, TBI/vehicle, TBI/Myr, TBI/E2, and TBI/Myr + E2 (Myr 50mg/kg and E2 33.3μg/kg via inhalation for 30min after TBI induction). Brain injury was induced by using Marmarou's method. Briefly, a 300-g weight was dropped down from a 2-m height through a free-falling tube onto the head of the anesthetized animals. Veterinary coma scale, learning and memory, brain water content, intracranial pressure, and cerebral perfusion pressure were impaired following TBI, and inflammation and oxidative stress were raised in the hippocampus after TBI. The BDNF level and PI3K/AKT signaling were impaired due to TBI. Inhalation of Myr and E2 had protective effects against all negative consequences of TBI by decreasing brain edema and the hippocampal content of inflammatory and oxidant factors and also by improving BDNF and PI3K/AKT in the hippocampus. Based on these data, there were no differences between alone and combination administrations. Our results propose that Myr and E2 have neuroprotective effects on cognition impairments due to TBI.

The effect of regulating MCU expression on experimental ischemic brain injury

Mitochondrial calcium uniporter (MCU) is a critical channel for Ca2+ influx into mitochondria. The present study aimed to determine if MCU knockdown has beneficial effects on ischemic brain injury and to explore the underlying mechanisms. The present study demonstrated that MCU knockdown but not total knockout (KO) attenuated ischemia infarction volume and primary cortical neuronal cells' ischemic damage. MCU knockdown maintained mitochondrial ultrastructure, alleviated calcium overload, and reduced mitochondrial apoptosis. Moreover, MCU knockdown regulated the changes of MICU1 and MICU2 after cerebral infarction, while no changes were observed in other mitochondrial calcium handling proteins. Based on metabolomics, MCU knockdown reversed middle cerebral artery occlusion (MCAO)-induced up-regulated phosphoenolpyruvate and down-regulated GDP to protect energy metabolism after cerebral infarction. Furthermore, a total of 87 and 245 differentially expressed genes (DEGs) were detected by transcriptome sequencing among WT mice, MCU KO mice and MCU knockdown mice in the MCAO model, respectively. Then, NR4A1 was identified as one of the DEGs in different MCU expressions in vivo ischemia stroke model via transcriptomic screening and genetic validation. Furthermore, MCU knockdown downregulated the ischemia-induced upregulation of NR4A1 expression. Together, this is the further evidence that the MCU knockdown exerts a protective role after cerebral infarction by promoting calcium homeostasis, inhibiting mitochondrial apoptosis and protecting energy metabolism.

Development of a weight drop injury device suitable for blunt, closed-head injury using a rodent model

The development and characterization of a weight drop injury (WDI) device intended to produce experimental brain injury is presented. This report describes the construction and operation of the in-house developed weight drop injury device which was designed to simulate any severity of TBI. Results show that the device can capture the impact response, providing impact dynamic measurements necessary for injury biomechanics. Furthermore, the injury device is capable of modeling closed head injury loads as seen in literature. Among the design's strengths is its high repeatability and controllability of injury dynamics.

Palmitoylethanolamide attenuates neurodevelopmental delay and early hippocampal damage following perinatal asphyxia in rats.

Impaired gas exchange close to labor causes perinatal asphyxia (PA), a neurodevelopmental impairment factor. Palmitoylethanolamide (PEA) proved neuroprotective in experimental brain injury and neurodegeneration models. This study aimed to evaluate PEA effects on the immature-brain, i.e., early neuroprotection by PEA in an experimental PA paradigm. Newborn rats were placed in a 37°C water bath for 19 min to induce PA. PEA 10 mg/kg, s.c., was administered within the first hour of life. Neurobehavioral responses were assessed from postnatal day 1 (P1) to postnatal day 21 (P21), recording the day of appearance of several reflexes and neurological signs. Hippocampal CA1 area ultrastructure was examined using electron microscopy. Microtubule-associated protein 2 (MAP-2), phosphorylated high and medium molecular weight neurofilaments (pNF H/M), and glial fibrillary acidic protein (GFAP) were assessed using immunohistochemistry and Western blot at P21. Over the first 3 weeks of life, PA rats showed late gait, negative geotaxis and eye-opening onset, and delayed appearance of air-righting, auditory startle, sensory eyelid, forelimb placing, and grasp reflexes. On P21, the hippocampal CA1 area showed signs of neuronal degeneration and MAP-2 deficit. PEA treatment reduced PA-induced hippocampal damage and normalized the time of appearance of gait, air-righting, placing, and grasp reflexes. The outcome of this study might prove useful in designing intervention strategies to reduce early neurodevelopmental delay following PA.

Roles of Rufy3 in experimental subarachnoid hemorrhage-induced early brain injury via accelerating neuronal axon repair and synaptic plasticity

RUN and FYVE domain-containing 3 (Rufy3) is a well-known adapter protein of a small GTPase protein family and is bound to the activated Ras family protein to maintain neuronal polarity. However, in experimental subarachnoid hemorrhage (SAH), the role of Rufy3 has not been investigated. Consequently, we aimed to investigate the potential role of Rufy3 in an in vivo model of SAH-induced early brain injury (EBI). In addition, we investigated the relevant brain-protective mechanisms. Oxyhemoglobin (OxyHb) stimulation of cultured primary neurons simulated vitro SAH condition. The SAH rat model was induced by infusing autologous blood into the optic chiasma pool and treating the rats with lentivirus-negative control 1 (LV-NC1), lentivirus-Rufy3 shRNA (LV-shRNA), lentivirus-negative control 2 (LV-NC2), lentivirus-Rufy3 (LV-Rufy3), or 8-pCPT-2′-O-Me-cAMP (8p-CPT) (Rap1 agonist). In experiment one, we found that the protein level of Rufy3 decreased and neuronal axon injury in the injured neurons but was rectified by LV-Rufy3 treatment. In experiment two, mRNA and protein levels of Rufy3 were downregulated in brain tissue and reached the lowest level at 24 h after SAH. In addition, the expression of Myelin Basic Protein was downregulated and that of anti-hypophosphorylated neurofilament H (N52) was upregulated after SAH. In experiments three and four, Rufy3 overexpression (LV-Rufy3) increased the interactions between Rufy3 and Rap1, the level of Rap1-GTP, and the ratio of Rap1-GTP/total GTP. In addition, LV-Rufy3 treatment inhibited axon injury and accelerated axon repair by activating the Rap1/Arap3/Rho/Fascin signaling pathway accompanied by upregulated protein expression levels of ARAP3, Rho, Fascin, and Facin. LV-Rufy3 also enhanced synaptic plasticity by activating the Rap1/MEK/ERK/synapsin I signaling pathway accompanied by upregulated protein expression levels of ERK1, p-ERK1, MEK1, p-MEK1, synaspin I, and p-synaspin I. Moreover, LV-Rufy3 also alleviated brain damage indicators, including cortical neuronal cell apoptosis and degeneration, brain edema, and cognitive impairment after SAH. However, the downregulation of Rufy3 had the opposite effect and aggravated EBI induced by SAH. Notably, the combined application of LV-Rufy3 and 8p-CPT showed a significant synergistic effect on the aforementioned parameters. Our findings suggest that enhanced Rufy3 expression may reduce EBI by inhibiting axon injury and promoting neuronal axon repair and synaptic plasticity after SAH.

Вплив карбацетаму на когнітивні порушення при експериментальній черепно-мозковій травмі, можлива роль вазопресину

Актуальність. Когнітивні порушення при черепно-мозковій травмі (ЧМТ) є актуальною і не до кінця ви­вченою проблемою, оскільки ступінь пригнічення функціонування центральної нервової системи характеризує тяжкість ЧМТ і визначає її результат. Новий фармакологічний засіб карбацетам належить до анксіолітиків, ендогенних модуляторів ГАМК-бензодіазепінового рецепторного комплексу, похідних β-карболіну. Використання модуляторів ГАМКергічної системи за умов ЧМТ може бути перспективним напрямком корекції когнітивних порушень. Мета дослідження. Визначити вплив карбацетаму на когнітивні порушення при експериментальній черепно-мозковій травмі. Матеріали та методи. Дослідження проведено на 45 білих безпородних щурах-самцях; ЧМТ відтворювали за методикою В.М. Єльського, С.В. Зябліцева (2005). Дослідні групи з ЧМТ становили по 15 тварин: 1-ша група — з уведенням карбацетаму (5 мг/кг маси), 2-га група — з уведенням актовегіну (16 мг/кг маси), група порівняння — з уведенням 1 мл фізіологічного розчину, внутрішньоочеревинно протягом 10 діб після травми. Когнітивні розлади досліджені за методиками: відкрите поле, нірковий рефлекс, восьмирукавний лабіринт через 1, 3, 7, 14 та 30 діб після травми. Результати. У групі порівняння протягом спостереження відзначено різке зменшення кількості пересічених квадратів і оглянутих отворів, що вказувало на повну відсутність мотивації, цікавості та когнітивних здібностей внаслідок ЧМТ. Різке збільшення латентного часу переходу щура до темної камери вказувало на дезорієнтованість тварин і неспроможність знайти нірку (когнітивні порушення). З усіх показників спонтанно відновлювався тільки нірковий рефлекс. Краща динаміка відновлення когнітивних функцій була відмічена у дослідній 1-й групі, де показники орієнтовно-рухової активності починали відновлюватися через тиждень. Через місяць отримано вірогідне (на 41,0 %) збільшення кількості вдалих заходів до рукавів щодо групи порівняння. Відновлення когнітивних процесів у щурів під впливом актовегіну починалося тільки через два тижня після ЧМТ. Через місяць показники орієнтовно-рухової активності у відкритому полі відновлювалися, але не повністю (кількість пересічених квадратів вірогідно збільшилася, але не досягала рівня до травми; p < 0,05). Кількість оглянутих отворів була вірогідно меншою на 23,3 % щодо дослідної 1-ї групи (p < 0,05), що вказувало на вірогідно менший ефект актовегіну щодо карбацетаму. Під впливом карбацетаму відбувалося відновлення секреції вазопресину, що спричиняє антистресорну дію та, нашу думку, обумовлює позитивний вплив препарату на когнітивні та мнестичні функції тварин із ЧМТ. Висновки. Отримані дані вказували на вірогідне відновлення когнітивних і мнестичних процесів у щурів під впливом карбацетаму протягом 30 діб спостереження, що могло бути опосередковано відновленням нейросекреції вазопресину.

DNA methylation in experimental ischemic brain injury

The enrichment of angioneurology with fundamental advances leads to the understanding of new important facets in the pathogenesis of cerebral ischemia. The knowledge of epigenetic mechanisms in the development of stroke, in particular, DNA methylation, which makes a significant contribution to the development and formation of cerebral damage, is becoming more and more relevant. This review reflects an analysis of animal studies proving the relationship of DNA methylation with cerebral ischemia. As a result of the search work, 282 articles from the PubMed database were selected for keywords that corresponded to this topic. Of these publications, 8 studies were devoted to genome-wide DNA methylation, and 6 published the results of DNA methylation of candidate genes in experimental cerebral ischemia. The results have demonstrated that brain DNA methylation in animals is associated with the development of ischemic stroke and may play a role in several pathogenetic mechanisms. In two studies, a decrease in the level of DNA methylation in 2 genes in ischemic brain tissues of laboratory animals was found, at the same time, in four studies, 8 genes, in which methylation increased after ischemic stroke, were reported. These data suggest that the assessment of the level of DNA methylation in stroke is a promising biomarker for the search and improvement of pharmacological and non-pharmacological methods for limiting brain damage in ischemic and reperfusion injury at the stages of preclinical and clinical studies.

Стадии развития синдрома эндогенной интоксикации при экспериментальной черепно-мозговой травме

Актуальность. В исследовании представлен анализ многолетней работы, выполненной под руководством члена-корреспондента НАМНУ, профессора В.Н. Ельского на кафедре патологической физиологии Донецкого национального медицинского университета имени М. Горького, по экспериментальному воспроизведению и анализу синдрома эндогенной интоксикации (СЭИ) при черепно-мозговой травме (ЧМТ). Цель исследования: разработать концепцию стадийности и ключевых механизмов развития СЭИ при ЧМТ. Материалы и методы. Исследование проведено на 555 белых беспородных крысах-самцах; ЧМТ воспроизводили по методике В.Н. Ельского, С.В. Зяблицева (2005). В крови определяли динамику 30 показателей гормонов, метаболитов, иммунологических и других биологически активных веществ; 7 показателей активности ферментов; дополнительно рассчитывали 5 индексов (всего в исследовании изучено 42 показателя). Нарушение функции центральной нервной системы оценивали по методике оценки неврологического дефицита в баллах по показателям уровня сознания, состояния рефлекторной сферы, слуха, мышечного тонуса туловища и конечностей, реакции на свет и боль, дыхания, движения и некоторых поведенческих реакций. Проводили также исследование морфологических показателей повреждения головного мозга. Результаты. Анализ изученных показателей и их соотношений позволил выделить четыре стадии развития СЭИ: реактивно-метаболическую, воспалительно-токсическую, стадию системной эндогенной интоксикации (окончательное развитие СЭИ) и стадию развития полиорганной недостаточности (ПОН). Реактивно-метаболическая стадия характеризовалась: гиперергической реакцией нейроэндокринных систем с катаболическим действием; гипергликемией, гиперинсулинизмом и инсулинорезистентностью; гиперметаболизмом. Воспалительно-токсическая стадия отличалась: выраженной гиперферментемией, указывающей на повреждение клеточных мембран и мембран лизосом; проявлениями эндогенной интоксикации (накопление в крови молекул средней массы и продуктов липопероксидации), генерализованными воспалительными реакциями (увеличение содержания в крови медиаторов воспаления, в том числе IL-1β, TNF-α, IL-6). Стадия системной эндогенной интоксикации выделялась: резким накоплением в крови лактата, что свидетельствовало о присоединении системной гипоксии; резким вторичным приростом молекул средней массы с накоплением низкомолекулярных и ароматических пептидов; резким вторичным приростом провоспалительных цитокинов; активацией ММP-9 и TIMP-1; резким приростом нейрональных белков S100В и NSE, что указывало на прогрессирование повреждения головного мозга. Стадия развития ПОН проявлялась: накоплением в крови мочевины и креатинина, повреждением эритроцитов, миокарда; резким приростом NSE; выявлением в крови большого количества антифосфолипидных антител, что отражало присоединение аутоиммунных процессов. Выводы. Полученные данные позволили разработать концепцию развития СЭИ при ЧМТ и определить ключевые звенья его патогенеза, что может быть использовано для разработки соответствующих мероприятий патогенетического лечения.

Experimental Brain Injury Induced by Acute Hypobaric Hypoxia Stimulates Changes in mRNA Expression and Stress Marker Status

The present study was proposed to investigate the brain injury under acute hypobaric hypoxia following alteration in mRNA expression and stress markers in a time-dependent manner. SD clean graded male rats were randomly divided into four groups for this experimental brain injury, the control group at Xining (altitude, 2270m) and hypoxia treatment groups with different time exposure day1, day2, and day3 at (altitude, 7000m) in a hypobaric chamber. After day3 exposure, the brain tissues were collected. The level of mRNA expression of VEGF and HIF1-α was assessed using qRT-PCR. The oxidative stress level of superoxide dismutase (SOD) and malondialdehyde (MDA) were determined with commercial kits. AHH with time duration significantly increased the MDA level and decreased in the activity of SOD was seen in all hypoxia treated groups as compared to the control (P< 0.001). The mRNA expression level of HIF1-α and VEGF in day1, day2, and day3 AHH groups was markedly raised when it is compared to control (P< 0.05). Ultimately, in conclusion, such results indicate that AHH stimulates oxidative stress induces brain damage in rats. Keywords: Acute hypobaric hypoxia, Brain injury, HIF-1α, Oxidative stress.

Rhamnazin Ameliorates Traumatic Brain Injury in Mice via Reduction in Apoptosis, Oxidative Stress, and Inflammation

Background: Traumatic brain injury (TBI) is posing serious health challenges for people across the globe due to high morbidity and mortality. However, none of the agents prevents or limits the damage caused by TBI because of its multifactorial etiology. Thus, the discovery of novel agents which can act via several pathways could serve the purpose and afford favorable consequence against TBI. Therefore, in the present article, we intended to investigate the protective effect of rhamnazin (RMZ), a dimethoxyflavone against experimentally induced TBI in mice. Methods: The effect of RMZ was investigated on cerebral edema and grip test score after induction of experimental brain injury in rats. The effect of RMZ was also investigated on neuronal degeneration in brain tissues of the experimental mice via Nissl staining and flow cytometry analysis. The expression of Bax and Bcl-2 was also quantified using Western blot analysis. The level of inflammatory cytokines (TNF-α and IL-1β) and oxidative stress markers (malondialdehyde, superoxide dismutase, and glutathione peroxidase) was also determined using enzyme-linked immunosorbent assay. Results: RMZ showed a significant reduction in edema and improved grip strength. It also prevented neuronal degeneration via inhibition of neuronal apoptosis as shown by flow cytometry analysis. RMZ showed an antiapoptotic effect via reduction of Bax and increased the expression of Bcl-2 in Western blot analysis. It also showed to inhibit oxidative stress and inflammation compared to the TBI group. Conclusion: Collectively, our study is first to demonstrate the protective effect of RMZ against experimentally induced TBI in rats.

Combined Use of Magnesium Sulfate and Fingolimod for Antenatal Neuroprotection against Inflammation-Mediated Experimental Preterm Brain Injury in a Rat Model

Background We compared the neuroprotective effects of Fingolimod (fng), a neuroprotective and anti-inflammatory drug, with that of magnesium sulfate (MgSO4), alone and in combination, in fetal rat whose mothers were exposed to endotoxin. Method Seven groups of pregnant rats (28 total) were evaluated at 0.8 gestation – Group1 – saline only; 2 – endotoxin only; 3 – endotoxin + MgSO4; 4 – endotoxin + fng; 5 – endotoxin + MgSO4 + fng; 6 – saline + fng; 7 – saline + MgSO4 + fng. Preterm labor was induced 4 h after intraperitoneal endotoxin administration. Fetal brain samples were examined immunohistochemically using S100β, IL-6, and IL-10. Results Endotoxin caused increased expression of S100β, IL-6, and IL-10. Compared with MgSO4 alone, combined treatment was associated with lower expression of IL-10, IL-6 and S100 β. Conclusion Fng decreases inflammatory markers after in-utero exposure to endotoxin, has a synergistic effect combined with MgSO4, and may be a candidate neuroprotective drug for inflammation-induced preterm brain injury.

An update on the rod microglia variant in experimental and clinical brain injury and disease

Contemporary microglia morphologies include ramified, activated and amoeboid, with the morphology of microglia considered highly coupled to the cellular function. Rod microglia are an additional activated microglia variant observed in the ageing, injured and diseased brain. Rod microglia were reported frequently in the early 1900s by neuropathologists in post-mortem cases of general paresis, Alzheimer’s disease and encephalitis, and then remained largely ignored for almost 100 years. Recent reports have renewed interest in rod microglia, most notably after experimental traumatic brain injury. Rod microglia are formed by the narrowing of the soma and retraction of planar processes, which results in the appearance of an elongated, rod-shaped cell. Rod microglia are most commonly observed in the cortex, aligned perpendicular to the dural surface and adjacent to neuronal processes; in the hippocampus, they are aligned perpendicular to hippocampal layers. Furthermore, rod microglia form trains with one another, apical end to basal end. By replicating the process of sketching microscopic observation, rod microglia are re-defined by circumnutation around the long axis. In this update, we summarize the rod microglia variant in clinical and experimental literature and advocate for investigation into mechanisms of rod microglia origin and function.

Spatial Distribution of Neuropathology and Neuroinflammation Elucidate the Biomechanics of Fluid Percussion Injury.

Diffuse brain injury is better described as multi-focal, where pathology can be found adjacent to seemingly uninjured neural tissue. In experimental diffuse brain injury, pathology and pathophysiology have been reported far more lateral than predicted by the impact site. We hypothesized that local thickening of the rodent skull at the temporal ridges serves to focus the intracranial mechanical forces experienced during brain injury and generate predictable pathology. We demonstrated local thickening of the skull at the temporal ridges using contour analysis on magnetic resonance imaging. After diffuse brain injury induced by midline fluid percussion injury (mFPI), pathological foci along the anterior-posterior length of cortex under the temporal ridges were evident acutely (1, 2, and 7 days) and chronically (28 days) post-injury by deposition of argyophilic reaction product. Area CA3 of the hippocampus and lateral nuclei of the thalamus showed pathological change, suggesting that mechanical forces to or from the temporal ridges shear subcortical regions. A proposed model of mFPI biomechanics suggests that injury force vectors reflect off the skull base and radiate toward the temporal ridge, thereby injuring ventral thalamus, dorsolateral hippocampus, and sensorimotor cortex. Surgically thinning the temporal ridge before injury reduced injury-induced inflammation in the sensorimotor cortex. These data build evidence for temporal ridges of the rodent skull to contribute to the observed pathology, whether by focusing extracranial forces to enter the cranium or intracranial forces to escape the cranium. Pre-clinical investigations can take advantage of the predicted pathology to explore injury mechanisms and treatment efficacy.

Experimental diffuse brain injury and a model of Alzheimer's disease exhibit disease-specific changes in sleep and incongruous peripheral inflammation.

Elderly populations (≥65years old) have the highest risk of developing Alzheimer's disease (AD) and/or obtaining a traumatic brain injury (TBI). Using translational mouse models, we investigated sleep disturbances and inflammation associated with normal aging, TBI and aging, and AD. We hypothesized that aging results in marked changes in sleep compared with adult mice, and that TBI and aging would result in sleep and inflammation levels similar to AD mice. We used female 16-month-old wild-type (WT Aged) and 3xTg-AD mice, as well as a 2-month-old reference group (WT Adult), to evaluate sleep changes. WT Aged mice received diffuse TBI by midline fluid percussion, and blood was collected from both WT Aged (pre- and post-TBI) and 3xTg-AD mice to evaluate inflammation. Cognitive behavior was tested, and tissue was collected for histology. Bayesian generalized additive and mixed-effects models were used for analyses. Both normal aging and AD led to increases in sleep compared with adult mice. WT Aged mice with TBI slept substantially more, with fragmented shorter bouts, than they did pre-TBI and compared with AD mice. However, differences between WT Aged and 3xTg-AD mice in immune cell populations and plasma cytokine levels were incongruous, cognitive deficits were similar, and cumulative sleep was not predictive of inflammation or behavior for either group. Our results suggest that in similarly aged individuals, TBI immediately induces more profound sleep alterations than in AD, although both diseases likely include cognitive impairments. Unique pathological sleep pathways may exist in elderly individuals who incur TBI compared with similarly aged individuals who have AD, which may warrant disease-specific treatments in clinical settings.

Research of the functional activity of immunocompetent brain cells on separate occasions after experimental traumatic brain injury

Objective: To investigate the functional activity of microglia and monocytic/macrophage cells on separate occasions after the rat model of experimental brain injury.Materials and methods. The rat model of experimental brain injury was simulated by dropping a load weighing 100 g from a height of 120 cm. Microglia and infiltrating CNS monocytes were isolated from rat brain tissue in a stepwise Percoll cushion. The activity of phagocytic brain cells was determined in the HCT test by the spectrophotometric method. Myeloperoxidase activity was determined in cell lysate by a quantitative spectrophotometric method.Results. It was found that after brain injury there is an increase in the number of microglial / monocyte cells and an increase in spontaneous production of toxic oxygen molecules by these cells, which depends on the duration of injury and the location of the injury. The greatest threefold increase in microglial and monocytic/macrophage cells is determined on the 5th day after brain injury in the hemisphere with a traumatic injury. The maximum increase in spontaneous production of superoxide anion radical by these cells is also determined on the 5th day after brain injury. In contrast, myeloperoxidase activity of this cell population increases as early as 24 h after brain injury and gradually decreases to control values on the 10th day after the injury, which indicates the gradual development of the process.Conclusion. The result of the researches demonstrated that on the 5th day after brain injury microglial and monocytic/macrophage M1 cells of pro-inflammatory phenotype prevail in the inflammation site. Influences on the cellular and molecular mechanisms that regulate the functional responses of microglia/macrophages after brain injury may facilitate the development of future therapeutic interventions aimed at the phenotypic transition of these cells from M1 to M2, which is necessary to improve CNS recovery.

Targeting chronic and evolving neuroinflammation following traumatic brain injury to improve long-term outcomes: insights from microglial-depletion models.

Targeting chronic and evolving neuroinflammation following traumatic brain injury to improve long-term outcomes: insights from microglial-depletion models.