MRTF-A-mediated protection against amyloid-ß-induced neuronal injury correlates with restoring autophagy via miR-1273g-3p/mTOR axis in Alzheimer models.

Myocardia-Related Transcription Factors-A (MRTF-A), which is enriched in the hippocampus and cerebral cortex, has been shown to have a protective function against ischemia hypoxia-induced neuronal apoptosis. However, the function of MRTF-A on ß-amyloid peptide (Aß)-induced neurotoxicity and autophagy dysfunction in Alzheimer's disease is still unclear. This study shows that the expression of MRTF-A in the hippocampus of Tg2576 transgenic mice is reduced, and the overexpression of MRTF-A mediated by lentiviral vectors carrying MRTF-A significantly reduces the accumulation of hippocampal ß-amyloid peptide and reduces cognition defect. Overexpression of MRTF-A inhibits neuronal apoptosis, increases the protein levels of microtubule-associated protein 1 light chain 3-II (MAP1LC3/LC3-II) and Beclin1, reduces the accumulation of SQSTM1/p62 protein, and promotes autophagosomes-Lysosomal fusion in vivo and in vitro. Microarray analysis and bioinformatics analysis show that MRTF-A reverses Aß-induced autophagy impairment by up-regulating miR-1273g-3p level leading to negative regulation of the mammalian target of rapamycin (mTOR), which is confirmed in Aß1-42-treated SH-SY5Y cells. Further, overexpression of MRTF-A reduces Aß1-42-induced neuronal apoptosis. And the effect was abolished by miR-1273g-3p inhibitor or MHY1485 (mTOR agonist), indicating that the protection of MRTF-A on neuronal damage is through targeting miR-1273g-3p/mTOR axis. Targeting this signaling may be a promising approach to protect against Aß-induced neuronal injury.

Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy.

Objectives: Hippocampus-sparing whole-brain radiotherapy (HS-WBRT) using tomotherapy is known to provide a better dose distribution than volumetric-modulated arc therapy but requires an extended irradiation time. The present study aimed to investigate whether irradiation time can be shortened by reducing the modulation factor (MF) without losing the target dose distribution. Methods: Using six tilted computed tomography images in the head area, the planning target volume (PTV) and hippocampal doses, and the irradiation time was investigated with a jaw width of 1 cm, a pitch of 0.200, and the MF changed from 3.0 to 2.6, 2.2, 1.8, and 1.4. Results: No significant changes in the PTV or hippocampus were found with MF in the range from 3.0 to 1.8, but marked deterioration was found with that of 1.4. The irradiation time showed a linear relationship with the MF within the range from 3.0 to 1.8, with 1334, 1158, 986, and 817 s at modulation factors of 3.0, 2.6, 2.2, and 1.8, respectively. However, when the MF was 1.4, the irradiation time was 808 s. Conclusions: When HS-WBRT is performed with a tilted body position and a jaw width of 1 cm, with a MF of 1.8, a favorable balance between dose parameters and irradiation time is achieved, whereas with a MF of 1.4, the quality of the radiotherapy plan deteriorates, and the irradiation time is approximately the same as that with a MF of 1.8.

Resveratrol protects against inorganic arsenic-induced oxidative damage and cytoarchitectural alterations in female mouse hippocampus.

Prolonged inorganic arsenic (iAs) exposure is widely associated with brain damage particularly in the hippocampus via oxidative and apoptotic pathways. Resveratrol (RES) has gained considerable attention because of its benefits to human health. However, its neuroprotective potential against iAs-induced toxicity in CA1 region of hippocampus remains unexplored. Therefore, we investigated the neuroprotective efficacy of RES against arsenic trioxide (As2O3)-induced adverse effects on neuronal morphology, apoptotic markers and oxidative stress parameters in mouse CA1 region (hippocampus). Adult female Swiss albino mice of reproductive maturity were orally exposed to either As2O3 (2 and 4 mg/kg bw) alone or in combination with RES (40 mg/kg bw) for a period of 45 days. After animal sacrifice on day 46, the perfusion fixed brain samples were used for the observation of neuronal morphology and studying the morphometric features. While the freshly dissected hippocampi were processed for biochemical estimation of oxidative stress markers and western blotting of apoptosis-associated proteins. Chronic iAs exposure led to significant decrease in Stratum Pyramidale layer thickness along with reduction in cell density and area of Pyramidal neurons in contrast to the controls. Biochemical analysis showed reduced hippocampal GSH content but no change in total nitrite (NO) levels following iAs exposure. Western blotting showed apparent changes in the expression levels of Bax and Bcl-2 proteins following iAs exposure, however the change was statistically insignificant. Contrastingly, iAs +RES co-treatment exhibited substantial reversal in morphological and biochemical observations. Together, these findings provide preliminary evidence of neuroprotective role of RES on structural and biochemical alterations pertaining to mouse hippocampus following chronic iAs exposure.

Object recognition and Morris water maze to detect cognitive impairment from mild hippocampal damage in rats: A reflection based on the literature and experience.

Object recognition (OR) and the Morris water maze (MWM) are classical tasks widely used to assess memory parameters and deficits in rodents. Learning processes in both tasks involve integrity of the hippocampus and associated regions, and prefrontal cortex connections. Here, we highlight the idea that these classical tests can be used to indicate memory deficits caused by models of disease that affect hippocampal function in rats, and identify some practical issues of OR and MWM, based on the literature and our experience. Additionally, we have shown that the performance of both tasks does not alter blood levels of corticosterone, considering exposure to a single task. Hence, taking into consideration the difficulties and care required during task execution, the infrastructure needed and the training of the experimenter, we suggest that OR and its variations offer minimal manageable stressful conditions, representing an effective and practical tool for hippocampal-related memory assessment of rats. Thus, OR may provide similar information to that of the MWM, despite controversy regarding hippocampus participation in OR and given due differences in the types of memory evaluated and researchers' objectives. We recommend the observation of some important precautions and details, also based on the literature and our own experience.

IL-6 Inhibition Reduces Neuronal Injury in a Murine Model of Ventilator-induced Lung Injury.

Mechanical ventilation is a known risk factor for delirium, a cognitive impairment characterized by dysfunction of the frontal cortex and hippocampus. Although IL-6 is upregulated in mechanical ventilation-induced lung injury (VILI) and may contribute to delirium, it is not known whether the inhibition of systemic IL-6 mitigates delirium-relevant neuropathology. To histologically define neuropathological effects of IL-6 inhibition in an experimental VILI model, VILI was simulated in anesthetized adult mice using a 35 cc/kg tidal volume mechanical ventilation model. There were two control groups, as follow: 1) spontaneously breathing or 2) anesthetized and mechanically ventilated with 10 cc/kg tidal volume to distinguish effects of anesthesia from VILI. Two hours before inducing VILI, mice were treated with either anti-IL-6 antibody, anti-IL-6 receptor antibody, or saline. Neuronal injury, stress, and inflammation were assessed using immunohistochemistry. CC3 (cleaved caspase-3), a neuronal apoptosis marker, was significantly increased in the frontal (P < 0.001) and hippocampal (P < 0.0001) brain regions and accompanied by significant increases in c-Fos and heat shock protein-90 in the frontal cortices of VILI mice compared with control mice (P < 0.001). These findings were not related to cerebral hypoxia, and there was no evidence of irreversible neuronal death. Frontal and hippocampal neuronal CC3 were significantly reduced with anti-IL-6 antibody (P < 0.01 and P < 0.0001, respectively) and anti-IL-6 receptor antibody (P < 0.05 and P < 0.0001, respectively) compared with saline VILI mice. In summary, VILI induces potentially reversible neuronal injury and inflammation in the frontal cortex and hippocampus, which is mitigated with systemic IL-6 inhibition. These data suggest a potentially novel neuroprotective role of systemic IL-6 inhibition that justifies further investigation.

Ischemia-Reperfusion under Hyperthermia Increases Heme Oxygenase-1 in Pyramidal Neurons and Astrocytes with Accelerating Neuronal Loss in Gerbil Hippocampus.

It has been studied that the damage or death of neurons in the hippocampus is different according to hippocampal subregions, cornu ammonis 1-3 (CA1-3), after transient ischemia in the forebrain, showing that pyramidal neurons located in the subfield CA1 (CA1) are most vulnerable to this ischemia. Hyperthermia is a proven risk factor for brain ischemia and can develop more severe and extensive brain damage related with mortality rate. It is well known that heme oxygenase-1 (HO-1) activity and expression is increased by various stimuli in the brain, including hyperthermia. HO-1 can be either protective or deleterious in the central nervous system, and its roles depend on the expression levels of enzymes. In this study, we investigated the effects of hyperthermia during ischemia on HO-1 expression and neuronal damage/death in the hippocampus to examine the relationship between HO-1 and neuronal damage/death following 5-min transient ischemia in the forebrain using gerbils. Gerbils were assigned to four groups: (1) sham-operated gerbils with normothermia (Normo + sham group); (2) ischemia-operated gerbils with normothermia (Normo + ischemia group); (3) sham-operated gerbils with hyperthermia (39.5 ± 0.2 °C) during ischemia (Hyper + sham group); and (4) ischemia-operated gerbils with hyperthermia during ischemia (Hyper + ischemia group). HO-1 expression levels in CA1-3 of the Hyper + ischemia group were significantly higher than those in the Normo + ischemia group. HO-1 immunoreactivity in the Hyper + ischemia group was significantly increased in pyramidal neurons and astrocytes with time after ischemia, and the immunoreactivity was significantly higher than that in the Normo + ischemia group. In the Normo + Ischemia group, neuronal death was shown in pyramidal neurons located only in CA1 at 5 days after ischemia. However, in the Hyper + ischemia group, pyramidal neuronal death occurred in CA1-3 at 2 days after ischemia. Taken together, our findings showed that brain ischemic insult during hyperthermic condition brings up earlier and severer neuronal damage/death in the hippocampus, showing that HO-1 expression in neurons and astrocytes is different according to brain subregions and temperature condition. Based on these findings, we suggest that hyperthermia in patients with ischemic stroke must be taken into the consideration in the therapy.

Inhibition of PTEN Ameliorates Secondary Hippocampal Injury and Cognitive Deficits after Intracerebral Hemorrhage: Involvement of AKT/FoxO3a/ATG-Mediated Autophagy.

Spontaneous intracerebral hemorrhage (ICH) commonly causes secondary hippocampal damage and delayed cognitive impairments, but the mechanisms remain elusive. Here, we sought to identify the molecular mechanisms underlying these hemorrhagic outcomes in a rat autologous blood model of ICH. First, a significant increase in phosphatase and tensin homolog (PTEN) expression was observed in nonhemorrhagic ipsilateral hippocampus. However, systemic administration of PTEN inhibitor BPV or hippocampal injection of PTEN siRNA could prevent hippocampal neuronal injury and cognitive dysfunctions after ICH. Furthermore, we also found that ICH robustly triggered autophagic neuronal death in the ipsilateral hippocampus, but which were strongly reduced by PTEN knockdown. Notably, suppression of autophagy effectively attenuated poststroke hippocampal inflammation, neuronal damage, and cognitive decline, suggesting the beneficial effects of PTEN deletion was associated with autophagy inactivation. Specifically, PTEN antagonized the PI3K/AKT signaling and downstream effector FoxO3a phosphorylation and subsequently enhanced nuclear translocation of FoxO3a to drive proautophagy gene program, but these changes were diminished upon PTEN inhibition. More importantly, lentivirus-mediated FoxO3a overexpression apparently abrogated the antiauotphagy effect of PTEN deletion via enhancing autophagy-related gene (ATG) transcription. Collectively, these results suggest that knockdown of PTEN alleviated progressive hippocampal injury and cognitive deficits by suppression of autophagy induction involving the AKT/FoxO3a/ATG axis after ICH. Thus, this study provides a novel and promising therapeutic target for the treatment of hemorrhagic stroke.

Brain injury after 50 h of lung-protective mechanical ventilation in a preclinical model.

Mechanical ventilation is the cornerstone of the Intensive Care Unit. However, it has been associated with many negative consequences. Recently, ventilator-induced brain injury has been reported in rodents under injurious ventilation settings. Our group wanted to explore the extent of brain injury after 50 h of mechanical ventilation, sedation and physical immobility, quantifying hippocampal apoptosis and inflammation, in a normal-lung porcine study. After 50 h of lung-protective mechanical ventilation, sedation and immobility, greater levels of hippocampal apoptosis and neuroinflammation were clearly observed in the mechanically ventilated group, in comparison to a never-ventilated group. Markers in the serum for astrocyte damage and neuronal damage were also higher in the mechanically ventilated group. Therefore, our study demonstrated that considerable hippocampal insult can be observed after 50 h of lung-protective mechanical ventilation, sedation and physical immobility.

Chronic Treatment of Ascorbic Acid Leads to Age-Dependent Neuroprotection against Oxidative Injury in Hippocampal Slice Cultures.

Increased oxidative damage in the brain, which increases with age, is the cause of abnormal brain function and various diseases. Ascorbic acid (AA) is known as an endogenous antioxidant that provides neuronal protection against oxidative damage. However, with aging, its extracellular concentrations and uptake decrease in the brain. Few studies have dealt with age-related functional changes in the brain to sustained ascorbate supplementation. This study aimed to investigate the susceptibility of hippocampal neurons to oxidative injury following acute and chronic AA administration. Oxidative stress was induced by kainic acid (KA, 5 µM) for 18 h in hippocampal slice cultures. After KA exposure, less neuronal cell death was observed in the 3 w cultured slice compared to the 9 w cultured slice. In the chronic AA treatment (6 w), the 9 w-daily group showed reduced neuronal cell death and increased superoxide dismutase (SOD) and Nrf2 expressions compared to the 9 w. In addition, the 9 w group showed delayed latencies and reduced signal activity compared to the 3 w, while the 9 w-daily group showed shorter latencies and increased signal activity than the 9 w. These results suggest that the maintenance of the antioxidant system by chronic AA treatment during aging could preserve redox capacity to protect hippocampal neurons from age-related oxidative stress.

Contribution of the hippocampus to performance on the traveling salesperson problem in rats.

The Traveling Salesman Problem (TSP) is an optimization problem in which the subject attempts to find the shortest possible route that passes through a set of fixed locations exactly once. The TSP is used in cognitive and behavioral research to study problem solving and spatial navigation. While the TSP has been studied in some depth from this perspective, the biological mechanisms underlying the behavior have not yet been explored. The hippocampus is a structure in the brain that is known to be involved in tasks that require spatial memory. Because the TSP requires spatial problem solving, we designed the current study to determine whether the hippocampus is required to find efficient solutions to the TSP, and if so, what role the hippocampus serves. Rats were pretrained on the TSP, which involved learning to retrieve bait from targets in a variety of spatial configurations. Matched for performance, rats were then divided into two groups, receiving either a hippocampal lesion or a control sham surgery. After recovering from surgery, the rats were tested on eight new configurations. A variety of behavioral measures were recorded, including distance travelled, number of revisits, memory span, and latency. The results showed that the sham group outperformed the lesion group on most of these measures. Based on the behavioral data and histological tissue analysis of each group, we determined that the hippocampus is involved in successful performance in the TSP, particularly regarding memory for which targets have already been visited.

Altered hippocampal-prefrontal functional network integrity in adult macaque monkeys with neonatal hippocampal lesions.

The dorsolateral prefrontal cortex (DLPFC) and ventral lateral prefrontal cortex (VLPFC) play critical but different roles in working memory (WM) processes. Resting-state functional MRI (rs-fMRI) was employed to investigate the effects of neonatal hippocampal lesions on the functional connectivity (FC) between the hippocampus (H) and the DLPFC and VLPFC and its relation to WM performance in adult monkeys. Adult rhesus monkeys with neonatal H lesions (Neo-H, n = 5) and age- and gender-matched sham-operated monkeys (Neo-C, n = 5) were scanned around 10 years of age. The FC of H-DLPFC and H-VLPFC in Neo-H monkeys was significantly altered as compared to controls, but also switched from being positive in the Neo-C to negative in the Neo-H. In addition, the altered magnitude of FC between right H and bilateral DLPFC was significantly associated with the extent of the hippocampal lesions. In particular, the effects of neonatal hippocampal lesion on FC appeared to be selective to the left hemisphere of the brain (i.e. asymmetric in the two hemispheres). Finally, FC between H and DLPFC correlated with WM task performance on the SU-DNMS and the Obj-SO tasks for the control animals, but only with the H-VLPFC and SU-DNMS task for the Neo-H animals. In conclusion, the present rsfMRI study revealed that the neonatal hippocampal lesions significantly but differently altered the integrity in the functional connectivity of H-DLPFC and H-VLPFC. The similarities between the behavioral, cognitive and neural alterations in Neo-H monkeys and Schizophrenia (SZ) patients provide a strong translational model to develop new therapeutic tools for SZ.

Reactive pericytes in early phase are involved in glial activation and late-onset hypersusceptibility to pilocarpine-induced seizures in traumatic brain injury model mice.

In this study, among neurovascular unit (NVU) cells, we focused on pericyte reactivity in mice subjected to controlled cortical impact (CCI) to understand how traumatic brain injury (TBI) causes uncoordinated crosstalk in the NVU and alters neuronal activity. Histological analyses of brain pericytes, microglia and astrocytes were performed for up to 28 days after CCI in the injured ipsilateral hippocampus. To evaluate altered neuronal activity caused by CCI, we measured seizure susceptibility to a sub-threshold dose of pilocarpine on postoperative day 7, 14, 21 and 28. Platelet-derived growth factor receptor (PDGFR) ß immunoreactivity in pericytes significantly increased from 1 h to 4 days after CCI. The expression of Iba1 and GFAP, as markers of microglia and astrocytes, respectively, increased from 4 to 28 days after CCI. The severity of seizure induced by pilocarpine gradually increased, becoming significant at 28 days after CCI. Then, we treated CCI mice with an inhibitor of PDGFR signaling, imatinib, during the postoperative day 0-4 period. Imatinib lowered seizure susceptibility to pilocarpine and suppressed microglial activation in the injured hippocampus at postoperative day 28. These findings indicate that brain pericytes with rapidly increased PDGFRß expression may drive TBI-induced dysregulation of NVU function and brain hyperexcitability.

Exercise reverses learning deficits induced by hippocampal injury by promoting neurogenesis.

Hippocampal atrophy and cognitive decline are common sequelae of many neurodegenerative disorders, including stroke. To determine whether cognitive decline can be ameliorated by exercise-induced neurogenesis, C57BL/6 mice in which a unilateral hippocampal injury had been induced by injecting the vasoconstrictor endothelin-1 into their right hippocampus, were run voluntarily for 21 days on a running-wheel. We found the severe deficits in spatial learning, as detected by active place-avoidance task, following injury were almost completely restored in animals that ran whereas those that did not run showed no improvement. We show the increase in neurogenesis found in both the injured and contralateral hippocampi following running was responsible for the restoration of learning since bilateral ablation of newborn doublecortin (DCX)-positive neurons abrogated the cognitive improvement, whereas unilateral ablations of DCX-positive neurons did not prevent recovery, demonstrating that elevated neurogenesis in either the damaged or intact hippocampus is sufficient to reverse hippocampal injury-induced deficits.

[Inflammatory mechanism of hippocampal tissue injury induced by PM2.5 in nasal drip in mice].

Objective: To investigate the inflammatory mechanism of nasal instillation of fine particulate matter (PM2.5)on hippocampal tissue injury in mice.Methods: Thirty C57BL/6J mice were randomly divided into 3 groups(n=10):control group, low-dose group, high-dose group. The nasal instillation doses of PM2.5 in the low-dose group and the high-dose group were 1.5 mg/kg BW and 7.5 mg/kg BW, respectively, and the control group was given saline with an equal volume. Saline was sprayed once every other time for 12 times. The serum levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) were determined by ELISA method. HE staining and electron microscopy were used to observe the pathological changes and ultrastructure of lung tissue and hippocampus. The inflammatory cytokine levels in hippocampus were detected by antibody chip technique. Results: There was no significant effect of PM2.5 nasal instillation on serum TNF-α, IL-1ß and IL-6 levels (P＞0.05), and there was no obvious pathological changes in lung tissue structure. In hippocampus, low-dose and high-dose PM2.5 exposure could lead to disordered neuronal arrangement in the hippocampal CA3 region, and there were neurological changes around the neuron cells and ultrastructural changes such as edema around small blood vessels. Compared with the control group, the levels of inflammatory cytokines such as CX3CL1, CSF2 and TECK in the low-dose group were increased significantly (P ＜0.05), while sTNFR1 was decreased significantly (P＜0.05); the inflammatory factors CX3CL1, CSF2, and TCA-3 were significantly increased in the high-dose group (P＜0.05), while leptin, MIG, and FASLG were significantly decreased (P＜0.05). Conclusion: Nasal instillation of PM2.5 can induce tissue damage in the hippocampus of mice, and its mechanism of action may be the olfactory brain pathway. The increasing of TNF-α and IL-6 and the decreasing of sTNFR1 and FASLG may be involved in inflammatory mechanisms.

Lycopene ameliorates chronic stress-induced hippocampal injury and subsequent learning and memory dysfunction through inhibiting ROS/JNK signaling pathway in rats.

The natural carotenoid lycopene (LYC) has strong antioxidant and neuroprotective capacities. This study investigated the effects and mechanisms of LYC on chronic stress-induced hippocampal lesions and learning and memory dysfunction. Rats were administered LYC and/or chronic restraint stress (CRS) for 21 days. Morris water maze results demonstrated that LYC prevented CRS-induced learning and memory dysfunction. Histopathological staining and transmission electron microscopy observation revealed that LYC ameliorated CRS-induced hippocampal microstructural and ultrastructural damage. Furthermore, LYC alleviated CRS-induced oxidative stress by reducing reactive oxygen species (ROS) production and enhancing antioxidant enzyme activities. LYC also improved CRS-induced hippocampal mitochondrial dysfunction by recovering mitochondrial membrane potential, and complex I (NADH dehydrogenase) and II (succinate dehydrogenase) activities. Moreover, LYC reduced CRS-induced apoptosis via the mitochondrial apoptotic pathway, and decreased the number of terminal deoxynucleotidyl transferase dUTP nick-end-labeled positive cells. Additionally, western blot analysis demonstrated that LYC inhibited CRS-induced activation of the c-Jun N-terminal kinase (JNK) signaling pathway. Correlation analysis indicated that ROS levels, JNK activation, and the mitochondrial apoptotic pathway were positively correlated. Further investigation of the underlying mechanisms revealed that the ROS scavenger N-acetyl-l-cysteine inhibited CRS-induced JNK activation. Furthermore, the JNK inhibitor SP600125 relieved CRS-induced hippocampal mitochondrial dysfunction, apoptosis via the mitochondrial apoptotic pathway, and learning and memory dysfunction. Together, these results suggest that LYC alleviates hippocampal oxidative stress, mitochondrial dysfunction, and apoptosis by inhibiting the ROS/JNK signaling pathway, thereby improving CRS-induced hippocampal injury and learning and memory dysfunction. This study provides a theoretical basis and new therapeutic strategies for the application of LYC to relieve chronic stress encephalopathy.

Effects of Gastrodin against Lead-Induced Brain Injury in Mice Associated with the Wnt/Nrf2 Pathway.

Gastrodin (GAS), the main phenolic glycoside extracted from Gastrodia elata Blume, exhibited potential neuroprotective properties. Here we examined the protective effects of GAS against lead(Pb)-induced nerve injury in mice, and explores its underlying mechanisms. Our research findings revealed that GAS improved behavioral deficits in Pb-exposed mice. GAS reduced the accumulation of p-tau and amyloid-beta (Aß). GAS inhibited Pb-induced inflammation in the brain, as indicated by the decreased levels of pro-inflammatory cytokines, including tumor necrosis factor-a (TNF-α), cyclooxygenase-2 (COX-2). GAS increased the expression levels of NR2A and neurotrophin brain-derived neurotrophic factor (BDNF). GAS inhibited Pb-induced apoptosis of neurons in hippocampus tissue, as indicated by the decreased levels of pro-apoptotic proteins Bax and cleaved caspase-3. Furthermore, the neuroprotective effects of GAS were associated with inhibiting oxidative stress by modulating nuclear factor-erythroid 2-related factor 2 (Nrf2)-mediated antioxidant signaling. GAS supplement activated the Wnt/ß-catenin signaling pathway and reduced the expression of Wnt inhibitor Dickkopf-1 (Dkk-1). Collectively, this study clarified that GAS exhibited neuroprotective property by anti-oxidant, anti-inflammatory and anti-apoptosis effects and its ability to regulate the Wnt/Nrf2 pathway.

Antagonizing effect of icaritin on apoptosis and injury of hippocampal neurocytes induced by amyloid beta via GR/BDNF signaling pathway.

Purpose: Amyloid beta is the main component of senile plaques deposited in the hippocampus of people with Alzheimer's disease (AD), with neurotoxicity and pro-apoptotic characteristics. Icaritin (ICA) has been found to have the properties of plerosis, regeneration, and anti-apoptosis in the neurocytes, its effects on Aß-induced hippocampal neurocytes were studied in this research.Methods: Different concentrations of Aß25-35 were used to treat mouse hippocampal neuron HT22 cells to determine the optimal concentration for constructing AD model; different concentrations of ICA were used to pretreat HT22 cells to explore their effects on cell activity. Cell injury was evaluated by measuring the viability and apoptosis of HT22 cells using MTT assay, and Annexin V/PI and Hoechst 33342 staining, respectively. Western blot and qPCR were performed to detect the expressions of glucocorticoid receptor (GR), brain-derived neurotrophic factor (BDNF), and apoptosis-related factors. Oxidative stress was assessed by the biochemical analysis of Lactate dehydrogenase (LDH) release and superoxidase dismutase (SOD) activity.Results: Aß25-35 inhibited the viability of HT22 cells and the expression of GR and BDNF in HT22 cells in a concentration-dependent manner. ICA at 20 µmol/L (ICA20) the most significantly increased the viability of HT22 cells and the expressions of GR and BDNF in HT22 cells. ICA20 increased viability, inhibited apoptosis and LDH release, promoted SOD activity and the expressions of GR, BDNF and Bcl-2, and inhibited the expressions of Bax and C Caspase-3 in AD. More importantly, shRNA-GR reversed the positive effects of ICA20 on AD.Conclusions: ICA protected hippocampal neurocytes against Aß25-35 via GR/BDNF signaling pathway.

Early experience with hippocampal avoidance whole brain radiation therapy and simultaneous integrated boost for brain metastases.

PURPOSE: Cranial irradiation results in cognitive decline, which is hypothesized to be partially attributable to hippocampal injury and stem cell loss. Recent advances allow for targeted reduction of radiation dose to the hippocampi while maintaining adequate dose coverage to the brain parenchyma and additional increasing dose to brain metastases, a approach called hippocampal avoidance whole brain radiation therapy with a simultaneous integrated boost (HA-WBRT + SIB.) We review our early clinical experience with HA-WBRT + SIB. MATERIALS AND METHODS: We evaluated treatments and clinical outcomes for patients treated with HA-WBRT + SIB between 2014 and 2018. RESULTS: A total of 32 patients (median age, 63.5 years, range 45.3-78.8 years) completed HA-WBRT + SIB. Median follow-up for patients alive at the time of analysis was 11.3 months. The most common histology was non-small cell lung cancer (n = 22). Most patients (n = 25) were prescribed with WBRT dose of 30 Gy with SIB to 37.5 Gy in 15 fractions. Volumetric modulated arc therapy reduced treatment time (p < 0.0001). Median freedom from intracranial progression and overall survival from completion of treatment were 11.4 months and 19.6 months, respectively. Karnofsky Performance Status was associated with improved survival (p = 0.008). The most common toxicities were alopecia, fatigue, and nausea. Five patients developed cognitive impairment, including grade 1 (n = 3), grade 2 (n = 1), and grade 3 (n = 1). CONCLUSION: HA-WBRT + SIB demonstrated durable intracranial disease control with modest side effects and merits further investigation as a means of WBRT toxicity reduction while improving long-term locoregional control in the brain.

Short photoperiod restores ventral subicular lesion-induced deficits in affective and socio-cognitive behavior in male Wistar rats.

Photoperiod (day-length) has enduring effects on an organism's physiological functions like metabolism and behavioral phenotypes including cognition and affect. Circadian rhythm manipulations are potentially effective non-pharmacological strategies in the management of central nervous system insults. In our previous study, we demonstrated the efficacy of short photoperiod regime (SPR; 06/18 hr light-dark cycle) in establishing functional recovery in ventral subicular lesion (VSL) rats. The present study further demonstrates the efficacy of SPR in mitigating anxiety and depression as well as facilitating socio-cognitive behavior in VSL rats. VSL elevated the basal plasma corticosterone levels, increased anxiety, anhedonia, and behavioral despair with decreased self-care. The VSL rats also exhibited a considerable degree of impaired social cognition, in terms of altered social preference and social novelty. Exposure to SPR for 21 days mitigated the anxiety- and depressive-like phenotypes as well as improved social cognition significantly. Thus, the study demonstrated the effectiveness of SPR strategy in reversing most of the behavioral deficits caused by VSL. SPR, perhaps, would have regulated the hypothalamo-pituitary-adrenal axis responsiveness as we observed a decrease in plasma corticosterone levels following SPR in VSL rats. The study implies the need for developing a task-dependent SPR strategy to achieve complete behavioral recovery as the functional demands of each behavior is distinct. In summary, the study highlights the efficacy of photoperiod manipulation as a novel, non-pharmacological approach in mitigating the affective and cognitive deficits associated with neuropsychiatric disorders such as bipolar disorder and Alzheimer's disease wherein circadian rhythm alterations are implicated.

Muscle Injury Induces Postoperative Cognitive Dysfunction.

Postoperative cognitive dysfunction (POCD) is a major complication affecting patients of any age undergoing surgery. This syndrome impacts everyday life up to months after hospital discharge, and its pathophysiology still remains unclear. Translational research focusing on POCD is based on a wide variety of rodent models, such as the murine tibial fracture, whose severity can limit mouse locomotion and proper behavioral assessment. Besides, influence of skeletal muscle injury, a lesion encountered in a wide range of surgeries, has not been explored in POCD occurrence. We propose a physical model of muscle injury in CX3CR1GFP/+ mice (displaying green fluorescent microglial cells) to study POCD, with morphological, behavioral and molecular approaches. We highlighted: alteration of short- and long-term memory after muscle regeneration, wide microglial reactivity in the brain, including hippocampus area, 24 hours after muscle injury, and an alteration of central brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) balance, 28 days after muscle injury. Our results suggest for the first time that muscle injury can have early as well as late impacts on the brain. Our CX3CR1GFP/+ model can also facilitate microglial investigation, more specifically their pivotal role in neuroinflammation and synaptic plasticity, in the pathophysiology of POCD.