Therapeutic efficacy of cinnamein, a component of balsam of Tolu/Peru, in controlled cortical impact mouse model of TBI

Traumatic brain injury (TBI) remains a major health concern which causes long-term neurological disability particularly in war veterans, athletes and young adults. In spite of intense clinical and research investigations, there is no effective therapy to cease the pathogenesis of the disease. It is believed that axonal injury during TBI is potentiated by neuroinflammation and demyelination and/or failure to remyelination. This study highlights the use of naturally available cinnamein, also chemically known as benzyl cinnamate, in inhibiting neuroinflammation, promoting remyelination and combating the disease process of controlled cortical impact (CCI)-induced TBI in mice. Oral delivery of cinnamein through gavage brought down the activation of microglia and astrocytes to decrease the expression of inducible nitric oxide synthase (iNOS), glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (Iba1) in hippocampus and cortex of TBI mice. Cinnamein treatment also stimulated remyelination in TBI mice as revealed by PLP and A2B5 double-labeling, luxol fast blue (LFB) staining and axonal double-labeling for neurofilament and MBP. Furthermore, oral cinnamein reduced the size of lesion cavity in the brain, improved locomotor functions and restored memory and learning in TBI mice. These results suggest a new neuroprotective property of cinnamein that may be valuable in the treatment of TBI.

Bone morphogenetic protein 4 derived from the cerebrospinal fluid in patients with postherpetic neuralgia induces allodynia via the crosstalk between microglia and astrocyte

INTRODUCTION

During postherpetic neuralgia (PHN), the cerebral spinal fluid (CSF) possesses the capability to trigger glial activation and inflammation, yet the specific changes in its composition remain unclear. Recent findings from our research indicate elevations of central bone morphogenetic protein 4 (BMP4) during neuropathic pain (NP), serving as an independent modulator of glial cells. Herein, the aim of the present study is to test the CSF-BMP4 expressions and its role in the glial modulation in the process of PHN.

METHODS

CSF samples were collected from both PHN patients and non-painful individuals (Control) to assess BMP4 and its antagonist Noggin levels. Besides, intrathecal administration of both CSF types was conducted in normal rats to evaluate the impact on pain behavior, glial activity, and inflammation.; Additionally, both Noggin and STAT3 antagonist-Stattic were employed to treat the PHN-CSF or exogenous BMP4 challenged cultured astrocytes to explore downstream signals. Finally, microglial depletion was performed prior to the PHN-CSF intervention so as to elucidate the microglia-astrocyte crosstalk.

RESULTS

BMP4 levels were significantly higher in PHN-CSF compared to Control-CSF (P < 0.001), with a positive correlation with pain duration (P < 0.05, r = 0.502). Comparing with the Control-CSF producing moderate paw withdrawal threshold (PWT) decline and microglial activation, PHN-CSF further exacerbated allodynia and triggered both microglial and astrocytic activation (P < 0.05). Moreover, PHN-CSF rather than Control-CSF evoked microglial proliferation and pro-inflammatory transformation, reinforced iron storage, and activated astrocytes possibly through both SMAD159 and STAT3 signaling, which were all mitigated by the Noggin application (P < 0.05). Next, both Noggin and Stattic effectively attenuated BMP4-induced GFAP and IL-6 upregulation, as well as SMAD159 and STAT3 phosphorylation in the cultured astrocytes (P < 0.05). Finally, microglial depletion diminished PHN-CSF induced astrogliosis, inflammation and endogenous BMP4 expression (P < 0.05).

CONCLUSION

Our study highlights the role of CSF-BMP4 elevation in glial activation and allodynia during PHN, suggesting a potential therapeutic avenue for future exploration.

Changes in the expression of satellite glial cell-specific markers during postnatal development of rat sympathetic ganglia

The sympathetic ganglia represent a final motor pathway that mediates homeostatic "fight and flight" responses in the visceral organs. Satellite glial cells (SGCs) form a thin envelope close to the neuronal cell body and synapses in the sympathetic ganglia. This unique morphological feature suggests that neurons and SGCs form functional units for regulation of sympathetic output. In the present study, we addressed whether SGC-specific markers undergo age-dependent changes in the postnatal development of rat sympathetic ganglia. We found that fatty acid-binding protein 7 (FABP7) is an early SGC marker, whereas the S100B calcium-binding protein, inwardly rectifying potassium channel, Kir4.1 and small conductance calcium-activated potassium channel, SK3 are late SGC markers in the postnatal development of sympathetic ganglia. Unlike in sensory ganglia, FABP7 + SGC was barely detectable in adult sympathetic ganglia. The expression of connexin 43, a gap junction channel gradually increased with age, although it was detected in both SGCs and neurons in sympathetic ganglia. Glutamine synthetase was expressed in sensory, but not sympathetic SGCs. Unexpectedly, the sympathetic SGCs expressed a water-selective channel, aquaporin 1 instead of aquaporin 4, a pan-glial marker. However, aquaporin 1 was not detected in the SGCs encircling large neurons. Nerve injury and inflammation induced the upregulation of glial fibrillary acidic protein, suggesting that this protein is a hall marker of glial activation in the sympathetic ganglia. In conclusion, our findings provide basic information on the in vivo profiles of specific markers for identifying sympathetic SGCs at different stages of postnatal development in both healthy and diseased states.

Onset of Alzheimer disease in apolipoprotein ɛ4 carriers is earlier in butyrylcholinesterase K variant carriers

BACKGROUND

The authors sought to examine the impact of the K-variant of butyrylcholinesterase (BCHE-K) carrier status on age-at-diagnosis of Alzheimer disease (AD) in APOE4 carriers.

METHODS

Patients aged 50-74 years with cerebrospinal fluid (CSF) biomarker-confirmed AD, were recruited to clinical trial (NCT03186989 since June 14, 2017). Baseline demographics, disease characteristics, and biomarkers were evaluated in 45 patients according to BCHE-K and APOE4 allelic status in this post-hoc study.

RESULTS

In APOE4 carriers (N = 33), the mean age-at-diagnosis of AD in BCHE-K carriers (n = 11) was 6.4 years earlier than in BCHE-K noncarriers (n = 22, P < .001, ANOVA). In APOE4 noncarriers (N = 12) there was no observed influence of BCHE-K. APOE4 carriers with BCHE-K also exhibited slightly higher amyloid and tau accumulations compared to BCHE-K noncarriers. A predominantly amyloid, limited tau, and limbic-amnestic phenotype was exemplified by APOE4 homozygotes with BCHE-K. In the overall population, multiple regression analyses demonstrated an association of amyloid accumulation with APOE4 carrier status (P < .029), larger total brain ventricle volume (P < .021), less synaptic injury (Ng, P < .001), and less tau pathophysiology (p-tau181, P < .005). In contrast, tau pathophysiology was associated with more neuroaxonal damage (NfL, P = .002), more synaptic injury (Ng, P < .001), and higher levels of glial activation (YKL-40, P = .01).

CONCLUSION

These findings have implications for the genetic architecture of prognosis in early AD, not the genetics of susceptibility to AD. In patients with early AD aged less than 75 years, the mean age-at-diagnosis of AD in APOE4 carriers was reduced by over 6 years in BCHE-K carriers versus noncarriers. The functional status of glia may explain many of the effects of APOE4 and BCHE-K on the early AD phenotype.

TRIAL REGISTRATION

NCT03186989 since June 14, 2017.

Characterization of pathological changes in the olfactory system of mice exposed to methylmercury

Methylmercury (MeHg) is a well-known environmental neurotoxicant that causes severe brain disorders such as Minamata disease. Although some patients with Minamata disease develop olfactory dysfunction, the underlying pathomechanism is largely unknown. We examined the effects of MeHg on the olfactory system using a model of MeHg poisoning in which mice were administered 30 ppm MeHg in drinking water for 8 weeks. Mice exposed to MeHg displayed significant mercury accumulation in the olfactory pathway, including the nasal mucosa, olfactory bulb, and olfactory cortex. The olfactory epithelium was partially atrophied, and olfactory sensory neurons were diminished. The olfactory bulb exhibited an increase in apoptotic cells, hypertrophic astrocytes, and amoeboid microglia, mainly in the granular cell layer. Neuronal cell death was observed in the olfactory cortex, particularly in the ventral tenia tecta. Neuronal cell death was also remarkable in higher-order areas such as the orbitofrontal cortex. Correlation analysis showed that neuronal loss in the olfactory cortex was strongly correlated with the plasma mercury concentration. Our results indicate that MeHg is an olfactory toxicant that damages the central regions involved in odor perception. The model described herein is useful for analyzing the mechanisms and treatments of olfactory dysfunction in MeHg-intoxicated patients.

Microglial ferroptotic stress causes non-cell autonomous neuronal death

BACKGROUND

Ferroptosis is a form of regulated cell death characterised by lipid peroxidation as the terminal endpoint and a requirement for iron. Although it protects against cancer and infection, ferroptosis is also implicated in causing neuronal death in degenerative diseases of the central nervous system (CNS). The precise role for ferroptosis in causing neuronal death is yet to be fully resolved.

METHODS

To elucidate the role of ferroptosis in neuronal death we utilised co-culture and conditioned medium transfer experiments involving microglia, astrocytes and neurones. We ratified clinical significance of our cell culture findings via assessment of human CNS tissue from cases of the fatal, paralysing neurodegenerative condition of amyotrophic lateral sclerosis (ALS). We utilised the SOD1G37R mouse model of ALS and a CNS-permeant ferroptosis inhibitor to verify pharmacological significance in vivo.

RESULTS

We found that sublethal ferroptotic stress selectively affecting microglia triggers an inflammatory cascade that results in non-cell autonomous neuronal death. Central to this cascade is the conversion of astrocytes to a neurotoxic state. We show that spinal cord tissue from human cases of ALS exhibits a signature of ferroptosis that encompasses atomic, molecular and biochemical features. Further, we show the molecular correlation between ferroptosis and neurotoxic astrocytes evident in human ALS-affected spinal cord is recapitulated in the SOD1G37R mouse model where treatment with a CNS-permeant ferroptosis inhibitor, CuII(atsm), ameliorated these markers and was neuroprotective.

CONCLUSIONS

By showing that microglia responding to sublethal ferroptotic stress culminates in non-cell autonomous neuronal death, our results implicate microglial ferroptotic stress as a rectifiable cause of neuronal death in neurodegenerative disease. As ferroptosis is currently primarily regarded as an intrinsic cell death phenomenon, these results introduce an entirely new pathophysiological role for ferroptosis in disease.

Glial Activation, Mitochondrial Imbalance, and Akt/mTOR Signaling May Be Potential Mechanisms of Cognitive Impairment in Heart Failure Mice

Heart failure (HF) is a major health burden worldwide, with approximately half of HF patients having a comorbid cognitive impairment (CI). However, it is still unclear how CI develops in patients with HF. In the present study, a mice model of heart failure was established by ligating the left anterior descending coronary artery. Echocardiography 1 month later confirmed the decline in ejection fraction and ventricular remodeling. Cognitive function was examined by the Pavlovian fear conditioning and the Morris water maze. HF group cued fear memory, spatial memory, and learning impairment, accompanied by activation of glial cells (astrocytes, microglia, and oligodendrocytes) in the hippocampus. In addition, the mitochondrial biogenesis genes TFAM and SIRT1 decreased, and the fission gene DRP1 increased in the hippocampus. Damaged mitochondria release excessive ROS, and the ability to produce ATP decreases. Damaged swollen mitochondria with altered morphology and aberrant inner-membrane crista were observed under a transmission electron microscope. Finally, Akt/mTOR signaling was upregulated in the hippocampus of heart failure mice. These findings suggest that activation of Akt/mTOR signaling, glial activation, and mitochondrial dynamics imbalance could trigger cognitive impairment in the pathological process of heart failure mice.

TRP Channels in Stroke

Ischemic stroke is a devastating disease that affects millions of patients worldwide. Unfortunately, there are no effective medications for mitigating brain injury after ischemic stroke. TRP channels are evolutionally ancient biosensors that detect external stimuli as well as tissue or cellular injury. To date, many members of the TRP superfamily have been reported to contribute to ischemic brain injury, including the TRPC subfamily (1, 3, 4, 5, 6, 7), TRPV subfamily (1, 2, 3, 4) and TRPM subfamily (2, 4, 7). These TRP channels share structural similarities but have distinct channel functions and properties. Their activation during ischemic stroke can be beneficial, detrimental, or even both. In this review, we focus on discussing the interesting features of stroke-related TRP channels and summarizing the underlying cellular and molecular mechanisms responsible for their involvement in ischemic brain injury.

Neuroimaging biomarkers of glial activation for predicting the annual cognitive function decline in patients with Alzheimer's disease

BACKGROUND

Glial activation is central to the pathogenesis of Alzheimer's disease (AD). However, researchers have not demonstrated its relationship to longitudinal cognitive deterioration. We aimed to compare the prognostic effects of baseline positron emission tomography (PET) imaging of glial activation and amyloid/tau pathology on the successive annual cognitive decline in patients with AD.

METHODS

We selected 17 patients diagnosed with mild cognitive impairment or AD. We assessed the annual changes in global cognition and memory. Furthermore, we assessed the predictive effects of baseline amyloid and tau pathology indicated by cerebrospinal fluid (CSF) concentrations and PET imaging of glial activation (11C-DPA-713-binding potential in the area of Braak 1-3 [11C-DPA-713-BPND]) on global cognition and memory using a stepwise regression analysis.

RESULTS

The final multiple regression model of annual changes in global cognition and memory scores included 11C-DPA-713-BPND as the predictor. The CSF Aβ42/40 ratios and p-tau concentrations were removed from the final model. In stepwise Bayesian regression analysis, the Bayes factor-based model comparison suggested that the best model included 11C-DPA-713-BPND as the predictor of decline in global cognition and memory.

CONCLUSIONS

Translocator protein-PET imaging of glial activation is a stronger predictor of AD clinical progression than the amount of amyloid/tau pathology measured using CSF concentrations. Glial activation is the primary cause of tau-induced neuronal toxicity and cognitive deterioration, thereby highlighting the potential of blocking maladaptive microglial responses as a therapeutic strategy for AD treatment.

Involvement of cannabinoid receptors and neuroinflammation in early sepsis: Implications for posttraumatic stress disorder

Sepsis is associated with several comorbidities in survivors, such as posttraumatic stress disorder (PTSD). This study investigated whether rats that survive sepsis develop the generalization of fear memory as a model of PTSD. Responses to interventions that target the endothelin-1 (ET-1)/cannabinoid system and glial activation in the initial stages of sepsis were evaluated. As a control, we evaluated hyperalgesia before fear conditioning. Sepsis was induced by cecal ligation and puncture (CLP) in Wistar rats. CLP-induced sepsis with one or three punctures resulted in fear generalization in the survivors 13 and 20 days after the CLP procedure, a process that was not associated with hyperalgesia. Septic animals were intracerebroventricularly treated with vehicle, the endothelin receptor A (ETA) antagonist BQ123, the cannabinoid CB1 and CB2 receptor antagonists AM251 and AM630, respectively, and the glial blocker minocycline 4 h after CLP. The blockade of either CB1 or ETA receptors increased the survival rate, but only the former reversed fear memory generalization. The endothelinergic system blockade is important for improving survival but not for fear memory. Treatment with the CB2 receptor antagonist or minocycline also reversed the generalization of fear memory but did not increase the survival rate that was associated with CLP. Minocycline treatment also reduced tumor necrosis factor-α levels in the hippocampus suggesting that neuroinflammation is important for the generalization of fear memory induced by CLP. The influence of CLP on the generalization of fear memory was not related to Arc protein expression, a regulator of synaptic plasticity, in the dorsal hippocampus.

Role of lipocalin 2 in stroke

Stroke is the second leading cause of death worldwide; however, the treatment choices available to neurologists are limited in clinical practice. Lipocalin 2 (LCN2) is a secreted protein, belonging to the lipocalin superfamily, with multiple biological functions in mediating innate immune response, inflammatory response, iron-homeostasis, cell migration and differentiation, energy metabolism, and other processes in the body. LCN2 is expressed at low levels in the brain under normal physiological conditions, but its expression is significantly up-regulated in multiple acute stimulations and chronic pathologies. An up-regulation of LCN2 has been found in the blood/cerebrospinal fluid of patients with ischemic/hemorrhagic stroke, and could serve as a potential biomarker for the prediction of the severity of acute stroke. LCN2 activates reactive astrocytes and microglia, promotes neutrophil infiltration, amplifies post-stroke inflammation, promotes blood-brain barrier disruption, white matter injury, and neuronal death. Moreover, LCN2 is involved in brain injury induced by thrombin and erythrocyte lysates, as well as microvascular thrombosis after hemorrhage. In this paper, we review the role of LCN2 in the pathological processes of ischemic stroke; intracerebral hemorrhage; subarachnoid hemorrhage; and stroke-related brain diseases, such as vascular dementia and post-stroke depression, and their underlying mechanisms. We hope that this review will help elucidate the value of LCN2 as a therapeutic target in stroke.

Endometriosis leads to central nervous system-wide glial activation in a mouse model of endometriosis

BACKGROUND

Chronic pelvic pain (CPP) is a common symptom of endometriosis. Women with endometriosis are also at a high risk of suffering from anxiety, depression, and other psychological disorders. Recent studies indicate that endometriosis can affect the central nervous system (CNS). Changes in the functional activity of neurons, functional magnetic resonance imaging signals, and gene expression have been reported in the brains of rat and mouse models of endometriosis. The majority of the studies thus far have focused on neuronal changes, whereas changes in the glial cells in different brain regions have not been studied.

METHODS

Endometriosis was induced in female mice (45-day-old; n = 6-11/timepoint) by syngeneic transfer of donor uterine tissue into the peritoneal cavity of recipient animals. Brains, spines, and endometriotic lesions were collected for analysis at 4, 8, 16, and 32 days post-induction. Sham surgery mice were used as controls (n = 6/timepoint). The pain was assessed using behavioral tests. Using immunohistochemistry for microglia marker ionized calcium-binding adapter molecule-1 (IBA1) and machine learning "Weka trainable segmentation" plugin in Fiji, we evaluated the morphological changes in microglia in different brain regions. Changes in glial fibrillary acidic protein (GFAP) for astrocytes, tumor necrosis factor (TNF), and interleukin-6 (IL6) were also evaluated.

RESULTS

We observed an increase in microglial soma size in the cortex, hippocampus, thalamus, and hypothalamus of mice with endometriosis compared to sham controls on days 8, 16, and 32. The percentage of IBA1 and GFAP-positive area was increased in the cortex, hippocampus, thalamus, and hypothalamus in mice with endometriosis compared to sham controls on day 16. The number of microglia and astrocytes did not differ between endometriosis and sham control groups. We observed increased TNF and IL6 expression when expression levels from all brain regions were combined. Mice with endometriosis displayed reduced burrowing behavior and hyperalgesia in the abdomen and hind-paw.

CONCLUSION

We believe this is the first report of central nervous system-wide glial activation in a mouse model of endometriosis. These results have significant implications for understanding chronic pain associated with endometriosis and other issues such as anxiety and depression in women with endometriosis.

Identifying clinically useful biomarkers in neurodegenerative disease through a collaborative approach: the NeuroToolKit

BACKGROUND

Alzheimer's disease (AD) is a complex and heterogeneous disease, which requires reliable biomarkers for diagnosis and monitoring disease activity. Preanalytical protocol and technical variability associated with biomarker immunoassays makes comparability of biomarker data across multiple cohorts difficult. This study aimed to compare cerebrospinal fluid (CSF) biomarker results across independent cohorts, including participants spanning the AD continuum.

METHODS

Measured on the NeuroToolKit (NTK) prototype panel of immunoassays, 12 CSF biomarkers were evaluated from three cohorts (ALFA+, Wisconsin, and Abby/Blaze). A correction factor was applied to biomarkers found to be affected by preanalytical procedures (amyloid-β1-42, amyloid-β1-40, and alpha-synuclein), and results between cohorts for each disease stage were compared. The relationship between CSF biomarker concentration and cognitive scores was evaluated.

RESULTS

Biomarker distributions were comparable across cohorts following correction. Correlations of biomarker values were consistent across cohorts, regardless of disease stage. Disease stage differentiation was highest for neurofilament light (NfL), phosphorylated tau, and total tau, regardless of the cohort. Correlation between biomarker concentration and cognitive scores was comparable across cohorts, and strongest for NfL, chitinase-3-like protein-1 (YKL40), and glial fibrillary acidic protein.

DISCUSSION

The precision of the NTK enables merging of biomarker datasets, after correction for preanalytical confounders. Assessment of multiple cohorts is crucial to increase power in future studies into AD pathogenesis.

Activation of Angiotensin-converting Enzyme 2 Protects Against Lipopolysaccharide-induced Glial Activation by Modulating Angiotensin-converting Enzyme 2/Angiotensin (1-7)/Mas Receptor Axis

Neuroinflammation is associated with activation of glial cells and pro-inflammatory arm of the central Renin Angiotensin System (RAS) namely, Angiotensin-Converting Enzyme/Angiotensin II/Angiotensin Type 1 Receptor (ACE/Ang II/AT1R) axis. Apart from this, another axis of RAS also exists, Angiotensin-Converting Enzyme 2/Angiotensin (1-7)/Mas Receptor (ACE2/Ang (1-7)/MasR), which counters ACE/Ang II/AT1R axis by showing anti-inflammatory properties. However, the role of ACE2/Ang (1-7)/MasR axis has not been explored in glial activation and neuroinflammation. Hence, the present study tries to unveil the role of ACE2/Ang (1-7)/MasR axis in lipopolysaccharide (LPS)-induced neuroinflammation using diminazene aceturate (DIZE), an ACE2 activator, in astroglial (C6) and microglial (BV2) cells as well as male SD rats. We found that ACE2 activation efficiently prevented LPS-induced changes by decreasing glial activation, inflammatory signaling, cell migration, ROS generation via upregulation of ACE2/Ang (1-7)/MasR signaling. In addition, activation of ACE2/Ang (1-7)/MasR axis by DIZE significantly suppressed the pro-inflammatory ACE/Ang II/AT1R axis by reducing Ang II level in neuroinflammatory conditions induced by LPS in both in vitro and in vivo. ACE2/Ang (1-7)/MasR axis activation further decreased mitochondrial depolarization and apoptosis, hence providing neuroprotection. Furthermore, to validate that the beneficial effect of the ACE2 activator was indeed through MasR, a selective MasR antagonist (A779) was used that significantly blocked the anti-inflammatory effect of ACE2 activation by DIZE. Hence, our study demonstrated that ACE2 activation imparted neuroprotection by enhancing ACE2/Ang (1-7)/MasR signaling which in turn decreased glial activation, neuroinflammation, and apoptosis and improved mitochondrial health.

Calcium Supplementation Ameliorates Cerebellar Oxidative Stress in Lactational Aluminum-induced Neurotoxicity in Rats

Introduction

The neurotoxic effects of aluminum exposure during the critical period of neurodevelopment have been well documented. This study investigated the known protective effects of calcium supplementation on the cerebellum of juvenile Wistar rats following aluminum-induced neurotoxicity during lactation.

Methods

Four groups of juvenile rats were exposed via lactation to distilled water (control group), aluminum (40 mg/kg/d), calcium supplement (50 mg/kg/d), and a combination of both aluminum and calcium from postnatal day 4 to day 28. The cerebella of the animals were excised to access the levels of antioxidant enzymes (superoxide dismutase [SOD], glutathione peroxidase [GPx]), lipid peroxidation (malondialdehyde), histomorphological alterations (hematoxylin and eosin staining), Nissl profile (cresyl fast violet staining), and glial activation (glial fibrillary acidic protein immunohistochemistry).

Results

Lactational aluminum significantly decreased the activities of superoxide dismutase and glutathione peroxidase while exacerbating lipid peroxidation and reactive astrocyte in cerebellar lysates. Lactational calcium supplementation normalized the activities of SOD and GPx, thereby preventing excessive lipid peroxidation and glial activation. Despite no apparent changes in the general histology of the cerebellum, aluminum-induced chromatolysis changes in the Purkinje cell layer, which was counteracted by the antioxidant propensities of calcium supplementation.

Conclusion

These findings support that calcium supplementation significantly protects the cerebellum against aluminum-induced oxidative stress, chromatolysis, and neuroinflammation.

COVID-19, Oxidative Stress, and Neuroinflammation in the Depression Route

COVID-19 is associated with oxidative stress, peripheral hyper inflammation, and neuroinflammation, especially in individuals with a more severe form of the disease. Some studies provide evidence on the onset or exacerbation of major depressive disorder (MDD), among other psychiatric disorders due to COVID-19. Oxidative stress and neuroinflammation are associated conditions, especially in the more severe form of MDD and in refractoriness to available therapeutic strategies. Inflammatory cytokines in the COVID-19 hyper inflammation process can activate the hypothalamic–pituitary–adrenal (HPA) axis and the indoleamine-2,3-dioxygenase (IDO) enzyme. IDO activation can reduce tryptophan and increase toxic metabolites of the kynurenine pathway, which increases glial activation, neuroinflammation, toxicity, and neuronal death. This review surveyed a number of studies and analyzed the mechanisms of oxidative stress, inflammation, and neuroinflammation involved in COVID-19 and depression. Finally, the importance of more protocols that can help elucidate the interaction between these mechanisms underlying COVID-19 and MDD and the possible therapeutic strategies involved in the interaction of these mechanisms are highlighted.

Central and peripheral effects of environmental enrichment in a mouse model of arthritis

This study analyzed whether environmental enrichment (EE) modulates the nociceptive and inflammatory responses in the mouse model of arthritis induced by Complete Freund's Adjuvant (CFA). Ninety male mice (C57BL/6-JUnib, 4-weeks-old; 20-25 g) were distributed into EE and standard (SE) groups. For EE, mice were kept in bigger cages using an alternation of materials to chew (wood and paper), for nesting (cotton), to use as hiding places (plastic tunnels), and for voluntary exercise (wheel running). Arthritis was induced by an injection of CFA (50 μL) into the right hind paw or saline solution in the control group. Separate groups received the anti-inflammatory drug dexamethasone (0.5 mg/kg; every 48 h). Inflammatory and pain measurements were performed from 1 to 35 days after CFA administration. EE per se reduced the acute paw edema formation and arthritis scores. The serum levels of tumor necrosis factor (TNF) were undetectable in any experimental groups. EE diminished the immunopositivity for the microglia marker IBA1 in the pre-frontal cortex, with slight changes for hippocampal GFAP-positive activated astrocytes. Finally, EE induced a marked increment of brain-derived nerve factor (BDNF) expression in the hippocampus, an effect that was fully prevented by dexamethasone. These data bring novel evidence on the peripheral and central effects of EE in a mouse arthritis model.

Neuroinflammation in Primary Cultures of the Rat Spinal Dorsal Horn Is Attenuated in the Presence of Adipose Tissue-Derived Medicinal Signalling Cells (AdMSCs) in a Co-cultivation Model

Neuroinflammation within the superficial dorsal horn (SDH) of the spinal cord induces inflammatory pain with symptoms of hyperalgesia and allodynia. Glial activation and production of inflammatory mediators (e.g. cytokines) is associated with modulation of nociceptive signalling. In this context, medicinal signalling cells, e.g. obtained from adipose tissue (AdMSCs), gained attention due to their capacity to modulate the inflammatory response in several diseases, e.g. spinal cord injury. We applied the recently established mixed neuroglial primary cell culture of the rat SDH to investigate effects of AdMSCs on the inflammatory response of SDH cells. Following establishment of a co-cultivation system, we performed specific bioassays for tumour necrosis factor alpha (TNFα) and interleukin (IL)-6, RT-qPCR and immunocytochemistry to detect changes in cytokine production and glial activation upon inflammatory stimulation with lipopolysaccharide (LPS). LPS-induced expression and release of pro-inflammatory cytokines (TNFα, IL-6) by SDH cells was significantly attenuated in the presence of AdMSCs. Further evidence for anti-inflammatory capacities of AdMSCs derived from a blunted LPS-induced TNFα/IL-10 expression ratio and suppressed nuclear translocation of the inflammatory transcription factor nuclear factor kappa B (NFκB) in SDH microglial cells. Expression of IL-10, transforming growth factor beta (TGF-β) and TNFα-stimulated gene-6 (TSG-6) was detected in AdMSCs, which are putative candidates for anti-inflammatory capacities of these cells. We present a novel co-cultivation system of AdMSCs with neuroglial primary cultures of the SDH to investigate immunomodulatory effects of AdMSCs at a cellular level.

Neuroinflammation in World Trade Center responders at midlife: A pilot study using [18F]-FEPPA PET imaging

Background

Neuroinflammation has long been theorized to arise from exposures to fine particulate matter and to be modulated when individuals experience chronic stress, both of which are also though to cause cognitive decline in part as a result of neuroinflammation.

Objectives

Hypothesizing that neuroinflammation might be linked to experiences at the World Trade Center (WTC) events, this study explored associations between glial activation and neuropsychological measures including post-traumatic stress disorder (PTSD) symptom severity and WTC exposure duration.

Methods

Translocator protein 18-kDa (TSPO) is overexpressed by activated glial cells, predominantly microglia and astrocytes, making TSPO distribution a putative biomarker for neuroinflammation. Twenty WTC responders completed neuropsychological assessments and in vivo PET brain scan with [¹⁸F]-FEPPA. Generalized linear modeling was used to test associations between PTSD, and WTC exposure duratiioni as the predictor and both global and regional [¹⁸F]-FEPPA total distribution volumes as the outcomes.

Result

Responders were 56.0 ​± ​4.7 years-old, and 75% were police officers on 9/11/2001, and all had at least a high school education. Higher PTSD symptom severity was associated with global and regional elevations in [¹⁸F]-FEPPA binding predominantly in the hippocampus (d ​= ​0.72, P ​= ​0.001) and frontal cortex (d ​= ​0.64, P ​= ​0.004). Longer exposure duration to WTC sites was associated with higher [¹⁸F]-FEPPA binding in the parietal cortex.

Conclusion

Findings from this study of WTC responders at midlife suggest that glial activation is associated with PTSD symptoms, and WTC exposure duration. Future investigation is needed to understand the important role of neuroinflammation in highly exposed WTC responders.

•

We examined the theory that glial activation is associated with 9/11 exposures.

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TSPO-Vt was examined using PET in 20 responders adjusting for TSPO genotype.

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Responders with PTSD had increased TSPO distribution volume in the hippocampus.

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Heavily exposed responders had increased TSPO distribution in the parietal cortex.

N-Acylethanolamine Acid Amidase Inhibition Potentiates Morphine Analgesia and Delays the Development of Tolerance

Opioids are essential drugs for pain management, although long-term use is accompanied by tolerance, necessitating dose escalation, and dependence. Pharmacological treatments that enhance opioid analgesic effects and/or attenuate the development of tolerance (with a desirable opioid-sparing effect in treating pain) are actively sought. Among them, N-palmitoylethanolamide (PEA), an endogenous lipid neuromodulator with anti-inflammatory and neuroprotective properties, was shown to exert anti-hyperalgesic effects and to delay the emergence of morphine tolerance. A selective augmentation in endogenous PEA levels can be achieved by inhibiting N-acylethanolamine acid amidase (NAAA), one of its primary hydrolyzing enzymes. This study aimed to test the hypothesis that NAAA inhibition, with the novel brain permeable NAAA inhibitor AM11095, modulates morphine's antinociceptive effects and attenuates the development of morphine tolerance in rats. We tested this hypothesis by measuring the pain threshold to noxious mechanical stimuli and, as a neural correlate, we conducted in vivo electrophysiological recordings from pain-sensitive locus coeruleus (LC) noradrenergic neurons in anesthetized rats. AM11095 dose-dependently (3-30 mg/kg) enhanced the antinociceptive effects of morphine and delayed the development of tolerance to chronic morphine in behaving rats. Consistently, AM11095 enhanced morphine-induced attenuation of the response of LC neurons to foot-shocks and prevented the attenuation of morphine effects following chronic treatment. Behavioral and electrophysiological effects of AM11095 on chronic morphine were paralleled by a decrease in glial activation in the spinal cord, an index of opioid-induced neuroinflammation. NAAA inhibition might represent a potential novel therapeutic approach to increase the analgesic effects of opioids and delay the development of tolerance.

Reduction of Lewy Body Pathology by Oral Cinnamon

α-Synucleinopathies in a broader sense comprise of several neurodegenerative disorders that primarily include Parkinson's disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). These disorders are well characterized by the accumulation of aggregated insoluble α-synuclein (α-syn) protein known as Lewy bodies. Till date no effective cure is available to reduce the burden of Lewy body. The present investigation underlines the importance of a naturally used spice and flavoring agent viz. cinnamon in reducing α-syn deposits in transgenic mice expressing mutant A53T human α-syn. Upon oral administration, cinnamon markedly reduced the level of insoluble α-syn in nigra, hippocampus and brain stem of A53T mice. We also demonstrated that sodium benzoate (NaB), a metabolite of cinnamon, a widely used food additive and a FDA-approved drug for glycine encephalopathy, was also capable of reducing α-syn deposits in A53T mice. In addition, both cinnamon and NaB treatments showed improvement in their motor and cognitive functions. Glial activation plays an important role in the pathogenesis of various neurodegenerative disorders including PD, DLB and MSA, and we found suppression of microglial and astroglial activation in the nigra of A53T mice upon cinnamon treatment. Moreover, neuroprotective proteins like DJ-1 and Parkin are known to reduce the formation of Lewy bodies in the CNS. Accordingly, we observed upregulation and/or normalization of DJ-1 and Parkin in the nigra of A53T mice by treatment with cinnamon and NaB. Together, these results highlight a new therapeutic property of cinnamon and suggest that cinnamon and NaB may be used to halt the progression of α-synucleinopathies.Graphical Abstract.

Piperine Improves Experimental Autoimmune Encephalomyelitis (EAE) in Lewis Rats Through its Neuroprotective, Anti-inflammatory, and Antioxidant Effects

Inflammation, demyelination, glial activation, and oxidative damage are the most pathological hallmarks of multiple sclerosis (MS). Piperine, a main bioactive alkaloid of black pepper, possesses antioxidant, anti-inflammatory, and neuroprotective properties whose therapeutic potential has been less studied in the experimental autoimmune encephalomyelitis (EAE) models. In this study, the efficiency of piperine on progression of EAE model and myelin repair mechanisms was investigated. EAE was induced in female Lewis rats and piperine and its vehicle were daily administrated intraperitoneally from day 8 to 29 post immunization. We found that piperine alleviated neurological deficits and EAE disease progression. Luxol fast blue and H&E staining and immunostaining of lumbar spinal cord cross sections confirmed that piperine significantly reduced the extent of demyelination, inflammation, immune cell infiltration, microglia, and astrocyte activation. Gene expression analysis in lumbar spinal cord showed that piperine treatment decreased the level of pro-inflammatory cytokines (TNF-α, IL-1β) and iNOS and enhanced IL-10, Nrf2, HO-1, and MBP expressions. Piperine supplementation also enhanced the total antioxidant capacity (FRAP) and reduced the level of oxidative stress marker (MDA) in the CNS of EAE rats. Finally, we found that piperine has anti-apoptotic and neuroprotective effect in EAE through reducing caspase-3 (apoptosis marker) and enhancing BDNF and NeuN expressing cells. This study strongly indicates that piperine has a beneficial effect on the EAE progression and could be considered as a potential therapeutic target for MS treatment. Upcoming clinical trials will provide a deeper understanding of piperine's role for the treatment of the MS.

The Role of Glia in Addiction: Dopamine as a Modulator of Glial Responses in Addiction

Addiction is a chronic and potentially deadly disease considered a global health problem. Nevertheless, there is still no ideal treatment for its management. The alterations in the reward system are the most known pathophysiological mechanisms. Dopamine is the pivotal neurotransmitter involved in neuronal drug reward mechanisms and its neuronal mechanisms have been intensely investigated in recent years. However, neuroglial interactions and their relation to drug addiction development and maintenance of drug addiction have been understudied. Many reports have found that most neuroglial cells express dopamine receptors and that dopamine activity may induce neuroimmunomodulatory effects. Furthermore, current research has also shown that pro- and anti-inflammatory molecules modulate dopaminergic neuron activity. Thus, studying the immune mechanisms of dopamine associated with drug abuse is vital in researching new pathophysiological mechanisms and new therapeutic targets for addiction management.

Early neuroinflammation is associated with lower amyloid and tau levels in cognitively normal older adults

CNS inflammation is a key factor in Alzheimer's Disease (AD), but its relation to pathological Aβ, tau, and APOE4 is poorly understood, particularly prior to the onset of cognitive symptoms. To better characterize early relationships between inflammation, APOE4, and AD pathology, we assessed correlations between cerebrospinal fluid (CSF) inflammatory markers and brain levels of Aβ and tau in cognitively normal older adults. Each participant received a lumbar puncture to collect and quantify CSF levels of TNFα, IL-6, IL-8, and IL-10, a T1-weighted MRI, and PET scanning with [¹⁸F]flortaucipir (FTP; n = 57), which binds to tau tangles and/or [¹⁸F]florbetapir (FBP; n = 58), which binds to Aβ. Parallel voxelwise regressions assessed relationships between each CSF inflammatory marker and FTP and FBP SUVR, as well as APOE4*CSF inflammation interactions. Unexpectedly, we detected significant negative associations between regional Aβ and tau PET uptake and CSF inflammatory markers. For Aβ PET, we detected negative associations with CSF IL-6 and IL-8 in regions known to show early accumulation of Aβ (i.e. lateral and medial frontal lobes). For tau PET, negative relationships were observed with CSF TNFα and IL-8, predominantly in regions known to exhibit early tau accumulation (i.e. medial temporal lobe). In subsequent analyses, significant interactions between APOE4 status and IL-8 on Aβ and tau PET levels were observed in spatially distinct regions from those showing CSF-Aβ/tau relationships. Results from the current cross-sectional study support previous findings that neuroinflammation may be protective against AD pathology at a given stage of the disease, and extend these findings to a cognitively normal aging population. This study provides new insight into a dynamic relationship between neuroinflammation and AD pathology and may have implications for whom and when neuroinflammatory therapies may be appropriate.

OTULIN is a new target of EA treatment in the alleviation of brain injury and glial cell activation via suppression of the NF-κB signalling pathway in acute ischaemic stroke rats

OBJECTIVE

Ovarian tumour domain deubiquitinase with linear linkage specificity (OTULIN) is a potent negative regulator of the nuclear factor-κB (NF-κB) signalling pathway, and it plays a strong neuroprotective role following acute ischemic stroke. Electroacupuncture (EA) is an effective adjuvant treatment for reducing brain injury and neuroinflammation via the inhibition of NF-κB p65 nuclear translocation, but the underlying mechanism is not clear. The present study investigated whether OTULIN was necessary for EA to mitigate brain injury and glial cell activation in a transient middle cerebral artery occlusion (tMCAO) model in rats.

METHODS

An acute ischaemic stroke model was established via tMCAO surgery in Sprague-Dawley (SD) rats. EA was performed once daily at "Baihui (GV 20)", "Hegu (LI 4)", and "Taichong (LR 3)" acupoints. The effect of EA on the spatiotemporal expression of OTULIN in the ischaemic penumbra of the cerebral cortex was detected within 7 days after reperfusion. The effects of OTULIN gene silencing on EA neurological deficits, cerebral infarct volume, neuronal damage, the activation of microglia and astrocytes, the contents of tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6), and the expression of p-IκBa, IκBa and nucleus/cytoplasm NF-κB p65 protein were assessed.

RESULTS

EA treatment increased endogenous OTULIN expression, which peaked at 48 h. Enhanced OTULIN was primarily located in neurons, but a small amount of OTULIN was detected in microglia. OTULIN silencing obviously reversed EA neuroprotection, which was demonstrated by worsened neurobehavioural performance, cerebral infarct volume and neuronal injury. The inhibitory effect of EA on the NF-κB pathway was also attenuated by enhanced IκBα phosphorylation and NF-κB p65 nuclear translocation. EA partially inhibited the transformation of microglia and astrocytes from resting states to activated states and reduced the secretion of TNF-α, IL-1β and IL-6. However, these preventive effects were reversed after the silencing of OTULIN expression.

CONCLUSIONS

OTULIN provides a new potential therapeutic target for EA to alleviate acute ischaemic stroke-induced brain injury and the activation of glial cells, which are related to suppression of the NF-κB signalling pathway.

Therapeutic effects of peripherally administrated neural crest stem cells on pain and spinal cord changes after sciatic nerve transection

BACKGROUND

Severe peripheral nerve injury significantly affects patients' quality of life and induces neuropathic pain. Neural crest stem cells (NCSCs) exhibit several attractive characteristics for cell-based therapies following peripheral nerve injury. Here, we investigate the therapeutic effect of NCSC therapy and associated changes in the spinal cord in a sciatic nerve transection (SNT) model.

METHODS

Complex sciatic nerve gap injuries in rats were repaired with cell-free and cell-laden nerve scaffolds for 12 weeks (scaffold and NCSC groups, respectively). Catwalk gait analysis was used to assess the motor function recovery. The mechanical withdrawal threshold and thermal withdrawal latency were used to assess the development of neuropathic pain. Activation of glial cells was examined by immunofluorescence analyses. Spinal levels of extracellular signal-regulated kinase (ERK), NF-κB P65, brain-derived neurotrophic factor (BDNF), growth-associated protein (GAP)-43, calcitonin gene-related peptide (CGRP), and inflammation factors were calculated by western blot analysis.

RESULTS

Catwalk gait analysis showed that animals in the NCSC group exhibited a higher stand index and Max intensity At (%) relative to those that received the cell-free scaffold (scaffold group) (p < 0.05). The mechanical and thermal allodynia in the medial-plantar surface of the ipsilateral hind paw were significantly relieved in the NCSC group. Sunitinib (SNT)-induced upregulation of glial fibrillary acidic protein (GFAP) (astrocyte) and ionized calcium-binding adaptor molecule 1 (Iba-1) (microglia) in the ipsilateral L4-5 dorsal and ventral horn relative to the contralateral side. Immunofluorescence analyses revealed decreased astrocyte and microglia activation. Activation of ERK and NF-κB signals and expression of transient receptor potential vanilloid 1 (TRPV1) expression were downregulated.

CONCLUSION

NCSC-laden nerve scaffolds mitigated SNT-induced neuropathic pain and improved motor function recovery after sciatic nerve repair. NCSCs also protected the spinal cord from SNT-induced glial activation and central sensitization.

Cytokine profile and glial activation following brachial plexus roots avulsion injury in mice

Inflammation and tissue infiltration by various immune cells play a significant role in the pathogenesis of neurons suffering the central nervous systems diseases. Although brachial plexus root avulsion (BPRA) leads to dramatic motoneurons (MNs) death and permanent loss of function, however, the knowledge gap on cytokines and glial reaction in the spinal cord injury is still existing. The current study is sought to investigate the alteration of specific cytokine expression patterns of the BPRA injured spinal cord during an acute and subacute period. The cytokine assay, transmission electron microscopy, and histological staining were utilized to assess cytokine network alteration, ultrastructure morphology, and glial activation and MNs loss within two weeks post-injury on a mouse unilateral BPRA model. The BPRA injury caused a progressively spinal MNs loss, reduced the alpha-(α) MNs synaptic inputs, whereas enhanced glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule-1 (IBA-1), F4/80 expression in ipsilateral but not the contralateral spinal segments. Additionally, cytokine assays revealed BPRA significantly altered the level of CXCL1, ICAM1, IP10, MCP-5, MIP1-α, and CD93. Notably, the elevated MIP1-α was mainly expressed in the injured spinal MNs. While the re-distribution of CD93 expression, from the cytoplasm to the nucleus, occasionally occurred at neurons of the ipsilateral spinal segment after injury. Overall, these findings suggest that the inflammatory cytokines associated with glial cell activation might contribute to the pathophysiology of the MNs death caused by nerve roots injury.

Involvement of Indoleamine-2,3-Dioxygenase and Kynurenine Pathway in Experimental Autoimmune Encephalomyelitis in Mice

The experimental autoimmune encephalomyelitis (EAE) is a model that mimics multiple sclerosis in rodents. Evidence has suggested that the activation of indoleamine-2,3-dioxygenase (IDO), the rate-limiting enzyme in the kynurenine pathway (KP), plays a crucial role in inflammation-related diseases. The present study aimed to investigate the involvement of the inflammatory process and KP components in a model of EAE in mice. To identify the role of KP in EAE pathogenesis, mice received IDO inhibitor (INCB024360) at a dose of 200 mg/kg (per oral) for 25 days. We demonstrated that IDO inhibitor mitigated the clinical signs of EAE, in parallel with the reduction of cytokine levels (brain, spinal cord, spleen and lymph node) and ionized calcium-binding adaptor protein-1 (Iba-1) gene expression in the central nervous system of EAE mice. Besides, IDO inhibitor causes a significant decrease in the levels of tryptophan, kynurenine and neurotoxic metabolites of KP, such as 3-hydroxykynurenine (3-HK) and quinolinic acid (QUIN) in the prefrontal cortex, hippocampus, spinal cord, spleen and lymph node of EAE mice. The mRNA expression and enzyme activity of IDO and kynurenine 3-monooxygenase (KMO) were also reduced by IDO inhibitor. These findings indicate that the inflammatory process concomitant with the activation of IDO/KP is involved in the pathogenic mechanisms of EAE. The modulation of KP is a promising target for novel pharmacological treatment of MS.

Chlorzoxazone exhibits neuroprotection against Alzheimer's disease by attenuating neuroinflammation and neurodegeneration in vitro and in vivo

Alzheimer's disease (AD), a complex and an age-related brain disease, is induced by the accumulation of amyloid beta (Aβ) and neuroinflammation. Chlorzoxazone (CZ) is a classical FDA-approved drug, and shows anti-inflammatory effects. However, up until now, its regulatory role in AD has not been investigated. Therefore, in this study we attempted to explore if CZ could be an effective therapeutic strategy for AD treatment. At first, the in vitro study was performed to mimic AD using Aβ. We found that Aβ caused p65 nuclear translocation in both primary microglial cells and astrocytes, which were, however, restrained by CZ treatments. Meanwhile, CZ incubation markedly decreased the expression of pro-inflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β). Aβ deposition was also markedly reduced in glial cells treated with CZ. Importantly, we found that glial activation and its-related pro-inflammation induced by Aβ led to obvious neurodegeneration and neuroinflammation, which were effectively attenuated by CZ pre-treatment in the isolated primary cortical neurons. Then, the in vivo study was performed using APP/PS1 mice with AD. Behavior tests showed that CZ administration effectively improved cognitive deficits in AD mice. Neuron death in hippocampus of AD mice was also inhibited by CZ. Aβ accumulation in brain was markedly decreased in CZ-treated AD mice. We finally found that hippocampal glial activation in AD mice was obviously blocked by CZ supplementation, along with remarkable decreases in TNF-α, IL-1β and p65 nuclear translocation. Together, these findings above demonstrated that CZ could inhibit glial activation and inflammatory response, contributing to the suppression of neurodegeneration and neuroinflammation. Therefore, CZ may be an effective therapeutic strategy for AD treatment.

Persistent pain induces mood problems and memory loss by the involvement of cytokines, growth factors, and supraspinal glial cells

Lesions of peripheral nerves lead to pain, hyperalgesia, and psychological comorbidities. However, the relationship between mood disorders and neuropathic pain is unclear, as well as the underlying mechanisms related to these disorders. Therefore, we investigated if nerve injury induces depression, anxiety, and cognitive impairment and if there were changes in cytokines, growth factors, and glial cell activation in cortical sites involved in processing pain and mood in animals with nerve injury. Nerve injury was induced by partial sciatic nerve ligation (PSNL) in male Swiss mice and compared to sham-operated animals. Nociceptive behavioral tests to mechanical and thermal (heat and cold) stimuli confirmed the development of hyperalgesia. We further examined mood disorders and memory behaviors. We show nerve injury induces a decrease in mechanical withdrawal thresholds and thermal latency to heat and cold. We also show that nerve injury causes depressive-like and anxiety-like behaviors as well as impairment in short-term memory in mice. There were increases in proinflammatory cytokines as well as Brain-Derived Neurotrophic Factor (BDNF) in the injured nerve. In the spinal cord, there were increases in both pro and anti-inflammatory cytokines, as well as of BDNF and Nerve Growth Factor (NGF). Further, in our data was a decrease in the density of microglia and astrocytes in the hippocampus and increased microglial density in the prefrontal cortex, areas associated with neuropathic pain conditions.

Effect of lycopene on pain facilitation and the SIRT1/mTOR pathway in the dorsal horn of burn injury rats

To explore the effect of intrathecal injection of lycopene on pain facilitation, glial activation, and the SIRT1/mTOR pathway in the dorsal horn of rats with burn injury pain (BIP). Here we found that the mechanical pain threshold increased in the lycopene group compared with that of the control group, (P < 0.05). Compared with expression in the sham group, mTOR, pS6, p4EBP, GFAP, and Iba-1 decreased and SIRT1 increased in the lycopene group (P < 0.01). Glial activation in the spinal dorsal horn of BIP rats was alleviated by lycopene (P < 0.01). The SIRT1 and mTOR were mainly distributed in neurons in the spinal dorsal horn in the BIP model. Intrathecal injection of 3-MA (a mTOR agonist) or EX-527 (an inhibitor of Sirt1) partially antagonized lycopene-induced analgesia. Intrathecal injection of rapamycin (an mTOR inhibitor) or SRT1720 (an agonist of Sirt1) induced analgesia in BIP rats. 3-MA abrogated the SRT1720-induced analgesic effects. The present data indicated that the SIRT1/mTOR pathway changed in the spinal dorsal horn of BIP rats; Lycopene alleviated the pain sensitization of BIP rats by regulating the SIRT1/mTOR pathway and glial activation in the spinal dorsal horn.

Concentrated ambient fine particulate matter (PM2.5) exposure induce brain damage in pre and postnatal exposed mice

Air pollution is a public health concern that has been associated with adverse effects on the development and functions of the central nervous system (CNS). However, studies on the effects of exposure to pollutants on the CNS across the entire developmental period still remain scarce. In this study, we investigated the impacts of prenatal and/or postnatal exposure to fine particulate matter (PM_2.5) from São Paulo city, on the brain structure and behavior of juvenile male mice. BALB/c mice were exposed to PM_2.5 concentrated ambient particles (CAP) at a daily concentration of 600 μg/m³ during the gestational [gestational day (GD) 1.5-18.5] and the postnatal periods [postnatal day (PND) 22-90] to filtered air (FA) in both periods (FA/FA), to CAP only in the postnatal period (FA/CAP), to CAP only in the gestational period (CAP/FA), and to CAP in both periods (CAP/CAP). Behavioral tests were performed when animals were at PND 30 and PND 90. Glial activation, brain volume, cortical neuron number, serotonergic and GABAergic receptors, as well as oxidative stress, were measured. Mice at PND 90 presented greater behavioral changes in the form of greater locomotor activity in the FA-CAP and CAP-CAP groups. In general, these same groups explored objects longer and the CAP-FA group presented anxiolytic behavior. There was no difference in total brain volume among groups, but a lower corpus callosum (CC) volume was observed in the CAP-FA group. Also, the CAP-CAP group presented an increase in microglia in the cortex and an increased in astrocytes in the cortex, CC, and C1A and dentate gyrus of hippocampus regions. Gene expression analysis showed a decrease in BDNF in the hippocampus of CAP-CAP group. Treatment of immortalized glial cells with non-cytotoxic doses of ambient PM_2.5 increased micronuclei frequencies, indicating genomic instability. These findings highlight the potential for negative neurodevelopmental outcomes induced by exposure to moderate levels of PM_2.5 in Sao Paulo city.

Piperine ameliorated memory impairment and myelin damage in lysolecethin induced hippocampal demyelination

AIMS

We still do not have effective treatment for hippocampal demyelination and memory deficit, the two common comorbidities in multiple sclerosis (MS). This study aimed to assess the therapeutic effect of Piperine (the main alkaloid of black pepper) in an experimental model of demyelination.

MAIN METHODS

Demyelination was induced in male Wistar rats by bilateral injection of lysolecithin (LPC) into the CA1 region of the hippocampus. Piperine (5, 10, 20 mg/kg) was daily injected intraperitoneally three days post LPC injection for ten days. The spatial memory was examined by the Morris water maze task. Demyelination and astrocyte activation were assessed by an immunohistological study. The gene expression analysis of TNF-α, IL1-β, NF-κB, IL-10, Foxp3, iNOS, Nrf2, HO1, MBP, and BDNF was done using qPCR. The total antioxidant capacity of hippocampal tissue was measured using FRAP assay.

KEY FINDINGS

Our results showed that piperine improved the memory performance and myelin repair in the hippocampal demyelination model. Piperine inhibited iNOS expression concomitant with enhanced expression levels of Nrf2, HO1 and the total antioxidant capacity in the hippocampal tissue. Piperine treatment significantly reduced the gene expression level of TNF-α, IL1-β, NF-κB, and glial activation in the injured area; however, the mRNA level of IL-10, Foxp3, BDNF and MBP were significantly increased.

SIGNIFICANCE

We found piperine to be an effective treatment for spatial memory impairment and myelin repair in the hippocampal demyelination model. However, further experimental evidence is needed to investigate the precise mechanisms underlying piperine as a promising therapeutic target in MS patients.

RNS60, a physically-modified saline, inhibits glial activation, suppresses neuronal apoptosis and protects memory in a mouse model of traumatic brain injury

Traumatic brain injury (TBI) is a serious health issue that causes long-term neurological disability, particularly in young adults, athletes and war veterans. Despite the use of different medications or surgical procedures, no effective therapy is currently available to halt its pathogenesis. Here, we have undertaken a novel approach to reduce neuroinflammation and improve cognitive, social and locomotor behaviors in a mouse model of TBI. RNS60 is a physiologic saline solution containing oxygen nanobubbles that is generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. Recently we have delineated that RNS60 inhibits the expression of proinflammatory molecules in glial cells via type 1A phosphatidylinositol-3 kinase (PI3K)-mediated upregulation of IκBα. In this study, we found that TBI decreased the level of IκBα and increased the activation of NF-κB in hippocampus and cortex as monitored by the upregulation of p-p65. However, intraperitoneal administration of RNS60 increased and/or restored the level of IκBα and inhibited the activation of NF-κB in hippocampus and cortex of TBI mice. Accordingly, RNS60 treatment decreased the activation of astrocytes and microglia and reduced neuronal apoptosis in the brain of TBI mice. RNS60 treatment also reduced vascular damage, attenuated blood-brain barrier leakage and decreased the size of lesion in the brain of TBI mice. Importantly, RNS60 treated mice showed significant improvements in memory, social behavior and locomotor activities while displaying reduction in depression-like behaviors. These results delineate a novel neuroprotective property of RNS60 and suggest its possible therapeutic use in TBI.

Monitoring diffuse injury during disease progression in experimental autoimmune encephalomyelitis with on resonance variable delay multiple pulse (onVDMP) CEST MRI

Multiple sclerosis (MS) is an autoimmune disorder that targets myelin proteins and results in extensive damage in the central nervous system in the form of focal lesions as well as diffuse molecular changes. Lesions are currently detected using T1-weighted, T2-weighted, and gadolinium-enhanced magnetic resonance imaging (MRI); however, monitoring such lesions has been shown to be a poor predictor of disease progression. Chemical exchange saturation transfer (CEST) MRI is sensitive to many of the biomolecules in the central nervous system altered in MS that cannot be detected using conventional MRI. We monitored disease progression in an experimental autoimmune encephalomyelitis (EAE) model of MS using on resonance variable delay multiple pulse (onVDMP) CEST MRI. Alterations in onVDMP signal were observed in regions responsible for hindlimb function throughout the central nervous system. Histological analysis revealed glial activation in areas highlighted in onVDMP CEST MRI. onVDMP signal changes in the 3rd ventricle preceded paralysis onset that could not be observed with conventional MRI techniques. Hence, the onVDMP CEST MRI signal has potential as a novel imaging biomarker and predictor of disease progression in MS.

A Novel Mathematical Model of Glaucoma Pathogenesis

Background

Conventional experimental approaches to understand glaucoma etiology and pathogenesis and, consequently, predict its course of progression have not seen much success due to the involvement of numerous molecular, cellular, and other moieties. An overwhelming number of these moieties at different levels combined with numerous environmental factors further complicate the intricacy. Interaction patterns between these factors are important to understand yet difficult to probe with conservative experimental approaches.

Methods

We performed a system-level analysis with mathematical modeling by developing and analyzing rate equations with respect to the cellular events in glaucoma pathogenesis. Twenty-two events were enlisted from the literature survey and were analyzed in terms of the sensitivity coefficient of retinal ganglion cells. A separate rate equation was developed for cellular stress also. The results were analyzed with respect to time, and the time course of the events with respect to various cellular moieties was analyzed.

Results

Our results suggest that microglia activation is among the earliest events in glaucoma pathogenesis. This modeling method yields a wealth of useful information which may serve as an important guide to better understand glaucoma pathogenesis and design experimental approaches and also identify useful diagnostic/predictive methods and important therapeutic targets.

Conclusion

We here report the first mathematical model for glaucoma pathogenesis which provides important insight into the sensitivity coefficient and glia-mediated pathology of glaucoma.

How to cite this article

Faiq MA, Sidhu T, et al. A Novel Mathematical Model of Glaucoma Pathogenesis. J Curr Glaucoma Pract 2019; 13(1):3–8.

Knockout of ALOX12 protects against spinal cord injury-mediated nerve injury by inhibition of inflammation and apoptosis

Spinal cord injury (SCI) is terrible damage leading to the deficiencies and results in infinite inconvenience to sufferers. The effective treatment for SCI still meets a larger number of problems. Herein, the underlying molecular mechanism and novel therapy of SCI are urgently to investigate. Arachidonate 12-lipoxygenase (ALOX12) is widely expressed in various cell types and plays important role in modulating different cellular processes, such as platelet aggregation, cell migration and cancer cell proliferation. Nevertheless, the effects of ALOX12 on SCI are unclear. In the study, SCI model was established in wild type (WT) mice and ALOX12 knockout mice. First, ALOX12 expression was up-regulated in spinal cord tissues of WT mice after SCI. ALOX12-knockout mice exhibited improved behavior after SCI operation. Glial activation triggered by SCI was also alleviated in mice with the loss of ALOX12, as evidenced by the down-regulated expression of glial fibrillary acidic protein (GFAP) and Iba-1 in spinal cord samples. Further, SCI-induced inflammation was markedly prevented in ALOX12-knockout mice through blocking inhibitor of NF-κB α (IκBα)/nuclear factor-κB (NF-κB) pathway signaling. Additionally, reducing ALOX12 expression attenuated apoptosis in spinal cord tissues of SCI mice by decreasing Cyto-c, cleaved Caspase-3 and poly (ADP-ribose) polymerases (PARP) expression. The protective role of ALOX12-decrease against SCI was verified in LPS-incubated glial cells through repressing inflammatory response and apoptotic formation. Moreover, transgenic mice with ALOX12 over-expression showed accelerated SCI, associated with intensified inflammation and apoptosis. Based on these results, strategies for inhibiting ALOX12 could be used to prevent SCI development by repressing inflammation and apoptosis.

High-Mobility Group Box 1 Neutralization Prevents Chronic Cerebral Hypoperfusion-Induced Optic Tract Injuries in the White Matter Associated with Down-regulation of Inflammatory Responses

Chronic cerebral hypoperfusion (CCH)-induced white matter lesions (WMLs) are region-specific with the optic tract (OT) displaying the most severe damages and leading to visual-based behavioral impairment. Previously we have demonstrated that anti-high-mobility group box 1 (HMGB1) neutralizing antibody (Ab) prevents CCH-induced hippocampal damages via inhibition of neuroinflammation. Here we tested the protective role of the Ab on CCH-induced OT injuries. Rats were treated with permanent occlusion of common carotid arteries (2-VO) or a sham surgery, and then administered with PBS, anti-HMGB1 Ab, or paired control Ab. Pupillary light reflex examination, visual water maze, and tapered beam-walking were performed 28 days post-surgery to investigate the behavioral deficits. Meanwhile, WMLs were measured by Klüver-Barrera (KB) and H&E staining, and glial activation was further assessed to evaluate inflammatory responses in OT. Results revealed that anti-HMGB1 Ab ameliorated the morphological damages (grade scores, vacuoles, and thickness) in OT area and preserved visual abilities. Additionally, the increased levels of inflammatory responses and expressions of TLR4 and NF-κB p65 and phosphorylated NF-κB p65 (p-p65) in OT area were partly down-regulated after anti-HMGB1 treatment. Taken together, these findings suggested that HMGB1 neutralization could ease OT injuries and visual-guided behavioral deficits via suppressing inflammatory responses.

Imaging and Spectral Characteristics of Amyloid Plaque Autofluorescence in Brain Slices from the APP/PS1 Mouse Model of Alzheimer's Disease

Amyloid deposits are one of the hallmark pathological lesions of Alzheimer's disease (AD). They can be visualized by thioflavin-S, silver impregnation, Congo red staining, and immunohistochemical reactions. However, that amyloid deposits generate blue autofluorescence (auto-F) has been ignored. Here, we report that visible light-induced auto-F of senile plaques (SPs) was detected and validated with conventional methods. Brain slices from APP/PS1 (amyloid precursor protein/presenilin 1) transgenic mice were mounted on slides, rinsed, coverslipped and observed for details of the imaging and spectral characteristics of the auto-F of SPs. Then the slices were treated with the above classic methods for comparative validation. We found that the SP auto-F was greatest under blue-violet excitation with a specific emission spectrum, and was much easier, more sensitive, and reliable than the classic methods. Because it does not damage slices, observation of auto-F can be combined with all post-staining techniques in slices and for brain-wide imaging in AD.

Sirt1 improves functional recovery by regulating autophagy of astrocyte and neuron after brain injury

Traumatic brain injury (TBI) triggers neuronal death mechanisms that significantly induce neuronal loss and neurological dysfunction. Our previous study revealed that Sirt1 could improve the neuroprotective effect by reducing the astrocyte activation after TBI. Nevertheless, the underlying mechanisms of Sirt1 attenuating astrocyte activation still remain unclear. The following study examined whether the protection of Sirt1 in nigrostriatal pathway injury is associated with autophagy regulation. We established a nigrostriatal pathway injury in the mouse brain in order to mimic the traumatic brain injury and up-regulated Sirt1 expression by resveratrol. Consequently, we analyzed the effect of Sirt1 up-regulation on LC3 and monitored the LC3 localization in the astrocytes, microglial cells and neurons. We found that the Sirt1 up-regulation by resveratrol increased the expression of LC3 around the lesion site after injury. Confocal results showed that Sirt1 up-regulation increased the expression of LC3 in astrocytes and decreased the expression in the neurons, while low effect was found on the microglial cells. Moreover, compared the resveratrol treatment groups, a typical nucleocytoplasmic localization with strong distribution in the nucleus (in astrocyte and neurons) was observed in the control group (treated with DMSO). To sum up, our data suggested that regulation of Sirt1 expression could enhance autophagy in the astrocytes and decrease the expression in the neurons. This mechanism, which may probably relate to the distribution of LC3 in cytoplasm and nucleus, provides a new theoretical basis for exploring the neuroprotective mechanism of Sirt1 after brain injury.

Myristica Fragrans Houtt Extract Attenuates Neuronal Loss and Glial Activation in Pentylenetetrazol-Induced Kindling Model

Inflammatory reactions are closely associated with the development and progression of epilepsy. It has been shown that inhibition of pro-inflammatory cytokines, which are released from activated astrocytes and microglia, are considered to be an effective therapeutic approach for the treatment of epileptic disorders. Regarding the anti-inflammatory effects of nutmeg (Myristica fragrans Houtt), the present study was designed to investigate whether the nutmeg ethanolic extract could exert anticonvulsant and inhibitory effects on glial activation in pentylenetetrazol (PTZ)-induced mice model of kindling. Ethanolic extract of nutmeg was administrated intraperitoneally (i.p.) 1 hour before PTZ injection or one week before PTZ as a separate group, to become fully-kindled. The chemical components of nutmeg extract were analyzed by gas chromatography mass spectrometry (GC-MS). Immunostaining against neuronal and glial markers was performed on hippocampus sections. GC-MS data indicated that the main components of nutmeg extract are myristic acid (39.93%), elemicin (22.16%) and myristicin (11.17%). Behavioral studies showed that pre-treatment of nutmeg extract effectively reduced seizures behavior, decreased cell death, and ameliorated glial activation that is followed by PTZ administration. In conclusion, nutmeg extract might be regarded as a useful supplementary agent in epilepsy treatment through its attenuation of neuronal loss and glial activation.

Microglial overexpression of fALS-linked mutant SOD1 induces SOD1 processing impairment, activation and neurotoxicity and is counteracted by the autophagy inducer trehalose

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease. Mutations in the gene encoding copper/zinc superoxide dismutase-1 (SOD1) are responsible for most familiar cases, but the role of mutant SOD1 protein dysfunction in non-cell autonomous neurodegeneration, especially in relation to microglial activation, is still unclear. Here, we focused our study on microglial cells, which release SOD1 also through exosomes. We observed that in rat primary microglia the overexpression of the most-common SOD1 mutations linked to fALS (G93A and A4V) leads to SOD1 intracellular accumulation, which correlates to autophagy dysfunction and microglial activation. In primary contact co-cultures, fALS mutant SOD1 overexpression by microglial cells appears to be neurotoxic by itself. Treatment with the autophagy-inducer trehalose reduced mutant SOD1 accumulation in microglial cells, decreased microglial activation and abrogated neurotoxicity in the co-culture model. These data suggest that i) the alteration of the autophagic pathway due to mutant SOD1 overexpression is involved in microglial activation and neurotoxicity; ii) the induction of autophagy with trehalose reduces microglial SOD1 accumulation through proteasome degradation and activation, leading to neuroprotection. Our results provide a novel contribution towards better understanding key cellular mechanisms in non-cell autonomous ALS neurodegeneration.

l-Cysteine suppresses hypoxia-ischemia injury in neonatal mice by reducing glial activation, promoting autophagic flux and mediating synaptic modification via H2S formation

We previously reported that l-Cysteine, an H₂S donor, significantly alleviated brain injury after hypoxia-ischemic (HI) injury in neonatal mice. However, the mechanisms underlying this neuroprotective effect of l-Cysteine against HI insult remain unknown. In the present study, we tested the hypothesis that the protective effects of l-Cysteine are associated with glial responses and autophagy, and l-Cysteine attenuates synaptic injury as well as behavioral deficits resulting from HI. Consistent with our previous findings, we found that treatment with l-Cysteine after HI reduced early brain injury, improved behavioral deficits and synaptic damage, effects which were associated with an up-regulation of synaptophysin and postsynaptic density protein 95 expression in the lesioned cortex. l-Cysteine attenuated the accumulation of CD11b⁺/CD45^high cells, activation of microglia and astrocytes and diminished HI-induced increases in reactive oxygen species and malondialdehyde within the lesioned cortex. In addition, l-Cysteine increased microtubule associated protein 1 light chain 3-II and Beclin1 expression, decreased p62 expression and phosphor-mammalian target of rapamycin and phosphor-signal transducer and activator of transcription 3. Further support for a critical role of l-Cysteine was revealed from results demonstrating that treatment with an inhibitor of the H₂S-producing enzyme, amino-oxyacetic acid, reversed the beneficial effects of l-Cysteine described above. These results demonstrate that l-Cysteine effectively alleviates HI injury and improves behavioral outcomes by inhibiting reactive glial responses and synaptic damage and an accompanying triggering of autophagic flux. Accordingly, l-Cysteine may provide a new a therapeutic approach for the treatment of HI via the formation of H₂S.

Integrated imaging of [11C]-PBR28 PET, MR diffusion and magnetic resonance spectroscopy 1H-MRS in amyotrophic lateral sclerosis

Objective

To determine the relationship between brain tissue metabolites measured by in vivo magnetic resonance spectroscopy (¹H-MRS), and glial activation assessed with [¹¹C]-PBR28 uptake in people with amyotrophic lateral sclerosis (ALS).

Methods

Forty ALS participants were evaluated clinically using the revised ALS functional rating scale (ALSFRS-R) and upper motor neuron burden (UMNB). All participants underwent simultaneous brain [¹¹C]-PBR28 PET and MR imaging including diffusion tensor imaging to acquire fractional anisotropy (FA). [¹¹C]-PBR28 uptake was measured as standardized uptake values normalized by whole brain mean (SUVR). ¹H-MRS metabolite ratios (myo-inositol/creatine, mI/Cr; N-acetylaspartate/creatine, NAA/Cr) were measured within the precentral gyri and brain stem (regions known to be involved in ALS pathophysiology), and precuneus (which served as a control region). Whole brain voxel-wise correlation analyses were employed to identify brain regions exhibiting an association between metabolites within the VOIs and [¹¹C]-PBR28 uptake.

Results

In the precentral gyri, [¹¹C]-PBR28 uptake correlated positively with mI/Cr and negatively with NAA/Cr. The same correlations were not statistically significant in the brain stem, or in the control precuneus region. Whole brain voxel-wise correlation analyses between the estimated brain metabolites within the VOIs and SUVR were highly correlated in the precentral gyri. Decreased FA values in the precentral gyri were correlated with reduced NAA/Cr and elevated mI/Cr. Higher UMNB was correlated with increased [¹¹C]-PBR28 uptake and mI/Cr, and decreased NAA/Cr. ALSFRS-R total score correlated positively with NAA/Cr and negatively with mI/Cr.

Conclusion

Integrated PET-MR and ¹H-MRS imaging demonstrates associations between markers for neuronal integrity and neuroinflammation and may provide valuable insights into disease mechanisms in ALS.

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This study evaluates the relationship between ¹H-MRS and [¹¹C]-PBR28 PET-MR measures in people with ALS.

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Myo-inositol/Creatine correlates positively with glial activation measured by [¹¹C]-PBR28 PET, and negatively with fractional anisotropy.

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N-acetyl-aspartate/Creatine correlates negatively with [¹¹C]-PBR28 PET, and positively with fractional anisotropy.

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Myo-inositol/Creatine and N-acetyl-aspartate/Creatine correlate with ALS-functional rating scale and upper motor neuron burden.

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¹H-MRS and PET-MR measures provide complementary information to better understand brain pathology in people with ALS.

Hesperetin reduces myelin damage and ameliorates glial activation in lysolecithin-induced focal demyelination model of rat optic chiasm

Visual impairment is considered as the most common initial manifestation of multiple sclerosis (MS) patients. It has been shown that hesperetin (Hst), a flavonoid of citrus fruit, possesses anti-inflammatory and antioxidant effects both in vitro and in vivo. The present study was designed to evaluate the pharmacological/medicinal effects of Hst treatment on myelin repair and glial activation in lysolecithin (LPC)-induced focal demyelination model. In order to induce local demyelination model, LPC 1% (2 μL) was injected into the optic chiasm of rats. Animals received oral administration of Hst at dose of 20 mg/kg for 14 or 21 days post lesion induction. Visual evoked potential (VEP) recordings were conducted before and also on days 7, 14 and 21 post LPC injection. Glial activation and myelination of optic chiasm were evaluated by immunostaining on brain sections. Analysis of VEPs data revealed that oral administration of Hst effectively reduced the latency of N1 waves. Immunostaining results showed the reduced number of astrocytes and microglia in animal which were treated with Hst. Furthermore, the extent of demyelination area was decreased in animals treated by Hst. Taken together; our results suggest that Hst treatment significantly protects and repairs myelin sheath, therefore it might be regarded as effective supplementary agent in demyelinating disorders, particularly MS.

In vivo spatiotemporal dynamics of NG2 glia activity caused by neural electrode implantation

Neural interface technology provides direct sampling and analysis of electrical and chemical events in the brain in order to better understand neuronal function and treat neurodegenerative disease. However, intracortical electrodes experience inflammatory reactions that reduce long-term stability and functionality and are understood to be facilitated by activated microglia and astrocytes. Emerging studies have identified another cell type that participates in the formation of a high-impedance glial scar following brain injury; the oligodendrocyte precursor cell (OPC). These cells maintain functional synapses with neurons and are a crucial source of neurotrophic support. Following injury, OPCs migrate toward areas of tissue injury over the course of days, similar to activated microglia. The delayed time course implicates these OPCs as key components in the formation of the outer layers of the glial scar around the implant. In vivo two-photon laser scanning microscopy (TPLSM) was employed to observe fluorescently-labeled OPC and microglia reactivity up to 72 h following probe insertion. OPCs initiated extension of cellular processes (2.5 ± 0.4 μm h-1) and cell body migration (1.6 ± 0.3 μm h-1) toward the probe beginning 12 h after insertion. By 72 h, OPCs became activated at a radius of about 190.3 μm away from the probe surface. This study characterized the early spatiotemporal dynamics of OPCs involved in the inflammatory response induced by microelectrode insertion. OPCs are key mediators of tissue health and are understood to have multiple fate potentials. Detailed spatiotemporal characterization of glial behavior under pathological conditions may allow identification of alternative intervention targets for mitigating the formation of a glial scar and subsequent neurodegeneration that debilitates chronic neural interfaces.

Querectin improves myelin repair of optic chiasm in lyolecithin-induced focal demyelination model

Although the beneficial effects of quercetin on oligodendrocyte precursor cell (OPCs) population has been evaluated in-vitro, there are few studies about the effects of quercetin on myelin repair in the context of demyelination. The aim of this study was to investigate the effects of querectin on functional recovery and myelin repair of optic chiasm in lysolecithin (LPC)-induced demyelination model. Demyelination was induced by local injection of LPC 1% (2 μl) into rat optic chiasm. Querectin at doses 25 or 50 mg/kg was administrated daily by oral gavage for 7 or 14 days post LPC. Visual evoked potential (VEPs) recordings were used to assess the functional property of the optic pathway. Immunostaining and myelin staining were performed on brain sections 7 or 14 days post lesion. Electrophysiological data indicated that LPC injection increased the latency of VEPs waves and quercetin effectively reduced the delay of visual signals. The level of glial activation was alleviated in animals under treatment of quercetin compared to vehicle group. Furthermore, quercetin treatment decreased the extent of demyelination areas and increased the remyelination process following LPC injection. Overall, our findings indicate that quercetin could remarkably improve the functional recovery of the optic pathway by its protective effects on myelin sheath and attenuation of glial activation.

Curcumin-loaded nanoparticles ameliorate glial activation and improve myelin repair in lyolecithin-induced focal demyelination model of rat corpus callosum

Curcumin has been introduced as effective anti-inflammatory agent in treatment of several inflammatory disorders. Despite the wide range pharmacological activities, clinical application of curcumin is restricted mainly due to the low water solubility of this substance. More recently, we could remarkably improve the aqueous solubility of curcumin by its encapsulation in chitosan-alginate-sodium tripolyphosphate nanoparticles (CS-ALG-STPP NPs). In this study, the anti-inflammatory and myelin protective effects of curcumin-loaded NPs were evaluated in lysolecithin (LPC)-induced focal demyelination model. Pharmacokinetic of curcumin was assessed using high performance liquid chromatography (HPLC). Local demyelination was induced by injection of LPC into corpus callosum of rats. Animals were pre-treated with intraperitoneal (i.p.) injections of curcumin or curcumin-loaded NPs at dose of 12.5 mg/kg, 10 days prior to LPC injection and the injections were continued for 7 or 14 days post lesion. Hematoxylin and eosin (H&E) staining and immunostaining against activated glial cells including astrocytes and microglia were carried out for assessment of inflammation level in lesion site. Myelin specific staining was performed to evaluate the effect of curcumin-loaded NPs on myelination of LPC receiving animals. HPLC results showed the higher plasma concentration of curcumin after administration of NPs. Histological evaluation demonstrated that, the extent of demyelination areas was reduced in animals under treatment of curcumin-loaded NPs. Furthermore, treatment with curcumin-loaded NPs effectively attenuated glial activation and inflammation in LPC-induced demyelination model compared to curcumin receiving animals. Overall; these findings indicate that treatment with curcumin-loaded NPs preserve myelinated axons through amelioration of glial activation and inflammation in demyelination context.

Curcumin-loaded chitosan-alginate-STPP nanoparticles ameliorate memory deficits and reduce glial activation in pentylenetetrazol-induced kindling model of epilepsy

Despite several beneficial effects of curcumin, its medical application has been hampered due to low water solubility. To improve the aqueous solubility of curcumin, it has been loaded on chitosan (CS)-alginate (ALG) - sodium tripolyphosphate (STPP) nanoparticles (NPs). Then, the effect of curcumin NPs on memory improvement and glial activation was investigated in pentylenetetrazol (PTZ)-induced kindling model. Male NMRI mice have received the daily injection of curcumin NPs at dose of 12.5 or 25mg/kg. All interventions were injected intraperitoneally (i.p), 10days before PTZ administration and the injections were continued until 1h before each PTZ injection. Spatial learning and memory was evaluated using Morris water maze test after the 7th PTZ injection. Animals have received 10 injections of PTZ and then, brain tissues were removed for histological evaluation. Nissl staining was used to determine the level of cell death in hippocampus and immunostaining method was performed against NeuN and GFAP/Iba1 for assessment of neuronal density and glial activation respectively. Behavioral results showed that curcumin NPs exhibit anticonvulsant activity and prevent cognitive impairment in fully kindled animals. The level of cell death and glial activation reduced in animals which have received curcumin NPs compared to those received free curcumin. To conclude, these findings suggest that curcumin NPs effectively ameliorate memory impairment and attenuate the level of activated glial cells in a mice model of chronic epilepsy.

Glibenclamide pretreatment protects against chronic memory dysfunction and glial activation in rat cranial blast traumatic brain injury

Blast traumatic brain injury (bTBI) affects both military and civilian populations, and often results in chronic deficits in cognition and memory. Chronic glial activation after bTBI has been linked with cognitive decline. Pharmacological inhibition of sulfonylurea receptor 1 (SUR1) with glibenclamide was shown previously to reduce glial activation and improve cognition in contusive models of CNS trauma, but has not been examined in bTBI. We postulated that glibenclamide would reduce chronic glial activation and improve long-term memory function after bTBI. Using a rat direct cranial model of bTBI (dc-bTBI), we evaluated the efficacy of two glibenclamide treatment paradigms: glibenclamide prophylaxis (pre-treatment), and treatment with glibenclamide starting after dc-bTBI (post-treatment). Our results show that dc-bTBI caused hippocampal astrocyte and microglial/macrophage activation that was associated with hippocampal memory dysfunction (rapid place learning paradigm) at 28days, and that glibenclamide pre-treatment, but not post-treatment, effectively protected against glial activation and memory dysfunction. We also report that a brief transient time-window of blood-brain barrier (BBB) disruption occurs after dc-bTBI, and we speculate that glibenclamide, which is mostly protein bound and does not normally traverse the intact BBB, can undergo CNS delivery only during this brief transient opening of the BBB. Together, our findings indicate that prophylactic glibenclamide treatment may help to protect against chronic cognitive sequelae of bTBI in warfighters and other at-risk populations.