Beneficial effects of curcumin on GFAP filament organization and down-regulation of GFAP expression in an in vitro model of Alexander disease

Small Molecules, α-Synuclein Pathology, and the Search for Effective Treatments in Parkinson's Disease

Parkinson's disease (PD) is a progressive age-related neurodegenerative disorder affecting millions of people worldwide. Essentially, it is characterised by selective degeneration of dopamine neurons of the nigro-striatal pathway and intraneuronal aggregation of misfolded α-synuclein with formation of Lewy bodies and Lewy neurites. Moreover, specific small molecules of intermediary metabolism may have a definite pathophysiological role in PD. These include dopamine, levodopa, reduced glutathione, glutathione disulfide/oxidised glutathione, and the micronutrients thiamine and ß-Hydroxybutyrate. Recent research indicates that these small molecules can interact with α-synuclein and regulate its folding and potential aggregation. In this review, we discuss the current knowledge on interactions between α-synuclein and both the small molecules of intermediary metabolism in the brain relevant to PD, and many other natural and synthetic small molecules that regulate α-synuclein aggregation. Additionally, we analyse some of the relevant molecular mechanisms potentially involved. A better understanding of these interactions may have relevance for the development of rational future therapies. In particular, our observations suggest that the micronutrients ß-Hydroxybutyrate and thiamine might have a synergistic therapeutic role in halting or reversing the progression of PD and other neuronal α-synuclein disorders.

Curcumin protects against aging-related stress and dysfunction through autophagy activation in rat brain

BACKGROUND

Curcumin (Curcuma longa) is a well-known medicinal plant that induces autophagy in various model species, helping maintain cellular homeostasis. Its role as a caloric restriction mimetic (CRM) is being investigated. This study explores the potential of curcumin (CUR), as a CRM, to provide neuroprotection in D galactose induced accelerated senescence model of rats through modulation of autophagy. For six weeks, male rats received simultaneous supplementation of D-gal (300 mg/kg b.w., subcutaneously) and CUR (200 mg/kg b.w., oral).

METHOD AND RESULTS

The oxidative stress indices, antioxidants, and electron transport chain complexes in brain tissues were measured using standard methods. Reverse transcriptase-polymerase chain reaction (RT-PCR) gene expression analysis was used to evaluate the expression of autophagy, neuroprotection, and aging marker genes. Our results show that curcumin significantly (p ≤ 0.05) enhanced the level of antioxidants and considerably lowered the level of oxidative stress markers. Supplementing with CUR also increased the activity of electron transport chain complexes in the mitochondria of aged brain tissue, demonstrating the antioxidant potential of CUR at the mitochondrial level. CUR was found to upregulate the expression of the aging marker gene (SIRT-1) and the genes associated with autophagy (Beclin-1 and ULK-1), as well as neuroprotection (NSE) in the brain. The expression of IL-6 and TNF-α was downregulated.

CONCLUSION

Our findings demonstrate that CUR suppresses oxidative damage brought on by aging by modulating autophagy. These findings imply that curcumin might be beneficial for neuroprotection in aging and age-related disorders.

Prediction of clinical progression in nervous system diseases: plasma glial fibrillary acidic protein (GFAP)

Glial fibrillary acidic protein (GFAP), an intracellular type III intermediate filament protein, provides structural support and maintains the mechanical integrity of astrocytes. It is predominantly found in the astrocytes which are the most abundant subtypes of glial cells in the brain and spinal cord. As a marker protein of astrocytes, GFAP may exert a variety of physiological effects in neurological diseases. For example, previous published literatures showed that autoimmune GFAP astrocytopathy is an inflammatory disease of the central nervous system (CNS). Moreover, the studies of GFAP in brain tumors mainly focus on the predictive value of tumor volume. Furthermore, using biomarkers in the early setting will lead to a simplified and standardized way to estimate the poor outcome in traumatic brain injury (TBI) and ischemic stroke. Recently, observational studies revealed that cerebrospinal fluid (CSF) GFAP, as a valuable potential diagnostic biomarker for neurosyphilis, had a sensitivity of 76.60% and specificity of 85.56%. The reason plasma GFAP could serve as a promising biomarker for diagnosis and prediction of Alzheimer's disease (AD) is that it effectively distinguished AD dementia from multiple neurodegenerative diseases and predicted the individual risk of AD progression. In addition, GFAP can be helpful in differentiating relapsing-remitting multiple sclerosis (RRMS) versus progressive MS (PMS). This review article aims to provide an overview of GFAP in the prediction of clinical progression in neuroinflammation, brain tumors, TBI, ischemic stroke, genetic disorders, neurodegeneration and other diseases in the CNS and to explore the potential therapeutic methods.

Desmethoxycurcumin aids IFNα's anti-HBV activity by antagonising CRYAB reduction and stabilising IFNAR1 protein

The eradication of chronic hepatitis B (CHB) caused by hepatitis B virus (HBV) infection is a crucial goal in clinical practice. Enhancing the anti-HBV activity of interferon type I (IFNI) is a key strategy for achieving a functional cure for CHB. In this study, we investigated the effect of combined treatment with IFNα and Desmethoxycurcumin (DMC) on HBV replication in HepG2 cells and explored the underlying mechanism. Our results indicated IFNα alone was ineffective in completely inhibiting HBV replication, which was attributed to the virus-induced down-regulation of IFNI receptor 1 (IFNAR1) protein. However, the addition of a low dose of DMC significantly synergized with IFNα, leading to notable enhancement of IFNα anti-HBV activity. This effect was achieved by stabilising the IFNAR1 protein. Further investigation revealed that low dose DMC effectively blocked the ubiquitination-mediated degradation of IFNAR1, which was accomplished by rescuing the protein levels of alphaB-crystallin (CRYAB) and orchestrating the interaction between CRYAB and the E3 ubiquitin ligase, β-Trcp. Importantly, over-expression of CRYAB was found to favour the antiviral activity of IFNα against HBV replication. In conclusion, our study demonstrates that low-dose DMC enhanced the anti-HBV activity of IFNα by counteracting the reduction of CRYAB and stabilising the IFNAR1 protein.

Alexander disease: the road ahead

Alexander disease is a rare neurodegenerative disorder caused by mutations in the glial fibrillary acidic protein, a type III intermediate filament protein expressed in astrocytes. Both early (infantile or juvenile) and adult onsets of the disease are known and, in both cases, astrocytes present characteristic aggregates, named Rosenthal fibers. Mutations are spread along the glial fibrillary acidic protein sequence disrupting the typical filament network in a dominant manner. Although the presence of aggregates suggests a proteostasis problem of the mutant forms, this behavior is also observed when the expression of wild-type glial fibrillary acidic protein is increased. Additionally, several isoforms of glial fibrillary acidic protein have been described to date, while the impact of the mutations on their expression and proportion has not been exhaustively studied. Moreover, the posttranslational modification patterns and/or the protein-protein interaction networks of the glial fibrillary acidic protein mutants may be altered, leading to functional changes that may modify the morphology, positioning, and/or the function of several organelles, in turn, impairing astrocyte normal function and subsequently affecting neurons. In particular, mitochondrial function, redox balance and susceptibility to oxidative stress may contribute to the derangement of glial fibrillary acidic protein mutant-expressing astrocytes. To study the disease and to develop putative therapeutic strategies, several experimental models have been developed, a collection that is in constant growth. The fact that most cases of Alexander disease can be related to glial fibrillary acidic protein mutations, together with the availability of new and more relevant experimental models, holds promise for the design and assay of novel therapeutic strategies.

Mitophagy: A promising therapeutic target for neuroprotection during ageing and age-related diseases

Mitochondria and mitochondria-mediated signalling pathways are known to control synaptic signalling, as well as long-lasting changes in neuronal structure and function. Mitochondrial impairment is linked to synaptic dysfunction in normal ageing and age-associated neurodegenerative ailments, including Parkinson's disease (PD) and Alzheimer's disease (AD). Both proteolysis and mitophagy perform a major role in neuroprotection, by maintaining a healthy mitochondrial population during ageing. Mitophagy, a highly evolutionarily conserved cellular process, helps in the clearance of damaged mitochondria and thereby maintains the mitochondrial and metabolic balance, energy supply, neuronal survival and neuronal health. Besides the maintenance of brain homeostasis, hippocampal mitophagy also helps in synapse formation, axonal development, dopamine release and long-term depression. In contrast, defective mitophagy contributes to ageing and age-related neurodegeneration by promoting the accumulation of damaged mitochondria leading to cellular dysfunction. Exercise, stress management, maintaining healthy mitochondrial dynamics and administering natural or synthetic pharmacological compounds are some of the strategies used for neuroprotection during ageing and age-related neurological diseases. The current review discusses the impact of defective mitophagy in ageing and age-associated neurodegenerative conditions, the underlying molecular pathways and potential therapies based on recently elucidated mitophagy-inducing strategies.

HIV Nef Expression Down-modulated GFAP Expression and Altered Glutamate Uptake and Release and Proliferation in Astrocytes

HIV infection of astrocytes leads to restricted gene expression and replication but abundant expression of HIV early genes Tat, Nef and Rev. A great deal of neuroHIV research has so far been focused on Tat protein, its effects on astrocytes, and its roles in neuroHIV. In the current study, we aimed to determine effects of Nef expression on astrocytes and their function. Using transfection or infection of VSVG-pseudotyped HIV viruses, we showed that Nef expression down-modulated glial fibrillary acidic protein (GFAP) expression. We then showed that Nef expression also led to decreased GFAP mRNA expression. The transcriptional regulation was further confirmed using a GFAP promoter-driven reporter gene assay. We performed transcription factor profiling array to compare the expression of transcription factors between Nef-intact and Nef-deficient HIV-infected cells and identified eight transcription factors with expression changes of 1.5-fold or higher: three up-regulated by Nef (Stat1, Stat5, and TFIID), and five down-regulated by Nef (AR, GAS/ISRE, HIF, Sp1, and p53). We then demonstrated that removal of the Sp1 binding sites from the GFAP promoter resulted in a much lower level of the promoter activity and reversal of Nef effects on the GFAP promoter, confirming important roles of Sp1 in the GFAP promoter activity and for Nef-induced GFAP expression. Lastly, we showed that Nef expression led to increased glutamate uptake and decreased glutamate release by astrocytes and increased astrocyte proliferation. Taken together, these results indicate that Nef leads to down-modulation of GFAP expression and alteration of glutamate metabolism in astrocytes, and astrocyte proliferation and could be an important contributor to neuroHIV.

Beneficial Effect of Phenytoin and Carbamazepine on GFAP Gene Expression and Mutant GFAP Folding in a Cellular Model of Alexander's Disease

Alexander’s disease (AxD) is a rare, usually relentlessly progressive disorder of astroglial cells in the central nervous system related to mutations in the gene encoding the type III intermediate filament protein, glial fibrillary acidic protein (GFAP). The pathophysiology of AxD is only partially understood. Available data indicate that an excessive GFAP gene expression may play a role. In particular, a “threshold hypothesis” has been reported, suggesting that mutant GFAP representing about 20% of the total cellular GFAP should be sufficient to cause disease. Thus, strategies based on reducing cellular mutant GFAP protein levels and/or activating biological processes involved in the correct protein folding could be effective in counteracting the toxic effect of misfolded GFAP. Considering that clomipramine (CLM), which has been selected by a wide small molecules screening as the greatest inhibitory potential drug against GFAP expression, is contraindicated because of its proconvulsant activity in the infantile form of AxD, which is also characterized by the occurrence of epileptic seizures, two powerful antiepileptic agents, carbamazepine (CBZ) and phenytoin (PHT), which share specific stereochemical features in common with CLM, were taken into consideration in a reliable in vitro model of AxD. In the present work, we document for the first time that CBZ and PHT have a definite inhibitory effect on pathological GFAP cellular expression and folding. Moreover, we confirm previous results of a similar beneficial effect of CLM. In addition, we have demonstrated that CBZ and CLM play a refolding effect on mutant GFAP proteins, likely ascribed at the induction of CRYAB expression, resulting in the decrease of mutant GFAP aggregates formation. As CBZ and PHT are currently approved for use in humans, their documented effects on pathological GFAP cellular expression and folding may indicate a potential therapeutic role as disease-modifying agents of these drugs in the clinical management of AxD, particularly in AxD patients with focal epilepsy with and without secondary generalization.

Clinical and radiological characteristics of older-adult-onset Alexander disease

BACKGROUND

Alexander disease (ALXDRD) affects a wide range of ages from infancy to adulthood. However, only a few cases involving patients with older-adult onset over 65 years of age have been reported. In contrast, regarding in-house data, 10.6% of 85 cases with the identification of GFAP mutations demonstrated older-adult onset. This discrepancy may be due to poor awareness of such cases.

METHODS

The subjects included 9 older-adult-onset cases, with an onset age of 65 years or older. We characterized older-adult-onset ALXDRD by assessing neurological findings and several magnetic resonance imaging (MRI) parameters.

RESULTS

The age at onset, mean age at diagnosis, and mean period from onset to diagnosis were 68.2 years, 70.4 years, and 2.2 years, respectively. The main neurological features at diagnosis included pyramidal signs with muscle weakness and/or cerebellar ataxia. Two-thirds of cases were dependent, and the dependence was significantly correlated with a longer period from onset to diagnosis. Quantitative MRI evaluation for brainstem atrophy demonstrated distinctive morphological features of bulbospinal ALXDRD. The corpus callosum index tended to be negatively correlated with the period from onset to diagnosis.

CONCLUSIONS

Although neurological and MRI findings of older-adult-onset ALXDRD patients showed typical features of bulbospinal ALXDRD, their disease progression was more severe than that in younger-adult-onset ALXDRD, and patients developed dependence within 2 years from onset. Cerebral white matter damage tended to progress in proportion to the duration of illness. Our case study may help to advance understanding of the clinical spectrum of ALXDRD.

Alexander Disease Modeling in Zebrafish: An In Vivo System Suitable to Perform Drug Screening

Alexander disease (AxD) is a rare astrogliopathy caused by heterozygous mutations, either inherited or arising de novo, on the glial fibrillary acid protein (GFAP) gene (17q21). Mutations in the GFAP gene make the protein prone to forming aggregates which, together with heat-shock protein 27 (HSP27), αB-crystallin, ubiquitin, and proteasome, contribute to form Rosenthal fibers causing a toxic effect on the cell. Unfortunately, no pharmacological treatment is available yet, except for symptom reduction therapies, and patients undergo a progressive worsening of the disease. The aim of this study was the production of a zebrafish model for AxD, to have a system suitable for drug screening more complex than cell cultures. To this aim, embryos expressing the human GFAP gene carrying the most severe p.R239C under the control of the zebrafish gfap gene promoter underwent functional validation to assess several features already observed in in vitro and other in vivo models of AxD, such as the localization of mutant GFAP inclusions, the ultrastructural analysis of cells expressing mutant GFAP, the effects of treatments with ceftriaxone, and the heat shock response. Our results confirm that zebrafish is a suitable model both to study the molecular pathogenesis of GFAP mutations and to perform pharmacological screenings, likely useful for the search of therapies for AxD.

Long-term survival of a dog with Alexander disease

A 1-year- and 11-month-old spayed female toy poodle had showed progressive ataxia and paresis in the hindlimbs since 11 months old. Magnetic resonance imaging revealed high signal intensity on T2-weighted and fluid-attenuated inversion recovery images at the thoracic and lumbar spinal cord. The dog’s neurological condition slowly deteriorated and flaccid tetraparesis was exhibited. At 4 years and 11 months old, the dog died of respiratory failure. On postmortem examination, eosinophilic corkscrew bundles (Rosenthal fibers) were observed mainly in the thoracic and lumbar spinal cord. Histological features were comparable to previously reported cases with Alexander disease. This is a first case report to describe the clinical course and long-term prognosis of a dog with Alexander disease.

Protective effects of curcumin and Ganoderma lucidum on hippocampal damage caused by the organophosphate insecticide chlorpyrifos in the developing rat brain: Stereological, histopathological and immunohistochemical study

The aim of this study is to draw attention to the possible effects of chlorpyrifos exposure on the developing rat hippocampus in the prenatal period and to determine whether these effects can be reduced with various antioxidant substances. Pregnant rats were divided into 7 groups.; Chlorpyrifos (CPF), Curcumin (CUR), Ganoderma lucidum (GNL), Chlorpyrifos + Curcumin (CPF + CUR), Chlorpyrifos + Ganoderma lucidum, (CPF + GNL), SHAM and Control (C). After the experiments, brain tissues were evaluated by stereological and immunohistochemical methods. As a result of the stereological analyzes, it was determined that the number of pyramidal neurons in the hippocampus of the CPF group decreased significantly from all other groups. In contrast, the number of neurons in the CPF + CUR and CPF + GNL groups was significantly higher than the CPF group. In addition, immunohistochemical analyzes showed that the density of cells stained with glial fibrillar acidic protein (GFAP) positive in all areas in the hippocampus of the rats in the CPF group was significantly higher compared to the control group, whereas in the CPF + CUR and CPF + GNL groups were less than the CPF group. As a result, the exposure of CPF in the prenatal period caused neurotoxicity in the brain hippocampus, whereas CUR and GNL reduced this toxicity caused by CPF.

P2 × 7 Receptor Inhibits Astroglial Autophagy via Regulating FAK- and PHLPP1/2-Mediated AKT-S473 Phosphorylation Following Kainic Acid-Induced Seizures

Recently, we have reported that blockade/deletion of P2X7 receptor (P2X7R), an ATP-gated ion channel, exacerbates heat shock protein 25 (HSP25)-mediated astroglial autophagy (clasmatodendrosis) following kainic acid (KA) injection. In P2X7R knockout (KO) mice, prolonged astroglial HSP25 induction exerts 5′ adenosine monophosphate-activated protein kinase/unc-51 like autophagy activating kinase 1-mediated autophagic pathway independent of mammalian target of rapamycin (mTOR) activity following KA injection. Sustained HSP25 expression also enhances AKT-serine (S) 473 phosphorylation leading to astroglial autophagy via glycogen synthase kinase-3β/bax interacting factor 1 signaling pathway. However, it is unanswered how P2X7R deletion induces AKT-S473 hyperphosphorylation during autophagic process in astrocytes. In the present study, we found that AKT-S473 phosphorylation was increased by enhancing activity of focal adhesion kinase (FAK), independent of mTOR complex (mTORC) 1 and 2 activities in isolated astrocytes of P2X7R knockout (KO) mice following KA injection. In addition, HSP25 overexpression in P2X7R KO mice acted as a chaperone of AKT, which retained AKT-S473 phosphorylation by inhibiting the pleckstrin homology domain and leucine-rich repeat protein phosphatase (PHLPP) 1- and 2-binding to AKT. Therefore, our findings suggest that P2X7R may be a fine-tuner of AKT-S473 activity during astroglial autophagy by regulating FAK phosphorylation and HSP25-mediated inhibition of PHLPP1/2-AKT binding following KA treatment.

Clinical characteristics of Alexander disease

Alexander disease (ALXDRD) is a primary astrocyte disease caused by GFAP gene mutation. The clinical features of ALXDRD vary from infantile-onset cerebral white matter involvement to adult-onset brainstem involvement. Several studies revealed that the level of GFAP overexpression is correlated with disease severity, and basic research on therapies to reduce abnormal GFAP accumulation has recently been published. Therefore, the accumulation of clinical data to advance understanding of the natural history is essential for clinical trials expected in the future. This review focuses on the clinical characteristics of ALXDRD including the clinical symptoms, imaging findings and genetics to provide diagnostic information useful in daily clinical practice.

[Clinical characteristics and diagnostic criteria on Alexander disease]

Alexander disease (ALXDRD) is a primary astrocyte disease caused by glial fibrillary acidic protein (GFAP) gene mutation. ALXDRD had been clinically regarded as a cerebral white matter disease that affects only children for about 50 years since the initial report in 1949; however, in the early part of the 21st century, case reports of adult-onset ALXDRD with medulla and spinal cord lesions increased. Basic research on therapies to reduce abnormal GFAP accumulation, such as drug-repositioning and antisense oligonucleotide suppression, has recently been published. The accumulation of clinical data to advance understanding of natural history is essential for clinical trials expected in the future. In this review, I classified ALXDRD into two subtypes: early-onset and late-onset, and detail the clinical symptoms, imaging findings, and genetic characteristics as well as the epidemiology and historical changes in the clinical classification described in the literature. The diagnostic criteria based on Japanese ALXDRD patients that are useful in daily clinical practice are also mentioned.

Effects of curcumin on neurological diseases: focus on astrocytes

Astrocytes are the most abundant glial cells in the central nervous system, and are important players in both brain injury and neurodegenerative disease. Curcumin (1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione), the major active component of turmeric, belongs to the curcuminoid family that was originally isolated from the plant Curcuma longa. Several studies suggest that curcumin may have a beneficial impact on the brain pathology and aging. These effects are due to curcumin's antioxidant, free-radical scavenging, and anti-inflammatory activity. In light of this, our current review aims to discuss the role of astrocytes as essential players in neurodegenerative diseases and suggest that curcumin is capable of direct inhibition of astrocyte activity with a particular focus on its effects in Alexander disease, Alzheimer's disease, ischemia stroke, spinal cord injury, Multiple sclerosis, and Parkinson's disease.

Mesenchymal stem cells versus curcumin in enhancing the alterations in the cerebellar cortex of streptozocin-induced diabetic albino rats. The role of GFAP, PLC and α-synuclein

BACKGROUND

Diabetes mellitus is the disease, termed either by insulin paucity or resistance and hyperglycemia. The selection of the cerebellum was built on its specific functions. The aim of this study was to investigate a comparison between the possible therapeutic effects of MSCs and curcumin against fluctuations in the cerebellar cortex of STZ-induced diabetic albino rats.

MATERIALS AND METHODS

Forty rats were divided into five groups: control, sham control, streptozotocin-induced diabetes, diabetes and MSCs administered and diabetes and curcumin administered. Light microscopic (H&E), immune-histochemical; Glial fibrillary acidic protein (GFAP), real-time PCR; phospholipase-C (PLC) and α-synuclein, histomorphometric analysis, oxidative / anti-oxidatants; malondialdehyde (MDA)/ superoxide dismutase (SOD) glutathione (GSH) and were made.

RESULTS

The histopathological examination of the STZ-induced diabetic rats revealed alterations in the molecular, purkinje and granular layers. Abnormal organizations, vacuolation, patchy loss of purkinje cells were detected. Some purkinje cells migrated into the granular layer.Hemorrhage in pia mater outspreading to cerebellar layers is discerned. Purkinje cells showed karyorrhexis. The mean value of area percentage for GFAP immune- reactivity revealed 360 % significant increase compared to that of the control group. Also, MDA level was significantly increased while the SOD and GSH levels were significantly lower when compared to the control group. Meanwhile, mean values of PLC demonstrated significant decrease, while α-synuclein levels displayed a significant increment in the diabetic group. Administration of curcumin and MSCs extremely ameliorated the previous alterations.

CONCLUSION

the deleterious alterations on the cerebellar cortex induced by diabetes were obviously improved when treated with either MSCs or curcumin.

Refining the concept of GFAP toxicity in Alexander disease

Background

Alexander disease is caused by dominantly acting mutations in glial fibrillary acidic protein (GFAP), the major intermediate filament of astrocytes in the central nervous system.

Main body

In addition to the sequence variants that represent the origin of disease, GFAP accumulation also takes place, together leading to a gain-of-function that has sometimes been referred to as “GFAP toxicity.” Whether the nature of GFAP toxicity in patients, who have mixtures of both mutant and normal protein, is the same as that produced by simple GFAP excess, is not yet clear.

Conclusion

The implications of these questions for the design of effective treatments are discussed.

Modulation of autophagy in human diseases strategies to foster strengths and circumvent weaknesses

Autophagy is central to the maintenance of intracellular homeostasis across species. Accordingly, autophagy disorders are linked to a variety of diseases from the embryonic stage until death, and the role of autophagy as a therapeutic target has been widely recognized. However, autophagy-associated therapy for human diseases is still in its infancy and is supported by limited evidence. In this review, we summarize the landscape of autophagy-associated diseases and current autophagy modulators. Furthermore, we investigate the existing autophagy-associated clinical trials, analyze the obstacles that limit their progress, offer tactics that may allow barriers to be overcome along the way and then discuss the therapeutic potential of autophagy modulators in clinical applications.

Pre and post treatment with curcumin and resveratrol protects astrocytes after oxidative stress

The two most studied polyphenolic compounds, curcumin (Cur) and resveratrol (Res), have been reported to protect oxidative damage of astrocytes. The present study is designed to examine the comparative anti-oxidative effect of Cur and Res on astrocytes by studying their potential to protect H₂O₂ induced oxidative stress at 4 h and 24 h time exposure. The effect of Cur and Res on cell viability, ROS production, inflammation and astrogliosis was compared. The effect of these two on Nrf2 expression and its translocation to nuclear compartment was investigated. The results showed that both Cur and Res significantly increase astrocytes survival after oxidative stress at both time points, however, Res demonstrated better effect on cell viability than the Cur. Res, showing significant inhibition of ROS production at both time points. Cur displayed significant inhibition of ROS production at 4 h, suggesting that Cur is more active on ROS inhibition in the earlier phase of insult. Comparing the expression of NF-κB, Cur showed better anti-inflammatory action on NF-κB while Res did not have any effect of NF-κB expression at 4 h. Interestingly, Cur showed an upregulation of nuclear Nrf2 expression at 24 h whereas Res displayed no effect after 24 h incubation. Both Cur and Res inhibited the H₂O₂ induced translocation of Nrf2 into nucleus. In conclusion, based on our observation, we found that Cur and Res both protected astrocytes from oxidative stress. In addition, we observed that Cur is most effective in early hours of insult while Res is effective in late hours suggesting that Res may or may not have immediate effect on astrocytes.

Curcumin decreases astrocytic reaction after gliotoxic injury in the rat brainstem

ABSTRACT Recent studies have demonstrated that curcumin (Cur) has antioxidant, anti-inflammatory and anti-fibrotic effects. Ethidium bromide (EB) injections into the central nervous system (CNS) are known to induce local oligodendroglial and astrocytic loss, resulting in primary demyelination and neuroinflammation. Peripheral astrogliosis is seen around the injury site with increased immunoreactivity to glial fibrillary acidic protein (GFAP). This investigation aimed to evaluate the effect of Cur administration on astrocytic response following gliotoxic injury. Wistar rats were injected with EB into the cisterna pontis and treated, or not, with Cur (100 mg/kg/day, intraperitoneal route) during the experimental period. Brainstem sections were collected at 15, 21 and 31 days after EB injection and processed for GFAP immunohistochemical staining. Astrocytic reactivity was measured in a computerized system for image analysis. In Cur-treated rats, the GFAP-stained area around the lesion was significantly smaller in all periods after EB injection compared to untreated animals, showing that Cur reduces glial scar development following injury.

Disturbed sensorimotor and electrophysiological patterns in lead intoxicated rats during development are restored by curcumin I

Lead poisoning is one of the most significant health problem of environmental origin. It is known to cause different damages in the central and peripheral nervous system which could be represented by several neurophysiological and behavioral symptoms. In this study we firstly investigated the effect of lead prenatal exposure in rats to (3g/L), from neonatal to young age, on the motor/sensory performances, excitability of the spinal cord and gaits during development. Then we evaluated neuroprotective effects of curcumin I (Cur I) against lead neurotoxicity, by means of grasping and cliff avoidance tests to reveal the impairment of the sensorimotor functions in neonatal rats exposed prenatally to lead. In addition, extracellular recordings of motor output in spinal cord revealed an hyper-excitability of spinal networks in lead treated rats. The frequency of induced fictive locomotion was also increased in treated rats. At the young age, rats exhibited an impaired locomotor gait. All those abnormalities were attenuated by Cur I treatment at a dose of 16g/kg. Based on our finding, Cur I has shown features of a potent chemical compound able to restore the neuronal and the relative locomotor behaviors disturbances induced by lead intoxication. Therefore, this chemical can be recommended as a new therapeutic trial against lead induced neurotoxicity.

Curcumin alleviates oxidative stress and mitochondrial dysfunction in astrocytes

Oxidative stress plays a critical role in various neurodegenerative diseases, thus alleviating oxidative stress is a potential strategy for therapeutic intervention and/or prevention of neurodegenerative diseases. In the present study, alleviation of oxidative stress through curcumin is investigated in A172 (human glioblastoma cell line) and HA-sp (human astrocytes cell line derived from the spinal cord) astrocytes. H2O2 was used to induce oxidative stress in astrocytes (A172 and HA-sp). Data show that H2O2 induces activation of astrocytes in dose- and time-dependent manner as evident by increased expression of GFAP in A172 and HA-sp cells after 24 and 12h respectively. An upregulation of Prdx6 was also observed in A172 and HA-sp cells after 24h of H2O2 treatment as compared to untreated control. Our data also showed that curcumin inhibits oxidative stress-induced cytoskeleton disarrangement, and impedes the activation of astrocytes by inhibiting upregulation of GFAP, vimentin and Prdx6. In addition, we observed an inhibition of oxidative stress-induced inflammation, apoptosis and mitochondria fragmentation after curcumin treatment. Therefore, our results suggest that curcumin not only protects astrocytes from H2O2-induced oxidative stress but also reverses the mitochondrial damage and dysfunction induced by oxidative stress. This study also provides evidence for protective role of curcumin on astrocytes by showing its effects on attenuating reactive astrogliosis and inhibiting apoptosis.

Ultrastructural characterization of craniopharyngioma at the tumor boundary: A structural comparison with an experimental toxic model using "oil machinery" fluid, with emphasis on Rosenthal fibers

Craniopharyngiomas (CPs) are cystic, encapsulated, slow-growing epithelial tumors. CPs can be aggressive forms invading and resorting surrounding structures of adjacent brain tissue, where Rosenthal fibers (RFs) are expressed. The aim of this study was to investigate the ultrastructure of these fibers in human biopsies and compare it with an experimental toxic model produced by the cortical infusion of the oil cyst fluid ("Oil machinery" fluid or OMF) from CPs to rats. For this purpose, the CPs from ten patients were examined by light and electron microscopy. OMF was administered to rats intracortically. Immunohistochemical detection of glial fibrillary acidic protein (GFAP) and vimentin was assessed. In both freshly obtained CPs and rat brain tissue, the presence of abundant cellular debris, lipid-laden macrophages, reactive gliosis, inflammation and extracellular matrix destruction were seen. Ultrastructural results suggest focal pathological disturbances and an altered microenvironment surrounding the tumor-brain junction, with an enhanced presence of RFs in human tumors. In contrast, in the rat brain different degrees of cellular disorganization with aberrant filament-filament interactions and protein aggregation were seen, although RFs were absent. Our immunohistochemical findings in CPs also revealed an enhanced expression of GFAP and vimentin in RFs at the peripheral, but not at the central (body) level. Through these findings we hypothesize that the continuous OMF release at the CPs boundary may cause tissue alterations, including damaging of the extracellular matrix, and possibly contributing to RFs formation, a condition that was not possible to reproduce in the experimental model. The presence of RFs at the CPs boundary might be considered as a major criterion for the degree of CPs invasiveness to normal tissue. The lack of RFs reactivity in the experimental model reveals that the invasive component of CPs is not present in the OMF, although the fluid per se can exert tissue damage.

Glial fibrillary acidic protein: from intermediate filament assembly and gliosis to neurobiomarker

Glial fibrillary acidic protein (GFAP) is an intermediate filament (IF) III protein uniquely found in astrocytes in the central nervous system (CNS), non-myelinating Schwann cells in the peripheral nervous system (PNS), and enteric glial cells. GFAP mRNA expression is regulated by several nuclear-receptor hormones, growth factors, and lipopolysaccharides (LPSs). GFAP is also subject to numerous post-translational modifications (PTMs), while GFAP mutations result in protein deposits known as Rosenthal fibers in Alexander disease. GFAP gene activation and protein induction appear to play a critical role in astroglial cell activation (astrogliosis) following CNS injuries and neurodegeneration. Emerging evidence also suggests that, following traumatic brain and spinal cord injuries and stroke, GFAP and its breakdown products are rapidly released into biofluids, making them strong candidate biomarkers for such neurological disorders.

Cell biological roles of αB-crystallin

αB-crystallin, also called HspB5, is a molecular chaperone able to interact with unfolding proteins. By interacting, it inhibits further unfolding, thereby preventing protein aggregation and allowing ATP-dependent chaperones to refold the proteins. αB-crystallin belongs to the family of small heat-shock proteins (sHsps), which in humans consists of 10 different members. The protein forms large oligomeric complexes, containing up to 40 or more subunits, which in vivo consist of heterooligomeric complexes formed by a mixture of αB-crystallin and other sHsps. αB-crystallin is highly expressed in the lens and to a lesser extent in several other tissues, among which heart, skeletal muscle and brain. αB-crystallin plays a role in several cellular processes, such as signal transduction, protein degradation, stabilization of cytoskeletal structures and apoptosis. Mutations in the αB-crystallin gene can have detrimental effects, leading to pathologies such as cataract and cardiomyopathy. This review describes the biological roles of αB-crystallin, with a special focus on its function in the eye lens, heart muscle and brain. In addition its therapeutic potential is discussed.