Role of Glial Cells in Neuronal Function, Mood Disorders, and Drug Addiction.

Mood disorders and substance use disorder (SUD) are of immense medical and social concern. Although significant progress on neuronal involvement in mood and reward circuitries has been achieved, it is only relatively recently that the role of glia in these disorders has attracted attention. Detailed understanding of the glial functions in these devastating diseases could offer novel interventions. Here, following a brief review of circuitries involved in mood regulation and reward perception, the specific contributions of neurotrophic factors, neuroinflammation, and gut microbiota to these diseases are highlighted. In this context, the role of specific glial cells (e.g., microglia, astroglia, oligodendrocytes, and synantocytes) on phenotypic manifestation of mood disorders or SUD are emphasized. In addition, use of this knowledge in the potential development of novel therapeutics is touched upon.

Iron toxicity, ferroptosis and microbiota in Parkinson's disease: Implications for novel targets.

Parkinson's Disease (PD) is a progressive neurodegenerative disease characterized by loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). Iron (Fe)-dependent programmed cell death known as ferroptosis, plays a crucial role in the etiology and progression of PD. Since SNpc is particularly vulnerable to Fe toxicity, a central role for ferroptosis in the etiology and progression of PD is envisioned. Ferroptosis, characterized by reactive oxygen species (ROS)-dependent accumulation of lipid peroxides, is tightly regulated by a variety of intracellular metabolic processes. Moreover, the recently characterized bi-directional interactions between ferroptosis and the gut microbiota, not only provides another window into the mechanistic underpinnings of PD but could also suggest novel interventions in this devastating disease. Here, following a brief discussion of PD, we focus on how our expanding knowledge of Fe-induced ferroptosis and its interaction with the gut microbiota may contribute to the pathophysiology of PD and how this knowledge may be exploited to provide novel interventions in PD.

The Phytochemical Agathisflavone Modulates miR146a and miR155 in Activated Microglia Involving STAT3 Signaling.

MicroRNAs (miRs) act as important post-transcriptional regulators of gene expression in glial cells and have been shown to be involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we investigated the effects of agathisflavone, a biflavonoid purified from the leaves of Cenostigma pyramidale (Tul.), on modulating the expression of miRs and inflammatory mediators in activated microglia. C20 human microglia were exposed to oligomers of the ß-amyloid peptide (Aß, 500 nM) for 4 h or to lipopolysaccharide (LPS, 1 µg/mL) for 24 h and then treated or not with agathisflavone (1 µM) for 24 h. We observed that ß-amyloid and LPS activated microglia to an inflammatory state, with increased expression of miR-146a, miR-155, IL1-ß, IL-6, and NOS2. Treatment with agathisflavone resulted in a significant reduction in miR146a and miR-155 induced by LPS or Aß, as well as inflammatory cytokines IL1-ß, IL-6, and NOS2. In cells stimulated with Aß, there was an increase in p-STAT3 expression that was reduced by agathisflavone treatment. These data identify a role for miRs in the anti-inflammatory effect of agathisflavone on microglia in models of neuroinflammation and AD.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.

Effect of the Flavonoid Rutin on the Modulation of the Myenteric Plexuses in an Experimental Model of Parkinson's Disease.

Recent discoveries have shown that enteric glial cells play an important role in different neurodegenerative disorders, such as Parkinson's disease (PD), which is characterized by motor dysfunctions caused by the progressive loss of dopaminergic neurons in the substance nigra pars compacta and non-motor symptoms including gastrointestinal dysfunction. In this study, we investigated the modulatory effects of the flavonoid rutin on the behavior and myenteric plexuses in a PD animal model and the response of enteric glia. Adult male Wistar rats were submitted to stereotaxic injection with 6-hydroxydopamine or saline, and they were untreated or treated with rutin (10 mg/kg) for 14 days. The ileum was collected to analyze tissue reactivity and immunohistochemistry for neurons (HuC/HuD) and enteric glial cells (S100ß) in the myenteric plexuses. Behavioral tests demonstrated that treatment with rutin improved the motor capacity of parkinsonian animals and improved intestinal transit without interfering with the cell population; rutin treatment modulated the reactivity of the ileal musculature through muscarinic activation, reducing relaxation through the signaling pathway of nitric oxide donors, and increased the longitudinal contractility of the colon musculature in parkinsonian animals. Rutin revealed modulatory activities on the myenteric plexus, bringing relevant answers regarding the effect of the flavonoid in this system and the potential application of PD adjuvant treatment.

Amburana cearensis seed extract stimulates astrocyte glutamate homeostatic mechanisms in hippocampal brain slices and protects oligodendrocytes against ischemia.

BACKGROUND: Stroke is a leading cause of death and disability worldwide. A major factor in brain damage following ischemia is excitotoxicity caused by elevated levels of the neurotransmitter glutamate. In the brain, glutamate homeostasis is a primary function of astrocytes. Amburana cearensis has long been used in folk medicine and seed extract obtained with dichloromethane (EDAC) have previously been shown to exhibit cytoprotective activity in vitro. The aim of the present study was to analyse the activity of EDAC in hippocampal brain slices. METHODS: We prepared a dichloromethane extract (EDAC) from A. cearensis seeds and characterized the chemical constituents by 1H and 13C-NMR. Hippocampal slices from P6-8 or P90 Wistar rats were used for cell viability assay or glutamate uptake test. Hippocampal slices from P10-12 transgenic mice SOX10-EGFP and GFAP-EGFP and immunofluorescence for GS, GLAST and GLT1 were used to study oligodendrocytes and astrocytes. RESULTS: Astrocytes play a critical role in glutamate homeostasis and we provide immunohistochemical evidence that in excitotoxicity EDAC increased expression of glutamate transporters and glutamine synthetase, which is essential for detoxifying glutamate. Next, we directly examined astrocytes using transgenic mice in which glial fibrillary acidic protein (GFAP) drives expression of enhanced green fluorescence protein (EGFP) and show that glutamate excitotoxicity caused a decrease in GFAP-EGFP and that EDAC protected against this loss. This was examined further in the oxygen-glucose deprivation (OGD) model of ischemia, where EDAC caused an increase in astrocytic process branching, resulting in an increase in GFAP-EGFP. Using SOX10-EGFP reporter mice, we show that the acute response of oligodendrocytes to OGD in hippocampal slices is a marked loss of their processes and EDAC protected oligodendrocytes against this damage. CONCLUSION: This study provides evidence that EDAC is cytoprotective against ischemia and glutamate excitotoxicity by modulating astrocyte responses and stimulating their glutamate homeostatic mechanisms.

Impact of Plant-Derived Compounds on Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal illness characterized by progressive motor neuron degeneration. Conventional therapies for ALS are based on treatment of symptoms, and the disease remains incurable. Molecular mechanisms are unclear, but studies have been pointing to involvement of glia, neuroinflammation, oxidative stress, and glutamate excitotoxicity as a key factor. Nowadays, we have few treatments for this disease that only delays death, but also does not stop the neurodegenerative process. These treatments are based on glutamate blockage (riluzole), tyrosine kinase inhibition (masitinib), and antioxidant activity (edaravone). In the past few years, plant-derived compounds have been studied for neurodegenerative disorder therapies based on neuroprotection and glial cell response. In this review, we describe mechanisms of action of natural compounds associated with neuroprotective effects, and the possibilities for new therapeutic strategies in ALS.

Protective Effects of Flavonoid Rutin Against Aminochrome Neurotoxicity.

Causes of dopaminergic neuronal loss in Parkinson's disease (PD) are subject of investigation and the common use of models of acute neurodegeneration induced by neurotoxins 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 6-hydroxydopamine, and rotenone contributed to advances in the study of PD. However, the use of study models more similar to the pathophysiology of PD is required for advances in early diagnosis and translational pharmacology. Aminochrome (AMI), a compound derived from dopamine oxidation and a precursor of neuromelanin, is able to induce all the mechanisms associated with neurodegeneration. Previously, we showed AMI is cytotoxic in primary culture of mesencephalic cells (PCMC) and induces in vitro and in vivo neuroinflammation. On the other hand, the effect of rutin in central nervous system cells has revealed anti-inflammatory, antioxidative, and neuroprotective potential. However, there have been no data studies on the effect of rutin against aminochrome neurotoxicity. Here, we show that rutin prevents lysosomal dysfunction and aminochrome-induced cell death in SHSY-5Y cells, protects PCMC against aminochrome cytotoxicity, and prevents in vivo loss of dopaminergic neurons in substantia nigra pars compacta (SNPc), as well as microgliosis and astrogliosis. Additionally, we show that rutin decreases levels of interleukin-1ß (IL-1ß) mRNA and increases levels of glia-derived neurotrophic factor (GDNF) and nerve-derived neurotrophic factor (NGF) mRNA. We evidence for the first time the protective effect of rutin on PD aminochrome-induced models and suggest the potential role of the anti-inflammatory activity and upregulation of NGF and GDNF in the mechanism of rutin action against aminochrome neurotoxicity.

Aminochrome Induces Neuroinflammation and Dopaminergic Neuronal Loss: A New Preclinical Model to Find Anti-inflammatory and Neuroprotective Drugs for Parkinson's Disease.

Studies have suggested aminochrome as an endogenous neurotoxin responsible for the dopaminergic neuron degeneration in Parkinson's disease (PD). However, neuroinflammation, an important alteration in PD pathogenesis, has been strictly induced in vitro by aminochrome. The aim of this study was to characterize the neuroinflammation induced in vivo by aminochrome. Wistar rats (male, 250-270 g) received a unilateral single dose by stereotaxic injection of saline into three sites in the striatum in the negative control group, or 32 nmol 6-hydroxydopamine (6-OHDA) in the positive control, or 6 nmol aminochrome. After 14 days, histological and molecular analyses were performed. We observed by immunofluorescence that aminochrome, as well as 6-OHDA, induced an increase in the number of Iba-1+ cells and in the number of activated (Iba-1+/ CD68+) microglia. An increase in the number of S100b+ cells and in the GFAP expression were also evidenced in the striatum and the SNpc of animals from aminochrome and positive control group. Dopaminergic neuronal loss was marked by reduction of TH+ cells and confirmed with reduction in the number of Nissl-stained neurons in the SNpc of rats from aminochrome and positive control groups. In addition, we observed by qPCR that aminocrhome induced an increase in the levels of IL-1ß, TNF-α, NLRP3, CCL5 and CCR2 mRNA in the SNpc. This work provides the first evidence of microgliosis, astrogliosis and neuroinflammation induced by aminochrome in an in vivo model. Since aminochrome is an endogenous molecule derived from dopamine oxidation present in the targeted neurons in PD, these results reinforce the potential of aminochrome as a useful preclinical model to find anti-inflammatory and neuroprotective drugs for PD. Aminochrome induced dopaminergic neuronal loss, microglial activation, astroglial activation and neuroinflammation marked by an increase in NLRP3, IL1ß, TNF-α, CCL2, CCL5 and CCR2.

JM-20, a Benzodiazepine-Dihydropyridine Hybrid Molecule, Inhibits the Formation of Alpha-Synuclein-Aggregated Species.

Studies showed that JM-20, a benzodiazepine-dihydropyridine hybrid molecule, protects against rotenone and 6-hydroxydopamine neurotoxicity. However, its protective effects against cytotoxicity induced by endogenous neurotoxins involved in Parkinson's disease (PD) pathogenesis have never been investigated. In this study, we evaluated the ability of JM-20 to inhibit alpha-synuclein (aSyn) aggregation. We also evaluated the interactions of JM-20 with aSyn by molecular docking and molecular dynamics and assessed the protective effect of JM-20 against aminochrome cytotoxicity. We demonstrated that JM-20 induced the formation of heterogeneous amyloid fibrils, which were innocuous to primary cultures of mesencephalic cells. Moreover, JM-20 reduced the average size of aSyn positive inclusions in H4 cells transfected with SynT wild-type and synphilin-1-V5, but not in HEK cells transfected with synphilin-1-GFP. In silico studies showed the interaction between JM-20 and the aSyn-binding site. Additionally, we showed that JM-20 protects SH-SY5Y cells against aminochrome cytotoxicity. These results reinforce the potential of JM-20 as a neuroprotective compound for PD and suggest aSyn as a molecular target for JM-20.

Astrocyte Reaction to Catechol-Induced Cytotoxicity Relies on the Contact with Microglia Before Isolation.

Astrocytes preserve the brain microenvironment homeostasis in order to protect other brain cells, mainly neurons, against damages. Glial cells have specific functions that are important in the context of neuronal survival in different models of central nervous system (CNS) diseases. Microglia are among these cells, secreting several molecules that can modulate astrocyte functions. Although 1,2-dihydroxybenzene (catechol) is a neurotoxic monoaromatic compound of exogenous origin, several endogenous molecules also present the catechol group. This study compared two methods to obtain astrocyte-enriched cultures from newborn Wistar rats of both sexes. In the first technique (P1), microglial cells began to be removed early 48 h after primary mixed glial cultures were plated. In the second one (P2), microglial cells were late removed 7 to 10 days after plating. Both cultures were exposed to catechol for 72 h. Catechol was more cytotoxic to P1 cultures than to P2, decreasing cellularity and changing the cell morphology. Microglial-conditioned medium (MCM) protected P1 cultures and inhibited the catechol autoxidation. P2 cultures, as well as P1 in the presence of 20% MCM, presented long, dense, and fibrillary processes positive for glial fibrillary acidic protein, which retracted the cytoplasm when exposed to catechol. The Ngf and Il1beta transcription increased in P1, meanwhile astrocytes expressed more Il10 in P2. Catechol decreased Bdnf and Il10 in P2 cultures, and it decreased the expression of Il1beta in both conditions. A prolonged contact with microglia before isolation of astrocyte-enriched cultures modifies astrocyte functions and morphology, protecting these cells against catechol-induced cytotoxicity.

Activation of the Kynurenine Pathway and Production of Inflammatory Cytokines by Astrocytes and Microglia Infected With Neospora caninum.

In the central nervous system, astrocytes and microglia contribute to homeostasis, regulating the immune response to infectious agents. Neospora caninum is an obligate intracellular protozoan that infects different animal species and it is encysted in their nervous tissue while triggering an immune response modulated by glia. This study aimed to evaluate the infection of primary cultures of rat glial cells by N. caninum through the catabolites of tryptophan, the expression of inflammatory mediators and the integrity of neural tissue. Infection with this coccidium resulted in morphological and functional changes, particularly astrogliosis and microgliosis, and increased the expression of the inflammatory mediators TNF, IL1ß, IL-10, and arginase, as well as mRNA for CCL5 and CCL2, molecules involved in the CNS chemotaxis. The infection with N. caninum in glial cells also triggered the activation of the tryptophan pathway, characterized by increased kynurenine 2,3 monooxygenase (KMO) mRNA expression, and by the production of the excitotoxin quinolinic acid (QUIN). Moreover, glia-neuron co-cultures, when exposed to the secretome derived from N. caninum infected glial cells, presented greater neurons distribution and formation of neurite extensions, associated to morphological changes in astrocytes compatible with neuro-preservation. Considering that the tryptophan catabolism is associated to immune response, these findings suggest that glial activation in N. caninum infection should be responsible for modulating the inflammatory status in an attempt to restore the nervous system homeostasis, since excessive inflammatory response can cause irreversible damage to tissue preservation.

Neuroimmunomodulatory Properties of Flavonoids and Derivates: A Potential Action as Adjuvants for the Treatment of Glioblastoma.

Glioblastomas (GBMs) are tumors that have a high ability to migrate, invade and proliferate in the healthy tissue, what greatly impairs their treatment. These characteristics are associated with the complex microenvironment, formed by the perivascular niche, which is also composed of several stromal cells including astrocytes, microglia, fibroblasts, pericytes and endothelial cells, supporting tumor progression. Further microglia and macrophages associated with GBMs infiltrate the tumor. These innate immune cells are meant to participate in tumor surveillance and eradication, but they become compromised by GBM cells and exploited in the process. In this review we discuss the context of the GBM microenvironment together with the actions of flavonoids, which have attracted scientific attention due to their pharmacological properties as possible anti-tumor agents. Flavonoids act on a variety of signaling pathways, counteracting the invasion process. Luteolin and rutin inhibit NFκB activation, reducing IL-6 production. Fisetin promotes tumor apoptosis, while inhibiting ADAM expression, reducing invasion. Naringenin reduces tumor invasion by down-regulating metalloproteinases expression. Apigenin and rutin induce apoptosis in C6 cells increasing TNFα, while decreasing IL-10 production, denoting a shift from the immunosuppressive Th2 to the Th1 profile. Overall, flavonoids should be further exploited for glioma therapy.

Agathisflavone Modifies Microglial Activation State and Myelination in Organotypic Cerebellar Slices Culture.

Oligodendrocytes produce the myelin that is critical for rapid neuronal transmission in the central nervous system (CNS). Disruption of myelin has devastating effects on CNS function, as in the demyelinating disease multiple sclerosis (MS). Microglia are the endogenous immune cells of the CNS and play a central role in demyelination and repair. There is a need for new potential therapies that regulate myelination and microglia to promote repair. Agathisflavone (FAB) is a non-toxic flavonoid that is known for its anti-inflammatory and neuroprotective properties. Here, we examined the effects of FAB (5-50 µM) on myelination and microglia in organotypic cerebellar slices prepared from P10-P12 Sox10-EGFP and Plp1-DsRed transgenic mice. Immunofluorescence labeling for myelin basic protein (MBP) and neurofilament (NF) demonstrates that FAB significantly increased the proportion of MBP + /NF + axons but did not affect the overall number of oligodendroglia or axons, or the expression of oligodendroglial proteins CNPase and MBP. FAB is known to be a phytoestrogen, but blockade of α- or ß- estrogen receptors (ER) indicated the myelination promoting effects of FAB were not mediated by ER. Examination of microglial responses by Iba1 immunohistochemistry demonstrated that FAB markedly altered microglial morphology, characterized by smaller somata and reduced branching of their processes, consistent with a decreased state of activation, and increased Iba1 protein expression. The results provide evidence that FAB increases the extent of axonal coverage by MBP immunopositive oligodendroglial processes and has a modulatory effect upon microglial cells, which are important therapeutic strategies in multiple neuropathologies.

Structural Design, Synthesis and Antioxidant, Antileishmania, Anti-Inflammatory and Anticancer Activities of a Novel Quercetin Acetylated Derivative.

Quercetin (Q) is a bioflavonoid with biological potential; however, poor solubility in water, extensive enzymatic metabolism and a reduced bioavailability limit its biopharmacological use. The aim of this study was to perform structural modification in Q by acetylation, thus, obtaining the quercetin pentaacetate (Q5) analogue, in order to investigate the biological potentials (antioxidant, antileishmania, anti-inflammatory and cytotoxicity activities) in cell cultures. Q5 was characterized by FTIR, 1H and 13C NMR spectra. The antioxidant potential was evaluated against the radical ABTS•+. The anti-inflammatory potential was evaluated by measuring the pro-inflammatory cytokine tumor necrosis factor (TNF) and the production of nitric oxide (NO) in peritoneal macrophages from BALB/c mice. Cytotoxicity tests were performed using the AlamarBlue method in cancer cells HepG2 (human hepatocarcinoma), HL-60 (promyelocytic leukemia) and MCR-5 (healthy human lung fibroblasts) as well as the MTT method for C6 cell cultures (rat glioma). Q and Q5 showed antioxidant activity of 29% and 18%, respectively, which is justified by the replacement of hydroxyls by acetyl groups. Q and Q5 showed concentration-dependent reductions in NO and TNF production (p < 0.05); Q and Q5 showed higher activity at concentrations > 40µM when compared to dexamethasone (20 µM). For the HL-60 lineage, Q5 demonstrated selectivity, inducing death in cancer cells, when compared to the healthy cell line MRC-5 (IC50 > 80 µM). Finally, the cytotoxic superiority of Q5 was verified (IC50 = 11 µM), which, at 50 µM for 24 h, induced changes in the morphology of C6 glioma cells characterized by a round body shape (not yet reported in the literature). The analogue Q5 had potential biological effects and may be promising for further investigations against other cell cultures, particularly neural ones.

JM-20 Treatment After Mild Traumatic Brain Injury Reduces Glial Cell Pro-inflammatory Signaling and Behavioral and Cognitive Deficits by Increasing Neurotrophin Expression.

Traumatic brain injury (TBI) is considered a public health problem and is often related to motor and cognitive disabilities, besides behavioral and emotional changes that may remain for the rest of the subject's life. Resident astrocytes and microglia are the first cell types to start the inflammatory cascades following TBI. It is widely known that continuous or excessive neuroinflammation may trigger many neuropathologies. Despite the large numbers of TBI cases, there is no effective pharmacological treatment available. This study aimed to investigate the effects of the new hybrid molecule 3-ethoxycarbonyl-2-methyl-4-(2-nitrophenyl)-4,11-dihydro1H-pyrido[2,3-b][1,5]benzodiazepine (JM-20) on TBI outcomes. Male Wistar rats were submitted to a weight drop model of mild TBI and treated with a single dose of JM-20 (8 mg/kg). Twenty-four hours after TBI, JM-20-treated animals showed improvements on locomotor and exploratory activities, and short-term memory deficits induced by TBI improved as well. Brain edema was present in TBI animals and the JM-20 treatment was able to prevent this change. JM-20 was also able to attenuate neuroinflammation cascades by preventing glial cells-microglia and astrocytes-from exacerbated activation, consequently reducing pro-inflammatory cytokine levels (TNF-α and IL-1ß). BDNF mRNA level was decreased 24 h after TBI because of neuroinflammation cascades; however, JM-20 restored the levels. JM-20 also increased GDNF and NGF levels. These results support the JM-20 neuroprotective role to treat mild TBI by reducing the initial damage and limiting long-term secondary degeneration after TBI.

JM-20 protects against 6-hydroxydopamine-induced neurotoxicity in models of Parkinson's disease: Mitochondrial protection and antioxidant properties.

We have previously shown that JM-20, a new chemical entity consisting of 1,5-benzodiazepine fused to a dihydropyridine moiety, protects against rotenone-induced neurotoxicity in an experimental model of Parkinson's disease (PD). The aim of this study was to investigate the effect of a novel hybrid molecule, named JM-20, in in vitro and in vivo models of PD induced by 6-hydroxydopamine (6-OHDA). PC-12 cells were exposed to 6-OHDA and treated with JM-20. Protection against mitochondrial damage induced by 6-OHDA was also investigated using isolated rat brain mitochondria. We found that JM-20 protected PC-12 cells against cytotoxicity induced by 6-OHDA and inhibited hydrogen peroxide generation, mitochondrial swelling and membrane potential dissipation. For in vivo experiments, adult male Wistar rats were lesioned in the substantia nigra pars compacta (SNpc) by 6-OHDA administration. JM-20 was orally administered (10, 20 or 40 mg/kg), intragastric via gavage, 24 h after surgery and daily for seven days. Treatment with JM-20 significantly reduced the percentage of motor asymmetry and increased vertical exploration. It improved the redox state of the SNpc and the striatal tissue of these animals. Also, JM-20 reduced glial fibrillary acidic protein overexpression and increased tyrosine hydroxylase-positive cell number, both in SNpc. Altogether, these results demonstrate that JM-20 is a potential neuroprotective agent against 6-OHDA-induced damage in both in vitro and in vivo models. The mechanism underlying JM-20 neuroprotection against 6-OHDA appears to be associated with the control of oxidative injury and mitochondrial impairment.

Amburana cearensis: Pharmacological and Neuroprotective Effects of Its Compounds.

Amburana cearensis A.C. Smith is an endemic tree from Northeastern Brazil used in folk medicine as teas, decocts and syrups for the treatment of various respiratory and inflammatory diseases, since therapeutic properties have been attributed to compounds from its stem bark and seeds. Numerous pharmacological properties of semi-purified extracts and isolated compounds from A. cearensis have been described in several biological systems, ranging from antimicrobial to anti-inflammatory effects. Some of these activities are attributed to coumarins and phenolic compounds, the major compounds present in A. cearensis seed extracts. Multiple lines of research demonstrate these compounds reduce oxidative stress, inflammation and neuronal death induced by glutamate excitotoxicity, events central to most neuropathologies, including Alzheimer's disease (AD) and Parkinson's Disease (PD). This review focuses on the botanical aspects, folk medicine use, biological effects and pharmacological activities of A. cearensis compounds and their potential as novel non-toxic drugs for the treatment of neurodegenerative diseases.

Neuroimmunomodulatory and Neuroprotective Effects of the Flavonoid Apigenin in in vitro Models of Neuroinflammation Associated With Alzheimer's Disease.

Neurodegenerative disorders (ND) are characterized by the progressive and irreversible loss of neurons. Alzheimer's Disease (AD) is the most incident age-related ND, in which the presence of a chronic inflammatory compound seems to be related to its pathogenesis. Different stimuli in the central nervous system (CNS) can induce activation, proliferation, and changes in phenotype and glial function, which can be modulated by anti-inflammatory agents. Apigenin (4,5,7-trihydroxyflavone) is a flavonoid found in abundance in many fruits and vegetables, that has shown important effects upon controlling the inflammatory response. This study evaluated the neuroprotective and neuroimmunomodulatory potential of apigenin using in vitro models of neuroinflammation associated with AD. Co-cultures of neurons and glial cells were obtained from the cortex of newborn and embryonic Wistar rats. After 26 days in vitro, cultures were exposed to lipopolysaccharide (LPS; 1 µg/ml), or IL-1ß (10 ng/ml) for 24 h, or to Aß oligomers (500 nM) for 4 h, and then treated with apigenin (1 µM) for further 24 h. It was observed that the treatment with apigenin preserved neurons and astrocytes integrity, determined by Rosenfeld's staining and immunocytochemistry for ß-tubulin III and GFAP, respectively. Moreover, it was observed by Fluoro-Jade-B and caspase-3 immunostaining that apigenin was not neurotoxic and has a neuroprotective effect against inflammatory damage. Additionally, apigenin reduced microglial activation, characterized by inhibition of proliferation (BrdU+ cells) and modulation of microglia morphology (Iba-1 + cells), and decreased the expression of the M1 inflammatory marker CD68. Moreover, as determined by RT-qPCR, inflammatory stimuli induced by IL-1ß increased the mRNA expression of IL-6, IL-1ß, and CCL5, and decreased the mRNA expression of IL-10. Contrary, after treatment with apigenin in inflammatory stimuli (IL-1ß or LPS) there was a modulation of the mRNA expression of inflammatory cytokines, and reduced expression of OX42, IL-6 and gp130. Moreover, apigenin alone and after an inflammatory stimulus with IL-1ß also induced the increase in the expression of brain-derived neurotrophic factor (BDNF), an effect that may be associated with anti-inflammatory and neuroprotective effects. Together these data demonstrate that apigenin presents neuroprotective and anti-inflammatory effects in vitro and might represent an important neuroimmunomodulatory agent for the treatment of neurodegenerative conditions.

The Flavonoid Agathisflavone from Poincianella pyramidalis Prevents Aminochrome Neurotoxicity.

Flavonoids have been suggested to protect dopaminergic neurons in Parkinson's disease based on studies that used exogenous neurotoxins. In this study, we tested the protective ability of agathisflavone in SH-SY5Y cells exposed to the endogenous neurotoxin aminochrome. The ability of aminochrome to induce loss of lysosome acidity is an important mechanism of its neurotoxicity. We demonstrated that the flavonoid inhibited cellular death and lysosomal dysfunction induced by aminochrome. In addition, we demonstrated that the protective effect of agathisflavone was suppressed by antagonists of estrogen receptors (ERα and ERß). These results suggest lysosomal protection and estrogen signaling as mechanisms involved in agathisflavone neuroprotection in a Parkinson's disease study model.