Curcumin protects dopaminergic neuron against LPS induced neurotoxicity in primary rat neuron/glia culture

The regulating effect of curcumin on NF-κB pathway in neurodegenerative diseases: a review of the underlying mechanisms

Neurodegenerative diseases are part of the central nervous system (CNS) disorders that indicate their presence with neuronal loss, neuroinflammation, and increased oxidative stress. Several pathophysiological factors and biomarkers are involved in this inflammatory process causing these neurological disorders. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is an inflammation element, which induced transcription and appears to be one of the important players in physiological procedures, especially nervous disorders. NF-κB can impact upon series of intracellular actions and induce or inhibit many inflammation-related pathways. Multiple reports have focused on the modification of NF-κB activity, controlling its expression, translocation, and signaling pathway in neurodegenerative disorders and injuries like Alzheimer's disease (AD), spinal cord injuries (SCI), and Parkinson's disease (PD). Curcumin has been noted to be a popular anti-oxidant and anti-inflammatory substance and is the foremost natural compound produced by turmeric. According to various studies, when playing an anti-inflammatory role, it interacts with several modulating proteins of long-standing disease signaling pathways and has an unprovocative consequence on pro-inflammatory cytokines. This review article determined to figure out curcumin's role in limiting the promotion of neurodegenerative disease via influencing the NF-κB signaling route. Preclinical studies were gathered from plenty of scientific platforms including PubMed, Scopus, Cochrane, and Google Scholar to evaluate this hypothesis. Extracted findings from the literature review explained the repressing impact of Curcumin on the NF-κB signaling pathway and, occasionally down-regulating the cytokine expression. Yet, there is an essential need for further analysis and specific clinical experiments to fully understand this subject.

Oxidative stress mediated decrement of spinal endomorphin-2 contributes to lumbar disc herniation sciatica in rats

Increasing evidence supported that oxidative stress induced by herniated lumbar disc played important role in the formation of lumbar disc herniation sciatica (LDHS), however, the neural mechanisms underlying LDHS need further clarification. Endomorphin-2 (EM2) is the endogenous ligand for mu-opioid receptor (MOR), and there is increasing evidence implicating the involvement of spinal EM2 in neuropathic pain. In this study, using an nucleus pulposus implantation induced LDHS rat model that displayed obvious mechanical allodynia, it was found that the expression of EM2 in dorsal root ganglion (DRG) and spinal cord was significantly decreased. It was further found that oxidative stress in DRG and spinal cord was significantly increased in LDHS rats, and the reduction of EM2 in DRG and spinal cord was determined by oxidative stress dominated increment of dipeptidylpeptidase IV activity. A systemic treatment with antioxidant could prevent the forming of mechanical allodynia in LDHS rats. In addition, MOR expression in DRG and spinal cord remained unchanged in LDHS rats. Intrathecal injection of MOR antagonist promoted pain behavior in LDHS rats, and the analgesic effect of intrathecal injection of EM2 was stronger than that of endomorphin-1 and morphine. Taken together, our findings suggest that oxidative stress mediated decrement of EM2 in DRG and spinal cord causes the loss of endogenous analgesic effects and enhances the pain sensation of LDHS.

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Empagliflozin repurposing in Parkinson's disease; modulation of oxidative stress, neuroinflammation, AMPK/SIRT-1/PGC-1α, and wnt/β-catenin pathways

Parkinson's disease is a neuroprogressive disorder characterized by loss of dopaminergic neurons in substantia nigra pars compacta. Empagliflozin (EMPA), a SGLT-2 inhibitor, is an oral hypoglycemic agent with reported anti-inflammatory and antioxidant effects. The current study aimed to evaluate the neuroprotective effect of EMPA in rotenone-induced Parkinson's disease. Rats were randomly distributed among five groups as follows: control, rotenone (2 mg/kg), rotenone + EMPA (10 mg/kg), rotenone + EMPA (20 mg/kg), and EMPA (20 mg/kg) groups. They were treated for 30 consecutive days. Rotenone reduced locomotor activity and retention time on the rotarod performance test while elongated descent latency time. On the other side, EMPA corrected these behavioral changes. These results were confirmed by histological examination and number of intact neurons. Moreover, rotenone induced alpha-synuclein accumulation, reduced tyrosine hydroxylase expression, dopamine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid concentrations. On the other side, EMPA reversed such effects induced by rotenone. Depending on previous results, EMPA (20 mg/kg) was selected for further mechanistic studies. Rotenone ameliorated superoxide dismutase and catalase activities and enhanced lipid peroxidation, interleukin-1β, and tumor necrosis factor-α levels. By contrast, EMPA opposed rotenone-induced effects on oxidative stress and inflammation. Besides, rotenone reduced the expression of pAMP-activated protein kinase (pAMPK), peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), and Sirtuin-1 (SIRT-1), as well as abrogated NAD+/NADH ratio. However, EMPA activated the AMPK/SIRT-1/PGC-1α pathway. Moreover, rotenone hindered the wnt/β-catenin pathway by reducing the wnt-3a level and β-catenin expression. On the other side, EMPA triggered activation of the wnt/β-catenin pathway. Collectively, EMPA may provide a promising solution for Parkinson's patients worldwide.

Honey and Alzheimer's Disease-Current Understanding and Future Prospects

Alzheimer's disease (AD), a leading cause of dementia, has been a global concern. AD is associated with the involvement of the central nervous system that causes the characteristic impaired memory, cognitive deficits, and behavioral abnormalities. These abnormalities caused by AD is known to be attributed by extracellular aggregates of amyloid beta plaques and intracellular neurofibrillary tangles. Additionally, genetic factors such as abnormality in the expression of APOE, APP, BACE1, PSEN-1, and PSEN-2 play a role in the disease. As the current treatment aims to treat the symptoms and to slow the disease progression, there has been a continuous search for new nutraceutical agent or medicine to help prevent and cure AD pathology. In this quest, honey has emerged as a powerful nootropic agent. Numerous studies have demonstrated that the high flavonoids and phenolic acids content in honey exerts its antioxidant, anti-inflammatory, and neuroprotective properties. This review summarizes the effect of main flavonoid compounds found in honey on the physiological functioning of the central nervous system, and the effect of honey intake on memory and cognition in various animal model. This review provides a new insight on the potential of honey to prevent AD pathology, as well as to ameliorate the damage in the developed AD.

Inhibition of Oxidative Stress and the NF-κB Pathway by a Vitamin E Derivative: Pharmacological Approach against Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder. In this study, PD was induced via (ip) injection of haloperidol (1 mg/kg/day). Animals were divided into seven groups (n = 70). Group I received the vehicle carboxymethylcellulose (CMC; 0.5%), group II was treated with designated 1 mg/kg haloperidol, and group III received the standard drug Sinemet (100 mg/kg), while groups IV-VII received a tocopherol derivative (Toco-D) at dose levels of 5, 10, 20, and 40 mg/kg, respectively, via the oral route. All groups received haloperidol for 23 consecutive days after their treatments except the control group. The improvement in locomotor activity and motor coordination was evaluated by using behavioral tests. Oxidative stress markers, neurotransmitters, and monoamine oxidase B (MAO-B) as well as NF-κB levels in the whole brain were measured. mRNA expression analysis of α-synuclein was carried out using the PCR technique. Toco-D at 20 mg/kg showed the maximum improvement in locomotor activity. The levels of antioxidant enzymes and neurotransmitters were also increased by the treatment with Toco-D. Inflammatory cytokine levels and mRNA expression of α-synuclein were decreased by Toco-D in treated animals. This study concluded that Toco-D might be effective in the improvement of locomotor activity and motor coordination in haloperidol-induced PD.

The Neuroprotective and Antioxidant Effects of Nanocurcumin Oral Suspension against Lipopolysaccharide-Induced Cortical Neurotoxicity in Rats

Lipopolysaccharide (LPS) proved to be an important tool, not only in the induction of neuroinflammatory models, but also in demonstrating the behavioral and cognitive consequences of endotoxemia. Curcumin, in its native form, has proven to be a worthy candidate for further development as it protects the dopaminergic neurons against LPS-induced neurotoxicity. However, it remains hindered by its poor bioavailability. In this study we aim to explore the possible molecular mechanism of LPS-induced neurotoxicity and the possible protective effects of orally supplemented nanocurcumin. Thirty-six adult male Wistar rats weighing 170-175 g were divided into six groups and treated with single I.P. (intra-peritoneal) dose of LPS (sigma and extracted; separately) (5 mg/kg BW) plus daily oral nanocurcumin (15 mg/kg BW). The rats were followed for 7 days after the LPS injection and nanocurcumin supplementations daily via oral gavage. After scarification, the levels of neurotransmitters, antioxidants, and amyloidogenesis markers were assessed in brain tissues. Nanocurcumin showed adequate antioxidant and neuroprotective effects, rescuing the rats which had been injected intraperitoneally with LPS endotoxin.

Calycosin Alleviates Paraquat-Induced Neurodegeneration by Improving Mitochondrial Functions and Regulating Autophagy in a Drosophila Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder with limited clinical treatments. The occurrence of PD includes both genetic and environmental toxins, such as the pesticides paraquat (PQ), as major contributors to PD pathology in both invertebrate and mammalian models. Calycosin, an isoflavone phytoestrogen, has multiple pharmacological properties, including neuroprotective activity. However, the paucity of information regarding the neuroprotective potential of calycosin on PQ-induced neurodegeneration led us to explore whether calycosin can mitigate PD-like phenotypes and the underlying molecular mechanisms. We used a PQ-induced PD model in Drosophila as a cost-effective in vivo screening platform to investigate the neuroprotective efficacy of natural compounds on PD. We reported that calycosin shows a protective role in preventing dopaminergic (DA) neuronal cell death in PQ-exposed Canton S flies. Calycosin-fed PQ-exposed flies exhibit significant resistance against PQ-induced mortality and locomotor deficits in terms of reduced oxidative stress, loss of DA neurons, the depletion of dopamine content, and phosphorylated JNK-caspase-3 levels. Additionally, mechanistic studies show that calycosin administration improves PQ-induced mitochondrial dysfunction and stimulates mitophagy and general autophagy with reduced pS6K and p4EBP1 levels, suggestive of a maintained energy balance between anabolic and catabolic processes, resulting in the inhibition of neuronal cell death. Collectively, this study substantiates the protective effect of calycosin against PQ-induced neurodegeneration by improving DA neurons' survival and reducing apoptosis, likely via autophagy induction, and it is implicated as a novel therapeutic application against toxin-induced PD pathogenesis.

The Chemistry and Pharmacology of Fungal Genus Periconia: A Review

Periconia is filamentous fungi belonging to the Periconiaceae family, and over the last 50 years, the genus has shown interest in natural product exploration for pharmacological purposes. Therefore, this study aims to analyze the different species of Periconia containing natural products such as terpenoids, polyketides, cytochalasan, macrosphelides, cyclopentenes, aromatic compounds, and carbohydrates carbasugar derivates. The isolated compound of this kind, which was reported in 1969, consisted of polyketide derivatives and their structures and was determined by chemical reaction and spectroscopic methods. After some years, 77 compounds isolated from endophytic fungus Periconia were associated with eight plant species, 28 compounds from sea hare Aplysia kurodai, and ten from endolichenic fungi Parmelia sp. The potent pharmacological agents from this genus are periconicin A, which acts as an antimicrobial, pericochlorosin B as an anti-human immunodeficiency virus (HIV), peribysin D, and pericosine A as cytotoxic agents, and periconianone A as an anti-inflammatory agent. Furthermore, information about taxol and piperine from Periconia producing species was also provided. Therefore, this study supports discovering new drugs produced by the Periconia species and compares them for future drug development.

The CD200R1 microglial inhibitory receptor as a therapeutic target in the MPTP model of Parkinson's disease

Background

It is suggested that neuroinflammation, in which activated microglial cells play a relevant role, contributes to the development of Parkinson’s disease (PD). Consequently, the modulation of microglial activation is a potential therapeutic target to be taken into account to act against the dopaminergic neurodegeneration occurring in this neurological disorder. Several soluble and membrane-associated inhibitory mechanisms contribute to maintaining microglial cells in a quiescent/surveillant phenotype in physiological conditions. However, the presence of activated microglial cells in the brain in PD patients suggests that these mechanisms have been somehow overloaded. We focused our interest on one of the membrane-associated mechanisms, the CD200-CD200R1 ligand-receptor pair.

Methods

The acute MPTP experimental mouse model of PD was used to study the temporal pattern of mRNA expression of CD200 and CD200R1 in the context of MPTP-induced dopaminergic neurodegeneration and neuroinflammation. Dopaminergic damage was assessed by tyrosine hydroxylase (TH) immunoreactivity, and neuroinflammation was evaluated by the mRNA expression of inflammatory markers and IBA1 and GFAP immunohistochemistry. The effect of the modulation of the CD200-CD200R1 system on MPTP-induced damage was determined by using a CD200R1 agonist or CD200 KO mice.

Results

MPTP administration resulted in a progressive decrease in TH-positive fibres in the striatum and TH-positive neurons in the substantia nigra pars compacta, which were accompanied by transient astrogliosis, microgliosis and expression of pro- and anti-inflammatory markers. CD200 mRNA levels rapidly decreased in the ventral midbrain after MPTP treatment, while a transient decrease of CD200R1 mRNA expression was repeatedly observed in this brain area at earlier and later phases. By contrast, a transient increase in CD200R1 expression was observed in striatum. The administration of a CD200R1 agonist resulted in the inhibition of MPTP-induced dopaminergic neurodegeneration, while microglial cells showed signs of earlier activation in CD200-deficient mice.

Conclusions

Collectively, these findings provide evidence for a correlation between CD200-CD200R1 alterations, glial activation and neuronal loss. CD200R1 stimulation reduces MPTP-induced loss of dopaminergic neurons, and CD200 deficiency results in earlier microglial activation, suggesting that the potentiation of CD200R1 signalling is a possible approach to controlling neuroinflammation and neuronal death in PD.

A Placebo-Controlled, Pseudo-Randomized, Crossover Trial of Botanical Agents for Gulf War Illness: Curcumin (Curcuma longa), Boswellia (Boswellia serrata), and French Maritime Pine Bark (Pinus pinaster)

This report is part of a larger study designed to rapidly and efficiently screen potential treatments for Gulf War Illness (GWI) by testing nine different botanicals. In this placebo-controlled, pseudo-randomized, crossover clinical trial of 20 men with GWI, we tested three botanical agents with putative peripheral and central anti-inflammatory actions: curcumin (Curcuma longa), boswellia (Boswellia serrata), and French maritime pine bark extract (Pinus pinaster). Participants completed 30 +/− 3 days of baseline symptom reports, followed by 30 +/− 3 days of placebo, 30 +/− 3 days of lower-dose botanical, and 30 +/− 3 days of higher-dose botanical. Participants then repeated the process with a new botanical until completing up to three botanical cycles. Data were analyzed using linear mixed models. Curcumin reduced GWI symptom severity significantly more than placebo at both the lower (p < 0.0001) and higher (p = 0.0003) dosages. Boswellia was not more effective than placebo at reducing GWI symptoms at either the lower (p = 0.726) or higher (p = 0.869) dosages. Maritime pine was not more effective than placebo at the lower dosage (p = 0.954) but was more effective than placebo at the higher dosage (p = 0.006). This study provides preliminary evidence that curcumin and maritime pine may help alleviate symptoms of GWI. As a screening study, a final determination of the efficacy of these compounds for all individuals with GWI cannot be made, and further studies will need to be conducted to determine strength and durability of effects, as well as optimal dosage. These results suggest that GWI may, at least in part, involve systemic inflammatory processes. This trial was registered on ClinicalTrials.gov (NCT02909686) on 13 September 2016.

GardeninA confers neuroprotection against environmental toxin in a Drosophila model of Parkinson's disease

Parkinson’s disease is an age-associated neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons from the midbrain. Epidemiological studies have implicated exposures to environmental toxins like the herbicide paraquat as major contributors to Parkinson’s disease etiology in both mammalian and invertebrate models. We have employed a paraquat-induced Parkinson’s disease model in Drosophila as an inexpensive in vivo platform to screen therapeutics from natural products. We have identified the polymethoxyflavonoid, GardeninA, with neuroprotective potential against paraquat-induced parkinsonian symptoms involving reduced survival, mobility defects, and loss of dopaminergic neurons. GardeninA-mediated neuroprotection is not solely dependent on its antioxidant activities but also involves modulation of the neuroinflammatory and cellular death responses. Furthermore, we have successfully shown GardeninA bioavailability in the fly heads after oral administration using ultra-performance liquid chromatography and mass spectrometry. Our findings reveal a molecular mechanistic insight into GardeninA-mediated neuroprotection against environmental toxin-induced Parkinson’s disease pathogenesis for novel therapeutic intervention.

Maitra and colleagues identify the neuroprotective properties of GardeninA against environmental toxin-induced neurodegeneration in Drosophila. This study has the potential to influence future research into toxin-induced Parkinson’s disease pathogenesis.

Curcumin inhibits APOE4-induced injury by activating peroxisome proliferator-activated receptor-γ (PPARγ) in SH-SY5Y cells

Objective(s):

The human apolipoprotein E4 (APOE4) is associated with various brain injuries and neurodegenerative changes. Curcumin is an active ingredient isolated from the root of turmeric and is believed to have therapeutic effects on neurodegenerative diseases. The aim of this study was to investigate the effects of curcumin on APOE4-induced neurological damage and explore its molecular mechanisms.

Materials and Methods:

SH-SY5Y cells were pretreated with curcumin for 24 hr and transfected with human APOE4 gene using Lipofectamine 2000. Then, the effect of curcumin on the transfected cells was detected by ELISA, immunofluorescence staining and Western blot.

Results:

The production or expression of proinflammatory cytokines and proteins, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was significantly increased in SH-SY5Y cells transfected with APOE4, and curcumin inhibited APOE4-induced cellular inflammatory damage. Western blot analysis showed that, after transfection with APOE4, the expression of total nuclear factor kappa B (NF-κB) p65 and p-NF-κB p65 in the nucleus was increased, and curcumin inhibited the nuclear translocation of p65. The overexpression of APOE4 inhibited the expression of peroxisome proliferator-activated receptor-γ (PPARγ), whereas curcumin reversed and increased the expression of PPARγ protein. Down-regulating PPAR-γ with the inhibitor GW9662 and the shPPARγ gene confirmed that the NF-κB signaling pathway was inhibited by PPARγ.

Conclusion:

This study suggests that APOE4 overexpression can induce cellular inflammatory damage, and pretreatment of curcumin could exert an anti-inflammatory effect by upregulating the expression of PPARγ to inhibit the activation of NF-κB signaling pathway.

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.

Can Brain Health Be Supported by Vitamin D-Based Supplements? A Critical Review

This review presents recent knowledge on the neuroprotective effects of vitamin D and their usefulness as oral supplementation when combined with other molecules, such as curcumin. A critical look at the effectiveness of vitamin D in this field is also provided. Vitamin D plays a crucial role in neuroprotection and in the cognitive decline associated with aging, where vitamin D’s levels are related to the levels of several neurotrophic factors. An important role of vitamin D has also been observed in the mechanism of neuroinflammation, which is the basis of several aging conditions, including cognitive decline and neurodegeration; furthermore, the neuroprotective effect of vitamin D in the cognitive decline of aging has recently been reported. For this reason, many food supplements created for humans contain vitamin D alone or combined with other molecules with antioxidant properties. However, recent studies also explored negative consequences of the use at a high dosage of vitamin D. Vitamin D in tissues or brain cells can also modulate calbindin-D28K, parvalbumin, and calretinin, and is involved in immune function, thanks also to the combination with curcumin. Curcumin acts as a free radical scavenger and antioxidant, inhibiting lipid peroxidation and oxidative DNA damage. In particular, curcumin is a potent immune-regulatory agent and its administration has been reported to attenuate cognitive impairments. These effects could be exploited in the future to control the mechanisms that lead to the brain decay typical of neurodegenerative diseases.

Purified anacardic acids exert multiple neuroprotective effects in pesticide model of Parkinson's disease: in vivo and in silico analysis

Parkinson's disease (PD) induced by environmental toxins involves a multifactorial cascade of harmful factors, thus motivating the search for therapeutic agents able to act on the greatest number of molecular targets. This study evaluated the efficacy of 50 mg/kg purified anacardic acids (AAs), isolated from cashew nut shell liquid, on multiple steps of oxidative stress and inflammation induced by rotenone in the substantia nigra (SN) and striatum. Adult mice were divided into four groups: Control, rotenone, AAs + rotenone, and AAs alone. Lipoperoxidation, nitric oxide (NO) levels, and reduced glutathione (GSH)/oxidized gluthatione (GSSG) ratio were evaluated. NF-kB-p65, pro-IL-1β, cleaved IL-1β, metalloproteinase-9, Tissue Inhibitory Factor-1 (TIMP-1), tyrosine hydroxylase (TH), and glial fibrillary acidic protein (GFAP) levels were assessed by Western blot. In silico studies were also made using the SwissADME web tool. Rotenone increased lipoperoxidation and NO production and reduced TH levels and GSH/GSSG ratio in both SN and striatum. It also enhanced NF-kB-p65, pro, and cleaved IL-1β, MMP-9, GFAP levels compared to control and AAs groups. The AAs alone reduced pro-IL-1β in the striatum while they augmented TIMP1 and reduced MMP-9 amounts in both regions. AAs reversed rotenone-induced effects on lipoperoxidation, NO production, and GSH/GSSG ratio, as well as increased TH and attenuated pro-IL-1β and MMP-9 levels in both regions, NF-kB-p65 in the SN and GFAP in the striatum. Altogether, the in vivo and in silico analysis reinforced multiple and defined molecular targets of AAs, identifying that they are promising neuroprotective drug candidates for PD, acting against oxidative and inflammatory conditions induced by rotenone.

Curcumin inhibits alloxan-induced pancreatic islet cell damage via antioxidation and antiapoptosis

The present study elucidates the possible protective effects of curcumin on β-cells damaged by oxidative stress and its significance in controlling diabetes mellitus in in vitro experiments. Pancreatic islet (RIN-m5F) cells were treated with 25 mmol/L alloxan (AXN) to induce cell damage and the protective effects of curcumin were observed. The results showed that curcumin significantly promoted the cellular activity of AXN-treated RIN-m5F cells, decreased the ratio of apoptosis, downregulated the level of malondialdehyde, upregulated the levels of superoxide dismutase and reactive oxygen species, increased the expression of Bcl-2, cleaved caspase-3, and cleaved PARP1, and decreased the expression of Bax in AXN-treated cells. These results suggest that curcumin inhibits AXN-induced damage in RIN-m5F cells via antioxidative and antiapoptotic mechanisms.

The Underlying Mechanisms of Curcumin Inhibition of Hyperglycemia and Hyperlipidemia in Rats Fed a High-Fat Diet Combined With STZ Treatment

Curcumin is the main secondary metabolite of Curcuma longa and other Curcuma spp, and has been reported to have some potential in preventing and treating some physiological disorders. This study investigated the effect of curcumin in inhibiting high-fat diet and streptozotocin (STZ)-induced hyperglycemia and hyperlipidemia in rats. Twenty-six male Sprague-Dawley (SD) rats (170–190 g) were randomly divided into a standard food pellet diet group (Control group), a high-fat diet and streptozotocin group (HF + STZ group), and a high-fat diet combined with curcumin and STZ group (HF + Cur + STZ group). Compared with the HF + STZ group, the HF + Cur + STZ group exhibited significantly reduced fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), alanine aminotransferase (AST), and aspartate transaminase (ALT) levels, as well as liver coefficients. In the livers of these rats, the expression of malondialdehyde (MDA) and Bax was downregulated, whereas that of superoxide dismutase (SOD) and Bcl-2 was upregulated. Moreover, the liver histology of these rats was improved and resembled that of the control rats. These results suggest that curcumin prevents high-fat diet and STZ-induced hyperglycemia and hyperlipidemia, mainly via anti-oxidant and anti-apoptotic mechanisms in the liver.

Curcumin prevents the midbrain dopaminergic innervations and locomotor performance deficiencies resulting from chronic aluminum exposure in rat

Aluminum (Al) among the abundant metals on the earth crust, is able to cross the biological barriers via the gastrointestinal and lung tissues. Once in the body, this heavy metal accumulates in different organs, especially the central nervous system. Though its influence is evidently shown in the substantia nigra of Parkinson's disease patients and other brain areas in other neurodegenerative diseases, few studies have demonstrated that Al could trigger profound changes in neurotransmission systems including the dopaminergic (DAergic) system. A variety of medicinal plants may be prescribed in such contamination, including some culinary spices such as Curcumin (Cur). Several studies have proven Cur to exhibit a wide variety of biological and pharmacological activities, especially its antioxidant potential. Using the immunohistochemistry, of tyrosine hydroxylase (TH), in the midbrain substantia nigra pars compact (SNc) and the ventral tegmental area (VTA) and the open field test, we examined the DAergic system together with the locomotor behavior respectively in rats exposed chronically to Al (0,3%) in drinking water during 4 months since the intra-uterine age, as well as the neuroprotective effect of the concomitant administration of Cur I (30 mg/kg B.W) of chronic Al exposed rats. Our results have shown a significant decrease of TH immureactivity in both SNc and VTA associated to a loss of the number of crossed boxes, leading to a difficient locomotor performance in the Al group while Cur I prevents such TH immunoreactivity impairment and maintains a higher locomotor activity in the Al-CurI group. Our findings lead to suppose a powerful and obvious neuroprotective potential of CurI against Al-induced neurotoxicity of the DAergic system involved in the control of the locomotor behavior.

Using Drosophila as a platform for drug discovery from natural products in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder with no cure. Despite intensive research, most of the currently available therapies are only effective in alleviating symptoms with no effect on disease progression. There is an urgent need for new therapeutics to impede disease progression. Natural products are valuable sources of bioactive compounds that can be exploited for novel therapeutic potential in PD pathogenesis. However, rapid screening of plant-derived natural products and characterization of bioactive compounds is costly and challenging. Drosophila melanogaster, commonly known as the fruit fly, has recently emerged as an excellent model for human neurodegenerative diseases, including PD. The high degree of conserved molecular pathways with mammalian models make Drosophila PD models an inexpensive solution to preliminary phases of target validation in the drug discovery pipeline. The present review provides an overview of drug discovery from natural extracts using Drosophila as a screening platform to evaluate the therapeutic potential of phytochemicals against PD.

Effects of Curcumin on Microglial Cells

Microglia are innate immune system cells which reside in the central nervous system (CNS). Resting microglia regulate the homeostasis of the CNS via phagocytic activity to clear pathogens and cell debris. Sometimes, however, to protect neurons and fight invading pathogens, resting microglia transform to an activated-form, producing inflammatory mediators, such as cytokines, chemokines, iNOS/NO and cyclooxygenase-2 (COX-2). Excessive inflammation, however, leads to damaged neurons and neurodegenerative diseases (NDs), such as Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Curcumin is a phytochemical isolated from Curcuma longa. It is widely used in Asia and has many therapeutic properties, including antioxidant, anti-viral, anti-bacterial, anti-mutagenic, anti-amyloidogenic and anti-inflammatory, especially with respect to neuroinflammation and neurological disorders (NDs). Curcumin is a pleiotropic molecule that inhibits microglia transformation, inflammatory mediators and subsequent NDs. In this mini-review, we discuss the effects of curcumin on microglia and explore the underlying mechanisms.

Neuroprotective potency of some spice herbs, a literature review

In recent years, growing attention has been given to traditional medicine. In traditional medicine a large number of plants have been used to cure neurodegenerative diseases such as Alzheimer's disease (AD) and other memory related disorders. Crocus sativus (C. sativus), Nigella sativa (N. sativa), Coriandrum sativum (C. sativum), Ferula assafoetida (F. assafoetida), Thymus vulgaris (T. vulgaris), Zataria multiflora (Z. multiflora) and Curcuma longa (C. longa) were used traditionally for dietary, food additive, spice and various medicinal purposes. The Major components of these herbs are carotenoids, monoterpenes and poly phenol compounds which enhanced the neural functions. These medicinal plants increased anti-oxidant, decreased oxidant levels and inhibited acetylcholinesterase activity in the neural system. Furthermore, neuroprotective of plants occur via reduced pro-inflammatory cytokines such as IL-6, IL-1β, TNF-α and total nitrite generation. Therefore, the effects of the above mentioned medicinal and their active constituents improved neurodegenerative diseases which indicate their therapeutic potential in disorders associated with neuro-inflammation and neurotransmitter deficiency such as AD and depression.

Anti-inflammatory Effects of Curcumin in Microglial Cells

Lipoteichoic acid (LTA) induces neuroinflammatory molecules, contributing to the pathogenesis of neurodegenerative diseases. Therefore, suppression of neuroinflammatory molecules could be developed as a therapeutic method. Although previous data supports an immune-modulating effect of curcumin, the underlying signaling pathways are largely unidentified. Here, we investigated curcumin’s anti-neuroinflammatory properties in LTA-stimulated BV-2 microglial cells. Inflammatory cytokine tumor necrosis factor-α [TNF-α, prostaglandin E2 (PGE2), and Nitric Oxide (NO] secretion in LTA-induced microglial cells were inhibited by curcumin. Curcumin also inhibited LTA-induced inducible NO synthases (iNOS) and cyclooxygenase-2 (COX-2) expression. Subsequently, our mechanistic studies revealed that curcumin inhibited LTA-induced phosphorylation of mitogen-activated protein kinase (MAPK) including ERK, p38, Akt and translocation of NF-κB. Furthermore, curcumin induced hemeoxygenase (HO)-1HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf-2) expression in microglial cells. Inhibition of HO-1 reversed the inhibition effect of HO-1 on inflammatory mediators release in LTA-stimulated microglial cells. Taken together, our results suggest that curcumin could be a potential therapeutic agent for the treatment of neurodegenerative disorders via suppressing neuroinflammatory responses.

ADAM17 regulates TNF-α expression upon lipopolysaccharide stimulation in oral keratinocytes

A disintegrin and metalloprotease 17 (ADAM17) is a tumor necrosis factor (TNF)-converting enzyme and was first identified as the enzyme that cleaves the prodomain of TNF-α, a proinflammatory cytokine that plays a central role in immune regulation and a variety of inflammatory responses in destructive periodontal disease. The aim of the present study was to verify the presence of ADAM17 in the gingival epithelium and elucidate its involvement in the release of TNF-αin oral keratinocytes. Immunohistochemical analyses of ADAM17 were performed in gingival tissues obtained from patients and in human oral keratinocytes (HOKs). Additionally, levels of TNF-α and ADAM17 in HOKs exposed to lipopolysaccharide (LPS) were assessed using enzyme-linked immunosorbent assays. Moreover, the effects of ADAM17 inhibitor, matrix metalloproteinase (MMP) inhibitor, and ADAM17 siRNA on TNF-α concentration were assessed. Strong immunoreactivity for ADAM17 was observed in the epithelium of the inflamed gingival tissues and in HOKs. Furthermore, treatment with either ADAM17 inhibitor or ADAM17 siRNA inhibited the generation of TNF-α induced by LPS in HOKs. The present study demonstrates that ADAM17 is strongly expressed in the epithelium of gingival tissues and suggests that ADAM17 may be a key enzyme that regulates the generation of TNF-α in oral keratinocytes.

A New Neolignan Derivative, Balanophonin Isolated from Firmiana simplex Delays the Progress of Neuronal Cell Death by Inhibiting Microglial Activation

Excessive activation of microglia causes the continuous production of neurotoxic mediators, which further causes neuron degeneration. Therefore, inhibition of microglial activation is a possible target for the treatment of neurodegenerative disorders. Balanophonin, a natural neolignoid from Firmiana simplex, has been reported to have anti-inflammatory and anti-cancer effects. In this study, we aimed to evaluate the anti-neuroinflammatory effects and mechanism of balanophonin in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. BV2 microglia cells were stimulated with LPS in the presence or absence of balanophonin. The results indicated that balanophonin reduced not only the LPS-mediated TLR4 activation but also the production of inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), Interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), in BV2 cells. Balanophonin also inhibited LPS-induced inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX2) protein expression and mitogen activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 MAPK. Interestingly, it also inhibited neuronal cell death resulting from LPS-activated microglia by regulating cleaved caspase-3 and poly ADP ribose polymerase (PARP) cleavage in N2a cells. In conclusion, our data indicated that balanophonin may delay the progression of neuronal cell death by inhibiting microglial activation.

The protective effect of fermented Curcuma longa L. on memory dysfunction in oxidative stress-induced C6 gliomal cells, proinflammatory-activated BV2 microglial cells, and scopolamine-induced amnesia model in mice

BACKGROUND

Curcuma longa L. is a well-known medicinal plant that has been used for its anti-cancer, neuroprotective, and hepatoprotective effects. However, the neuroprotective effect of fermented C. longa (FCL) has not been reported. Therefore, in this study, the effectiveness of FCL for the regulation of memory dysfunction was investigated in two brain cell lines (rat glioma C6 and murine microglia BV2) and scopolamine-treated mice.

METHODS

C. longa powder was fermented by 5% Lactobacillus plantarum K154 containing 2% (w/v) yeast extract at 30 °C for 72 h followed by sterilization at 121 °C for 15 min. The protective effects of fermented C. longa (FCL) on oxidative stress induced cell death were analyzed by MTT assay in C6 cells. The anti-inflammatory effects of FCL were investigated by measuring the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) as well as the expression levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated BV2 cells. The step-through passive avoidance test, Morris water maze test, acetylcholinesterase (AChE) activity, and expression of cAMP response element-binding protein (CREB) and brain-derived neurotropic factor (BDNF) were employed to determine the effects of FCL on scopolamine-induced memory deficit in mice. The contents of curcuminoids were analyzed through LC/MS.

RESULTS

Pretreatment with FCL effectively prevented the cell death induced by oxidative stress in C6 cells. Moreover, FCL inhibited the production NO and PGE₂ via the inhibition of iNOS and COX-2 expression in BV2 cells. FCL significantly attenuated scopolamine-induced memory impairment in mice and prevented scopolamine-induced AChE activity in the hippocampus. Additionally, FCL reversed the reduction of CREB and BDNF expression. The curcuminoids content in FCL was 1.44%.

CONCLUSION

FCL pretreatment could alleviate scopolamine-induced memory impairment in mice, as well as oxidative stress and inflammation in C6 and BV2 cells, respectively. Thus, FCL might be a useful material for preventing impairment of learning and memory.

Two Furanharzianones with 4/7/5/6/5 Ring System from Microbial Transformation of Harzianone

Furanharzianones A and B (2 and 3), two new harziane-type diterpenoids with a tetrahydrofuran and unusual 4/7/5/6/5 ring system, were obtained from the microbial transformation of harzianone (1) by a bacterial strain Bacillus sp. IMM-006. The structures, including the stereochemistry, of the two new compounds were elucidated by extensive spectroscopic analysis. The absolute configuration of 2 was unambiguously determined by single-crystal X-ray diffraction. In addition, a plausible bioconversion pathway was proposed.

Neuroprotective effects of phytochemicals on dopaminergic neuron cultures

INTRODUCTION

Parkinson's disease is a progressive neurodegenerative disorder characterised by a loss of dopaminergic neurons in the substantia nigra pars compacta, which results in a significant decrease in dopamine levels and consequent functional motor impairment.

DEVELOPMENT

Although its aetiology is not fully understood, several pathogenic mechanisms, including oxidative stress, have been proposed. Current therapeutic approaches are based on dopamine replacement drugs; these agents, however, are not able to stop or even slow disease progression. Novel therapeutic approaches aimed at acting on the pathways leading to neuronal dysfunction and death are under investigation.

CONCLUSIONS

In recent years, such natural molecules as polyphenols, alkaloids, and saponins have been shown to have a neuroprotective effect due to their antioxidant and anti-inflammatory properties. The aim of our review is to analyse the most relevant studies worldwide addressing the benefits of some phytochemicals used in in vitro models of Parkinson's disease.

Nutraceuticals in Parkinson's Disease

Current pharmacological strategies for Parkinson’s disease (PD), the most common neurological movement disorder worldwide, are predominantly symptom relieving and are often plagued with undesirable side effects after prolonged treatment. Despite this, they remain as the mainstay treatment for PD due to the lack of better alternatives. Nutraceuticals are compounds derived from natural food sources that have certain therapeutic value and the advent of which has opened doors to the use of alternative strategies to tackle neurodegenerative diseases such as PD. Notably, nutraceuticals are able to position themselves as a “safer” strategy due to the fact that they are naturally derived compounds, therefore possibly having less side effects. Significant efforts have been put into better comprehending the role of nutraceuticals in PD, and we will look at some of them in this review. Broadly speaking, these compounds execute their positive effects via modulating signalling pathways, inhibiting oxidative stress, inflammation and apoptosis, as well as regulating mitochondrial homoeostasis. Importantly, we will highlight how a component of green tea, epigallocatechin-3-gallate (EGCG), confers neuroprotection in PD via its ability to activate AMP kinase and articulate how its beneficial effects in PD are possibly due to enhancing mitochondrial quality control.

Dietary phytochemicals and neuro-inflammaging: from mechanistic insights to translational challenges

An extensive literature describes the positive impact of dietary phytochemicals on overall health and longevity. Dietary phytochemicals include a large group of non-nutrients compounds from a wide range of plant-derived foods and chemical classes. Over the last decade, remarkable progress has been made to realize that oxidative and nitrosative stress (O&NS) and chronic, low-grade inflammation are major risk factors underlying brain aging. Accumulated data strongly suggest that phytochemicals from fruits, vegetables, herbs, and spices may exert relevant negative immunoregulatory, and/or anti-O&NS activities in the context of brain aging. Despite the translational gap between basic and clinical research, the current understanding of the molecular interactions between phytochemicals and immune-inflammatory and O&NS (IO&NS) pathways could help in designing effective nutritional strategies to delay brain aging and improve cognitive function. This review attempts to summarise recent evidence indicating that specific phytochemicals may act as positive modulators of IO&NS pathways by attenuating pro-inflammatory pathways associated with the age-related redox imbalance that occurs in brain aging. We will also discuss the need to initiate long-term nutrition intervention studies in healthy subjects. Hence, we will highlight crucial aspects that require further study to determine effective physiological concentrations and explore the real impact of dietary phytochemicals in preserving brain health before the onset of symptoms leading to cognitive decline and inflammatory neurodegeneration.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.

HIV-1 increases TLR responses in human primary astrocytes

Astrocytes are the major glial cell within the central nervous system and have a number of important physiological properties related to brain homeostasis. They provide trophic support to neurons and are immune cells with key roles during states-of-inflammation. The potential for production of proinflammatory cytokines and its consequences has been studied in the context of HIV-1 infection of normal human astrocytes (NHA). NHA express TLR3, TLR4, and TLR5. TLR3 ligation induced the strongest proinflammatory polarizing response, characterized by generation of high levels of TNF-α, IL-6, and IL-8. HIV-1 increased the transient production of key inflammatory mediators, and exposure to LPS of HIV-1-infected cells increased significantly the cytokine secretion. We confirmed that it is necessary viral gene expression from the moment of pretreatment with antiretrovirals inhibited totally HIV-1-induced TLR response. The higher response to LPS from HIV-1-infected cells did not correlate with TLR4 or MyD88 increased expression. LPS responsiveness of infected cells parallels MHC class II expression, but not CD14. HIV-1-infected NHA present increased sensitivity to the proinflammatory effects of LPS. If this phenomenon occurs in vivo, it will contribute to the immunopathogenesis of this disease and may ultimately offer novel targets for immunomodulatory therapy.

DAT isn't all that: cocaine reward and reinforcement require Toll-like receptor 4 signaling

The initial reinforcing properties of drugs of abuse, such as cocaine, are largely attributed to their ability to activate the mesolimbic dopamine system. Resulting increases in extracellular dopamine in the nucleus accumbens (NAc) are traditionally thought to result from cocaine's ability to block dopamine transporters (DATs). Here we demonstrate that cocaine also interacts with the immunosurveillance receptor complex, Toll-like receptor 4 (TLR4), on microglial cells to initiate central innate immune signaling. Disruption of cocaine signaling at TLR4 suppresses cocaine-induced extracellular dopamine in the NAc, as well as cocaine conditioned place preference and cocaine self-administration. These results provide a novel understanding of the neurobiological mechanisms underlying cocaine reward/reinforcement that includes a critical role for central immune signaling, and offer a new target for medication development for cocaine abuse treatment.

Eremophilane Sesquiterpenes and Polyketones Produced by an Endophytic Guignardia Fungus from the Toxic Plant Gelsemium elegans

A cultured endophytic fungus, Guignardia mangiferae, isolated from the toxic plant Gelsemium elegans yielded five new sesquiterpenes (1-5), two new polyketones (6 and 7), and two known terpene polyketones (8 and 9). Their structures were elucidated using spectroscopic methods. On the basis of circular dichroism, the absolute configurations of the new compounds were determined. Compounds 1, 3, 4, and 9 inhibited lipopolysaccharide-induced NO production in BV2 cells with IC50 values of 15.2, 6.4, 4.2, and 4.5 μM, respectively (positive control curcumin, IC50 = 3.9 μM).

Cytoprotective and anti-inflammatory effects of kernel extract from Adenanthera pavonina on lipopolysaccharide-stimulated rat peritoneal macrophages

OBJECTIVE

To investigate mechanism of anti-inflammatory activity of Adenanthera pavonina (A. pavonina) extracts.

METHODS

Rat peritoneal macrophages were treated with different concentrations of lipopolysaccharide and H2O2 in the presence and absence of kernel extract from A. pavonina. Nitric oxide, Superoxide anion generation, cell viability and nuclear fragmentation were investigated.

RESULTS

The pre-treatment of kernel extract from A. pavonina suppressed nitric oxide, superoxide anion, cell death, nuclear fragmentation in lipopolysaccharide and H2O2 stimulated or induced macrophages, respectively.

CONCLUSIONS

These results suggest that A. pavonina extract suppresses the intra cellular peroxide production.

A survey from 2012 of evidence for the role of neuroinflammation in neurotoxin animal models of Parkinson's disease and potential molecular targets

Parkinson's disease (PD) is a neurodegenerative movement disorder that results from the progressive loss of dopaminergic neurons in the midbrain substantia nigra pars compacta (SNpc). The specific molecular events that cause PD are currently not known; however, progress to better understand PD pathogenesis has been made using various animal models of the disease. In this review, we have highlighted reports from 2012 in which neurochemical/neurotoxins have been used in rodents to specifically address the role of neuroinflammation in the development and/or progression of PD-like pathology and in particular nigral degeneration. A number of studies have been summarized in which plausible pro-inflammatory, anti-inflammatory, or therapeutic agents targeting inflammatory pathways were introduced and/or investigated by various groups for neuroprotective effects. From these studies, it is clear that neuroinflammation acts to exacerbate the toxic outcomes that are set in motion within neurons following exposure to neurotoxins. Additionally, it is noted that future work is still needed to better understand the underlying mechanisms mediating the neuroinflammatory and neurotoxic phenotypes reported in rodent models of PD-like pathology to maximize the translation potential of these interventions to the clinic to prevent and/or delay PD onset and/or progression in humans.

Curcumin attenuates acute inflammatory injury by inhibiting the TLR4/MyD88/NF-κB signaling pathway in experimental traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) initiates a neuroinflammatory cascade that contributes to substantial neuronal damage and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of thiscascade. In the current study, we tested the hypothesis that curcumin, a phytochemical compound with potent anti-inflammatory properties that is extracted from the rhizome Curcuma longa, alleviates acute inflammatory injury mediated by TLR4 following TBI.

METHODS

Neurological function, brain water content and cytokine levels were tested in TLR4⁻/⁻ mice subjected to weight-drop contusion injury. Wild-type (WT) mice were injected intraperitoneally with different concentrations of curcumin or vehicle 15 minutes after TBI. At 24 hours post-injury, the activation of microglia/macrophages and TLR4 was detected by immunohistochemistry; neuronal apoptosis was measured by FJB and TUNEL staining; cytokines were assayed by ELISA; and TLR4, MyD88 and NF-κB levels were measured by Western blotting. In vitro, a co-culture system comprised of microglia and neurons was treated with curcumin following lipopolysaccharide (LPS) stimulation. TLR4 expression and morphological activation in microglia and morphological damage to neurons were detected by immunohistochemistry 24 hours post-stimulation.

RESULTS

The protein expression of TLR4 in pericontusional tissue reached a maximum at 24 hours post-TBI. Compared with WT mice, TLR4⁻/⁻ mice showed attenuated functional impairment, brain edema and cytokine release post-TBI. In addition to improvement in the above aspects, 100 mg/kg curcumin treatment post-TBI significantly reduced the number of TLR4-positive microglia/macrophages as well as inflammatory mediator release and neuronal apoptosis in WT mice. Furthermore, Western blot analysis indicated that the levels of TLR4 and its known downstream effectors (MyD88, and NF-κB) were also decreased after curcumin treatment. Similar outcomes were observed in the microglia and neuron co-culture following treatment with curcumin after LPS stimulation. LPS increased TLR4 immunoreactivity and morphological activation in microglia and increased neuronal apoptosis, whereas curcumin normalized this upregulation. The increased protein levels of TLR4, MyD88 and NF-κB in microglia were attenuated by curcumin treatment.

CONCLUSIONS

Our results suggest that post-injury, curcumin administration may improve patient outcome by reducing acute activation of microglia/macrophages and neuronal apoptosis through a mechanism involving the TLR4/MyD88/NF-κB signaling pathway in microglia/macrophages in TBI.

Spinal changes of a newly isolated neuropeptide endomorphin-2 concomitant with vincristine-induced allodynia

Chemotherapy-induced neuropathic pain (CNP) is the major dose-limiting factor in cancer chemotherapy. However, the neural mechanisms underlying CNP remain unclear. There is increasing evidence implicating the involvement of spinal endomorphin-2 (EM2) in neuropathic pain. In this study, we used a vincristine-evoked rat CNP model displaying mechanical allodynia and central sensitization, and observed a significant decrease in the expression of spinal EM2 in CNP. Also, while intrathecal administration of exogenous EM2 attenuated allodynia and central sensitization, the mu-opioid receptor antagonist β-funaltrexamine facilitated these events. We found that the reduction in spinal EM2 was mediated by increased activity of dipeptidylpeptidase IV, possibly as a consequence of chemotherapy-induced oxidative stress. Taken together, our findings suggest that a decrease in spinal EM2 expression causes the loss of endogenous analgesia and leads to enhanced pain sensation in CNP.

Bisindole alkaloids with neural anti-inflammatory activity from Gelsemium elegans

Three new trace bisindole alkaloids geleganimines A and B (1, 2) and geleganamide (3) were isolated from the aerial parts of Gelsemium elegans. Their structures were elucidated by spectroscopy, particularly from their carbon-proton coupling constants, and electronic circular dichroism. Compounds 1-3 are the first bisindole alkaloids discovered from the genus Gelsemium. Geleganimine B exhibited anti-inflammatory activity indirectly by suppressing lipopolysaccharide-induced pro-inflammatory factors in BV2 microglial cells with an IC50 value of 10.2 μM. These findings confirm the importance of bioactive trace components in medicinal plant research.

Curcumin and its derivatives: their application in neuropharmacology and neuroscience in the 21st century

Curcumin (diferuloylmethane), a polyphenol extracted from the plant Curcuma longa, is widely used in Southeast Asia, China and India in food preparation and for medicinal purposes. Since the second half of the last century, this traditional medicine has attracted the attention of scientists from multiple disciplines to elucidate its pharmacological properties. Of significant interest is curcumin's role to treat neurodegenerative diseases including Alzheimer's disease (AD), and Parkinson's disease (PD) and malignancy. These diseases all share an inflammatory basis, involving increased cellular reactive oxygen species (ROS) accumulation and oxidative damage to lipids, nucleic acids and proteins. The therapeutic benefits of curcumin for these neurodegenerative diseases appear multifactorial via regulation of transcription factors, cytokines and enzymes associated with (Nuclear factor kappa beta) NFκB activity. This review describes the historical use of curcumin in medicine, its chemistry, stability and biological activities, including curcumin's anti-cancer, anti-microbial, anti-oxidant, and anti-inflammatory properties. The review further discusses the pharmacology of curcumin and provides new perspectives on its therapeutic potential and limitations. Especially, the review focuses in detail on the effectiveness of curcumin and its mechanism of actions in treating neurodegenerative diseases such as Alzheimer's and Parkinson's diseases and brain malignancies.

The neurotoxic effect of astrocytes activated with toll-like receptor ligands

Toll-like receptors (TLRs) are key molecules in the innate immune system in the central nervous system. Although astrocytes are believed to play physiological roles in regulating neuronal activity and synaptic transmission, activated astrocytes may also be toxic to neurons. Here, we show that the ligands for TLRs 2, 4, 5 and 6 induce neuronal cell death in neuron-astrocytes co-cultures through the production of reactive oxygen species (ROS). Inhibition of ROS production by NADPH oxidase inhibitor apocynin significantly suppresses neuronal cell death. ROS induced in astrocytes via TLRs may be involved in neuroinflammation and a therapeutic target for neurotoxicity by activated astrocytes.