Protective effects of Chunghyuldan against ROS-mediated neuronal cell death in models of Parkinson's disease

IL-6 expression-suppressing Lactobacillus reuteri strains alleviate gut microbiota-induced anxiety and depression in mice

Fecal microbiota transplantation from patients with depression/inflammatory bowel disease (PDI) causes depression with gut inflammation in mice. Here, we investigated the effects of six Lactobacillus reuteri strains on brain-derived neurotropic factor (BDNF), serotonin, and interleukin (IL)-6 expression in neuronal or macrophage cells and PDI fecal microbiota-cultured microbiota (PcM)-induced depression in mice. Of these strains, L6 most potently increased BDNF and serotonin levels in corticosterone-stimulated SH-SY5Y and PC12 cells, followed by L3. L6 most potently decreased IL-6 expression in lipopolysaccharide (LPS)-stimulated macrophages. When L1 (weakest in vitro), L3, and L6 were orally administered in mice with PcM-induced depression, L6 most potently suppressed depression-like behaviors and hippocampal TNF-α and IL-6 expression and increased hippocampal serotonin, BDNF, 5HT7, GABAARα1, and GABABR1b expression, followed by L3 and L1. L6 also suppressed TNF-α and IL-6 expression in the colon. BDNF or serotonin levels in corticosterone-stimulated neuronal cells were negatively correlated with depression-related biomarkers in PcM-transplanted mice, while IL-6 levels in LPS-stimulated macrophage were positively correlated. These findings suggest that IL-6 expression-suppressing and BDNF/serotonin expression-inducing LBPs in vitro, particularly L6, may alleviate gut microbiota-involved depression with colitis in vivo.

A Comparative Study on the Neuroprotective Effect of Geopung-Chunghyuldan on In Vitro Oxygen-Glucose Deprivation and In Vivo Permanent Middle Cerebral Artery Occlusion Models

Geopung-Chunghyuldan (GCD), which is a mixture of Chunghyuldan (CD), Radix Salviae Miltiorrhizae, Radix Notoginseng, and Borneolum Syntheticum, is used to treat ischemic stroke in traditional Korean medicine. This study aimed to investigate the effects of GCD and CD on ischemic brain damage using in vitro and in vivo stroke models, as well as to elucidate the synergistic effects of GCD against ischemic insult. To study the effect of GCD in an in vitro ischemia model, SH-SY5Y cells were exposed to oxygen-glucose deprivation (OGD). Cell death after 16 h of OGD exposure was measured using the MTT assay and live/dead cell counting methods. An in vivo ischemia mice model was established through permanent middle cerebral artery occlusion (pMCAO). To determine the neuroprotective effect of GCD, it was orally administered immediately and 2 h after pMCAO. The infarct volume was measured through 2,3,5-triphenyltetrazolium chloride staining at 24 h after pMCAO. Compared with the control group, GCD treatment significantly reduced OGD-induced cell death in SH-SY5Y cells; however, CD treatment did not show a significant protective effect. In the pMCAO model, compared with the control group, treatment with GCD and CD significantly and mildly reduced the infarct volume, respectively. Our findings indicate that compared with CD, GCD may allow a more enhanced neuroprotective effect in acute ischemic stroke, indicating a potential synergistic neuroprotective effect. The possibility of GCD as a novel alternative choice for the prevention and treatment of ischemic stroke is suggested.

Effect of pH on the structure and function of cyclin-dependent kinase 6

Cyclin-dependent kinase 6 (CDK6) is an important protein kinase that regulates cell growth, development, cell metabolism, inflammation, and apoptosis. Its overexpression is associated with reprogramming glucose metabolism through alternative pathways and apoptosis, which ultimately plays a significant role in cancer development. In the present study, we have investigated the structural and conformational changes in CDK6 at varying pH employing a multi-spectroscopic approach. Circular dichroism (CD) spectroscopy revealed at extremely acidic conditions (pH 2.0–4.0), the secondary structure of CDK6 got significantly disrupted, leading to aggregates formation. These aggregates were further characterized by employing Thioflavin T (ThT) fluorescence. No significant secondary structural changes were observed over the alkaline pH range (pH 7.0–11.0). Further, fluorescence and UV spectroscopy revealed that the tertiary structure of CDK6 was disrupted under extremely acidic conditions, with slight alteration occurring in mild acidic conditions. The tertiary structure remains intact over the entire alkaline range. Additionally, enzyme assay provided an insight into the functional aspect of CDK at varying pH; CDK6 activity was optimal in the pH range of 7.0–8.0. This study will provide a platform that provides newer insights into the pH-dependent dynamics and functional behavior of CDK6 in different CDK6 directed diseased conditions, viz. different types of cancers where changes in pH contribute to cancer development.

Neuroinflammation in neurological disorders: pharmacotherapeutic targets from bench to bedside

Neuroinflammation is one of the host defensive mechanisms through which the nervous system protects itself from pathogenic and or infectious insults. Moreover, neuroinflammation occurs as one of the most common pathological outcomes in various neurological disorders, makes it the promising target. The present review focuses on elaborating the recent advancement in understanding molecular mechanisms of neuroinflammation and its role in the etiopathogenesis of various neurological disorders, especially Alzheimer's disease (AD), Parkinson's disease (PD), and Epilepsy. Furthermore, the current status of anti-inflammatory agents in neurological diseases has been summarized in light of different preclinical and clinical studies. Finally, possible limitations and future directions for the effective use of anti-inflammatory agents in neurological disorders have been discussed.

Reduced intracellular antioxidant capacity in platelets contributes to primary immune thrombocytopenia via ROS-NLRP3-caspase-1 pathway

Primary immune thrombocytopenia (ITP) is a common acquired autoimmune hemorrhagic disease characterized by a low platelet count and increased risk of bleeding. However, some patients do not respond well to current therapeutic approaches. Further studies on pathogenesis and pathophysiology of ITP are needed to discover new therapeutic targets. We explored the role of enhanced intracellular oxidative stress and NLRP3 inflammasome activation of platelets in ITP. The expression of NLRP3 inflammasome was assessed in platelets from active ITP patients and healthy donors. Both the mRNA and protein expression level of platelet NLRP3 inflammasome was upregulated in ITP patients compared with healthy donors. Besides, the elevated caspase-1 activity and increased co-localization of NLRP3 and its adaptor molecule ASC indicated activation of NLRP3 inflammasome in ITP platelets. Significantly decreased intracellular antioxidant capacity was observed in ITP platelets. H₂O₂ supplementation elevated the expression of NLRP3 inflammasome and increased IL-1β secretion in ITP platelets. Preincubating ITP platelets with NAC down-regulated the expression of NLRP3 inflammasome. Pretreating ITP platelets with NLRP3 inhibitor MCC950 or caspase-1 inhibitor Z-YVAD-FMK significantly reduced the proportion of pyroptotic cells in H₂O₂-treated ITP platelets and suppressed IL-1β secretion in supernatants. Hence, platelet NLRP3 inflammasome activation resulted from reduced intracellular antioxidant capacity plays a critical role in ITP and might have potential diagnostic or therapeutic implications.

The Role of Oxidative Stress in Parkinson's Disease

Parkinson’s disease (PD) is caused by progressive neurodegeneration of dopaminergic (DAergic) neurons with abnormal accumulation of α-synuclein in substantia nigra (SN). Studies have suggested the potential involvement of dopamine, iron, calcium, mitochondria and neuroinflammation in contributing to overwhelmed oxidative stress and neurodegeneration in PD. Function studies on PD-causative mutations of SNCA, PRKN, PINK1, DJ-1, LRRK2, FBXO7 and ATP13A2 further indicate the role of oxidative stress in the pathogenesis of PD. Therefore, it is reasonable that molecules involved in oxidative stress, such as DJ-1, coenzyme Q10, uric acid, 8-hydroxy-2’-deoxyguanosin, homocysteine, retinoic acid/carotenes, vitamin E, glutathione peroxidase, superoxide dismutase, xanthine oxidase and products of lipid peroxidation, could be candidate biomarkers for PD. Applications of antioxidants to modulate oxidative stress could be a strategy in treating PD. Although a number of antioxidants, such as creatine, vitamin E, coenzyme Q10, pioglitazone, melatonin and desferrioxamine, have been tested in clinical trials, none of them have demonstrated conclusive evidence to ameliorate the neurodegeneration in PD patients. Difficulties in clinical studies may be caused by the long-standing progression of neurodegeneration, lack of biomarkers for premotor stage of PD and inadequate drug delivery across blood–brain barrier. Solutions for these challenges will be warranted for future studies with novel antioxidative treatment in PD patients.

Evaluation of the Anti-apoptotic and Anti-cytotoxic Effect of Epicatechin Gallate and Edaravone on SH-SY5Y Neuroblastoma Cells

Introduction:

Parkinson disease (PD) is the second most common neurodegenerative disease affecting older individuals with signs of motor disability and cognitive impairment. Epicatechin (EC) and edaravone have neuroprotective effects most probably due to their antioxidant activity; however, a limited number of studies have considered their role in PD. This research aimed at investigating the neuroprotective effect of EC and edaravone in a neurotoxin-induced model of PD.

Methods:

An in vitro model of PD was made by subjecting SH-SY5Y neuroblastoma cells to neurotoxin: 6-hydroxydopamine (6-OHDA) 100 μM/well. The cytoprotective effect of EC and edaravone in five concentrations on cell viability was tested using the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. The apoptotic assay was done by annexin V and propidium iodide method using flow cytometry.

Results:

According to the MTT assay analysis, EC and edaravone had protective effects against 6-OH DA-induced cytotoxicity in SH-SY5Y neuroblastoma cells that were much more significant for edaravone and also a relative synergistic effect between EC and edaravone was observed. The apoptotic analysis showed that edaravone alone could decrease early and late apoptosis, whereas EC diminished early apoptosis, but enhanced late apoptosis and necrosis. Besides, co-treatment of edaravone and EC had a synergistic effect on decreasing apoptosis and increasing cell viability.

Conclusion:

The protective effect of edaravone on apoptosis and cytotoxicity was demonstrated clearly and EC had a synergistic effect with edaravone.

Bruceine D elevates Nrf2 activation to restrain Parkinson's disease in mice through suppressing oxidative stress and inflammatory response

Parkinson's disease (PD) is neurodegenerative disease, featured by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), characteristic motor symptoms and cognitive impairment. Development of effective therapeutic drugs for PD is necessary. In this study, we investigated the potential of Bruceine D (BD) during PD progression. After establishment of PD mouse models, we found that BD markedly improved the motor function of mice and alleviated chemically induced dopaminergic neuron loss of tyrosine hydroxylase (TH) in the SNpc area. BD treatments markedly repressed the neuroinflammation in SNpc by restricting nuclear factor κB (NF-κB) activation, accompanied with the reduced activity of astrocytes and microglial. BD also improved the antioxidant system in MPTP-challenged mice, as proved by the up-regulated superoxide dismutase (SOD) and glutathione (GSH), and down-regulated malondialdehyde (MDA) in SNpc and striatum (STR). The anti-oxidant effects of BD were regulated by the activation of nuclear factor E2-related factor 2 (Nrf2) signaling, contributing to the expression of Nrf2 down-streaming signals such as heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidoreductase 1 (NQO1) and glutathione cysteine ligase modulatory subunit (GCLM). In MPP⁺-challenged mouse neurons, BD exhibited cytoprotective effects by improving the Nrf2-meditated antioxidant system and abolished the MPP⁺-triggered inflammatory response through hindering the activation of the NF-κB signal. The pharmacokinetic parameters and organ distribution findings demonstrated that BD showed a brain tissue targeting function. Moreover, both in vivo and in vitro analysis indicated that BD had few side effects. Collectively, results here demonstrated that BD was effective for the inhibition of dopaminergic neuronal loss and PD progression by activating Nrf2 without toxicity.

Effects of Combined Treatment with Acupuncture and Chunggan Formula in a Mouse Model of Parkinson's Disease

Parkinson's disease is the second most common neurodegenerative disease. Patients with Parkinson's disease can be treated with a combination of acupuncture and herbal medicine, but studies on the synergistic effects of the combined treatment have not yet been conducted. Thus, we subjected an MPTP-induced Parkinson's disease mouse model to the combined treatment. We used acupoint GB34 for acupuncture and modified Chunggantang (KD5040) as the herbal medicine, as they have been reported to be effective in Parkinson's disease. We investigated the suboptimal dose of KD5040 and then used this dose in the combined treatment. The results showed that the combined treatment had a synergistic effect on improvements in abnormal motor function and neurodegeneration compared with the use of acupuncture or herbal medicine alone. The combined treatment also had a neuroprotective effect via the PI3K/AKT and MAPK/ERK signaling pathways. These findings suggest that the combined treatment with acupuncture and KD5040 can help improve the symptoms of Parkinson's disease.

Collagen Based Multicomponent Interpenetrating Networks as Promising Scaffolds for 3D Culture of Human Neural Stem Cells, Human Astrocytes, and Human Microglia

This work describes for the first time the fabrication and characterization of multicomponent interpenetrating networks composed of collagen I, hyaluronic acid, and poly(ethylene glycol) diacrylate for the 3D culture of human neural stem cells, astrocytes, and microglia. The chemical composition of the scaffolds can be modulated while maintaining values of complex moduli within the range of the mechanical performance of brain tissue (∼6.9 kPa) and having cell viability exceeding 84%. The developed scaffolds are a promising new family of biomaterials that can potentially serve as 3D in vitro models for studying the physiology and physiopathology of the central nervous system.

Neuroprotective effect of α-mangostin on mitochondrial dysfunction and α-synuclein aggregation in rotenone-induced model of Parkinson's disease in differentiated SH-SY5Y cells

The study was designed to evaluate the protective effect of α-mangostin and explore its mechanism in an in vitro model of Parkinson's disease (PD) induced by rotenone. SH-SY5Y cells were treated with rotenone and α-mangostin for 24 h. α-Mangostin significantly and concentration-dependently inhibited rotenone-induced cytotoxicity. The rotenone-induced aggregation of α-synuclein and loss of TH were alleviated by α-mangostin. α-Mangostin treatment also reversed the rotenone-induced overproduction of reactive oxygen species, activation of caspases (-8 and -3) and mitochondrial dysfunction, reflected by decrease in mitochondrial membrane potential and cellular ATP levels. These findings suggest that α-mangostin has neuroprotective effects against PD-related neuronal injury.

The Effects of Chunghyul-Dan, an Agent of Korean Medicine, on a Mouse Model of Traumatic Brain Injury

Chunghyul-Dan (CHD) is the first choice agent for the prevention and treatment of stroke at the Kyung Hee Medical Hospital. To date, CHD has been reported to have beneficial effects on brain disease in animals and humans, along with antioxidative and anti-inflammatory effects. The aim of this study was to evaluate the pharmacological effects of CHD on a traumatic brain injury (TBI) mouse model to explore the possibility of CHD use in patients with TBI. The TBI mouse model was induced using the controlled cortical impact method. CHD was orally administered twice a day for 5 d after TBI induction; mice were assessed for brain damage, brain edema, blood-brain barrier (BBB) damage, motor deficits, and cognitive impairment. Treatment with CHD reduced brain damage seen on histological examination and improved motor and cognitive functions. However, CHD did not reduce brain edema and BBB damage. In conclusion, CHD could be a candidate agent in the treatment of patients with TBI. Further studies are needed to assess the exact mechanisms of the effects during the acute-subacute phase and pharmacological activity during the chronic-convalescent phase of TBI.

Chemical constituents from a Gynostemma laxum and their antioxidant and neuroprotective activities

Background

A few bioactivities of constituents from Gynostemma laxum, which has been collected in Vietnam, have been reported until now. There is no report about the effects of constituents from G. laxum although the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated heme oxygenase-1 (HO-1) antioxidant defense system is involved in neuroprotection in the brain. Therefore, we investigated whether quercetin (2), benzoic acid (10) and their analogues (1, 3–9 and 11) from G. laxum have the antioxidant and neuroprotective activities and also their underlying mechanism.

Methods

To examine their neuroprotective and antioxidant activities, oxytosis, total oxidant scavenging capacity (TOSC), 2,7-dichlorofluorescein (DCFDA), dihydroethidium (DHE), antioxidant response element (ARE)-luciferase reporter gene assays, Western blot analysis, real time-PCR, immunocytochemistry and in silico 3D molecular docking simulation were performed.

Results

The study of constituents using chromatographic techniques and spectroscopic analysis showed that G. laxum contained an abundance of quercetin (2), benzoic acid (10) and their analogues (1, 3–9 and 11). Our data demonstrated that quercetin (2) and its analogue (4) among the constituents from G. laxum showed the strongest neuroprotective effect against oxytosis triggered by the excessive amount of glutamate. Compounds 2, 4, 6 and 11 exhibited reactive oxygen species (ROS) inhibitory and ARE transcriptional activities in immortalized hippocampal HT22 cell line. Among them, compound 4, a second active compound, induced Nrf2/HO-1 activation. They were also fit stable onto the Tramtrack and Bric-à-Brac (BTB) domain of Kelch-like ECH-associated protein 1 (Keap1), a known Nrf2 inhibitor protein, based on the results of docking and interaction energies. Overall, these data suggest that –OH and –OCH₃ groups of quercetin and its analogues are responsible for their neuroprotective effect.

Conclusions

In summary, the major constituents of G. laxum had strong antioxidant and neuroprotective activities so that they could consider as a natural antioxidant supplement. Furthermore, G. laxum might be used beneficially in reducing oxidative complications with the further deep investigation in vivo.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-017-0136-y) contains supplementary material, which is available to authorized users.

Antioxidant and neuroprotector effect of Lepidium meyenii (maca) methanol leaf extract against 6-hydroxy dopamine (6-OHDA)-induced toxicity in PC12 cells

Reactive oxygen species (ROS) are normally produced during cell metabolism, there is strong evidence to suggest that ROS produced in excess impair the cell and may be etiologically related to various neurodegenerative diseases. This study was undertaken to examine the effects of Lepidium meyenii (MACA) methanol leaf extract on neurotoxicity in PC12 cell exposed to 6-hydroxydopamine (6-OHDA). Fresh samples of "maca" leaves were processed in order to obtain foliar extracts and to evaluate the neurobiological activity on PC12 cells, subjected to the cytotoxic effect of 6-OHDA through the determination of the capacity antioxidant, cell viability and cytotoxicity assays on PC12 cells. The results of the tests of antioxidant activity, showed maximum values of 2262.37 and 1305.36 expressed in Trolox equivalents (TEAC), for the methanolic and aqueous fractions respectively. Cell viability assays at a dose of 10 μg extract showed an increase of 31% and 60% at 6 and 12 h of pretreatment, respectively. Cytotoxicity assays at the same dose and exposure time showed a 31.4% and 47.8% reduction in lactate dehydrogenase (LDH) activity and an increase in superoxide dismutase (SOD) activity. The results allow us to affirm that the methanolic foliar extract of "maca" presents in vitro neurobiological activity of antioxidant protection, increase in cell viability and reduction of cytotoxicity against oxidative stress generated by 6-OHDA. In conclusion, the present study shows a protective role for Lepidium meyenii leaf extract on 6-OHDA-induced toxicity by an antioxidant effect.

The Effect of Chunghyul-Dan on Hyperventilation-Induced Carbon Dioxide Reactivity of the Middle Cerebral Artery in Normal Subjects: A Dose-Dependent Study

Background. This study was conducted to show the prompt effect of chunghyul-dan (CHD) on cerebral hemodynamics in order to provide evidence for its use in stroke prevention. Methods. Hyperventilation-induced CO₂ reactivity of the middle cerebral artery was measured in 12 healthy male volunteers (mean age: 26.3 ± 1.1 years) using transcranial Doppler sonography. All subjects were examined before and for 3 hours after administration, with an interval of 1 week between measurements. Results. Compared to baseline, the CO₂ reactivity of the middle cerebral artery increased significantly at 2 and 3 hours after the administration of CHD (600 mg and 1200 mg). The mean blood pressure and heart rate did not vary from the baseline values in all groups. Conclusion. These data suggest that CHD administration (especially 600 mg) immediately improves cerebral blood flow.

The Role of Reactive Oxygen Species in the Pathogenesis of Alzheimer's Disease, Parkinson's Disease, and Huntington's Disease: A Mini Review

Neurodegenerative diseases affect not only the life quality of aging populations, but also their life spans. All forms of neurodegenerative diseases have a massive impact on the elderly. The major threat of these brain diseases includes progressive loss of memory, Alzheimer's disease (AD), impairments in the movement, Parkinson's disease (PD), and the inability to walk, talk, and think, Huntington's disease (HD). Oxidative stress and mitochondrial dysfunction are highlighted as a central feature of brain degenerative diseases. Oxidative stress, a condition that occurs due to imbalance in oxidant and antioxidant status, has been known to play a vital role in the pathophysiology of neurodegenerative diseases including AD, PD, and HD. A large number of studies have utilized oxidative stress biomarkers to investigate the severity of these neurodegenerative diseases and medications are available, but these only treat the symptoms. In traditional medicine, a large number of medicinal plants have been used to treat the symptoms of these neurodegenerative diseases. Extensive studies scientifically validated the beneficial effect of natural products against neurodegenerative diseases using suitable animal models. This short review focuses the role of oxidative stress in the pathogenesis of AD, PD, and HD and the protective efficacy of natural products against these diseases.

Effects of MgSO4 and magnesium transporters on 6-hydroxydopamine-induced SH-SY5Y cells

AIMS

The magnesium ion (Mg²⁺) fulfils several important functions for living organisms. We investigated whether there is a protective effect of MgSO₄ on 6-OHDA-induced neurotoxicity in SH-SY5Y cells, and gained insight into the effects of cellular mRNA and protein expression of the magnesium transporters SLC41A1, NIPA1, MagT1 and CNNM2 on 6-OHDA-induced neurotoxicity.

MAIN METHODS

The effect of MgSO₄ on cell viability in 6-OHDA-treated SH-SY5Y cells was measured using a CCK-8 kit. The mRNA and protein expression of SLC41A1, NIPA1, MagT1, and CNNM2 were detected using reverse transcription-qPCR and Western blot.

KEY FINDINGS

The results showed that SH-SY5Y cells treated with 25-50μM 6-OHDA for 24h significantly decreased cell viability, while if pre-incubated with 0.125-1mM MgSO₄ for 1h before adding 6-OHDA it partially prevented the cell damage. There was a significant decrease in cellular mRNA and protein expression of SLC41A1, NIPA1, MagT1 and CNNM2 in 6-OHDA treated SH-SY5Y cells, and MgSO₄ can reverse its decline.

SIGNIFICANCE

Our results suggest that MgSO₄ may protect SH-SY5Y cells against 6-OHDA-induced cell injury and that gene expression of SLC41A1, NIPA1, MagT1, and CNNM2 might be involved in dopaminergic neurons.

Autophagy regulates MAVS signaling activation in a phosphorylation-dependent manner in microglia

Mitochondrial antiviral signaling (MAVS) protein has an important role in antiviral immunity and autoimmunity. However, the pathophysiological role of this signaling pathway, especially in the brain, remains elusive. Here we demonstrated that MAVS signaling existed and mediated poly(I:C)-induced inflammation in the brain. Along with the MAVS signaling activation, there was an induction of autophagic activation. Autophagy negatively regulated the activity of MAVS through direct binding of LC3 to the LIR motif Y(9)xxI(12) of MAVS. We also found that c-Abl kinase phosphorylated MAVS and regulated its interaction with LC3. Interestingly, tyrosine phosphorylation of MAVS was required for downstream signaling activation. Importantly, in vivo data showed that the deficiency of MAVS or c-Abl prevented MPTP-induced microglial activation and dopaminergic neuron loss. Together, our findings reveal the molecular mechanisms underlying the regulation of MAVS-dependent microglial activation in the nervous system, thus providing a potential target for the treatment of microglia-driven inflammatory brain diseases.

The Effects of Chunghyul-Dan (A Korean Medicine Herbal Complex) on Cardiovascular and Cerebrovascular Diseases: A Narrative Review

Chunghyul-dan (CHD) is a herbal complex containing 80% ethanol extract and is composed of Scutellariae Radix, Coptidis Rhizoma, Phellodendri Cortex, Gardeniae Fructus, and Rhei Rhizoma. We have published several experimental and clinical research articles on CHD. It has shown antilipidemic, antihypertensive, antiatherosclerotic, and inhibitory effects on ischemic stroke recurrence with clinical safety in the previous studies. The antilipidemic effect of CHD results from 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and pancreatic lipase-inhibitory activity. The antihypertensive effect likely results from the inhibitory effect on endogenous catecholamine(s) release and harmonization of all components showing the antihypertensive effects. Furthermore, anti-inflammatory and antioxidant effects on endothelial cells are implicated to dictate the antiatherosclerotic effects of CHD. It also showed neuroprotective effects on cerebrovascular and parkinsonian models. These effects of CHD could be helpful for the prevention of the recurrence of ischemic stroke. Therefore, we suggest that CHD could be a promising medication for treating and preventing cerebrovascular and cardiovascular diseases. However, to validate and better understand these findings, well-designed clinical studies are required.

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.

EGCG Protects against 6-OHDA-Induced Neurotoxicity in a Cell Culture Model

Background. Parkinson's disease (PD) is a progressive neurodegenerative disease that causes severe brain dopamine depletion. Disruption of iron metabolism may be involved in the PD progression. Objective. To test the protective effect of (-)-epigallocatechin-3-gallate (EGCG) against 6-hydroxydopamine- (6-OHDA-) induced neurotoxicity by regulating iron metabolism in N27 cells. Methods. Protection by EGCG in N27 cells was assessed by SYTOX green assay, MTT, and caspase-3 activity. Iron regulatory gene and protein expression were measured by RT-PCR and Western blotting. Intracellular iron uptake was measured using (55)Fe. The EGCG protection was further tested in primary mesencephalic dopaminergic neurons by immunocytochemistry. Results. EGCG protected against 6-OHDA-induced cell toxicity. 6-OHDA treatment significantly (p < 0.05) increased divalent metal transporter-1 (DMT1) and hepcidin and decreased ferroportin 1 (Fpn1) level, whereas pretreatment with EGCG counteracted the effects. The increased (55)Fe (by 96%, p < 0.01) cell uptake confirmed the iron burden by 6-OHDA and was reduced by EGCG by 27% (p < 0.05), supporting the DMT1 results. Pretreatment with EGCG and 6-OHDA significantly increased (p < 0.0001) TH(+) cell count (~3-fold) and neurite length (~12-fold) compared to 6-OHDA alone in primary mesencephalic neurons. Conclusions. Pretreatment with EGCG protected against 6-OHDA-induced neurotoxicity by regulating genes and proteins involved in brain iron homeostasis, especially modulating hepcidin levels.

Mitochondria-Targeted Protective Compounds in Parkinson's and Alzheimer's Diseases

Mitochondria are cytoplasmic organelles that regulate both metabolic and apoptotic signaling pathways; their most highlighted functions include cellular energy generation in the form of adenosine triphosphate (ATP), regulation of cellular calcium homeostasis, balance between ROS production and detoxification, mediation of apoptosis cell death, and synthesis and metabolism of various key molecules. Consistent evidence suggests that mitochondrial failure is associated with early events in the pathogenesis of ageing-related neurodegenerative disorders including Parkinson's disease and Alzheimer's disease. Mitochondria-targeted protective compounds that prevent or minimize mitochondrial dysfunction constitute potential therapeutic strategies in the prevention and treatment of these central nervous system diseases. This paper provides an overview of the involvement of mitochondrial dysfunction in Parkinson's and Alzheimer's diseases, with particular attention to in vitro and in vivo studies on promising endogenous and exogenous mitochondria-targeted protective compounds.

Targeting cyclin D3/CDK6 activity for treatment of Parkinson's disease

At present, treatment for Parkinson's disease (PD) is only symptomatic; therefore, it is important to identify new targets tackling the molecular causes of the disease. We previously found that lymphoblasts from sporadic PD patients display increased activity of the cyclin D3/CDK6/pRb pathway and higher proliferation than control cells. These features were considered systemic manifestations of the disease, as aberrant activation of the cell cycle is involved in neuronal apoptosis. The main goal of this work was to elucidate whether the inhibition of cyclin D3/CDK6-associated kinase activity could be useful in PD treatment. For this purpose, we investigated the effects of two histone deacetylase (HDAC) inhibitors, suberoylanilide hydroxamic (SAHA) acid and sodium butyrate (NaB), and the m-TOR inhibitor rapamycin on cell viability and cyclin D3/CDK6 activity. Moreover, the potential neuroprotective action of these drugs was evaluated in 6-hydroxy-dopamine (6-OHDA) treated dopaminergic SH-SY5Y cells and primary rat mesencephalic cultures. Here, we report that both compounds normalized the proliferative activity of PD lymphoblasts and reduced the 6-OHDA-induced cell death in neuronal cells by preventing the over-activation of the cyclin D3/CDK6/pRb cascade. Considering that these drugs are already used in clinic for treatment of other diseases with good tolerance, it is plausible that they may serve as novel therapeutic drugs for PD. We report here that peripheral cells from Parkinson's disease (PD) patients show an enhanced proliferative activity due to the activation of cyclin D3/CDK6-mediated phosphorylation of retinoblastoma protein (pRb). Treatment of PD lymphoblasts with inhibitors of histone deacetylases like suberoylanilide hydroxamic acid (SAHA) and sodium butyrate (NaB), or with rapamycin, inhibitor of mechanistic target of rapamycin (mTOR) normalized the proliferation of PD lymphoblasts by preventing the over-activation of the cyclin D3/CDK6/pRb cascade. These drugs were shown to have neuroprotective effects in both human neuroblastoma SH-SY5Y cells and primary rat mid-brain dopaminergic neuronal cultures toxicity induced by 6-hidroxydopamine. Considering that these drugs are already used in clinic for treatment of other diseases with good tolerance, it seems reasonable to believe that the repositioning of these drugs toward PD holds promise as a novel therapeutic strategy.

Edible bird's nest ameliorates oxidative stress-induced apoptosis in SH-SY5Y human neuroblastoma cells

Background

Parkinson’s disease (PD) is the second most common neurodegenerative disorder affecting the senile population with manifestation of motor disability and cognitive impairment. Reactive oxygen species (ROS) is implicated in the progression of oxidative stress-related apoptosis and cell death of the midbrain dopaminergic neurons. Its interplay with mitochondrial functionality constitutes an important aspect of neuronal survival in the perspective of PD. Edible bird’s nest (EBN) is an animal-derived natural food product made of saliva secreted by swiftlets from the Aerodamus genus. It contains bioactive compounds which might confer neuroprotective effects to the neurons. Hence this study aims to investigate the neuroprotective effect of EBN extracts in the neurotoxin-induced in vitro PD model.

Methods

EBN was first prepared into pancreatin-digested crude extract and water extract. In vitro PD model was generated by exposing SH-SY5Y cells to neurotoxin 6-hydroxydopamine (6-OHDA). Cytotoxicity of the extracts on SH-SY5Y cells was tested using MTT assay. Then, microscopic morphological and nuclear examination, cell viability test and ROS assay were performed to assess the protective effect of EBN extracts against 6-OHDA-induced cellular injury. Apoptotic event was later analysed with Annexin V-propidium iodide flow cytometry. To understand whether the mechanism underlying the neuroprotective effect of EBN was mediated via mitochondrial or caspase-dependent pathway, mitochondrial membrane potential (MMP) measurement and caspase-3 quantification were carried out.

Results

Cytotoxicity results showed that crude EBN extract did not cause SH-SY5Y cell death at concentrations up to 75 μg/ml while the maximum non-toxic dose (MNTD) of water extract was double of that of crude extract. Morphological observation and nuclear staining suggested that EBN treatment reduced the level of 6-OHDA-induced apoptotic changes in SH-SY5Y cells. MTT study further confirmed that cell viability was better improved with crude EBN extract. However, water extract exhibited higher efficacy in ameliorating ROS build up, early apoptotic membrane phosphatidylserine externalization as well as inhibition of caspase-3 cleavage. None of the EBN treatment had any effect on MMP.

Conclusions

Current findings suggest that EBN extracts might confer neuroprotective effect against 6-OHDA-induced degeneration of dopaminergic neurons, particularly through inhibition of apoptosis. Thus EBN may be a viable nutraceutical option to protect against oxidative stress-related neurodegenerative disorders such as PD.

Neuroprotective effect of Chunghyuldan from amyloid beta oligomer induced neuroinflammation in vitro and in vivo

Microglia-mediated inflammation is a major pathological mechanism contributing to Alzheimer's disease (AD), and has been proposed as a potential therapeutic target. Chunghyuldan (CHD; Qingxue-dan in Chinese and Daio-Orengedokuto in Japanese) possesses wide-ranging biological effects, including anti-hyperlipidemic, anti-stroke, anti-inflammatory, and antioxidant activities that could affect neurological functions. In this study, we examined the effects of CHD in in-vitro and in-vivo models of AD induced by the oligomeric form of amyloid-beta (Aβ oligomer), which acts directly on microglia-mediated neuroinflammation to result in neuronal damage and cognitive impairment. CHD at 0.1-100 μg·mL(-1) significantly protected PC12 cells and rat primary hippocampal cells from Aβ oligomer1-42 toxicity. In addition, CHD at 1-10 μg·mL(-1) inhibited Aβ oligomer1-42 induced production of nitric oxide, tumor necrosis factor-α, and interleukin-1β in microglial cells. In an in-vivo AD model, administration of CHD (50 mg·(kg body mass)(-1), for 5 days, per oral) inhibited the activation of astrocytes and microglia in the dentate gyrus and neuronal damage in the CA1 of the ipsilateral hippocampus. Moreover, CHD ameliorated cognitive impairment induced by Aβ oligomer1-42 toxicity. These results demonstrate the neuroprotective effects of CHD through inhibition of microglia-mediated neuroinflammation in in-vitro and in-vivo AD-like models induced by Aβ oligomer1-42 toxicity.

Up-regulated GLT-1 resists glutamate toxicity and attenuates glutamate-induced calcium loading in cultured neurocytes

Glutamate transporter-1 (GLT-1) plays a dual role in glutamate transportation: both normally devotion to the clearance of glutamate and during some pathological conditions extruding glutamate to the extracellular space. Therefore, it is uncertain whether increased expression of GLT-1 will actually be helpful against glutamate excitotoxicity. In this study, GLT-1 up-regulation was induced by ceftriaxone, and L-glutamate was added to induce glutamate toxicity in primary cultured rat cortical cells. The results showed that up-regulated GLT-1 induced by 1 μM ceftriaxone for 2 days markedly increased cell viability, decreased apoptotic cell death and alleviated ultrastructural damage induced by 50 μM glutamate 15 min. as well as promoted L-[(3) H]-glutamate uptake in cultured cells. GLT-1 up-regulation had no effect on the intracellular free calcium concentration ([Ca(2+) ](i) ) in the resting situation, while relieved intracellular calcium overloading by reducing the elevation and promoting the recovery of [Ca(2+) ](i) following stimulation of 50 μM glutamate for 2 min. Applying 100 μM dihydrokainic acid (GLT-1 antagonist) 30 sec. before glutamate eliminated the above effect of GLT-1 up-regulation on [Ca(2+) ](i) . In conclusion, GLT-1 up-regulation induced by ceftriaxone plays a positive glutamate transporting role against glutamate toxicity in primary cultured rat cortical cells.

Anti-Parkinsonian drug discovery from herbal medicines: what have we got from neurotoxic models?

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal medicines are used to treat Parkinson's disease (PD) in ancient medical systems in Asian countries such as India, China, Japan and Korea based on their own anecdotal or experience-based theories.

AIM OF THE REVIEW

To systematically summarize and analyze the anti-Parkinsonian activities of herbal preparations (including active compounds, herbal extracts and formulations) investigated in the neurotoxic models of PD and provide future references for basic and clinical investigations.

MATERIALS AND METHODS

All the herbal materials tested on in vitro and in vivo neurotoxic models of PD were retrieved from PubMed database by using pre-set searching strings. The relevant compounds and herbal extracts with anti-Parkinsonian activities were included and analyzed according to their chemical classifications or biological activities.

RESULTS

A total of 51 herbal medicines were analyzed. A diversity of compounds isolated from herbal materials were reported to be effective on neurotoxic models of PD by modulating multiple key events or signaling pathways implicated in the pathogenesis of PD. The main structure types of these compounds belong to catechols, stilbenoids, flavonoids, phenylpropanoids and lignans, phenylethanoid glycosides and terpenes. Although some herbal extracts and formulations have shown positive results on PD animal models, the relative compounds accounting for the effects and the underlying mechanisms remain to be further investigated.

CONCLUSIONS

Herbal medicines can be an alternative and valuable source for anti-Parkinsonian drug discovery. Compounds classified into stilbenoids, flavonoids, catechols and terpenes may be the most promising candidates for further investigation. Some well-studies compounds such as baicalein, puerarin, resveratrol, curcumin and ginsenosides deserve further consideration in clinical trials. In-depth experimental studies are still needed to evaluate the efficacy of herbal extracts and formulations in PD models.

Gami-Chunghyuldan ameliorates memory impairment and neurodegeneration induced by intrahippocampal Aβ 1-42 oligomer injection

Soluble oligomeric forms of amyloid beta (AβO) are regarded as a main cause of synaptic and cognitive dysfunction in Alzheimer's disease (AD) and have been a primary target in the development of drug treatments for AD. The present study utilized a mouse model of AD induced by intrahippocampal injection of AβO (10 μM) to investigate the effects of Gami-Chunghyuldan (GCD), a standardized multi-herbal medicinal formula, on the presentation of memory deficits and neurohistological pathogenesis. GCD (10 and 50mg/kg/day, 5 days, p.o.) improved AβO-induced memory impairment as well as reduced neuronal cell death, astrogliosis, and microgliosis in the hippocampus. In addition, GCD prevented AβO-triggered synaptic disruption and cholinergic fiber loss. These results suggest that GCD may be useful in the prevention and treatment of AD.

Protective effect of Chrysanthemum indicum Linne against 1-methyl-4-phenylpridinium ion and lipopolysaccharide-induced cytotoxicity in cellular model of Parkinson's disease

Chrysanthemum indicum Linn. (CI) has been used in Oriental medicine for several centuries. In the present study, the effect of CI extract was evaluated against 1-methyl-4-phenylpridinium ion (MPP(+))-induced damage in SH-SY5Y cells and lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Cell viability, oxidative damage, reactive oxygen species, expression of Bcl-2/Bax, and poly (ADP-ribose) polymerase (PARP) proteolysis were evaluated using SH-SY5Y cells. Production of iNOS, prostaglandin E(2), and pro-inflammatory cytokines like tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-6, expression of cyclooxygenase type-2 (COX-2) and type-1 (COX-1) were examined in activated BV-2 microglia. At 1, 10 and 100 μg, CI inhibited cell loss, decreased the reactive oxygen species production, regulated the Bax/Bcl-2 ratio and inhibited PARP proteolysis in MPP(+)-induced SH-SY5Y cells. Furthermore, CI suppressed the production of prostaglandin E(2,) expression of cyclooxygenase type-2 (COX-2), blocked IκB-α degradation and activation of NF-κB p65 in BV-2 cells in a dose-dependent manner. The molecular mechanisms involved by CI might involve its inhibitory actions both on neuronal apoptosis and neuroinflammatory NF-κB/IκB-α signaling pathway. The present investigation scientifically supports the long history and safe usage of CI as an important functional food with potential benefits in ameliorating deleterious conditions seen in PD.