Tripchlorolide protects against MPTP-induced neurotoxicity in C57BL/6 mice

Herbal/Natural Compounds Resist Hallmarks of Brain Aging: From Molecular Mechanisms to Therapeutic Strategies

Aging is a complex process of impaired physiological integrity and function, and is associated with increased risk of cardiovascular disease, diabetes, neurodegeneration, and cancer. The cellular environment of the aging brain exhibits perturbed bioenergetics, impaired adaptive neuroplasticity and flexibility, abnormal neuronal network activity, dysregulated neuronal Ca²⁺ homeostasis, accumulation of oxidatively modified molecules and organelles, and clear signs of inflammation. These changes make the aging brain susceptible to age-related diseases, such as Alzheimer's and Parkinson's diseases. In recent years, unprecedented advances have been made in the study of aging, especially the effects of herbal/natural compounds on evolutionarily conserved genetic pathways and biological processes. Here, we provide a comprehensive review of the aging process and age-related diseases, and we discuss the molecular mechanisms underlying the therapeutic properties of herbal/natural compounds against the hallmarks of brain aging.

Assessment of antioxidant and antiparkinsonian potential of a new diterpene isolated from Croton argyrophylloides

Oxidative stress is related to health problems including neurological and neurodegenerativedisturbs, such as Parkinson's disease. Natural compounds are reported as source of antioxidant molecules. Therefore, this study aimed to analyze the antioxidant and neuroprotective potential of a new diterpene isolated from C. argyrophylloides (MP-1). Male Wistar rats (250-300 g) were used to evaluate MP-1 antiparkinsonian potential through neurodegenerative model induced by the neurotoxin 6-hydroxydopamine (21 μg). On the 14th day, animals were submitted to behavioral tests and on the 15th day, brain areas were dissected to neurochemical analyzes. MP-1 demonstrated a high antioxidant capacity in vitro and decreased the parkinsonian effects, such as behavioral changes, motor alterations, and body weight loss. MP-1 was also able to control the upregulated levels of nitrosative stress and lipid peroxidation. These findings suggest MP-1 as a diterpene with high antioxidant capacity which might be used to development of new approach against Parkinson's disease.

The therapeutic potential of triptolide and celastrol in neurological diseases

Neurological diseases are complex diseases affecting the brain and spinal cord, with numerous etiologies and pathogenesis not yet fully elucidated. Tripterygium wilfordii Hook. F. (TWHF) is a traditional Chinese medicine with a long history of medicinal use in China and is widely used to treat autoimmune and inflammatory diseases such as systemic lupus erythematosus and rheumatoid arthritis. With the rapid development of modern technology, the two main bioactive components of TWHF, triptolide and celastrol, have been found to have anti-inflammatory, immunosuppressive and anti-tumor effects and can be used in the treatment of a variety of diseases, including neurological diseases. In this paper, we summarize the preclinical studies of triptolide and celastrol in neurological diseases such as neurodegenerative diseases, brain and spinal cord injury, and epilepsy. In addition, we review the mechanisms of action of triptolide and celastrol in neurological diseases, their toxicity, related derivatives, and nanotechnology-based carrier system.

What and How Can Physical Activity Prevention Function on Parkinson's Disease?

Aim

This study was aimed at investigating the effects and molecular mechanisms of physical activity intervention on Parkinson's disease (PD) and providing theoretical guidance for the prevention and treatment of PD.

Methods

Four electronic databases up to December 2019 were searched (PubMed, Springer, Elsevier, and Wiley database), 176 articles were selected. Literature data were analyzed by the logic analysis method.

Results

(1) Risk factors of PD include dairy products, pesticides, traumatic brain injury, and obesity. Protective factors include alcohol, tobacco, coffee, black tea, and physical activity. (2) Physical activity can reduce the risk and improve symptoms of PD and the beneficial forms of physical activity, including running, dancing, traditional Chinese martial arts, yoga, and weight training. (3) Different forms of physical activity alleviate the symptoms of PD through different mechanisms, including reducing the accumulation of α-syn protein, inflammation, and oxidative stress, while enhancing BDNF activity, nerve regeneration, and mitochondrial function.

Conclusion

Physical activity has a positive impact on the prevention and treatment of PD. Illustrating the molecular mechanism of physical activity-induced protective effect on PD is an urgent need for improving the efficacy of PD therapy regimens in the future.

Phytotherapy in treatment of Parkinson's disease: a review

Context: Parkinson's disease (PD) is a neurodegenerative disorder due to gradual loss of dopaminergic nerves in the substantia nigra (SN) in the midbrain. PD leads to certain motor disorders including resting tremor, muscle stiffness and slow movement. Medicinal plants have shown positive pharmacological effects in treating different models of PD. Objective: Tendency to use natural products, especially plants, for the treatment of PD has been growing. This article reviews the basic aspects of medicinal plants and their bioactive compounds that could be used to treat PD. Methods: Reliable articles indexed in databases ISI, SID, PubMed, PubMed Central, Scopus and Web of Science were used. A total of 12 plant-derived active ingredients and 18 herbal extracts were included. Different compounds have so far been isolated from plants that affect PD especially by targeting pathways associated with the pathogenesis of the disease. Results: Although some herbal extracts such as Hibiscus asper Hook. f. (Malvaceae), Ginkgo biloba L. (Ginkgoaceae), Carthamus tinctorius L (Asteraceae) and certain active ingredients, such as berberine and curcumin, have shown positive effects in animal models of PD, potential active ingredients and mechanisms of action should be investigated in additional studies. Discussion and conclusions: Despite the wide variety of plants in the world, a limited number of them have been studied for anti-Parkinsonian activity, and therefore, there are numerous perspectives in this field for future studies on plants and their bioactive compounds.

Tripchlorolide May Improve Spatial Cognition Dysfunction and Synaptic Plasticity after Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological mechanism that underlies cognitive decline and degenerative processes in dementia and other neurodegenerative diseases. Low cerebral blood flow (CBF) during CCH leads to disturbances in the homeostasis of hemodynamics and energy metabolism, which in turn results in oxidative stress, astroglia overactivation, and synaptic protein downregulation. These events contribute to synaptic plasticity and cognitive dysfunction after CCH. Tripchlorolide (TRC) is an herbal compound with potent neuroprotective effects. The potential of TRC to improve CCH-induced cognitive impairment has not yet been determined. In the current study, we employed behavioral techniques, electrophysiology, Western blotting, immunofluorescence, and Golgi staining to investigate the effect of TRC on spatial learning and memory impairment and on synaptic plasticity changes in rats after CCH. Our findings showed that TRC could rescue CCH-induced spatial learning and memory dysfunction and improve long-term potentiation (LTP) disorders. We also found that TRC could prevent CCH-induced reductions in N-methyl-D-aspartic acid receptor 2B, synapsin I, and postsynaptic density protein 95 levels. Moreover, TRC upregulated cAMP-response element binding protein, which is an important transcription factor for synaptic proteins. TRC also prevented the reduction in dendritic spine density that is caused by CCH. However, sham rats treated with TRC did not show any improvement in cognition. Because CCH causes disturbances in brain energy homeostasis, TRC therapy may resolve this instability by correcting a variety of cognitive-related signaling pathways. However, for the normal brain, TRC treatment led to neither disturbance nor improvement in neural plasticity. Additionally, this treatment neither impaired nor further improved cognition. In conclusion, we found that TRC can improve spatial learning and memory, enhance synaptic plasticity, upregulate the expression of some synaptic proteins, and increase the density of dendritic spines. Our findings suggest that TRC may be beneficial in the treatment of cognitive impairment induced by CCH.

Gintonin Mitigates MPTP-Induced Loss of Nigrostriatal Dopaminergic Neurons and Accumulation of α-Synuclein via the Nrf2/HO-1 Pathway

Gintonin, a ginseng-derived glycolipoprotein isolated from ginseng, has been shown to be neuroprotective in several neurological disorders such as Alzheimer's disease models and depressive-like behaviors. In this study, we sought to investigate the potential protective mechanisms of gintonin in an in vivo MPTP and in vitro MPP+-mediated Parkinson's disease (PD) model. We hypothesized that activation of nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1, potential therapeutic targets for neurodegeneration) with gintonin could abrogate PD-associated neurotoxicity by modulating the accumulation of α-synuclein, neuroinflammation, and apoptotic cell death in an MPTP/MPP+ models of PD. Our in vivo and in vitro findings suggest that the neuroprotective effects of gintonin were associated with the regulation of the Nrf2/HO-1 pathway, which regulated the expression of proinflammatory cytokines and nitric oxide synthase and apoptotic markers in the substantia nigra and striatum of the mice. Moreover, the neuroprotective effects of gintonin were also associated with a reduction in α-synuclein accumulation in the mouse substantia nigra and striatum. The neuroprotective effects of gintonin were further validated by analyzing the effects of gintonin on MPP+-treated SH-SY5Y cells, which confirmed the protective effects of gintonin. It remains for future basic and clinical research to determine the potential use of gintonin in Parkinson's disease. However, to the best of our knowledge, marked alterations in biochemical and morphological setup of midbrain dopaminergic pathways by gintonin in MPTP mice model have not been previously reported. We believe that gintonin might be explored as an important therapeutic agent in the treatment of PD.

Natural products against Alzheimer's disease: Pharmaco-therapeutics and biotechnological interventions

Alzheimer's disease (AD) is a severe, chronic and progressive neurodegenerative disease associated with memory and cognition impairment ultimately leading to death. It is the commonest reason of dementia in elderly populations mostly affecting beyond the age of 65. The pathogenesis is indicated by accumulation of the amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFT) in brain tissues and hyperphosphorylation of tau protein in neurons. The main cause is considered to be the formation of reactive oxygen species (ROS) due to oxidative stress. The current treatment provides only symptomatic relief by offering temporary palliative therapy which declines the rate of cognitive impairment associated with AD. Inhibition of the enzyme acetylcholinesterase (AChE) is considered as one of the major therapeutic strategies offering only symptomatic relief and moderate disease-modifying effect. Other non-cholinergic therapeutic approaches include antioxidant and vitamin therapy, stem cell therapy, hormonal therapy, use of antihypertensive or lipid-lowering medications and selective phosphodiesterase (PDE) inhibitors, inhibition of β-secretase and γ-secretase and Aβ aggregation, inhibition of tau hyperphosphorylation and intracellular NFT, use of nonsteroidal anti-inflammatory drugs (NSAIDs), transition metal chelators, insulin resistance drugs, etanercept, brain-derived neurotrophic factor (BDNF) etc. Medicinal plants have been reported for possible anti-AD activity in a number of preclinical and clinical trials. Ethnobotany, being popular in China and in the Far East and possibly less emphasized in Europe, plays a substantial role in the discovery of anti-AD agents from botanicals. Chinese Material Medica (CMM) involving Chinese medicinal plants has been used traditionally in China in the treatment of AD. Ayurveda has already provided numerous lead compounds in drug discovery and many of these are also undergoing clinical investigations. A number of medicinal plants either in their crude forms or as isolated compounds have exhibited to reduce the pathological features associated with AD. In this present review, an attempt has been made to elucidate the molecular mode of action of various plant extracts, phytochemicals and traditional herbal formulations investigated against AD as reported in various preclinical and clinical tests. Herbal synergism often found in polyherbal formulations were found effective to combat disease heterogeneity as found in complex pathogenesis of AD. Finally a note has been added to describe biotechnological improvement, genetic and genomic resources and mathematical and statistical techniques for empirical model building associated with anti-AD plant secondary metabolites and their source botanicals.

Treadmill exercise facilitates synaptic plasticity on dopaminergic neurons and fibers in the mouse model with Parkinson's disease

Exercise for patients with Parkinson's disease (PD) helps to alleviate clinical symptoms such as tremor, balance instability, gait dysfunction, and rigidity. However, molecular mechanism about effect of exercise is poorly unknown. In this study, we investigated effect of exercise in synapse and dendritic spine of nigrostriatal dopaminergic neurons on mice with PD. The C57BL/6J male mice (n=40) were divided by sham group, sham-exercise treated group, 1-Methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) treated group, and MPTP-exercise treated group. For exercise treatment, the mice were put on the treadmill to run for 8m/min, 30min/day, and 5 times/week for 2 weeks. Coordination ability was checked by rota rod test. Expression of tyrosine hydroxylase (TH), synaptophysin, and post-synaptic density protein 95 (PSD-95) was confirmed at substantia nigra pars compacta (SNpc) or striatum using western blotting, or immunohistochemistry. To check dendritic spine in striatum, we used Golgi staining. The results revealed that MPTP treated group displayed poor coordination ability compared with sham group. However, MPTP-exercise treated group showed good coordination ability compared with MPTP treated group. As well as, we also found that MPTP-exercise group increases expression of synaptophysin, PSD-95, TH, and dendritic spine in nigrostriatal dopaminergic neurons and fibers than MPTP treated group (p<0.05). Our findings suggest that exercise may give beneficial effects to patients with PD by facilitating synaptic plasticity and increasing dendritic spines.

Neurotrophic natural products: chemistry and biology

Neurodegenerative diseases and spinal cord injury affect approximately 50 million people worldwide, bringing the total healthcare cost to over 600 billion dollars per year. Nervous system growth factors, that is, neurotrophins, are a potential solution to these disorders, since they could promote nerve regeneration. An average of 500 publications per year attests to the significance of neurotrophins in biomedical sciences and underlines their potential for therapeutic applications. Nonetheless, the poor pharmacokinetic profile of neurotrophins severely restricts their clinical use. On the other hand, small molecules that modulate neurotrophic activity offer a promising therapeutic approach against neurological disorders. Nature has provided an impressive array of natural products that have potent neurotrophic activities. This Review highlights the current synthetic strategies toward these compounds and summarizes their ability to induce neuronal growth and rehabilitation. It is anticipated that neurotrophic natural products could be used not only as starting points in drug design but also as tools to study the next frontier in biomedical sciences: the brain activity map project.

A novel kindling model of temporal lobe epilepsy in rhesus monkeys induced by Coriaria lactone

One of the major challenges in developing novel therapeutics for human epileptic disorders derives from the limitation of knowledge of the processes by which epilepsy is generated (epileptogenesis). Furthermore, the inability to obtain human samples at the early stage of epilepsy hinders studies designed to further understand epileptogenesis. Thus, an effective animal model is critical for studies investigating this process. The purpose of this study was to establish a new primate kindling model of temporal lobe epilepsy (TLE) as an animal model of epileptogenesis. Here, repeated injections of Coriaria lactone (CL) at a subthreshold dose elicited partial seizures that culminated in secondarily generalized tonic-clonic seizures. The sequence of events and features of the behaviors observed in this model simulated those observed in human TLE. Electroencephalogram monitoring revealed the temporal lobe origins of the epileptiform potentials, which were consistent with the behavioral changes observed. A total of 7 rhesus monkeys (78%) were kindled with a median of 48 (41 to 60) CL injections. Both the seizure-induction and mortality rates were dose-dependent. A CL injection at 1.50mg/kg showed the lowest animal mortality rate (0%) and the highest seizure-induction rate (100%). Extensive kindling by CL injections with a median of 97 injections (overkindling) subsequently resulted in the recurrence of spontaneous seizures in rhesus monkeys with frequency patterns that were similar to those observed in human TLE. In addition, rhesus monkeys subjected to large numbers of kindling stimuli displayed mitochondrial damage and astrocyte activation in a pattern that was similar to the neuropathological changes characteristic of human TLE. Thus, a kindling TLE model in rhesus monkeys representing a primate animal model of epileptogenesis was established for the first time using repeated intramuscular injections of Coriaria lactone. This model was easily and efficiently performed and resulted in behavioral, electrographical, and anatomical characteristics of human TLE. Thus, this model might be used in future investigations of the mechanisms involved in the epileptogenesis of TLE and in the development of new antiepileptic drugs.

Dynamic expressions of Beclin 1 and tyrosine hydroxylase in different areas of 6-hydroxydopamine-induced Parkinsonian rats

Beclin 1, a regulator of the autophagy pathway, plays an important role in Parkinson's disease (PD). However, the crucial mechanism of Beclin 1 in PD remains unclear. Therefore, we investigated dynamic expressions of Beclin 1 and tyrosine hydroxylase (TH) in different brain areas of 6-OHDA-induced rats. Beclin 1 and TH expressions were analyzed by flow cytometry and immunohistochemistry, respectively. The results showed that Beclin 1 expressions were low in the sham group, but rose significantly after 6-OHDA injection. In the striatum and cortex, Beclin 1 increased at 3 h, peaking at 12 h, while in the hippocampus, it increased at 3 h and peaked at 24 h, then it declined slowly and remained steady at 72 h. Beclin 1 expression in the striatum and cortex areas was higher than that of the hippocampus area at 12 h. In addition, the time-course of TH expression in the striatum was similar to that in the mesencephalon. TH expression declined dramatically between 0 and 12 h. Pearson analysis showed significant negative correlations between TH and Beclin 1 expression in the areas we analyzed. While TH expression declined gradually between 12 and 72 h, significant positive correlations between TH and Beclin 1 were detected during that interval. This indicated that activation of Beclin 1-dependent autophagy may inhibit the loss of TH-positive neurons.

Extract of Tripterygium wilfordii Hook F Protect Dopaminergic Neurons Against Lipopolysaccharide-Induced Inflammatory Damage

Activation of microglia is a critical pathological marker of Parkinson's disease. Activated microglia produces proinflammatory and neurotoxic factors, which cause neurons to induce neurodegeneration. Although it is believed that Chinese herbs, such as Tripterygium wilfordii Hook F, can ease inflammatory diseases, little is known about its benefit to neurodegenerative disease, like Parkinson's disease. In this study, we report the extract of Tripterygium wilfordii Hook F with a novel extraction method significantly protected dopaminergic neurons from LPS-induced degeneration in rat mesencephalic neuron-glia cultures. Cells pretreated with the extract have shown dose-dependent inhibition of LPS-induced TNFα and excessive NO production. More importantly, the total number of activated microglia was greatly reduced in these pretreated cells. Our results suggest that the extract of Tripterygium wilfordii Hook F has a strong bioactive function to diminish the pro-inflammatory factors, such as TNFα and NO. These data might also shed light for future neurodegenerative disease therapy.

Reduced calcium/calmodulin-dependent protein kinase II activity in the hippocampus is associated with impaired cognitive function in MPTP-treated mice

Parkinson's disease (PD) patients frequently reveal deficit in cognitive functions during the early stage in PD. The dopaminergic neurotoxin, MPTP-induced neurodegeneration causes an injury of the basal ganglia and is associated with PD-like behaviors. In this study, we demonstrated that deficits in cognitive functions in MPTP-treated mice were associated with reduced calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation and impaired long-term potentiation (LTP) induction in the hippocampal CA1 region. Mice were injected once a day for 5days with MPTP (25mg/kg i.p.). The impaired motor coordination was observed 1 or 2week after MPTP treatment as assessed by rota-rod and beam-walking tasks. In immunoblotting analyses, the levels of tyrosine hydroxylase protein and CaMKII autophosphorylation in the striatum were significantly decreased 1week after MPTP treatment. By contrast, deficits of cognitive functions were observed 3-4weeks after MPTP treatment as assessed by novel object recognition and passive avoidance tasks but not Y-maze task. Impaired LTP in the hippocampal CA1 region was also observed in MPTP-treated mice. Concomitant with impaired LTP induction, CaMKII autophosphorylation was significantly decreased 3weeks after MPTP treatment in the hippocampal CA1 region. Finally, the reduced CaMKII autophosphorylation was closely associated with reduced AMPA-type glutamate receptor subunit 1 (GluR1; Ser-831) phosphorylation in the hippocampal CA1 region of MPTP-treated mice. Taken together, decreased CaMKII activity with concomitant impaired LTP induction in the hippocampus likely account for the learning disability observed in MPTP-treated mice.

DJ-1-binding compounds prevent oxidative stress-induced cell death and movement defect in Parkinson's disease model rats

Parkinson's disease (PD) is caused by neuronal cell death. Although a precursor of dopamine and inhibitors of dopamine degradation have been used for PD therapy, cell death progresses during treatment. DJ-1, a causative gene product of a familial form of PD, PARK7, plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in the onset of PD. Superfluous oxidation of cysteine at amino acid 106 (C106) of DJ-1 renders DJ-1 inactive, and such oxidized DJ-1 has been observed in patients with the sporadic form of PD. In this study, we isolated compounds that bind to the region at C106 by a virtual screening. These compounds prevented oxidative stress-induced death of SH-SY5Y cells, embryonic stem cell-derived dopaminergic cells and primary neuronal cells of the ventral mesencephalon, but not that of DJ-1-knockdown cells of SH-SY5Y and NIH3T3 cells, indicating that the effect of the compounds is specific to DJ-1. These compounds inhibited production of reactive oxygen species and restored activities of mitochondrial complex I and tyrosine hydroxylase that had been compromised by oxidative stress. These compounds prevented dopaminergic cell death in the substantia nigra and restored movement abnormality in 6-hydroxyldopamine-injected PD model rats. One mechanism of action of these compounds is prevention of superfluous oxidation of DJ-1, and the compounds passed through the blood-brain barrier in vitro. Taken together, the results indicate that these compounds should become fundamental drugs for PD therapy.

Retrospect and prospect of active principles from Chinese herbs in the treatment of dementia

With an ageing population, dementia has become one of the world's primary health challenges. However, existing remedies offer limited benefits with certain side effects, which has prompted researchers to seek complementary and alternative therapies. China has long been known for abundant usage of various herbs. Some of these herbal decoctions are effective in stimulating blood circulation, supplementing vital energy and resisting aging, the lack of which are believed to underlie dementia. These herbs are regarded as new and promising sources of potential anti-dementia drugs. With the rapid evolution of life science and technology, numerous active components have been identified that are highly potent and multi-targeted with low toxicity, and therefore meet the requirements for dementia therapy. This review updates the research progress of Chinese herbs in the treatment of dementia, focusing on their effective principles.

Identification of glial-cell-line-derived neurotrophic factor-regulated proteins of striatum in mouse model of Parkinson disease

Glial-cell-line-derived neurotrophic factor (GDNF) is a potent survival factor for dopaminergic neurons, and hence serves as a therapeutic candidate for the treatment of Parkinson's disease. However, despite the potential clinical and physiological importance of GDNF, its mechanism of action is unclear. Therefore, we employed a state-of-the-art proteomic technique, DIGE, along with MS and a bioinformatics tool called Database for Annotation, Visualization and Integrated Discovery (DAVID), to profile proteome changes in the parkinsonian mouse striatum after GDNF challenge. Forty-six unique differentially expressed proteins were successfully identified, which were found either up-regulated and/or down-regulated at the two time points 4 and 72 h compared with the control. Proteins involved in cell differentiation and system development formed the largest part of the proteins regulated under GDNF. Furthermore, the aberrant expression of HSPs and mitochondria-associated proteins were noticeable. Moreover, mitochondrial stress 70 protein and heat shock cognate 71 kDa protein, whose relative levels increased significantly in GDNF-treated striatum, were further evaluated with Western blot and RT-PCR, demonstrating a good agreement with quantitative proteomic data. These data will provide some clues for understanding the mechanisms by which GDNF promotes the survival of dopaminergic neurons.

Ghrelin antagonizes MPTP-induced neurotoxicity to the dopaminergic neurons in mouse substantia nigra

Ghrelin, a stomach-derived hormone which induces growth hormone release and promotes positive energy balance, has been reported to inhibit cell apoptosis in endotheliocytes, osteoblasts and cardiocytes. Recent evidence has shown that ghrelin can also inhibit neuronal apoptosis of the hypothalamus and the hippocampus. However, little is known about the effects of ghrelin on the substantia nigra pars compacta (SNpc) neurons in which ghrelin's receptor, growth hormone secretagogue receptor (GHSR)-1a, is highly expressed. In the present study, we investigated whether ghrelin could protect nigral dopaminergic neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in mice. We observed that ghrelin, acting through GHS-R 1a, inhibited MPTP-induced dopaminergic neuronal loss in the SNpc as well as dopamine depletion in the striatum. Ghrelin could also reverse the down-regulated the expression of Bcl-2, up-regulated the expression of Bax, and caspase-3 activation caused by MPTP. This study demonstrated that ghrelin might be a potential protector of dopaminergic neurons in a therapeutic strategy for Parkinson's disease.