Neuroprotective and Neurorescue Mode of Action of Bacopa monnieri (L.) Wettst in 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-Induced Parkinson’s Disease: An In Silico and In Vivo Study

Ethnopharmacological Relevance: Parkinson’s disease (PD) is characterized by progressive death of dopaminergic neurons. The presently used medicines only tackle the symptoms of PD, but none makes a dent on the processes that underpin the disease’s development. Herbal medicines have attracted considerable attention in recent years. Bacopa monnieri (L.) Wettst (Brahmi) has been used in Indian Ayurvedic medicine to enhance memory and intelligence. Herein, we assessed the neuroprotective role of Bacopa monnieri (L.) Wettst on Parkinson’s disease.Aim of the Study:Bacopa monnieri (L.) Wettst, a medicinal herb, is widely used as a brain tonic. We investigated the neuroprotective and neurorescue properties of Bacopa monnieri (L.) Wettst extract (BME) in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice model of PD.Materials and Methods: The mice model of MPTP-induced PD is used in the study. In the neuroprotective (BME + MPTP) and neurorescue (MPTP + BME) experiments, the animals were administered 40 mg/kg body weight BME orally before and after MPTP administration, respectively. Effect of BME treatment was evaluated by accessing neurobehavioral parameters and levels of dopamine, glutathione, lipid peroxide, and nitrites. An in silico study was performed using AutoDock Tools 1.5.6 (ADT).Results: A significant recovery in behavioral parameters, dopamine level, glutathione level, lipid peroxides, and nitrite level was observed in BME-treated mice. Treatment with BME before or after MPTP administration has a protective effect on dopaminergic neurons, as evidenced by a significant decrease in GFAP immunostaining and expression of inducible nitric oxide synthase (iNOS) in the substantia nigra region; however, the degree of improvement was more prominent in mice receiving BME treatment before MPTP administration. Moreover, the in silico study revealed that the constituents of BM, including bacosides, bacopasides, and bacosaponins, can inactivate the enzyme monoamine oxidase B, thus preventing the breakdown of MPTP to MPP+.Conclusion: Our results showed that BME exerts both neuroprotective and neurorescue effects against MPTP-induced degeneration of the nigrostriatal dopaminergic neurons. Moreover, BME may slow down the disease progression and delay the onset of neurodegeneration in PD.

Mfn2 Overexpression Attenuates MPTP Neurotoxicity In Vivo

Mitochondrial dysfunction represents a critical event in the pathogenesis of Parkinson’s disease (PD). Increasing evidence demonstrates that disturbed mitochondrial dynamics and quality control play an important role in mitochondrial dysfunction in PD. Our previous study demonstrated that MPP+ induces mitochondrial fragmentation in vitro. In this study, we aimed to assess whether blocking MPTP-induced mitochondrial fragmentation by overexpressing Mfn2 affords neuroprotection in vivo. We found that the significant loss of dopaminergic neurons in the substantia nigra (SN) induced by MPTP treatment, as seen in wild-type littermate control mice, was almost completely blocked in mice overexpressing Mfn2 (hMfn2 mice). The dramatic reduction in dopamine neuronal fibers and dopamine levels in the striatum caused by MPTP administration was also partially inhibited in hMfn2 mice. MPTP-induced oxidative stress and inflammatory response in the SN and striatum were significantly alleviated in hMfn2 mice. The impairment of motor function caused by MPTP was also blocked in hMfn2 mice. Overall, our work demonstrates that restoration of mitochondrial dynamics by Mfn2 overexpression protects against neuronal toxicity in an MPTP-based PD mouse model, which supports the modulation of mitochondrial dynamics as a potential therapeutic target for PD treatment.

Pretreatment with Human Lactoferrin Had a Positive Effect on the Dynamics of Mouse Nigrostriatal System Recovery after Acute MPTP Exposure

We studied the effect of human lactoferrin (hLf) on degenerative changes in the nigrostriatal system and associated behavioral deficits in the animal model of Parkinson disease. Nigrostriatal dopaminergic injury was induced by single administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 40 mg/kg) to five-month-old C57Bl/6 mice. Behavioral disturbances were assessed in the open field and rotarod tests and by the stride length analysis. Structural deficits were assessed by the counts of tyrosine hydroxylase (TH)-immunoreactive neurons in the substantia nigra and optical density (OD) of TH-immunolabeled fibers in the striatum. Acute MPTP treatment induced long-term behavioral deficit and degenerative changes in the nigrostriatal system. Pretreatment with hLf prevented body weight loss and promoted recovery of motor functions and exploratory behavior. Importantly, OD of TH-positive fibers in the striatum of mice treated with hLf almost returned to normal, and the number of TH-positive cells in the substantia nigra significantly increased on day 28. These results indicate that hLf produces a neuroprotective effect and probably stimulates neuroregeneration under conditions of MPTP toxicity in our model. A relationship between behavioral deficits and nigrostriatal system disturbances at delayed terms after MPTP administration was found.

Ellagic Acid Prevents Dopamine Neuron Degeneration from Oxidative Stress and Neuroinflammation in MPTP Model of Parkinson’s Disease

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases and is characterized by progressive dopaminergic neurodegeneration in the substantia nigra pars compacta area. In the present study, treatment of EA for 1 week at a dose of 10 mg/kg body weight prior to MPTP (25 mg/kg body weight) was carried out. MPTP administration caused oxidative stress, as evidenced by decreased activities of superoxide dismutase and catalase, and the depletion of reduced glutathione with a concomitant rise in the lipid peroxidation product, malondialdehyde. It also significantly increased the pro-inflammatory cytokines and elevated the inflammatory mediators like cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the striatum. Immunohistochemical analysis revealed a loss of dopamine neurons in the SNc area and a decrease in dopamine transporter in the striatum following MPTP administration. However, treatment with EA prior to MPTP injection significantly rescued the dopaminergic neurons and dopamine transporter. EA treatment further restored antioxidant enzymes, prevented the depletion of glutathione and inhibited lipid peroxidation, in addition to the attenuation of pro-inflammatory cytokines. EA also reduced the levels of COX-2 and iNOS. The findings of the present study demonstrate that EA protects against MPTP-induced PD and the observed neuroprotective effects can be attributed to its potent antioxidant and anti-inflammatory properties.

Chronic Systemic Inflammation Exacerbates Neurotoxicity in a Parkinson’s Disease Model

Systemic inflammation is a crucial factor for microglial activation and neuroinflammation in neurodegeneration. This work is aimed at assessing whether previous exposure to systemic inflammation potentiates neurotoxic damage by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and how chronic systemic inflammation participates in the physiopathological mechanisms of Parkinson’s disease. Two different models of systemic inflammation were employed to explore this hypothesis: a single administration of lipopolysaccharide (sLPS; 5 mg/kg) and chronic exposure to low doses (mLPS; 100 μg/kg twice a week for three months). After three months, both groups were challenged with MPTP. With the sLPS administration, Iba1 staining increased in the striatum and substantia nigra, and the cell viability lowered in the striatum of these mice. mLPS alone had more impact on the proinflammatory profile of the brain, steadily increasing TNFα levels, activating microglia, reducing BDNF, cell viability, and dopamine levels, leading to a damage profile similar to the MPTP model per se. Interestingly, mLPS increased MAO-B activity possibly conferring susceptibility to MPTP damage. mLPS, along with MPTP administration, exacerbated the neurotoxic effect. This effect seemed to be coordinated by microglia since minocycline administration prevented brain TNFα increase. Coadministration of sLPS with MPTP only facilitated damage induced by MPTP without significant change in the inflammatory profile. These results indicate that chronic systemic inflammation increased susceptibility to MPTP toxic effect and is an adequate model for studying the impact of systemic inflammation in Parkinson’s disease.

Olive oil limited motor disruption and neuronal damage in parkinsonism induced by MPTP administration

Some vegetable oils show beneficial effects in modulating neurodegeneration; in this work, we evaluated the therapeutic potential of corn and olive oils against neurodegenerative processes using the acute parkinsonism murine model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in C57BL6 mice. The effects of corn and olive oils were quantified by the performance of mice in the open field and rotarod, and grasp strength tests and neuronal survival in the substantia nigra and striatum were determined by immunohistochemistry. Extra-virgin olive oil decreased the toxicity induced by MPTP administration judged by the performance in the behavioral motor tests and the number of total neurons in the analyzed brain regions. In contrast, corn oil only produced discrete changes in the behavioral and histological evaluations. Despite the numerous benefits of olive oil, its active substances that confer desirable effects and their mechanism of action remain unclear. Our observations can help to understand the ameliorative effects of some natural oils on neurodegeneration induced by some toxins, particularly the attenuation of neural damage related to toxin-induced parkinsonism or other pathologies that comprise neuronal death and motor disruption.

Эффекты производных адамантана на поведенческую активность мышей на разных стадиях экспериментального паркинсонического синдрома

Ключевым звеном патогенеза болезни Паркинсона (БП) является гибель дофаминергических нейронов в черной субстанции, вызывающая резкое снижение уровня дофамина в стриатуме головного мозга. Длительное терапевтическое применение предшественника дофамина L-ДОФА приводит к развитию тяжелых побочных эффектов и прогрессированию заболевания. Новый антипаркинсонический препарат, производный адамантана - гимантан (N-(2-адамантил)-гексаметиленимина гидрохлорид) обладает нейропротекторными и противовоспалительными свойствами. Цель работы: провести сравнительное изучение влияния производных адамантана - гимантана и амантадина - на параметры локомоторной активности мышей на разных стадиях развития паркинсонического синдрома (ПС). Материал и методы. Эксперименты проводили на мышах-самцах линии C57Bl/6 (n = 98) в возрасте 3-4 месяцев и массой тела 22-24 г. Стадии (начальную, среднюю и позднюю) ПС моделировали внутрибрюшинным введением нейротоксина1-метил-4-фенил-1,2,3,6-тетрагидропиридина (МФТП) однократно (в дозе 16 мг/кг, 30 мг/кг, 40 мг/кг), или многократно (4 раза по 12 мг/кг или 4 раза по 20 мг/кг с интервалом 2 часа). Гимантан и амантадин гидрохлорид (мидантан) вводили животным в дозе 20 мг/кг однократно за 30 мин до введения МФТП, или 4 раза при многократном введении нейротоксина. Развитие ПС оценивали по выраженности мышечной ригидности и изменению двигательной активности животных. Результаты. Показано, что введение гимантана и амантадина увеличивало длину пробега, число стоек мышей, а также снижало выраженность ригидности и степень нарушения координации движений животных с ПС, вызванным МФТП в дозе 16 мг/кг (однократно) и 4 × 12 мг/кг (многократно). При этом эффекты гимантана были более выраженными в сравнении с эффектами амантадина. Антипаркинсонический эффект обоих препаратов был слабее на промежуточной стадии ПС, вызванного однократным введением МФТП в дозе 30 мг/кг, и отсутствовал на поздней стадии ПС, вызванного многократным введением МФТП в дозе 4 × 20 мг/кг. Заключение. В сравнении с амантадином гимантан при предварительном введении более эффективно предупреждал снижение двигательной активности, нарушение координации движения и развитие ригидности животных на ранней стадии развития ПС.A key element in the pathogenesis Parkinson’s disease (PD) is death of dopaminergic neurons in substantia nigra, which leads to a sharp decrease in striatal concentration of dopamine. Long-term use of levodopa-containing drugs results in severe side effects and the disease progression. A new antiparkinsonian drug, the adamantine derivative, hemantane (N-(2-adamantyl)-hexamethyleneimine hydrochloride), has neuroprotective and anti-inflammatory features. Objective: To compare effects of hematane and amantadine on locomotor activity of mice at different stages of the parkinsonian syndrome (PS). Methods. Experiments were performed on C57Bl/6 male mice (n = 98) aged 3-4 months and weighing 22-24 g. The stages (early stage, mid-stage, and advanced stage) of parkinsonian syndrome (PS) were simulated in C57Bl/6 mice by intraperitoneal injections of a neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), either at a single dose of 16 mg/kg, 30 mg/kg, and 40 mg/kg, or repeatedly, 4 times at 12 mg/kg or 4 times at 20 mg/kg at 2-h intervals. Gimantan and amantadine hydrochloride (midantan) were administered to animals at a single dose of 20 mg/kg 30 minutes prior to MPTP administration or 4 times with the repeated administration of the neurotoxin. The development of PS was detected by muscle rigidity and changes in motor activity. Results. Administration of either hematane or amantadine increased the distance traveled and the number of rearings, and also reduced severity of the rigidity and impairment of movement coordination when PS was induced by a single injection of MPTP 16 mg/kg and repeated injections of MPTP 4 × 12 mg/kg. Furthermore, the effects of gimantan were more pronounced in comparison with the effects of amantadine. The antiparkinsonian effect of both drugs was weaker at the mid-stage of PS caused by a single injection of MPTP 30 mg/kg and was absent at the advanced stage of PS caused by repeated injections of MPTP 4 × 20 mg/kg. Conclusion. Compared to amantadine, the prior administration of gimantan more effectively prevented the decrease in motor activity, impaired coordination of movements and development of stiffness in animals at the early stage of PS.

α-Synuclein Expression Is Preserved in Substantia Nigra GABAergic Fibers of Young and Aged Neurotoxin-Treated Rhesus Monkeys

α-Synuclein (α-syn) is a small presynaptic protein distributed ubiquitously in the central and peripheral nervous system. In normal conditions, α-syn is found in soluble form, while in Parkinson’s disease (PD) it may phosphorylate, aggregate, and combine with other proteins to form Lewy bodies. The purpose of this study was to evaluate, in nonhuman primates, whether α-syn expression is affected by age and neurotoxin challenge. Young adult ( n = 5, 5–10 years old) and aged ( n = 4, 23–25 years old) rhesus monkeys received a single unilateral carotid artery injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Three months post-MPTP the animals were necropsied by transcardiac perfusion, and their brains extracted and processed with immunohistochemical methods. Quantification of tyrosine hydroxylase (TH)-positive substantia nigra (SN) neurons showed a significant 80–89% decrease in the side ipsilateral to MPTP administration in young and old animals. Optical density of TH- immunoreactivity (-ir) in the caudate and putamen presented a 60–70% loss compared with the contralateral side. α-Syn-ir was present in both ipsi- and contra- lateral MPTP-treated nigra, caudate, and putamen, mostly in fibers; its intracellular distribution was not affected by age. Comparison of α-syn-ir between MPTP-treated young and aged monkeys revealed significantly higher optical density for both the ipsi- and contralateral caudate and SN in the aged animals. TH and α-syn immunofluorescence confirmed the loss of nigral TH-ir dopaminergic neurons in the MPTP-treated side of intoxicated animals, but bilateral α-syn expression. Colabeling of GAD67 and α-syn immunofluorescence showed that α-syn expression was present mainly in GABAergic fibers. Our results demonstrate that, 3 months post unilateral intracarotid artery infusion of MPTP, α-syn expression in the SN is largely present in GABAergic fibers, regardless of age. Bilateral increase of α-syn expression in SN fibers of aged, compared with young rhesus monkeys, suggests that α-syn-ir may increase with age, but not after neurotoxin-induced dopaminergic nigral cell loss.

The effect of intranasal administration of glutamate antibody on experimental parkinsonian syndrome

Изучали влияние интраназального, в 2 режимах, введения антител к L-глутамату (АТ-Глу) на экспериментальный паркинсонический синдром (ПС) у мышей C57BL/6j, вызванный 1-метил-4-фенил-1,2,3,6-тетрагидропиридином (МФТП). Показано, что интраназальное введение АТ-Глу мышам параллельно с введением МФТП в течение 10 сут. ослабляло развитие паркинсонических симптомов - олигокинезию и ригидность. В сыворотке крови мышей, которым вводили АТ-Глу и/или МФТП были обнаружены аутоантитела к L-глутамату в большем количестве, чем у контрольных животных. Однократное интраназальное введение АТ-Глу мышам C57BL/6j на 11-е сут. с формировавшимся ПС не влияло на выраженность паркинсонической симптоматики. Effects of two schedules of intranasal treatment with glutamate antibody (AT-Glu) on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonian syndrome (PS) were studied in C57BL/6j mice. Intranasal AT-Glu administration along with MPTP administration for 10 days attenuated the development of parkinsonian symptoms, oligokinesia and rigidity. The serum of mice treated with AT-Glu and / or MPTP contained a greater amount of glutamate autoantibody than the serum of control animals. A single intranasal administration of AT-Glu on day 11 to C57BL/6j mice with developed PS did not influence the severity of parkinsonian symptoms.