4'-fluorocannabidiol associated with capsazepine restrains L-DOPA-induced dyskinesia in hemiparkinsonian mice: Contribution of anti-inflammatory and anti-glutamatergic mechanisms

We tested the efficacy of 4'-fluorocannabidiol (4'-F-CBD), a semisynthetic cannabidiol derivative, and HU-910, a cannabinoid receptor 2 (CB2) agonist in resolving l-DOPA-induced dyskinesia (LID). Specifically, we were interested in studying whether these compounds could restrain striatal inflammatory responses and rescue glutamatergic disturbances characteristic of the dyskinetic state. C57BL/6 mice were rendered hemiparkinsonian by unilateral striatal lesioning with 6-OHDA. Abnormal involuntary movements were then induced by repeated i.p. injections of l-DOPA + benserazide. After LID was installed, the effects of a 3-day treatment with 4'-F-CBD or HU-910 in combination or not with the TRPV1 antagonist capsazepine (CPZ) or CB2 agonists HU-308 and JWH015 were assessed. Immunostaining was conducted to investigate the impacts of 4'-F-CBD and HU-910 (with CPZ) on inflammation and glutamatergic synapses. Our results showed that the combination of 4'-F-CBD + CPZ, but not when administered alone, decreased LID. Neither HU-910 alone nor HU-910+CPZ were effective. The CB2 agonists HU-308 and JWH015 were also ineffective in decreasing LID. Both combination treatments efficiently reduced microglial and astrocyte activation in the dorsal striatum of dyskinetic mice. However, only 4'-F-CBD + CPZ normalized the density of glutamate vesicular transporter-1 (vGluT1) puncta colocalized with the postsynaptic density marker PSD95. These findings suggest that 4'-F-CBD + CPZ normalizes dysregulated cortico-striatal glutamatergic inputs, which could be involved in their anti-dyskinetic effects. Although it is not possible to rule out the involvement of anti-inflammatory mechanisms, the decrease in striatal neuroinflammation markers by 4'-F-CBD and HU-910 without an associated reduction in LID indicates that they are insufficient per se to prevent LID manifestations.

AMPK-mediated autophagy pathway activation promotes ΔFosB degradation to improve levodopa-induced dyskinesia

BACKGROUND

Parkinson's disease patients on chronic levodopa often suffer from motor complications, which tend to reduce their quality of life. Levodopa-induced dyskinesia (LID) is one of the most prevalent motor complications, often characterized by abnormal involuntary movements, and the pathogenesis of LID is still unclear but recent studies have suggested the involvement of autophagy.

METHODS

The onset of LID was mimicked by chronic levodopa treatment in a unilateral 6-hydroxydopamine (6-OHDA) -lesion rat model. Overexpression of ΔFosB in HEK293 cells to mimic the state of ΔFosB accumulation. The modulation of the AMP-activated protein kinase (AMPK)-mediated autophagy pathway using by metformin, AICAR (an AMPK activator), Compound C (an AMPK inhibitor) and chloroquine (an autophagy pathway inhibitor). The severity of LID was assessed by axial, limb, and orofacial (ALO) abnormal involuntary movements (AIMs) score and in vivo electrophysiology. The activity of AMPK pathway as well as autophagy markers and FosB-ΔFosB levels were detected by western blotting. RT-qPCR was performed to detect the transcription level of FosB-ΔFosB. The mechanism of autophagy dysfunction was further explored by immunofluorescence and transmission electron microscopy.

RESULTS

In vivo experiments demonstrated that chronic levodopa treatment reduced AMPK phosphorylation, impaired autophagosome-lysosomal fusion and caused FosB-ΔFosB accumulation in the striatum of PD rats. Long-term metformin intervention improved ALO AIMs scores as well as reduced the mean power of high gamma (hγ) oscillations and the proportion of striatal projection neurons unstable in response to dopamine for LID rats. Moreover, the intervention of metformin promoted AMPK phosphorylation, ameliorated the impairment of autophagosome-lysosomal fusion, thus, promoting FosB-ΔFosB degradation to attenuate its accumulation in the striatum of LID rats. However, the aforementioned roles of metformin were reversed by Compound C and chloroquine. The results of in vitro studies demonstrated the ability of metformin and AICAR to attenuate ΔFosB levels by promoting its degradation, while Compound C and chloroquine could block this effect.

CONCLUSIONS

In conclusion, our results suggest that long-term metformin treatment could promote ΔFosB degradation and thus attenuate the development of LID through activating the AMPK-mediated autophagy pathway. Overall, our results support the AMPK-mediated autophagy pathway as a novel therapeutic target for LID and also indicate that metformin is a promising therapeutic candidate for LID.

Aerobic exercise modulates the striatal Erk/MAPK signaling pathway and improves LID in a mouse model of Parkinson's disease

OBJECTIVE

To investigate the role of the striatal extracellular signal-regulated kinase (Erk1/2) and its phosphorylation (p-Erk1/2) in aerobic training to alleviate the development of the L-DOPA induced dyskinesia (LID) in PD mice.

METHODS

Forty-eight male C57BL/6 N mice were randomly divided into the 6-OHDA surgery group (6-OHDA, n=42) and the sham surgery group (Sham, n=6). A two-point injection of 6-OHDA into the right striatum was used to establish a lateralized injury PD model. PD mice were randomly divided into a PD control group (PD, n=13) and a PD exercise group (PDE, n=16), this is followed by 4 weeks of L-DOPA treatment, and PDE mice received concurrent running table training (18 m/min, 40 min/day, 5 times/week). AIM scores were performed weekly, and mice were assessed for motor function after 4 weeks using the rotarod, open field, and gait tests. Immunohistochemistry was used to test nigrostriatal TH expression, Western blot was used to determine Erk1/2 and p-Erk1/2 protein expression, and immunofluorescence double-labeling technique was used to detect Erk1/2 and p-Erk1/2 co-expression with prodynorphin (PDYN).

RESULTS

(1) All AIM scores of PD and PDE mice increased significantly (P < 0.05) with the prolongation of L-DOPA treatment. Compared with PD, all AIM scores were significantly lower in PDE mice (P < 0.05). (2) After 4 weeks, the motor function of PD mice was significantly reduced compared with Sham (P < 0.05 or P < 0.01); compared with PD, the motor function of PDE mice was significantly increased (P < 0.05). (3) Compared with Sham, the expression of Erk1/2 protein, the number of positive cells of Erk1/2 and p-Erk1/2 and the number of positive cells co-expressed with PDYN were significantly increased in PD mice (P < 0.05); compared with PD, Erk1/2 protein expression was significantly decreased in PDE mice (P < 0.05), and the number of Erk1/2 and p-Erk1/2 positive cells was significantly reduced (P < 0.05).

CONCLUSION

4 weeks of aerobic exercise can effectively alleviate the development of L-DOPA-induced dyskinesia and improve motor function in PD mice. The related mechanism may be related to the inhibition of striatal Erk/MAPK signaling pathway overactivation by aerobic exercise, but this change did not occur selectively in D1-MSNs.

A neoteric annotation on the advances in combination therapy for Parkinson's disease: nanocarrier-based combination approach and future anticipation. Part I: exploring theoretical insights and pharmacological advances

INTRODUCTION

Parkinson's disease (PD) is a neurological condition defined by a substantial reduction in dopamine-containing cells in the substantia nigra. Levodopa (L-Dopa) is considered the gold standard in treatment. Recent research has clearly shown that resistance to existing therapies can develop. Moreover, the involvement of multiple pathways in the nigrostriatal dopaminergic neuronal loss suggests that modifying the treatment strategy could effectively reduce this degeneration.

AREAS COVERED

This review summarizes the key concerns with treating PD patients and the combinations, aimed at effectively managing PD. Part I focuses on the clinical diagnosis at every stage of the disease as well as the pharmacological treatment strategies that are applied throughout its course. It methodically elucidates the potency of multifactorial interventions in attenuating the disease trajectory, substantiating the rationale for co-administration of dual or multiple therapeutic agents. Significant emphasis is laid on evidence-based pharmacological combinations for PD management.

EXPERT OPINION

By utilizing multiple drugs in a combination fashion, this approach can leverage the additive or synergistic effects of these agents, amplify the spectrum of treatment, and curtail the risk of side effects by reducing the dose of each drug, demonstrating significantly greater efficacy.

A neoteric annotation on the advances in combination therapy for Parkinson's disease: nanocarrier-based combination approach and future anticipation. Part II: nanocarrier design and development in focus

INTRODUCTION

The current treatment modalities available for Parkinson's disease (PD) prove inadequate due to the inherent constraints in effectively transporting bioactive compounds across the blood-brain barrier. The utilization of synergistic combinations of multiple drugs in conjunction with advanced nanotechnology, emerges as a promising avenue for the treatment of PD, offering potential breakthroughs in treatment efficacy, targeted therapy, and personalized medicine.

AREAS COVERED

This review provides a comprehensive analysis of the efficacy of multifactorial interventions for PD, simultaneously addressing the primary challenges of conventional therapies and highlighting how advanced technologies can help overcome these limitations. Part II focuses on the effectiveness of nanotechnology for improving pharmacokinetics of conventional therapies, through the synergistic use of dual or multiple therapeutic agents into a single nanoformulation. Significant emphasis is laid on the advancements toward innovative integrations, such as CRISPR/Cas9 with neuroprotective agents and stem cells, all effectively synergized with nanocarriers.

EXPERT OPINION

By using drug combinations, we can leverage their combined effects to enhance treatment efficacy and mitigate side effects through lower dosages. This article is meant to give nanocarrier-mediated co-delivery of drugs and the strategic incorporation of CRISPR/Cas9, either as an independent intervention or synergized with a neuroprotective agent.

Decreased hepatic enzymes reflect the decreased vitamin B6 levels in Parkinson's disease patients

The study aims to investigate the vitamin B6 levels in Parkinson's disease (PD) patients and their association with liver enzymes and evaluate how much dysregulation is associated with levodopa dose. Furthermore, to evaluate the effect of Opicapone, a catechol-o-methyl-transferase inhibitor, on vitamin B6 levels by monitoring the AST and ALT levels in patients treated with Levodopa-Carbidopa Intestinal Gel Infusion (LCIG). For these aims, serum vitamin B6 levels were measured (PD, n = 72 and controls, n = 31). The vitamin B6 level was compared with the total levodopa dose, clinical parameters, and blood homocysteine, albumin, and hemoglobin levels in PD patients. Correlations between vitamin B6 levels and AST and ALT levels, as well as the ratio ALT/AST, were analyzed. Changes in the AST and ALT levels and ALT/AST were analyzed in the patients treated with LCIG before and after the therapy (n = 24) and in the patients treated with LCIG + Opicapone before and after Opicapone treatment (n = 12). We found vitamin B6 levels were significantly lower in PD patients. Total levodopa dose and albumin levels were independently associated with vitamin B6 levels. Decreased vitamin B6 levels appeared as lower AST and ALT levels and ALT/AS. Treatment with LCIG decreased the AST and ALT levels and ALT/AST. Adjunctive therapy with Opicapone to LCIG ameliorated the decreased ALT and ALT/AST. We conclude that the ALT and ALT/AST can be useful parameters for monitoring vitamin B6 levels and Opicapone can ameliorate the dysregulated vitamin B6 in PD patients.

Design, Synthesis and In Vitro Evaluation of Levodopa Stearic Acid Hydrazide Conjugate for the Management of Parkinson's DiseaseNovel Conjugate for Parkinson's Disease

Parkinson's disease is the highest prevalent neurodegenerative disease in elderly individuals after Alzheimer's disease. The pathological identification for Parkinson's disease is loss of dopaminergic neurons in substantia nigra region of the brain that in turn leads to dopamine deficiency that affects the body's normal physiological and neurological disorder. The important drawback in the modality of treatment is levodopa is only supplying depleted dopamine in the brain, it does not affect neurodegeneration. Even though levodopa manages the disease, an alternative treatment strategy is required to stop or prevent further degeneration of neuron. The compound with neuroprotector activity suits the requirement. Of them, stearic acid plays a vital role in protecting neurons against oxidative stress through a Phosphoinositide 3-kinase-dependent mechanism. Hence, our present study aimed to design, synthesize, and characterize the levodopa stearic acid hydrazide conjugate. Additionally, evaluate the cytotoxicity of synthesized compound in SHSY5Y: cell lines. In brief, levodopa was conjugated to the stearic acid successfully and was confirmed with Fourier-transform infrared spectroscopy, Nuclear magnetic resonance, and Mass Spectroscopy. In vitro cell viability study in SHSY5Y: cell lines showed elevated cell viability in 0.134 µm concentration of Conjugate, and 0.563 µm concentration of levodopa. Showing that the synthesized compound could offer an improved treatment strategy for Parkinson's disease.

New fraternine analogues: Evaluation of the antiparkinsonian effect in the model of Parkinson's disease

Venom-derived peptides are important sources for the development of new therapeutic molecules, especially due to their broad pharmacological activity. Previously, our research group identified a novel natural peptide, named fraternine, with promising effects for the treatment of Parkinson's disease. In the present paper, we synthesized three peptides bioinspired in fraternine: fra-10, fra-14, and fra-24. They were tested in the 6-OHDA-induced model of parkinsonism, quantifying motor coordination, levels of TH+ neurons in the substantia nigra pars compacta (SN), and inflammation mediators TNF-α, IL-6, and IL-1ß in the cortex. Peptides fra-14 and fra-10 improved the motor coordination in relation to 6-OHDA lesioned animals. However, most of the peptides were toxic in the doses applied. All three peptides reduced the intensity of the lesion induced rotations in the apomorphine test. Fra-24 higher dose increased the number of TH+ neurons in SN and reduced the concentration of TNF-α in the cortex of 6-OHDA lesioned mice. Overall, only the peptide fra-24 presented a neuroprotection effect on dopaminergic neurons of SN and a reduction of cytokine TNF-α levels, making it worthy of consideration for the treatment of PD.

Piperine improves levodopa availability in the 6-OHDA-lesioned rat model of Parkinson's disease by suppressing gut bacterial tyrosine decarboxylase

AIM

Tyrosine decarboxylase (TDC) presented in the gut-associated strain Enterococcus faecalis can convert levodopa (L-dopa) into dopamine (DA), and its increased abundance would potentially minimize the availability and efficacy of L-dopa. However, the known human decarboxylase inhibitors are ineffective in this bacteria-mediated conversion. This study aims to investigate the inhibition of piperine (PIP) on L-dopa bacterial metabolism and evaluates the synergistic effect of PIP combined with L-dopa on Parkinson's disease (PD).

METHODS

Metagenomics sequencing was adopted to determine the regulation of PIP on rat intestinal microbiota structure, especially on the relative abundance of E. faecalis. Then, the inhibitory effects of PIP on L-dopa conversion and TDC expression of E. faecalis were tested in vitro. We examined the synergetic effect of the combination of L-dopa and PIP on 6-hydroxydopamine (6-OHDA)-lesioned rats and tested the regulations of L-dopa bioavailability and brain DA level by pharmacokinetics study and MALDI-MS imaging. Finally, we evaluated the microbiota-dependent improvement effect of PIP on L-dopa availability using pseudo-germ-free and E. faecalis-transplanted rats.

RESULTS

We found that PIP combined with L-dopa could better ameliorate the move disorders of 6-OHDA-lesioned rats by remarkably improving L-dopa availability and brain DA level than L-dopa alone, which was associated with the effect of PIP on suppressing the bacterial decarboxylation of L-dopa via effectively downregulating the abnormal high abundances of E. faecalis and TDC in 6-OHDA-lesioned rats.

CONCLUSION

Oral administration of L-dopa combined with PIP can improve L-dopa availability and brain DA level in 6-OHDA-lesioned rats by suppressing intestinal bacterial TDC.

Motivational Vigor in Parkinson's Disease Requires the Short and Long Duration Response to Levodopa

BACKGROUND

Impaired movement vigor (bradykinesia) is a cardinal feature of Parkinson's disease (PD) and hypothesized to result from abnormal motivational processes-impaired motivation-vigor coupling. Dopamine replacement therapy (DRT) improves bradykinesia, but the response to DRT is multifaceted, comprising a short-duration response (SDR) and a long-duration response (LDR) only manifesting with chronic treatment. Prior experiments assessing motivation-vigor coupling in PD used chronically treated subjects, obscuring the roles of the SDR and LDR.

METHODS

To disambiguate the SDR and LDR, 11 de novo PD subjects (6 male [M]:5 female [F]; mean age, 67) were studied before treatment, after an acute levodopa (l-dopa) dose, and in both the practical "off" (LDR) and "on" (LDR + SDR) states after chronic stable treatment. At each visit, subjects were characterized with a standard battery including the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and an incentivized joystick task to assess motor performance in response to varying rewards.

RESULTS

l-Dopa induced a robust SDR and LDR, with further improvement in the combined SDR + LDR state. At baseline, after acute treatment (SDR), and after LDR induction, subjects did not exhibit the normal increase in movement speed with increasing reward. Only in the combined SDR + LDR state was there restoration of motivation-vigor coupling.

CONCLUSIONS

Although consistent with prior results in chronically treated PD subjects, the significant improvement in motor performance observed with the SDR and LDR suggests that bradykinesia is not solely secondary to deficient modulation of motivational processes. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Rab29-dependent asymmetrical activation of leucine-rich repeat kinase 2

Gain-of-function mutations in LRRK2, which encodes the leucine-rich repeat kinase 2 (LRRK2), are the most common genetic cause of late-onset Parkinson's disease. LRRK2 is recruited to membrane organelles and activated by Rab29, a Rab guanosine triphosphatase encoded in the PARK16 locus. We present cryo-electron microscopy structures of Rab29-LRRK2 complexes in three oligomeric states, providing key snapshots during LRRK2 recruitment and activation. Rab29 induces an unexpected tetrameric assembly of LRRK2, formed by two kinase-active central protomers and two kinase-inactive peripheral protomers. The central protomers resemble the active-like state trapped by the type I kinase inhibitor DNL201, a compound that underwent a phase 1 clinical trial. Our work reveals the structural mechanism of LRRK2 spatial regulation and provides insights into LRRK2 inhibitor design for Parkinson's disease treatment.

The ratio of M1 to M2 microglia in the striatum determines the severity of L-Dopa-induced dyskinesias

L-Dopa, while treating motor symptoms of Parkinson's disease, can lead to debilitating L-Dopa-induced dyskinesias, limiting its use. To investigate the causative relationship between neuro-inflammation and dyskinesias, we assessed if striatal M1 and M2 microglia numbers correlated with dyskinesia severity and whether the anti-inflammatories, minocycline and indomethacin, reverse these numbers and mitigate against dyskinesia. In 6-OHDA lesioned mice, we used stereology to assess numbers of striatal M1 and M2 microglia populations in non-lesioned (naïve) and lesioned mice that either received no L-Dopa (PD), remained non-dyskinetic even after L-Dopa (non-LID) or became dyskinetic after L-Dopa treatment (LID). We also assessed the effect of minocycline/indomethacin treatment on striatal M1 and M2 microglia and its anti-dyskinetic potential via AIMs scoring. We report that L-Dopa treatment leading to LIDs exacerbates activated microglia numbers beyond that associated with the PD state; the severity of LIDs is strongly correlated to the ratio of the striatal M1 to M2 microglial numbers; in non-dyskinetic mice, there is no M1/M2 microglia ratio increase above that seen in PD mice; and reducing M1/M2 microglia ratio using anti-inflammatories is anti-dyskinetic. Parkinson's disease is associated with increased inflammation, but this is insufficient to underpin dyskinesia. Given that L-Dopa-treated non-LID mice show the same ratio of M1/M2 microglia as PD mice that received no L-Dopa, and, given minocycline/indomethacin reduces both the ratio of M1/M2 microglia and dyskinesia severity, our data suggest the increased microglial M1/M2 ratio that occurs following L-Dopa treatment is a contributing cause of dyskinesias.

The effects of safinamide according to gender in Chinese parkinsonian patients

The incidence and prevalence of Parkinson's disease (PD) is expected to raise dramatically over the next decades. Gender-related differences are not yet widely recognized, particularly regarding the response to dopaminergic medications. To analyse gender differences in the clinical effects of safinamide, compared to placebo, in Chinese PD patients of the pivotal XINDI trial. The XINDI study was a phase III, randomized, double-blind, placebo-controlled, multicenter trial. Patients were followed for 16 weeks receiving safinamide or placebo as add-on to levodopa. The primary efficacy endpoint was the change in the mean total daily OFF time. Secondary efficacy endpoints included total daily ON time, ON time with no/non-troublesome dyskinesia, Unified Parkinson's Disease Rating Scale and Parkinson's Disease Questionnaire-39 items. A post-hoc analysis was performed to describe the efficacy of safinamide in both genders on motor symptoms, motor fluctuations and quality of life. 128 (42%) out of 305 patients enrolled were women and 177 (58%) men. Our additional analyses of the XINDI study have shown that safinamide, compared to placebo, was associated with improvements in motor symptoms, motor fluctuations and quality of life in both genders, with some differences in the response that did not reach statistical significance, possibly due to sample size limitation and post-hoc design of the study. The changes from baseline at week 16 were > 50% higher in the females compared to males for the total daily OFF time (- 1.149 h vs - 0.764 h in males), the total daily ON time (1.283 h vs 0.441 h in males), the UPDRS total score (- 8.300 points vs - 5.253 points in males) and the UPDRS part II score (- 2.574 points vs - 1.016 points in males). The changes from baseline at week 16 were higher in the females compared to males in the "ADL" domain (- 6.965 points vs - 5.772 points in males), the "Emotional well-being" domain (- 6.243 points vs - 4.203 in males), the "Stigma" domain (- 6.185 points vs - 4.913 points in males) and the "Bodily discomfort" domain (- 5.196 points vs 1.099 points in males), while were higher in males in the "Mobility" score (- 6.523 points vs - 4.961 points in females) and the "Communication" score (- 3.863 points vs - 1.564 points in females). Safinamide was shown to improve PD symptoms and quality of life in both male and female Chinese patients. Possible differences in the response between genders need to be further studied in larger and different ethnic populations.

Aberrations in temporal dynamics of cognitive processing induced by Parkinson's disease and Levodopa

The motor symptoms of Parkinson's disease (PD) have been shown to significantly improve by Levodopa. However, despite the widespread adoption of Levodopa as a standard pharmaceutical drug for the treatment of PD, cognitive impairments linked to PD do not show visible improvement with Levodopa treatment. Furthermore, the neuronal and network mechanisms behind the PD-induced cognitive impairments are not clearly understood. In this work, we aim to explain these cognitive impairments, as well as the ones exacerbated by Levodopa, through examining the differential dynamic patterns of the phase-amplitude coupling (PAC) during cognitive functions. EEG data recorded in an auditory oddball task performed by a cohort consisting of controls and a group of PD patients during both on and off periods of Levodopa treatment were analyzed to derive the temporal dynamics of the PAC across the brain. We observed distinguishing patterns in the PAC dynamics, as an indicator of information binding, which can explain the slower cognitive processing associated with PD in the form of a latency in the PAC peak time. Thus, considering the high-level connections between the hippocampus, the posterior and prefrontal cortices established through the dorsal and ventral striatum acting as a modulatory system, we posit that the primary issue with cognitive impairments of PD, as well as Levodopa's cognitive deficit side effects, can be attributed to the changes in temporal dynamics of dopamine release influencing the modulatory function of the striatum.

AI molecular property prediction for Parkinson's Disease reveals potential repurposing drug candidates based on the increase of the expression of PINK1

BACKGROUND AND OBJECTIVE

Parkinson's Disease (PD), a common neurodegenerative disorder and one of the major current challenges in neuroscience and pharmacology, may potentially be tackled by the modern AI techniques employed in drug discovery based on molecular property prediction. The aim of our study was to explore the application of a machine learning setup for the identification of the best potential drug candidates among FDA approved drugs, based on their predicted PINK1 expression-enhancing activity.

METHODS

Our study relies on supervised machine learning paradigm exploiting in vitro data and utilizing the scaffold splits methodology in order to assess model's capability to extract molecular patterns and generalize from them to new, unseen molecular representations. Models' predictions are combined in a meta-ensemble setup for finding new pharmacotherapies based on the predicted expression of PINK1.

RESULTS

The proposed machine learning setup can be used for discovering new drugs for PD based on the predicted increase of expression of PINK1. Our study identified nitazoxanide as well as representatives of imidazolidines, trifluoromethylbenzenes, anilides, nitriles, stilbenes and steroid esters as the best potential drug candidates for PD with PINK1 expression-enhancing activity on or inside the cell's mitochondria.

CONCLUSIONS

The applied methodology allows to reveal new potential drug candidates against PD. Next to novel indications, it allows also to confirm the utility of already known antiparkinson drugs, in the new context of PINK1 expression, and indicates the potential for simultaneous utilization of different mechanisms of action.

Adopting the Rumsfeld approach to understanding the action of levodopa and apomorphine in Parkinson's disease

Dopaminergic therapies dominate the treatment of the motor and non-motor symptoms of Parkinson's disease (PD) but there have been no major advances in therapy in many decades. Two of the oldest drugs used appear more effective than others-levodopa and apomorphine-but the reasons for this are seldom discussed and this may be one cause for a lack of progress. This short review questions current thinking on drug action and looks at whether adopting the philosophy of ex-US Secretary of State Donald Rumsfeld reveals 'unknown' aspects of the actions of levodopa and apomorphine that provide clues for a way forward. It appears that both levodopa and apomorphine have a more complex pharmacology than classical views would suggest. In addition, there are unexpected facets to the mechanisms through which levodopa acts that are either forgotten as 'known unknowns' or ignored as 'unknown unknowns'. The conclusion reached is that we may not know as much as we think about drug action in PD and there is a case for looking beyond the obvious.

Effect of the mGlu4 positive allosteric modulator ADX-88178 on parkinsonism, psychosis-like behaviours and dyskinesia in the MPTP-lesioned marmoset

RATIONALE

Positive allosteric modulation of metabotropic glutamate type 4 (mGlu4) receptors is a promising strategy to alleviate parkinsonian disability and L-3,4-dihydroxyphenylalanine (L-DOPA) induced dyskinesia. ADX-88178 is a highly selective mGlu4 positive allosteric modulator (PAM) that previously enhanced the anti-parkinsonian action of L-DOPA in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease (PD).

OBJECTIVES

We sought to explore the effects of ADX-88178 on psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. We also aimed to determine the effect of ADX-88178 on parkinsonism and dyskinesia.

METHODS

Six MPTP-lesioned marmosets were administered L-DOPA chronically to induce stable PLBs and dyskinesias. They were then administered ADX-88178 (0.01, 0.1 and 1 mg/kg) or vehicle, in combination with L-DOPA/benserazide (15/3.75 mg/kg), both sub-cutaneously, in a randomised fashion. PLBs, parkinsonism and dyskinesia were then measured.

RESULTS

ADX-88178 mildly worsened global PLBs at the dose of 1 mg/kg (by 13%, P = 0.020). L-DOPA alone conferred 158 min of on-time, while the duration of on-time was 212 min (34% increase, P = 0.011), after adding ADX-88178 1 mg/kg to L-DOPA. Accordingly, ADX-88178 1 mg/kg reduced global parkinsonian disability, by 38% (P = 0.0096). ADX-88178 1 mg/kg diminished peak dose dyskinesia by 34% (P = 0.015). Minimal effects were provided by lower doses.

CONCLUSIONS

Whereas these results provide additional evidence of the anti-parkinsonian and anti-dyskinetic effects of mGlu4 positive allosteric modulation as an adjunct to L-DOPA, they also suggest that ADX-88178 may exacerbate dopaminergic psychosis. Further studies are needed to evaluate this possible adverse effect of mGlu4 PAMs on PD psychosis.

Treatment Detection and Movement Disorder Society-Unified Parkinson's Disease Rating Scale, Part III Estimation Using Finger Tapping Tasks

The validation of objective and easy-to-implement biomarkers that can monitor the effects of fast-acting drugs among Parkinson's disease (PD) patients would benefit antiparkinsonian drug development. We developed composite biomarkers to detect levodopa/carbidopa effects and to estimate PD symptom severity. For this development, we trained machine learning algorithms to select the optimal combination of finger tapping task features to predict treatment effects and disease severity. Data were collected during a placebo-controlled, crossover study with 20 PD patients. The alternate index and middle finger tapping (IMFT), alternative index finger tapping (IFT), and thumb-index finger tapping (TIFT) tasks and the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III were performed during treatment. We trained classification algorithms to select features consisting of the MDS-UPDRS III item scores; the individual IMFT, IFT, and TIFT; and all three tapping tasks collectively to classify treatment effects. Furthermore, we trained regression algorithms to estimate the MDS-UPDRS III total score using the tapping task features individually and collectively. The IFT composite biomarker had the best classification performance (83.50% accuracy, 93.95% precision) and outperformed the MDS-UPDRS III composite biomarker (75.75% accuracy, 73.93% precision). It also achieved the best performance when the MDS-UPDRS III total score was estimated (mean absolute error: 7.87, Pearson's correlation: 0.69). We demonstrated that the IFT composite biomarker outperformed the combined tapping tasks and the MDS-UPDRS III composite biomarkers in detecting treatment effects. This provides evidence for adopting the IFT composite biomarker for detecting antiparkinsonian treatment effect in clinical trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The mGluR2/3 orthosteric agonist LY-404,039 reduces dyskinesia, psychosis-like behaviours and parkinsonism in the MPTP-lesioned marmoset

LY-404,039 is an orthosteric agonist of metabotropic glutamate 2 and 3 receptors (mGluR2/3) that may harbour additional agonist effect at dopamine D2 receptors. LY-404,039 and its pro-drug, LY-2140023, have previously entered clinical trials as treatment options for schizophrenia. They could therefore be repurposed, if proven efficacious, for other conditions, notably Parkinson's disease (PD). We have previously shown that the mGluR2/3 orthosteric agonist LY-354,740 alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia and psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. Unlike LY-404,039, LY-354,740 does not stimulate dopamine D2 receptors, suggesting that LY-404,039 may elicit broader therapeutic effects in PD. Here, we sought to investigate the effect of this possible additional dopamine D2-agonist action of LY-404,039 by assessing its efficacy on dyskinesia, PLBs and parkinsonism in the MPTP-lesioned marmoset. We first determined the pharmacokinetic profile of LY-404,039 in the marmoset, in order to select doses resulting in plasma concentrations known to be well tolerated in the clinic. Marmosets were then injected L-DOPA with either vehicle or LY-404,039 (0.1, 0.3, 1 and 10 mg/kg). The addition of LY-404,039 10 mg/kg to L-DOPA resulted in a significant reduction of global dyskinesia (by 55%, P < 0.01) and PLBs (by 50%, P < 0.05), as well as reduction of global parkinsonism (by 47%, P < 0.05). Our results provide additional support of the efficacy of mGluR2/3 orthosteric stimulation at alleviating dyskinesia, PLBs and parkinsonism. Because LY-404,039 has already been tested in clinical trials, it could be repurposed for indications related to PD.

Effects of Amantadine Sulfate on Motor Impairment and Execution of Motor Sequences in Patients With Parkinson Disease

BACKGROUND

Intravenous application of amantadine sulfate induces a rapid improvement of motor behavior in patients with Parkinson disease.

OBJECTIVES

To determine efficacy of daily infusion of 200 mg amantadine sulfate on scored motor symptoms and performance of standardized movement sequences with components of low and high cognitive efforts.

METHODS

Thirty-one participants received infusions of amantadine sulfate in addition to their previous stable drug regimens on 3 consecutive days. Motor symptoms of upper limbs were determined with selected items of the part motor examination of the Unified Parkinson's Disease Rating Scale. Instrumental tasks were executed under cued conditions before and after the infusions.

RESULTS

Scored motor symptoms and components with a need for a higher cognitive load became better. Performance of motion series, characterized by an automated set with low cognitive efforts, did not improve.

CONCLUSION

Our trial outcomes suggest that the amantadine has a positive impact on cognitive abilities, drive, and vigilance, all of which are necessary for carrying out of higher brain functions.

BDNF/TrkB pathway activation in D1 receptor-expressing striatal projection neurons plays a protective role against L-DOPA-induced dyskinesia

L-DOPA-induced dyskinesia (LID) is a frequent adverse side effect of L-DOPA treatment in Parkinson's disease (PD). Understanding the mechanisms underlying the development of these motor disorders is needed to reduce or prevent them. We investigated the role of TrkB receptor in LID, in hemiparkinsonian mice treated by chronic L-DOPA administration. Repeated L-DOPA treatment for 10 days specifically increased full-length TrkB receptor mRNA and protein levels in the dopamine-depleted dorsal striatum (DS) compared to the contralateral non-lesioned DS or to the DS of sham-operated animals. Dopamine depletion alone or acute L-DOPA treatment did not significantly increase TrkB protein levels. In addition to increasing TrkB protein levels, chronic L-DOPA treatment activated the TrkB receptor as evidenced by its increased tyrosine phosphorylation. Using specific agonists for the D1 or D2 receptors, we found that TrkB increase is D1 receptor-dependent. To determine the consequences of these effects, the TrkB gene was selectively deleted in striatal neurons expressing the D1 receptor. Mice with TrkB floxed gene were injected with Cre-expressing adeno-associated viruses or crossed with Drd1-Cre transgenic mice. After unilateral lesion of dopamine neurons in these mice, we found an aggravation of axial LID compared to the control groups. In contrast, no change was found when TrkB deletion was induced in the indirect pathway D2 receptor-expressing neurons. Our study suggests that BDNF/TrkB signaling plays a protective role against the development of LID and that agonists specifically activating TrkB could reduce the severity of LID.

Antinociceptive effects of carbidopa levodopa on normal rats and Parkinson's disease mice

Carbidopa levodopa is widely used to ameliorate motor symptoms of Parkinson's disease (PD) patients. Pain is one of common symptoms of PD. The aim of this experiment is to study antinociceptive effects of carbidopa levodopa on normal rats and PD mice. Rats were intragastrically treated with carbidopa levodopa and the hind paw withdrawal latency (HWL) was investigated. PD mouse model was prepared with MPTP and then the antinociceptive effects of carbidopa levodopa on PD mice were evaluated. In normal rats, the HWL to thermal stimulus was augmented after carbidopa levodopa administration (p<0.05 or p<0.01) and carbidopa levodopa increased the HWL (p<0.05 or p<0.01) to mechanical stimulus. In PD mice, carbidopa levodopa elevated the HWL of the thermal stimulus in PD mice (p<0.05). Furthermore, the HWL in the inflammatory pain of PD mice was also increased by carbidopa levodopa treatmet (p<0.01). The current findings indicate that carbidopa levodopa has an antinociceptive effects in normal rats and PD mice. The analgesic effect of carbidopa levodopa on patients with or without PD is worth studying in further research.

Analgesic effect of safinamide mesylate in a rat model of neuropathic pain

Pain is one of the most frequent non-motor symptoms of Parkinson's disease (PD). Neuropathic pain is highly prevalent in PD and negatively affects the quality of life of patients with PD. However, there is currently no evidence-based treatment for its control. Safinamide, a monoamine oxidase (MAO)-B inhibitor with a sodium channel inhibitory effect, showed improvement in PD-related pain in several clinical trials. However, it is unclear for which of the various types of pain in PD safinamide is effective. The aim of the present study was to examine the effect of safinamide on neuropathic pain in a rat model of chronic constriction injury (CCI). Pain was evaluated on postoperative days 14 and 21 using von Frey or weight-bearing tests. Male CCI model rats showed a decreased paw withdrawal threshold and a weight-bearing deficit on postoperative days 14 and 21. Single oral administration of safinamide (15, 30, 45 or 70 mg/kg) dose-dependently improved neuropathic pain in both pain assessments on day 14. Subsequently, the 15 and 45 mg/kg dose groups were administered safinamide orally once daily until day 21. With repeated administration, the effect of safinamide on pain was enhanced. The present findings show that safinamide improves neuropathic pain in male CCI model rats. Further animal model research and pathological and molecular pharmacological investigations are warranted.

Literature-Based Discovery Predicts Antihistamines Are a Promising Repurposed Adjuvant Therapy for Parkinson's Disease

Parkinson's disease (PD) is a movement disorder caused by a dopamine deficit in the brain. Current therapies primarily focus on dopamine modulators or replacements, such as levodopa. Although dopamine replacement can help alleviate PD symptoms, therapies targeting the underlying neurodegenerative process are limited. The study objective was to use artificial intelligence to rank the most promising repurposed drug candidates for PD. Natural language processing (NLP) techniques were used to extract text relationships from 33+ million biomedical journal articles from PubMed and map relationships between genes, proteins, drugs, diseases, etc., into a knowledge graph. Cross-domain text mining, hub network analysis, and unsupervised learning rank aggregation were performed in SemNet 2.0 to predict the most relevant drug candidates to levodopa and PD using relevance-based HeteSim scores. The top predicted adjuvant PD therapies included ebastine, an antihistamine for perennial allergic rhinitis; levocetirizine, another antihistamine; vancomycin, a powerful antibiotic; captopril, an angiotensin-converting enzyme (ACE) inhibitor; and neramexane, an N-methyl-D-aspartate (NMDA) receptor agonist. Cross-domain text mining predicted that antihistamines exhibit the capacity to synergistically alleviate Parkinsonian symptoms when used with dopamine modulators like levodopa or levodopa-carbidopa. The relationship patterns among the identified adjuvant candidates suggest that the likely therapeutic mechanism(s) of action of antihistamines for combatting the multi-factorial PD pathology include counteracting oxidative stress, amending the balance of neurotransmitters, and decreasing the proliferation of inflammatory mediators. Finally, cross-domain text mining interestingly predicted a strong relationship between PD and liver disease.

Foliglurax, a positive allosteric modulator of the metabotrophic glutamate receptor 4, protects dopaminergic neurons in MPTP-lesioned male mice

Overactivity of the corticostriatal glutamatergic pathway is documented in Parkinson's disease (PD) and stimulation of presynaptic metabotropic glutamate (mGlu) receptors 4 on these striatal afferents inhibits glutamate release normalizing neuronal activity in the basal ganglia. Moreover, mGlu4 receptors are also expressed in glial cells and are able to modulate glial function making this receptor a potential target for neuroprotection. Hence, we investigated whether foliglurax, a positive allosteric modulator of mGlu4 receptors with high brain exposure after oral administration, has neuroprotective effects in MPTP mice to model early PD. Male mice were treated daily from day 1 to 10 with 1, 3 or 10 mg/kg of foliglurax and administered MPTP on the 5th day then euthanized on the 11th day. Dopamine neuron integrity was assessed with measures of striatal dopamine and its metabolites levels, striatal and nigral dopamine transporter (DAT) binding and inflammation with markers of striatal astrocytes (GFAP) and microglia (Iba1). MPTP lesion produced a decrease in dopamine, its metabolites and striatal DAT specific binding that was prevented by treatment with 3 mg/kg of foliglurax, whereas 1 and 10 mg/kg had no beneficial effect. MPTP mice had increased levels of GFAP; foliglurax treatment (3 mg/kg) prevented this increase. Iba1 levels were unchanged in MPTP mice compared to control mice. There was a negative correlation between dopamine content and GFAP levels. Our results show that positive allosteric modulation of mGlu4 receptors with foliglurax provided neuroprotective effects in the MPTP mouse model of PD.

Clinical benefit of MAO-B and COMT inhibition in Parkinson's disease: practical considerations

Inhibitors of monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are major strategies to reduce levodopa degradation and thus to increase and prolong its effect in striatal dopaminergic neurotransmission in Parkinson's disease patients. While selegiline/rasagiline and tolcapone/entacapone have been available on the market for more than one decade, safinamide and opicapone have been approved in 2015 and 2016, respectively. Meanwhile, comprehensive data from several post-authorization studies have described the use and specific characteristics of the individual substances in clinical practice under real-life conditions. Here, we summarize current knowledge on both medication classes, with a focus on the added clinical value in Parkinson's disease. Furthermore, we outline practical considerations in the treatment of motor fluctuations and provide an outlook on ongoing studies with MAO-B and COMT inhibitors.

The Development and Design Strategy of Leucine-Rich Repeat Kinase 2 Inhibitors: Promising Therapeutic Agents for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of people worldwide. Mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) are the most common genetic risk factor for PD. Elevated LRRK2 kinase activity is found in idiopathic and familial PD cases. LRRK2 mutations are involved in multiple PD pathogeneses, including dysregulation of mitochondrial homeostasis, ciliogenesis, etc. Here, we provide a comprehensive overview of the biological function, structure, and mutations of LRRK2. We also examine recent advances and challenges in developing LRRK2 inhibitors and address prospective protein-based targeting strategies. The binding mechanisms, structure-activity relationships, and pharmacokinetic features of inhibitors are emphasized to provide a comprehensive compendium on the rational design of LRRK2 inhibitors. We hope that this publication can serve as a guide for designing novel LRRK2 inhibitors based on the summarized facts and perspectives.

Phytoconstituents of Datura metel extract improved motor coordination in haloperidol-induced cataleptic mice: Dual-target molecular docking and behavioural studies

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a prominent health challenge characterized by complex aetiology and limited therapeutic breakthroughs. Datura metel (DM) is a medicinal plant containing active phytoconstituents with neuropharmacological potentials. In traditional medicine, it exerts anticholinergic, anti-inflammatory and antioxidant effects, and protection from organophosphate poisoning inclusively involved in the pharmacotherapy of PD. Its other PD-related medicinal potency includes treatment of motor sickness and bradycardia. However, the exact mechanisms of anti-PD effects of its phytoconstituents remain underexplored.

MATERIALS AND METHODS

In this study, methanolic extract of DM was evaluated for anti-PD behavioural effects in vivo haloperidol-induced cataleptic mice. The GC-MS-identified phytochemicals were studied for one-drug-multi-target inhibitory mechanisms against some key targets for PD treatment, alpha-synuclein (ASN) and dopa decarboxylase (DDC) using molecular docking.

RESULTS

and discussion: Chronic administration of 50, 100 and 200 mg/kg of DM extract improved the 14-s latency time induced by haloperidol to 54, 54 and 57 s respectively, whereas levodopa (30 mg/kg) produced 47 s in rotarod tests. Similarly, the descending times for haloperidol-induced cataleptic mice were significantly reduced from 110 s to 17.7, 17.7 and 12.5 s by the respective chronic doses of DM extract, whereas levodopa-administered mice spent 17.5 s descending the same 30 cm pole. The interesting motor coordination enhancements are suggestively due to synergistic inhibition of ASN and DCC by the phytoconstituents of DM, especially, atropine and scopolamine. From the docking analysis, the two phytochemicals interacted more potently with the active therapeutic sites of the dual targets than levodopa and carbidopa.

CONCLUSION

Methanolic extract of DM contains active phytochemicals for multi-target-directed antiparkinsonian mechanisms amenable for further studies.

An Update on Nondopaminergic Treatments for Motor and Non-motor Symptoms of Parkinson's Disease

Nondopaminergic neurotransmitters such as adenosine, norepinephrine, serotonin, glutamate, and acetylcholine are all involved in Parkinson's disease (PD) and promote its symptoms. Therefore, nondopaminergic receptors are key targets for developing novel preparations for the management of motor and non-motor symptoms in PD, without the potential adverse events of dopamine replacement therapy. We reviewed English-written articles and ongoing clinical trials of nondopaminergic treatments for PD patients till 2014 to summarize the recent findings on nondopaminergic preparations for the treatment of PD patients. The most promising research area of nondopaminergic targets is to reduce motor complications caused by traditional dopamine replacement therapy, including motor fluctuations and levodopa-induced dyskinesia. Istradefylline, Safinamide, and Zonisamide were licensed for the management of motor fluctuations in PD patients, while novel serotonergic and glutamatergic agents to improve motor fluctuations are still under research. Sustained- release agents of Amantadine were approved for treating levodopa induced dyskinesia (LID), and serotonin 5HT1B receptor agonist also showed clinical benefits to LID. Nondopaminergic targets were also being explored for the treatment of non-motor symptoms of PD. Pimavanserin was approved globally for the management of hallucinations and delusions related to PD psychosis. Istradefylline revealed beneficial effect on daytime sleepiness, apathy, depression, and lower urinary tract symptoms in PD subjects. Droxidopa may benefit orthostatic hypotension in PD patients. Safinamide and Zonisamide also showed clinical efficacy on certain non-motor symptoms of PD patients. Nondopaminergic drugs are not expected to replace dopaminergic strategies, but further development of these drugs may lead to new approaches with positive clinical implications.

Advances in the Therapeutic Use of Non-Ergot Dopamine Agonists in the Treatment of Motor and Non-Motor Symptoms of Parkinson's Disease

Dopamine (DA) agonists, as an excellent dopamine replacement therapy for patients with early and advanced Parkinson's disease (PD), play a vital role in controlling motor and several nonmotor symptoms. Besides, the application of DA agonists may delay levodopa therapy and the associated risk of motor complications. Indeed, each DA agonist has unique pharmacokinetic and pharmacodynamic characteristics and therefore has different therapeutic efficacy and safety profile. The comorbidities, significant non-motor manifestations, concomitant medications, and clinical features of PD individuals should guide the selection of a specific DA agonist to provide a more patient-tailored treatment option. Thorough knowledge of DA agonists helps clinicians better balance clinical efficacy and side effects. Therefore, this review refers to recent English-written articles on DA agonist therapy for PD patients and summarizes the latest findings on non-ergot DA agonists as well as the advantages and disadvantages of each compound to help clinicians in the selection of a specific DA agonist. In addition, novel D1/D5 partial agonists and new formulations of DA agonists are also discussed.

The Role of Monoamine Oxidase B Inhibitors in the Treatment of Parkinson's Disease - An Update

Parkinson's disease (PD) is a progressive neurodegenerative disease characterised by reduced dopamine levels in the substantial nigra. This may lead to typical motor features such as bradykinesia, resting tremors and rigid muscles, as well as non-motor symptoms such as neuropsychiatric symptoms, sleep disorders, autonomic dysfunction, and sensory disturbances. Inhibitors of monoamine oxidase B (MAO-B) are used to alleviate symptoms by reducing monoamine oxidase-catalysed degradation of dopamine; hence, preserving functional levels of dopamine. The very first MAO-B inhibitor used therapeutically was selegiline, followed by rasagiline, its indane derivative which has superior efficacy and selectivity. Both inhibitors can be used as monotherapy or in combination with other anti- Parkinson drugs. Safinamide, a reversible MAO-B inhibitor that utilises both dopaminergic and non-dopaminergic mechanisms, was recently approved by the European Medicines Agency (EMA) (2015) and U.S. FDA (2017) as an add-on therapy for patients with mid- or late-stage Parkinson's disease. Furthermore, MAO-B inhibitors were found to be associated with potential neuroprotective and disease modifying effects. However, evidence of their efficacy and role in PD models is scarce and warrants further investigation.

Trial of Deferiprone in Parkinson's Disease

BACKGROUND

Iron content is increased in the substantia nigra of persons with Parkinson's disease and may contribute to the pathophysiology of the disorder. Early research suggests that the iron chelator deferiprone can reduce nigrostriatal iron content in persons with Parkinson's disease, but its effects on disease progression are unclear.

METHODS

We conducted a multicenter, phase 2, randomized, double-blind trial involving participants with newly diagnosed Parkinson's disease who had never received levodopa. Participants were assigned (in a 1:1 ratio) to receive oral deferiprone at a dose of 15 mg per kilogram of body weight twice daily or matched placebo for 36 weeks. Dopaminergic therapy was withheld unless deemed necessary for symptom control. The primary outcome was the change in the total score on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS; range, 0 to 260, with higher scores indicating more severe impairment) at 36 weeks. Secondary and exploratory clinical outcomes at up to 40 weeks included measures of motor and nonmotor disability. Brain iron content measured with the use of magnetic resonance imaging was also an exploratory outcome.

RESULTS

A total of 372 participants were enrolled; 186 were assigned to receive deferiprone and 186 to receive placebo. Progression of symptoms led to the initiation of dopaminergic therapy in 22.0% of the participants in the deferiprone group and 2.7% of those in the placebo group. The mean MDS-UPDRS total score at baseline was 34.3 in the deferiprone group and 33.2 in the placebo group and increased (worsened) by 15.6 points and 6.3 points, respectively (difference, 9.3 points; 95% confidence interval, 6.3 to 12.2; P<0.001). Nigrostriatal iron content decreased more in the deferiprone group than in the placebo group. The main serious adverse events with deferiprone were agranulocytosis in 2 participants and neutropenia in 3 participants.

CONCLUSIONS

In participants with early Parkinson's disease who had never received levodopa and in whom treatment with dopaminergic medications was not planned, deferiprone was associated with worse scores in measures of parkinsonism than those with placebo over a period of 36 weeks. (Funded by the European Union Horizon 2020 program; FAIRPARK-II ClinicalTrials.gov number, NCT02655315.).

Green Spectrophotometric Platforms for Resolving Overlapped Spectral Signals of Recently Approved Antiparkinsonian Drug (Safinamide) in the Presence of Its Synthetic Precursor (4-Hydroxybenzaldehyde): Applying Ecological Appraisal and Comparative Statistical Studies

BACKGROUND

Safinamide, a highly specific inhibitor of monoamine oxidase B, is a new approved prodigious therapy used to cure Parkinson's disease (PD).

OBJECTIVE

Before marketing and selling a medicine, manufacturers must guarantee that the manufacturing process is consistent by monitoring levels of process-related chemicals and drug contaminants. Therefore, five precise, fast, and accurate spectrophotometric techniques were employed and evaluated for the simultaneous measurement of safinamide and its synthetic precursor, 4-hydroxybenzaldehyde.

METHODS

The first derivative, derivative ratio, ratio difference, dual wavelength, and Fourier self-deconvolution methods worked well to resolve spectral overlap of safinamide and its synthetic precursor, 4-hydroxybenzaldehyde.

RESULTS

Safinamide detection limits ranged from 0.598 to 1.315 µg/mL, whereas the 4-hydroxybenzaldehyde detection limit was found to be as low as 0.327 µg/mL.

CONCLUSION

According to International Council for Harmonisation (ICH) criteria, all procedures were verified and confirmed to be accurate, robust, repeatable, and precise within reasonable range. No considerable variation was found when comparing the outcomes of the suggested approaches to the findings of previously published methods. The ecological value of established methods was measured: the national environmental methods index (NEMI), the analytical eco-scale, the analytical greenness metric (AGREE), and the green analytical process index (GAPI) were used.

HIGHLIGHTS

This is the first spectrophotometric determination of safinamide drug in the presence of its synthetic precursor. Five simple and efficient spectrophotometric approaches were employed to determine a newly approved antiparkinsonian drug in the presence of its synthetic precursor simultaneously. Ecological appraisal was performed for the developed methods using four assessment tools.

Effects of Generic Exchange of Levodopa Medication in Patients With Parkinson Disease

OBJECTIVES

Generic exchange is common practice in most healthcare systems. This study investigated how patients with Parkinson disease (PD) perceived a switch of their levodopa medication and the resulting effects on their PD symptoms.

METHODS

A questionnaire was developed, piloted, and finally distributed to 13,857 members of the national PD patient support group. It was designed to be completed by patients and their pharmacies. χ 2 tests for independence statistics with or without Monte Carlo simulation were performed. Cramér φ and Cramér V were calculated. McNemar test was used to investigate whether a generic switch of a levodopa-containing medication had an impact on PD symptoms.

RESULTS

Analyses were done with 410 finalized respondents of 13,857 distributed questionnaires. More than half of the responders were 75 years or older and rated themselves Hoehn and Yahr stages 3 to 5. Most patients were confused by a change of their medication. A total of 54.7% of the switchers (n = 148) reported swallowing difficulties with medication, which was significantly more frequent than with nonswitchers (37.3% of 204, P = 0.001). Adverse effects related to the switch were reported by 26.6% of all switchers (switchback rate, 20.5%). The patients at higher Hoehn and Yahr stages were affected to a greater extend.

CONCLUSIONS

Patients, who experienced any brand switch of their levodopa medication, frequently expressed distrust and confusion. Swallowing difficulties and negative effects on their symptoms were problems, which were more pronounced in advanced disease stages. It remains unclear whether the detrimental impact on therapy was caused by the brand switch or by a nocebo effect.

Dendrobine inhibits dopaminergic neuron apoptosis via MANF-mediated ER stress suppression in MPTP/MPP+-induced Parkinson's disease models

BACKGROUND

Parkinson's disease (PD) is an age-related neurodegenerative disorder without effective treatments. Mesencephalic astrocyte-derived neurotrophic factor (MANF) has been suggested to be capable of protecting against PD by inhibiting endoplasmic reticulum (ER) stress-mediated neuronal apoptosis.

PURPOSE

This study was aimed to evaluate the antiparkinsonian effect of dendrobine and reveal its underlying mechanisms from the perspective of MANF-mediated ER stress suppression.

METHODS

Behavioral assessments of PD mice as well as LDH/CCK-8 assay in SH-SY5Y cells and primary midbrain neurons were carried out to detect the antiparkinsonian effect of dendrobine. Immunofluorescence, western blot, flow cytometry and shRNA-mediated MANF knockdown were used to determine the apoptosis of dopaminergic neurons and the expressions of ER stress-related proteins for investigating the underlying mechanism of dendrobine.

RESULTS

Dendrobine significantly ameliorated the motor performance of PD mice and attenuated the injuries of dopaminergic neurons. Dendrobine could also relieve neuronal apoptosis, up-regulate MANF expression and inhibit ER stress, which were largely abolished by shRNA-mediated MANF knockdown in PD model.

CONCLUSION

Dendrobine might protect against PD by inhibiting dopaminergic neuron apoptosis, which was achieved by facilitating MANF-mediated ER stress suppression. Our study suggested that dendrobine could act as a MANF up-regulator to protect against PD, and provided a potential candidate for exploring etiological agents of PD.

Sensitivity to gait improvement after levodopa intake in Parkinson's disease: A comparison study among synthetic kinematic indices

The synthetic indices are widely used to describe balance and stability during gait. Some of these are employed to describe the gait features in Parkinson's disease (PD). However, the results are sometimes inconsistent, and the same indices are rarely used to compare the individuals affected by PD before and after levodopa intake (OFF and ON condition, respectively). Our aim was to investigate which synthetic measure among Harmonic Ratio, Jerk Ratio, Golden Ratio and Trunk Displacement Index is representative of gait stability and harmony, and which of these are more sensitive to the variations between OFF and ON condition. We found that all indices, except the Jerk Ratio, significantly improve after levodopa. Only the improvement of the Trunk Displacement Index showed a direct correlation with the motor improvement measured through the clinical scale UPDRS-III (Unified Parkinson's Disease Rating Scale-part III). In conclusion, we suggest that the synthetic indices can be useful to detect motor changes induced by, but not all of them clearly correlate with the clinical changes achieved with the levodopa administration. In our analysis, only the Trunk Displacement Index was able to show a clear relationship with the PD clinical motor improvement.

Two-step screening method to identify α-synuclein aggregation inhibitors for Parkinson's disease

Parkinson's disease is a neurodegenerative disease characterized by the formation of neuronal inclusions of α-synuclein in patient brains. As the disease progresses, toxic α-synuclein aggregates transmit throughout the nervous system. No effective disease-modifying therapy has been established, and preventing α-synuclein aggregation is thought to be one of the most promising approaches to ameliorate the disease. In this study, we performed a two-step screening using the thioflavin T assay and a cell-based assay to identify α-synuclein aggregation inhibitors. The first screening, thioflavin T assay, allowed the identification of 30 molecules, among a total of 1262 FDA-approved small compounds, which showed inhibitory effects on α-synuclein fibrilization. In the second screening, a cell-based aggregation assay, seven out of these 30 candidates were found to prevent α-synuclein aggregation without causing substantial toxicity. Of the seven final candidates, tannic acid was the most promising compound. The robustness of our screening method was validated by a primary neuronal cell model and a Caenorhabditis elegans model, which demonstrated the effect of tannic acid against α-synuclein aggregation. In conclusion, our two-step screening system is a powerful method for the identification of α-synuclein aggregation inhibitors, and tannic acid is a promising candidate as a disease-modifying drug for Parkinson's disease.

DA-9805 protects dopaminergic neurons from endoplasmic reticulum stress and inflammation

Parkinson's disease (PD) is a multifactorial neurodegenerative disease with damages to mitochondria and endoplasmic reticulum (ER), followed by neuroinflammation. We previously reported that a triple herbal extract DA-9805 in experimental PD toxin-models had neuroprotective effects by alleviating mitochondrial damage and oxidative stress. In the present study, we investigated whether DA-9805 could suppress ER stress and neuroinflammation in vitro and/or in vivo. Pre-treatment with DA-9805 (1 μg/ml) attenuated upregulation of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and cleaved caspase-3 in SH-SY5Y neuroblastoma cells treated with thapsigargin (1 µg/ml) or tunicamycin (2 µg/ml). In addition, DA-9805 prevented the production of IL-1β, IL-6, TNF-α and nitric oxide through inhibition of NF-κB activation in BV2 microglial cells stimulated with lipopolysaccharides (LPS). Intraperitoneal injection of LPS (10 mg/kg) into mice can induce acute neuroinflammation and dopaminergic neuronal cell death. Oral administration of DA-9805 (10 or 30 mg/kg/day for 3 days before LPS injection) prevented loss of dopaminergic neurons and activation of microglia and astrocytes in the substantia nigra in LPS-injected mouse models. Taken together, these results indicate that DA-9805 can effectively prevent ER stress and neuroinflammation, suggesting that DA-9805 is a multitargeting and disease-modifying therapeutic candidate for PD.

Effects of bee venom and dopamine-loaded nanoparticles on reserpine-induced Parkinson's disease rat model

Parkinson's disease (PD) is a progressive chronic neurodegenerative condition characterized by the loss of dopaminergic neurons within the substantia nigra. Current PD therapeutic strategies are mainly symptomatic and can lead to motor complications overtime. As a result, alternative medicine may provide an effective adjuvant treatment for PD as an addition to or as a replacement of the conventional therapies. The aim of this work was to evaluate the effects of Bee Venom (BV) and dopamine (DA)-loaded nanoparticles in a reserpine-induced animal model of PD. After inducing PD with reserpine injection, different groups of male rats were treated with L-Dopa, BV, DA-nanoparticles. Our findings showed that BV and DA-nanoparticles administration restored monoamines, balanced glutamate/GABA levels, halted DNA fragmentation, decreased pro-inflammatory mediators (IL-1β and TNF-α), and elevated anti-inflammatory mediators (PON1) and neurotropic factor (BDNF) levels in comparison with conventional therapy of PD. Furthermore, in a reserpine-induced PD rat model, the ameliorative effects of BV were significantly superior to that of DA-nanoparticles. These findings imply that BV and DA-nanoparticles could be useful as adjuvant treatments for PD.

Inhibition of NLRP3 inflammasome by glibenclamide attenuated dopaminergic neurodegeneration and motor deficits in paraquat and maneb-induced mouse Parkinson's disease model

Pesticides exposure can lead to damage of dopaminergic neurons, which are associated with increased risk of Parkinson's disease (PD). However, the etiology of PD remains poorly understood and no therapeutic strategy is available. Previous studies suggested the involvement of NLRP3 inflammasome in the onset of PD. This study was designed to investigate whether glibenclamide, an inhibitor of NLRP3 inflammasome, could offer a reliable protective strategy for PD in a mouse PD model induced by paraquat and maneb. We found that glibenclamide exerted potent neuroprotection against paraquat and maneb-induced upregulation of α-synuclein, dopaminergic neurodegeneration and motor impairment in brain of mice. Mechanistically, glibenclamide treatment blocked NLRP3 inflammasome activation evidenced by reduced expressions of NLRP3, activated caspase-1 and mature interleukin-1β in glibenclamide co-treated mice compared with those in paraquat and maneb group mice. Furthermore, glibenclamide treatment mitigated paraquat and maneb-induced microglial M1 proinflammatory response and nuclear factor-κB activation in mice. Finally, the increased superoxide production, lipid peroxidation, protein levels of NADPH oxidase 2 (NOX2) and inducible nitric oxide synthase (iNOS) induced by paraquat and maneb were all attenuated by glibenclamide. Overall, our findings demonstrated that glibenclamide protected dopaminergic neurons in a mouse PD model induced by combined exposures of paraquat and maneb through suppression of NLRP3 inflammasome activation, microglial M1 polarization and oxidative stress.

UHPLC-MS-based metabolomics and chemoinformatics study reveals the neuroprotective effect and chemical characteristic in Parkinson's disease mice after oral administration of Wen-Shen-Yang-Gan decoction

Parkinson's disease (PD), the typical neurodegenerative disease, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN). However, no therapeutic agent used currently could slow down neuronal cell loss so as to decelerate or halt the progression of PD. Traditional Chinese medicine (TCM) has been utilized to treat the dysfunction of the autonomic nervous system. Wen-Shen-Yang-Gan decoction (WSYGD) has a good effect on the clinical treatment of PD with constipation. However, it is not clear which ingredients and what mechanism are responsible for the therapeutic effect. In this study, the pharmacodynamic study of WSYGD in PD mice was applied. Concurrently, a novel method for the identification of metabolic profiles of WSYGD has been developed. Finally, we found that WSYGD could protect the PD mice induced by rotenone. The underlying mechanism of the protective effect may be related to the reduction of the DA neurons apoptosis via reducing inflammatory reaction. By virtue of UPLC-MS and chemoinformatics method, 35 prototype compounds and 27 metabolites were filtered out and tentatively characterized. In conclusion, this study provides an insight into the metabolism of WSYGD in vivo to enable understanding of the metabolic process and therapeutic mechanism of PD.

Antiparkinsonian activity of Cucurbita pepo seeds along with possible underlying mechanism

Cucurbita pepo is used as a vegetable in Pakistan and its seeds are also rich in tocopherol. Data showed the pivotal role of tocopherol in the treatment of Parkinson's disease (PD). The current study was designed to probe into the antiparkinson activity of methanolic extract of C. pepo (MECP) seeds in the haloperidol-induced Parkinson rat model. Behavioral studies showed improvement in motor functions. The increase in catalase, superoxide dismutase, glutathione levels whereas the decreases in the malondialdehyde and nitrite levels were noted in a dose-dependent manner. Acetylcholine-esterase (AchE) activity was increased. Molecular docking results revealed significant binding interaction of selected phytoconstituents within an active site of target protein AchE (PDB ID: 4EY7). Furthermore, α-synuclein was up regulated with down regulation of TNF-α and IL-1β in the qRT-PCR study. Subsequently, ADMET results on the basis of structure to activity predictions in terms of pharmacokinetics and toxicity estimations show that selected phytochemicals exhibited moderately acceptable properties. These properties add knowledge towards the structural features which could improve the bioavailability of selected phytochemicals before moving towards the initial phase of the drug development. Our integrated drug discovery scheme concluded that C. pepo seeds could ameliorate symptoms of PD and may prove a lead remedy for the treatment of PD.

MPTP-induced mouse model of Parkinson's disease: A promising direction of therapeutic strategies

Among the popular animal models of Parkinson's disease (PD) commonly used in research are those that employ neurotoxins, especially 1-methyl- 4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). This neurotoxin exerts it neurotoxicity by causing a barrage of insults, such as oxidative stress, mitochondrial apoptosis, inflammation, excitotoxicity, and formation of inclusion bodies acting singly and in concert, ultimately leading to dopaminergic neuronal damage in the substantia nigra pars compacta and striatum. The selective neurotoxicity induced by MPTP in the nigrostriatal dopaminergic neurons of the mouse brain has led to new perspectives on PD. For decades, the MPTP-induced mouse model of PD has been the gold standard in PD research even though it does not fully recapitulate PD symptomatology, but it does have the advantages of simplicity, practicability, affordability, and fewer ethical considerations and greater clinical correlation than those of other toxin models of PD. The model has rejuvenated PD research and opened new frontiers in the quest for more novel therapeutic and adjuvant agents for PD. Hence, this review summarizes the role of MPTP in producing Parkinson-like symptoms in mice and the experimental role of the MPTP-induced mouse model. We discussed recent developments of more promising PD therapeutics to enrich our existing knowledge about this neurotoxin using this model.

Activation of Nrf2 in Astrocytes Suppressed PD-Like Phenotypes via Antioxidant and Autophagy Pathways in Rat and Drosophila Models

The oxidative-stress-induced impairment of autophagy plays a critical role in the pathogenesis of Parkinson's disease (PD). In this study, we investigated whether the alteration of Nrf2 in astrocytes protected against 6-OHDA (6-hydroxydopamine)- and rotenone-induced PD-like phenotypes, using 6-OHDA-induced rat PD and rotenone-induced Drosophila PD models. In the PD rat model, we found that Nrf2 expression was significantly higher in astrocytes than in neurons. CDDO-Me (CDDO methyl ester, an Nrf2 inducer) administration attenuated PD-like neurodegeneration mainly through Nrf2 activation in astrocytes by activating the antioxidant signaling pathway and enhancing autophagy in the substantia nigra and striatum. In the PD Drosophila model, the overexpression of Nrf2 in glial cells displayed more protective effects than such overexpression in neurons. Increased Nrf2 expression in glial cells significantly reduced oxidative stress and enhanced autophagy in the brain tissue. The administration of the Nrf2 inhibitor ML385 reduced the neuroprotective effect of Nrf2 through the inhibition of the antioxidant signaling pathway and autophagy pathway. The autophagy inhibitor 3-MA partially reduced the neuroprotective effect of Nrf2 through the inhibition of the autophagy pathway, but not the antioxidant signaling pathway. Moreover, Nrf2 knockdown caused neurodegeneration in flies. Treatment with CDDO-Me attenuated the Nrf2-knockdown-induced degeneration in the flies through the activation of the antioxidant signaling pathway and increased autophagy. An autophagy inducer, rapamycin, partially rescued the neurodegeneration in Nrf2-knockdown Drosophila by enhancing autophagy. Our results indicate that the activation of the Nrf2-linked signaling pathways in glial cells plays an important neuroprotective role in PD models. Our findings not only provide a novel insight into the mechanisms of Nrf2-antioxidant-autophagy signaling, but also provide potential targets for PD interventions.

Pharmacological evaluation of vanillic acid in rotenone-induced Parkinson's disease rat model

In the present study, we investigated the anti-Parkinson's effect of vanillic acid (VA) (12 mg/kg, 25 mg/kg, 50 mg/kg p.o.) against rotenone (2 mg/kg s.c.) induced Parkinson's disease (PD) in rats. The continuous administration of rotenone for 35 days resulted in rigidity in muscles, catalepsy, and decrease in locomotor activity, body weight, and rearing behaviour along with the generation of oxidative stress in the brain (rise in the TBARS, and SAG level and reduced CAT, and GSH levels). Co-treatment of VA and levodopa-carbidopa (100 mg/kg + 25 mg/kg p.o.) lead to a significant (P < 0.001) reduction in the muscle rigidity and catalepsy along with a significant (P < 0.001) increase in body weight, rearing behaviour, locomotion and muscle activity as compared to the rotenone-treated group in the dose dependent manner, showing maximum effect at the 50 mg/kg. It also showed reversal of levels of oxidative stress parameters thus, reducing the neuronal oxidative stress. The level of DA was also estimated which showed an increase in the level of DA in the VA plus standard drug treated animals as compared to rotenone treated group. Histopathological evaluation showed a high number of eosinophilic lesions in the rotenone group which were found to be very less in the VA co-treated group. The study thus proved that co-treatment of VA and levodopa-carbidopa, significantly protected the brain from neuronal damage due to oxidative stress and attenuated the motor defects indicating the possible therapeutic potential of VA as a neuroprotective in PD.

A Systematic Review of Parkinson's Disease Pharmacogenomics: Is There Time for Translation into the Clinics?

BACKGROUND

Parkinson's disease (PD) is the second most frequent neurodegenerative disease, which creates a significant public health burden. There is a challenge for the optimization of therapies since patients not only respond differently to current treatment options but also develop different side effects to the treatment. Genetic variability in the human genome can serve as a biomarker for the metabolism, availability of drugs and stratification of patients for suitable therapies. The goal of this systematic review is to assess the current evidence for the clinical translation of pharmacogenomics in the personalization of treatment for Parkinson's disease.

METHODS

We performed a systematic search of Medline database for publications covering the topic of pharmacogenomics and genotype specific mutations in Parkinson's disease treatment, along with a manual search, and finally included a total of 116 publications in the review.

RESULTS

We analyzed 75 studies and 41 reviews published up to December of 2020. Most research is focused on levodopa pharmacogenomic properties and catechol-O-methyltransferase (COMT) enzymatic pathway polymorphisms, which have potential for clinical implementation due to changes in treatment response and side-effects. Likewise, there is some consistent evidence in the heritability of impulse control disorder via Opioid Receptor Kappa 1 (OPRK1), 5-Hydroxytryptamine Receptor 2A (HTR2a) and Dopa decarboxylase (DDC) genotypes, and hyperhomocysteinemia via the Methylenetetrahydrofolate reductase (MTHFR) gene. On the other hand, many available studies vary in design and methodology and lack in sample size, leading to inconsistent findings.

CONCLUSIONS

This systematic review demonstrated that the evidence for implementation of pharmacogenomics in clinical practice is still lacking and that further research needs to be done to enable a more personalized approach to therapy for each patient.

Average beta burst duration profiles provide a signature of dynamical changes between the ON and OFF medication states in Parkinson's disease

Parkinson's disease motor symptoms are associated with an increase in subthalamic nucleus beta band oscillatory power. However, these oscillations are phasic, and there is a growing body of evidence suggesting that beta burst duration may be of critical importance to motor symptoms. This makes insights into the dynamics of beta bursting generation valuable, in particular to refine closed-loop deep brain stimulation in Parkinson's disease. In this study, we ask the question "Can average burst duration reveal how dynamics change between the ON and OFF medication states?". Our analysis of local field potentials from the subthalamic nucleus demonstrates using linear surrogates that the system generating beta oscillations is more likely to act in a non-linear regime OFF medication and that the change in a non-linearity measure is correlated with motor impairment. In addition, we pinpoint the simplest dynamical changes that could be responsible for changes in the temporal patterning of beta oscillations between medication states by fitting to data biologically inspired models, and simpler beta envelope models. Finally, we show that the non-linearity can be directly extracted from average burst duration profiles under the assumption of constant noise in envelope models. This reveals that average burst duration profiles provide a window into burst dynamics, which may underlie the success of burst duration as a biomarker. In summary, we demonstrate a relationship between average burst duration profiles, dynamics of the system generating beta oscillations, and motor impairment, which puts us in a better position to understand the pathology and improve therapies such as deep brain stimulation.

Effects of Levodopa on quality of sleep and nocturnal movements in Parkinson's Disease

BACKGROUND

Sleep disturbances are common in Parkinson's Disease (PD), with nocturnal akinesia being one of the most burdensome. Levodopa is frequently used in clinical routine to improve nocturnal akinesia, although evidence is not well proven.

METHODS

We assessed associations of Levodopa intake with quality of sleep and perception of nocturnal akinesia in three PD cohorts, using the Parkinson's Disease Sleep Scale (PDSS-2) in two cohorts and a question on nocturnal immobility in one cohort. In one cohort also objective assessment of mobility during sleep was performed, using mobile health technology.

RESULTS

In an independent analysis of all three cohorts (in total n = 1124 PD patients), patients taking Levodopa CR reported a significantly higher burden by nocturnal akinesia than patients without Levodopa. Higher Levodopa intake and MDS-UPDRS part IV scores (indicating motor fluctuations) predicted worse PDSS-2 and higher subjective nocturnal immobility scores, while disease duration and severity were not predictive. Levodopa intake was not associated with objectively changed mobility during sleep.

CONCLUSION

Our results showed an association of higher Levodopa intake with perception of worse quality of sleep and nocturnal immobility in PD, indicating that Levodopa alone might not be suitable to improve subjective feeling of nocturnal akinesia in PD. In contrast, Levodopa intake was not relevantly associated with objectively measured mobility during sleep. PD patients with motor fluctuations may be particularly affected by subjective perception of nocturnal mobility. This study should motivate further pathophysiological and clinical investigations on the cause of perception of immobility during sleep in PD.

Locomotor activity and resting local field potential oscillatory rhythms of 6-OHDA mouse model of Parkinson's disease in response to acute and repeated treatments with L-dopa

Phase-amplitude coupling (PAC) of local field potential (LFP) has been recognized as higher-order representation of brain states. Neuronal loss in the striatum leads to Parkinson's disease (PD) symptoms and modifies LFP oscillation. However, PAC in the striatum of PD mouse model induced by 6-hydroxydopamne (6-OHDA) remained to be investigated. Male Swiss albino ICR mice were implanted with intracranial electrode and injected with 6-OHDA to the left striatum. Levodopa (L-dopa) (10 mg/kg, oral) was used for treatment once a day from day 15-19. Locomotor activity and resting LFP signals were selectively analyzed on day 15 and 19. One-way ANOVA revealed significant decreases in travelled distance induced by 6-OHDA on both days (p ≤ 0.05). However, the decreased travelled distances were significantly reversed by L-dopa. On day 15, LFP powers of theta, alpha, beta and low gamma waves were significantly increased by 6-OHDA injection and the powers of beta and low gamma were significantly reversed to control level by treatment with L-dopa. On day 19, LFP powers of delta, theta, alpha, beta and low gamma waves were significantly increased by 6-OHDA injection and the powers of low gamma were significantly reversed to control level by treatment with L-dopa. Theta-gamma PAC analyses also confirmed significant increase in modulation index (MI) induced by 6-OHDA on day 19. However, L-dopa failed to significantly reverse the MI to control level. These findings indicated theta-gamma coupling in the striatum of PD mouse model. Taken together, change in striatal theta-gamma PAC might be one of biomarkers in addition to hypokinesia and increased LFP powers that reflect disrupted neural mechanisms in PD mouse model.

Identification of anti-Parkinson's Disease Lead Compounds from Aspergillus ochraceus Targeting Adenosin Receptors A2A

Two novel alkaloids compounds together with fifteen know metabolites were identified from Aspergillus ochraceus. The stereochemistry features of the new molecules were determined via HRESIMS, NMR, ECD, and XRD analyses. Amongst these, compounds two compounds exhibited potential efficacy as anti-Parkinson's disease with the EC50 values of 2.30 and 2.45 μM, respectively. ADMET prediction showed that these compounds owned favorable drug-like characteristics and safe toxicity scores towards CNS drugs. Virtual screening analyses manifested that the compounds exhibited not only robust and reliable interactions to adenosine receptors A2A , but also higher binding selectivity to A2A receptors than to A1 and A3 receptors. Molecular dynamics simulation demonstrated the reliability of molecular docking results and the stability of the complexes obtained with the novel compounds and A2A receptors in natural environments. It is the first time that anti-PD lead compounds have been identified from Aspergillus ochraceus and targeting adenosine A2A receptors.