Rotenone destroys dopaminergic neurons and induces parkinsonian symptoms in rats

Chemical composition and studying the possible neuroprotective effect of iridoids-rich fraction from Pentas lanceolata leaves using rotenone model of Parkinson's disease in mice

Parkinsonism is an age-related neurodegenerative illness that affects motor coordination leading to loss of dopaminergic neurons. Many medications are used for the treatment of Parkinson's disease but are only symptomatic and have a limited effect on the progression of this ailment. Therefore, bioactive compounds which derived from plants have been examined for their ability to improve the neuronal damage and cell death happened in parkinsonian patients. In this study the iridoids-rich fraction isolated from Pentas lanceolata (PIRF) leaves was investigated for its phytoconstituents. Seven iridoids (1-7) and one flavonol diglycoside (8) were isolated, and their chemical structures were achieved by 1H and 13C nuclear magnetic resonance and ESI-MS spectral data. Compound 1 (6β,7β-epoxy-8-epi-splendoside) and 5 (gaertneroside) were isolated for the first time from Pentas genus as well as compound 8 (kaempferol-3-O-robinobioside). The current study aims to investigate the possible anti-parkinsonian effect of PIRF using a rotenone model of Parkinsonism in mice. Behavioural tests (wirehanging, stair and wooden-walking tests) were done to examine the motor coordination in mice after treatment. Biochemical and histopathological examinations for brain striatum in different groups were also evaluated. Results revealed that rotenone-treated mice had poor motor functions described by depletion of dopamine and Ach levels, a significant increase in proinflammatory cytokines, IL-1B, TNF-α and Mcp-1 and oxidative biomarkers with subsequent reduction in antioxidant mediators. Disorganization of striatum, degenerated neurocytes, slight vacuolation, shrunken neurons with pyknotic nuclei and apoptotic cells are displayed by histopathological examinations. Treatment with PIRF ameliorates the neurodegeneration-induced by rotenone in the brain of mice. The anti-parkinsonian effect of PIRF could be attributed to their bioactive constituents of iridoids.

6-Shogaol Abrogates Parkinson's Disease in Rotenone-Induced Rodents: Based on In Silico Study and Inhibiting TNF-α/NF-κB/IL-1β/MAO-B

Background/Objectives: 6-Shogaol is a comparatively innovative anti-Parkinson's remedy with antioxidant and anti-inflammatory characteristics. This investigation intended to determine the role of 6-shogaol in the Parkinson's disease (PD) paradigm in rotenone-induced rats. Methods: Thirty male Wistar rats (10-12 weeks old; 180 ± 20 g) were divided into five groups. Animals with rotenone-induced experimental PD were subsequently treated with 6-shogaol-10 at 20 mg/kg for 28 days. After the experimental duration, behavioural investigations were performed, i.e., open field test, forced swim test, rotarod test, and catalepsy test. Biochemical assessments like AChE, GSH, CAT, SOD, MDA, nitrite, ceruloplasmin, proinflammatory markers such as IL-1β, NF-κB, TNF-α, and catecholamines markers (DA, GABA, and MAO-B) were determined. The docking procedure was conducted using the AutoDock Vina docking protocol. Furthermore, histopathology was performed. Results: Rotenone significantly increased the level of MAO-B, oxidative, nitrative, and pro-inflammatory markers. However, there was a decline in ceruloplasmin, dopamine, and endogenous antioxidants. Treatment with 6-shogaol (10 and 20 mg/kg) considerably sustained the elevation of oxidative stress and inflammatory indicators and decreased AChE activity and dopamine levels. In the histology of the brain, 6-shogaol improved the neuronal structure and reduced the degeneration of neurons. Based on the binding energy values, compound 6-shogaol demonstrates a favourable binding affinity to AChE, MAO-B, DA, and GABA with respective binding energies of -8.214, -8.133, -7.396 and -6.189 kcal/mol. Conclusions: In this study, 6-shogaol exhibited neuroprotective properties against PD, which could be employed as a prospective medication for PD.

Experimental models of Parkinson's disease: Challenges and Opportunities

Parkinson's disease (PD) is a widespread neurodegenerative disorder occurs due to the degradation of dopaminergic neurons present in the substantia nigra pars compacta (SNpc). Millions of people are affected by this devastating disorder globally, and the frequency of the condition increases with the increase in the elderly population. A significant amount of progress has been made in acquiring more knowledge about the etiology and the pathogenesis of PD over the past decades. Animal models have been regarded to be a vital tool for the exploration of complex molecular mechanisms involved in PD. Various animals used as models for disease monitoring include vertebrates (zebrafish, rats, mice, guinea pigs, rabbits and monkeys) and invertebrate models (Drosophila, Caenorhabditis elegans). The animal models most relevant for study of PD are neurotoxin induction-based models (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 6-Hydroxydopamine (6-OHDA) and agricultural pesticides (rotenone, paraquat), pharmacological models (reserpine or haloperidol treated rats), genetic models (α-synuclein, Leucine-rich repeat kinase 2 (LRRK2), DJ-1, PINK-1 and Parkin). Several non-mammalian genetic models such as zebrafish, Drosophila and Caenorhabditis elegance have also gained popularity in recent years due to easy genetic manipulation, presence of genes homologous to human PD, and rapid screening of novel therapeutic molecules. In addition, in vitro models (SH-SY5Y, PC12, Lund human mesencephalic (LUHMES) cells, Human induced pluripotent stem cell (iPSC), Neural organoids, organ-on-chip) are also currently in trend providing edge in investigating molecular mechanisms involved in PD as they are derived from PD patients. In this review, we explain the current situation and merits and demerits of the various animal models.

Mass Spectrometry Analysis of Neurotransmitter Shifting during Neurogenesis and Neurodegeneration of PC12 Cells

Parkinson's disease (PD) affects movement; however, most patients with PD also develop nonmotor symptoms, such as hyposmia, sleep disorder, and depression. Dopamine levels in the brain have a critical influence on movement control, but other neurotransmitters are also involved in the progression of PD. This study analyzed the fluctuation of neurotransmitters in PC12 cells during neurogenesis and neurodegeneration by performing mass spectrometry. We found that the dopaminergic metabolism pathway of PC12 cells developed vigorously during the neuron differentiation process and that the neurotransmitters were metabolized into 3-methoxytyramine, which was released from the cells. The regulation of the intracellular and extracellular concentrations of adenosine indicated that adenine nucleotides were actively utilized in neural differentiation. Moreover, we exposed the differentiated PC12 cells to rotenone, which is a suitable material for modeling PD. The cells exposed to rotenone in the early stage of differentiation exhibited stimulated serotoninergic metabolism, and the contents of the serotoninergic neurotransmitters returned to their normal levels in the late stage of differentiation. Interestingly, the nondifferentiated cells can resist the toxicant rotenone and produce normal dopaminergic metabolites. However, when differentiated neuron cells were exposed to rotenone, they were seriously damaged, leading to a failure to produce dopaminergic neurotransmitters. In the low-dosage damage process, the amino acids that functioned as dopaminergic pathway precursors could not be absorbed by the cells, and dopamine and L-dopa were secreted and unable to be reuptaken to trigger the cell damage.

An exploratory study on the ability of manganese to supplement rotenone neurotoxicity in rats

Parkinson's disease (PD) is a complex disorder, primarily of idiopathic origin, with environmental stressors like rotenone and manganese linked to its development. This study explores their potential interaction and resulting neurotoxicity, aiming to understand how environmental factors contribute to PD. In an eight-day experiment, male Wistar rats weighing 280-300 g were subjected to rotenone, manganese, or a combination of both. Various parameters were assessed, including body weight, behavior, serum markers, tissue damage, protein levels (tyrosine hydroxylase, Dopamine- and cAMP-regulated neuronal phosphoprotein -DARPP-32-, and α-synuclein), and mitochondrial function. Manganese heightened rotenone's impact on reducing food intake without causing kidney or liver dysfunction. However, the combined exposure intensified neurotoxicity, which was evident in augmented broken nuclei and decreased tyrosine hydroxylase and DARPP-32 levels in the striatum. While overall mitochondrial function was preserved, co-administration reduced complex IV activity in the midbrain and liver. In conclusion, our findings revealed a parallel toxic effect induced by rotenone and manganese. Notably, while these substances do not target the same dopaminergic regions, a notable escalation in toxicity is evident in the striatum, the brain region where their toxic effects converge. This study highlights the need for further exploration regarding the interaction of environmental factors and their possible impact on the etiology of PD.

Insomnia-related rodent models in drug discovery

Despite the widespread prevalence and important medical impact of insomnia, effective agents with few side effects are lacking in clinics. This is most likely due to relatively poor understanding of the etiology and pathophysiology of insomnia, and the lack of appropriate animal models for screening new compounds. As the main homeostatic, circadian, and neurochemical modulations of sleep remain essentially similar between humans and rodents, rodent models are often used to elucidate the mechanisms of insomnia and to develop novel therapeutic targets. In this article, we focus on several rodent models of insomnia induced by stress, diseases, drugs, disruption of the circadian clock, and other means such as genetic manipulation of specific neuronal activity, respectively, which could be used to screen for novel hypnotics. Moreover, important advantages and constraints of some animal models are discussed. Finally, this review highlights that the rodent models of insomnia may play a crucial role in novel drug development to optimize the management of insomnia.

Tricompartmental Microcarriers with Controlled Release for Efficient Management of Parkinson's Disease

Parkinson's is a progressive neurodegenerative disease of the nervous system. It has no cure, but its symptoms can be managed by supplying dopamine artificially to the brain.This work aims to engineer tricompartmental polymeric microcarriers by electrohydrodynamic cojetting technique to encapsulate three PD (Parkinson's disease) drugs incorporated with high encapsulation efficiency (∼100%) in a single carrier at a fixed drug ratio of 4:1:8 (Levodopa (LD): Carbidopa(CD): Entacapone (ENT)). Upon oral administration, the drug ratio needs to be maintained during subsequent release from microparticles to enhance the bioavailability of primary drug LD. This presents a notable challenge, as the three drugs vary in their aqueous solubility (LD > CD > ENT). The equilibrium of therapeutic release was achieved using a combination of FDA-approved polymers (PLA, PLGA, PCL, and PEG) and the disc shape of particles. In vitro studies demonstrated the simultaneous release of all the three therapeutics in a sustained and controlled manner. Additionally, pharmacodynamics and pharmacokinetics studies in Parkinson's disease rats induced by rotenone showed a remarkable improvement in PD conditions for the microparticles-fed rats, thereby showing a great promise toward efficient management of PD.

Neuroprotective potential of traditionally used medicinal plants of Manipur against rotenone-induced neurotoxicity in SH-SY5Y neuroblastoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Alternanthera sessilis (L.) R. Br. ex DC., Eryngium foetidum L., and Stephania japonica (Thunb.) Miers plants are traditionally used to treat various central nervous system disorders like paralysis, epilepsy, seizure, convulsion, chronic pain, headache, sleep disturbances, sprain, and mental disorders. However, their possible neuroprotective effects have not been evaluated experimentally so far.

AIM OF THE STUDY

The study aims to examine the neuroprotective potential of the three plants against cytotoxicity induced by rotenone in SH-SY5Y neuroblastoma cells and assess its plausible mechanisms of neuroprotection.

MATERIALS AND METHODS

The antioxidant properties of the plant extracts were determined chemically by DPPH and ABTS assay methods. The cytotoxicity of rotenone and the cytoprotective activities of the extracts were evaluated using MTT assays. Microtubule-associated protein 2 (MAP2) expression studies in cells were performed to assess neuronal survival after rotenone and extract treatments. Mitochondrial membrane potential and intracellular levels of reactive oxygen species were evaluated using Rhodamine 123 and DCF-DA dye, respectively. Catalase, glutathione peroxidase, and superoxide dismutase activities were also measured. Apoptotic nuclei were examined using DAPI staining. Liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS) analysis of the plant extracts was also performed.

RESULTS

The methanol extracts of A. sessilis, S. japonica, and E. foetidum showed excellent free radical scavenging activities. MAP2 expression studies show that A. sessilis and S. japonica have higher neuroprotective effects against rotenone-induced neurotoxicity in SH-SY5Y cells than E. foetidum. Pre-treating cells with the plant extracts reverses the rotenone-induced increase in intracellular ROS. The plant extracts could also restore the reduced mitochondrial membrane potential induced by rotenone treatment and reinstate rotenone-induced increases in catalase, glutathione peroxidase, and superoxide dismutase activities. All the extracts inhibited rotenone-induced changes in nuclear morphology and DNA condensation, an early event of cellular apoptosis. LC-QTOF-MS analysis of the plant extracts shows the presence of neuroprotective compounds.

CONCLUSIONS

The plant extracts showed neuroprotective activities against rotenone-treated SH-SY5Y cells through antioxidant and anti-apoptotic mechanisms. These findings support the ethnopharmacological uses of these plants in treating neurological disorders. They probably are a good source of neuroprotective compounds that could be further explored to develop treatment strategies for neurodegenerative diseases like Parkinson's disease.

Epigenetic associations of GPNMB rs199347 variant with alcohol consumption in Parkinson's disease

Introduction

Alcohol consumption can induce a neuroinflammatory response and contribute to the progression of neurodegeneration. However, its association with Parkinson's disease (PD), the second most common neurodegenerative disorder, remains undetermined. Recent studies suggest that the glycoprotein non-metastatic melanoma protein B (GPNMB) is a potential biomarker for PD. We evaluated the association of rs199347, a variant of the GPNMB gene, with alcohol consumption and methylation upstream of GPNMB.

Methods

We retrieved genetic and DNA methylation data obtained from participants enrolled in the Taiwan Biobank (TWB) between 2008 and 2016. After excluding individuals with incomplete or missing information about potential PD risk factors, we included 1,357 participants in our final analyses. We used multiple linear regression to assess the association of GPNMB rs199347 and chronic alcohol consumption (and other potential risk factors) with GPNMB cg17274742 methylation.

Results

There was no difference between the distribution of GPNMB rs199347 genotypes between chronic alcohol consumers and the other study participants. A significant interaction was observed between the GPNMB rs199347 variant and alcohol consumption (p = 0.0102) concerning cg17274742 methylation. Compared to non-chronic alcohol consumers with the AA genotype, alcohol drinkers with the rs199347 GG genotype had significantly lower levels (hypomethylation) of cg17274742 (p = 0.0187).

Conclusion

Alcohol consumption among individuals with the rs199347 GG genotype was associated with lower levels of cg17274742 methylation, which could increase expression of the GPNMB gene, an important neuroinflammatory-related risk gene for PD.

Effects of Chronic Exposure to Low Doses of Rotenone on Dopaminergic and Cholinergic Neurons in the CNS of Hemigrapsus sanguineus

Rotenone, as a common pesticide and insecticide frequently found in environmental samples, may be present in aquatic habitats worldwide. Exposure to low concentrations of this compound may cause alterations in the nervous system, thus contributing to Parkinsonian motor symptoms in both vertebrates and invertebrates. However, the effects of chronic exposure to low doses of rotenone on the activity of neurotransmitters that govern motor functions and on the specific molecular mechanisms leading to movement morbidity remain largely unknown for many aquatic invertebrates. In this study, we analyzed the effects that rotenone poisoning exerts on the activity of dopamine (DA) and acetylcholine (ACh) synthesis enzymes in the central nervous system (CNS) of Asian shore crab, Hemigrapsus sanguineus (de Haan, 1835), and elucidated the association of its locomotor behavior with Parkinson's-like symptoms. An immunocytochemistry analysis showed a reduction in tyrosine hydroxylase (TH) in the median brain and the ventral nerve cord (VNC), which correlated with the subsequent decrease in the locomotor activity of shore crabs. We also observed a variation in cholinergic neurons' activity, mostly in the ventral regions of the VNC. Moreover, the rotenone-treated crabs showed signs of damage to ChAT-lir neurons in the VNC. These data suggest that chronic treatment with low doses of rotenone decreases the DA level in the VNC and the ACh level in the brain and leads to progressive and irreversible reductions in the crab's locomotor activity, life span, and changes in behavior.

Anti-Parkinson potential of hesperetin nanoparticles: in vivo and in silico investigations

Parkinson's disease (PD) is characterised by the gradual demise of dopaminergic neurons. In recent years, there has been significant interest in herbal treatments. In this study, hesperetin nanoparticles (HTN) were developed and compared their anti-PD potential with hesperetin (HT) on rotenone induced PD rats. Molecular docking was also performed to evaluate the binding affinity of hesperetin on pathological protein, i.e. D2 dopamine receptors (DR2), using Auto Dock Vina tools. The results showed a higher binding relationship of HTN on dopamine receptors (-7.2 kcal/mol) compared to L-dopa (-6.4 kcal/mol), supporting their potential as drug candidates for PD therapy. HTN was effectively synthesised using the fabrication technique and characterised by zeta potential and SEM analysis. HTN had favourable characteristics, including a size of 249.8 ± 14.9 nm and a Z-potential of -32.9 mV. After being administered orally, HTN demonstrated a notable anti-Parkinsonian effects, indicated by the significant improvement in motor function as assessed by the rota rod test (p < .001***), pole test (p < .001***), stair test (p < .01**), wood walk test (p < .01**) and an increase in substantia nigra (SN) antioxidant levels, CAT (p < .001***), SOD (p < .001***), GSH (p < .01**). Additionally, HTN led to increased dopamine levels (p < .01**) and a decrease in the oxidant system, MDA levels (p < .01**). Furthermore, histopathological examination revealed decreased SN neuronal necrosis in diseased animals treated with HTN compared to those treated with HT in a rat model of Parkinson's disease. Therefore, HTN can be regarded as a viable platform for efficient therapy of PD.

Assessing the Safety and Therapeutic Efficacy of Cannabidiol Lipid Nanoparticles in Alleviating Metabolic and Memory Impairments and Hippocampal Histopathological Changes in Diabetic Parkinson's Rats

Diabetic Parkinson's disease (DP) is a progressive neurodegenerative disease with metabolic syndrome that is increasing worldwide. Emerging research suggests that cannabidiol (CBD) is a neuropharmacological compound that acts against this disease, especially CBD in nano-formulation. The safety of cannabidiol lipid nanoparticles (CBD-LNP) was evaluated by assessing in vitro cytotoxicity in neurons and therapeutic outcomes in a DP animal model, including metabolic parameters and histopathology. CBD-LNPs were fabricated by using a microfluidization technique and showed significantly lower cytotoxicity than the natural form of CBD. The DP rats were induced by streptozotocin followed by a 4-week injection of MPTP with a high-fat diet. Rats were treated orally with a vehicle, CBD, CBD-LNP, or levodopa for 4 weeks daily. As a result, vehicle-treated rats exhibited metabolic abnormalities, decreased striatal dopamine levels, and motor and memory deficits. CBD-LNP demonstrated reduced lipid profiles, enhanced insulin secretion, and restored dopamine levels compared to CBD in the natural form. CBD-LNP also had comparable efficacy to levodopa in ameliorating motor deficits and memory impairment in behavior tests. Interestingly, CBD-LNP presented migration of damaged neuronal cells in the hippocampus more than levodopa. These findings suggest that CBD-LNP holds promise as an intervention addressing both metabolic and neurodegenerative aspects of DP, offering a potential therapeutic strategy.

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

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

Rotenone impairs brain glial energetics and locomotor behavior in bumblebees

Bumblebees are essential pollinators of both wildflowers and crops and face multiple anthropogenic stressors, particularly the utilization of pesticides. Rotenone is an extensively applied neurotoxic pesticide that possesses insecticidal activities against a wide range of pests. However, whether environmentally realistic exposure levels of rotenone can damage neurons in bumblebee brains is still uncertain. Using single-cell RNA-seq, we revealed that rotenone induced cell-specific responses in bumblebee brains, emphasizing the disruption of energy metabolism and mitochondrial dysfunction in glial cells. Correspondingly, the gene regulatory network associated with neurotransmission was also suppressed. Notably, rotenone could specially reduce the number of dopaminergic neurons, impairing bumblebee's ability to fly and crawl. We also found impaired intestinal motility in rotenone-treated bumblebees. Finally, we demonstrated that many differentially expressed genes in our snRNA-seq data overlapped with rotenone-induced Parkinson's disease risk genes, especially in glial cells. Although rotenone is widely used owing to its hypotoxicity, we found that environmentally realistic exposure levels of rotenone induced disturbed glial energetics and locomotor dysfunction in bumblebees, which may lead to an indirect decline in this essential pollinator.

FTY720 Nanoformulation Induces O-GlcNacylation of Synuclein to Alleviate Synucleinopathy

The post-translational modification and aggregation of alpha-synuclein are one of the major causes of Parkinson's disease (PD) regulation. In that, the phosphorylation and nitration of synuclein elevate the aggregation, while O-GlcNacylation prevents the aggregation of synuclein. The inhibition of synuclein aggregation directs the development of PD therapy. The endowed O-GlcNacylation of synuclein could be a promising strategy to inhibit synucleinopathy. Therefore, the neuroprotective chitosan-based FTY720 nanoformulation, PP2A (Protein phosphatase 2) activator has been employed to evaluate the PP2A role in the O-GlcNacylation of synuclein in an in vivo PD model. The neuroprotective effect of our nanoformulation is attributed to the upregulation of tyrosine hydroxylase (TH), the PD therapeutic target, with behavioral improvement in animals against rotenone-induced PD deficits. The neuroprotective molecular insights revealed the camouflaged role of PP2A by endowing the OGT activity that induces O-GlcNacylation of synuclein in the reduction of synucleinopathy.

Morphological hallmarks of dopaminergic neurodegeneration are associated with altered neuron function in Caenorhabditis elegans

Caenorhabditis elegans (C. elegans) is an excellent model system to study neurodegenerative diseases, such as Parkinson's disease, as it enables analysis of both neuron morphology and function in live animals. Multiple structural changes in neurons, such as cephalic dendrite morphological abnormalities, have been considered hallmarks of neurodegeneration in this model, but their relevance to changes in neuron function are not entirely clear. We sought to test whether hallmark morphological changes associated with chemically induced dopaminergic neuron degeneration, such as dendrite blebbing, breakage, and loss, are indicative of neuronal malfunction and result in changes in behavior. We adapted an established dopaminergic neuronal function assay by measuring paralysis in the presence of exogenous dopamine, which revealed clear differences between cat-2 dopamine deficient mutants, wildtype worms, and dat-1 dopamine abundant mutants. Next, we integrated an automated image processing algorithm and a microfluidic device to segregate worm populations by their cephalic dendrite morphologies. We show that nematodes with dopaminergic dendrite degeneration markers, such as blebbing or breakage, paralyze at higher rates in a dopamine solution, providing evidence that dopaminergic neurodegeneration morphologies are correlated with functional neuronal outputs.

Effect of Rotenone on the Neurodegeneration among Different Models

Rotenone is a naturally occurring plant product used as an insecticide, pesticide and piscicide. It is lipophilic in nature and can cross the blood-brain barrier and induce the degeneration of neurons. It inhibits the mitochondrial respiratory chain complex I and stops the transfer of electrons. It induces ROS generation, which impairs mitochondrial activity. Rotenone is a toxic agent which causes the death of neurons. The present review describes the effect of rotenone on neurodegeneration with an emphasis on behavioral, pathological and neuropathological components carried out on various experimental models such as cell lines, Drosophila melanogaster, mice and rats.

The role of gut-brain axis in a rotenone-induced rat model of Parkinson's disease

Parkinson's disease (PD) is a widespread neurodegenerative condition affecting millions globally. This investigation centered on the gut-brain axis in a rotenone-induced PD rat model. Researchers monitored behavioral shifts, histological modifications, neurodegeneration, and inflammation markers throughout the rats' bodies. Results revealed that rotenone-treated rats displayed reduced exploration (p = 0.004) and motor coordination (p < 0.001), accompanied by decreased Nissl staining and increased alpha-synuclein immunoreactivity in the striatum (p = 0.009). Additionally, these rats exhibited weight loss (T3, mean = 291.9 ± 23.67; T19, mean = 317.5 ± 17.53; p < 0.05) and substantial intestinal histological alterations, such as shortened villi, crypt architecture loss, and inflammation. In various regions, researchers noted elevated immunoreactivity to ionized binding adapter molecule (IBA)-1 (p < 0.05) and reduced immunoreactivity to glial fibrillary acidic protein (p < 0.05) and S100B (p < 0.001), indicating altered glial cell activity. Overall, these findings imply that PD is influenced by gut-brain axis changes and may originate in the intestine, impacting bidirectional gut-brain communication.

In vitro modeling of the human dopaminergic system using spatially arranged ventral midbrain-striatum-cortex assembloids

Ventral midbrain dopaminergic neurons project to the striatum as well as the cortex and are involved in movement control and reward-related cognition. In Parkinson's disease, nigrostriatal midbrain dopaminergic neurons degenerate and cause typical Parkinson's disease motor-related impairments, while the dysfunction of mesocorticolimbic midbrain dopaminergic neurons is implicated in addiction and neuropsychiatric disorders. Study of the development and selective neurodegeneration of the human dopaminergic system, however, has been limited due to the lack of an appropriate model and access to human material. Here, we have developed a human in vitro model that recapitulates key aspects of dopaminergic innervation of the striatum and cortex. These spatially arranged ventral midbrain-striatum-cortical organoids (MISCOs) can be used to study dopaminergic neuron maturation, innervation and function with implications for cell therapy and addiction research. We detail protocols for growing ventral midbrain, striatal and cortical organoids and describe how they fuse in a linear manner when placed in custom embedding molds. We report the formation of functional long-range dopaminergic connections to striatal and cortical tissues in MISCOs, and show that injected, ventral midbrain-patterned progenitors can mature and innervate the tissue. Using these assembloids, we examine dopaminergic circuit perturbations and show that chronic cocaine treatment causes long-lasting morphological, functional and transcriptional changes that persist upon drug withdrawal. Thus, our method opens new avenues to investigate human dopaminergic cell transplantation and circuitry reconstruction as well as the effect of drugs on the human dopaminergic system.

Sericin alleviates motor dysfunction by modulating inflammation and TrkB/BDNF signaling pathway in the rotenone-induced Parkinson's disease model

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the degeneration of nigrostriatal dopaminergic neurons and movement impairment. Based on theories, neuroinflammatory processes may be vital in the etiology of PD and other neurodegenerative diseases. Reports show that rotenone has neurotoxic, inflammatory, and motor impairment effects in PD. Sericin is a natural polymer with effective properties, such as neuroprotective and anti-inflammatory. Therefore, this study aimed to examine the effects of sericin administration on motor dysfunction by modulating inflammation and tyrosine kinase B/brain-derived neurotrophic factor (TrkB/BDNF) pathway in the rotenone-induced PD model.

METHODS

Wistar male rats (3-months-old) were treated with rotenone (2 mg/kg every 48 h for 30 days) to induce a rotenone-induced PD model. Also, sericin was administered orally at dose of 200 mg/kg every 48 h for 30 days. Rotarod and bar tests were performed for motor dysfunction. The protein levels of BDNF, c-fos, TrkB, tumor necrosis factor- α (TNF-α), interleukin-6 (IL-6) and catalase activity were evaluated in the striatum area.

RESULTS

Results showed that sericin increased latent time in the rotarod test and decreased the time staying on the pole in the bar test compared to the PD group (P < 0.001 for both tests). Moreover, sericin treatments decreased TNF-α (P < 0.001) and IL-6 (P < 0.001) concentration levels and enhanced the levels of BDNF (P < 0.001), c-fos (P < 0.001), TrkB (P < 0.001) proteins and catalase activity (P < 0.05) in the striatum area compared to the PD group.

CONCLUSION

These results support a protective benefit of sericin therapy in a rotenone-induced PD paradigm by reducing motor impairment, inflammatory response, and disruption of the TrkB/BDNF signaling pathway.

Jobelyn® improves motor dysfunctions induced by haloperidol in mice via neuroprotective mechanisms relating to modulation of cAMP response-element binding protein and mitogen-activated protein kinase

The clinical efficacy of haloperidol in the treatment of psychosis has been limited by its tendency to cause parkinsonian-like motor disturbances such as bradykinesia, muscle rigidity and postural instability. Oxidative stress-evoked neuroinflammation has been implicated as the key neuropathological mechanism by which haloperidol induces loss of dopaminergic neurons and motor dysfunctions. This study was therefore designed to evaluate the effect of Jobelyn® (JB), an antioxidant supplement, on haloperidol-induced motor dysfunctions and underlying molecular mechanisms in male Swiss mice. The animals were distributed into 5 groups (n = 8), and treated orally with distilled water (control), haloperidol (1 mg/kg) alone or in combination with each dose of JB (10, 20 and 40 mg/kg), daily for 14 days. Thereafter, changes in motor functions were evaluated on day 14. Brain biomarkers of oxidative stress, proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), cAMP response-element binding protein (CREB), mitogen-activated protein kinase (MAPK) and histomorphological changes were also investigated. Haloperidol induces postural instability, catalepsy and impaired locomotor activity, which were ameliorated by JB. Jobelyn® attenuated haloperidol-induced elevated brain levels of MDA, nitrite, proinflammatory cytokines and also boosted neuronal antioxidant profiles (GSH and catalase) of mice. It also restored the deregulated brain activities of CREB and MAPK, and reduced the histomorphological distortions as well as loss of viable neuronal cells in the striatum and prefrontal cortex of haloperidol-treated mice. These findings suggest possible benefits of JB as adjunctive remedy in mitigating parkinsonian-like adverse effects of haloperidol through modulation of CREB/MAPK activities and oxidative/inflammatory pathways.

Investigating affective neuropsychiatric symptoms in rodent models of Parkinson's disease

Affective neuropsychiatric disorders such as depression, anxiety and apathy are among the most frequent non-motor symptoms observed in people with Parkinson's disease (PD). These conditions often emerge during the prodromal phase of the disease and are generally considered to result from neurodegenerative processes in meso-corticolimbic structures, occurring in parallel to the loss of nigrostriatal dopaminergic neurons. Depression, anxiety, and apathy are often treated with conventional medications, including selective serotonin reuptake inhibitors, tricyclic antidepressants, and dopaminergic agonists. The ability of these pharmacological interventions to consistently counteract such neuropsychiatric symptoms in PD is still relatively limited and the development of reliable experimental models represents an important tool to identify more effective treatments. This chapter provides information on rodent models of PD utilized to study these affective neuropsychiatric symptoms. Neurotoxin-based and genetic models are discussed, together with the main behavioral tests utilized to identify depression- and anxiety-like behaviors, anhedonia, and apathy. The ability of various therapeutic approaches to counteract the symptoms observed in the various models is also reviewed.

Epigenetic regulation of Parkinson's disease risk variant GPNMB cg17274742 methylation by sex and exercise from Taiwan Biobank

Background

Parkinson's disease (PD) is a complex neurodegenerative disease with an elusive etiology that involves the interaction between genetic, behavioral, and environmental factors. Recently, epigenetic modifications, particularly DNA methylation, have been recognized to play an important role in the onset of PD. Glycoprotein non-metastatic melanoma protein B (GPNMB), a type I transmembrane protein crucial for immune cell activation and maturation, has emerged as a potential biomarker for the risk of PD. This research aims to investigate the influence of exercise and gender on the regulation of methylation levels of GPNMB cg17274742 in individuals.

Methods

We analyze data from 2,474 participants in the Taiwan Biobank, collected from 2008 and 2016. Methylation levels at the GPNMB cg17274742 CpG site were measured using Illumina Infinium MethylationEPIC beads. After excluding individuals with incomplete data or missing information on possible risk factors, our final analysis included 1,442 participants. We used multiple linear regression models to assess the association between sex and exercise with adjusted levels of GPNMB cg17274742 for age, BMI, smoking, drinking, coffee consumption, serum uric acid levels, and hypertension.

Results

Our results demonstrated that exercise significantly influenced the methylation levels of GPNMB cg17274742 in males (β = -0.00242; p = 0.0026), but not in females (β = -0.00002362; p = 0.9785). Furthermore, male participants who exercised showed significantly lower levels of methylation compared to the reference groups of the female and non-exercising reference groups (β = -0.00357; p = 0.0079). The effect of the interaction between gender and exercise on the methylation of GPNMB cg17274742 was statistically significant (p = 0.0078).

Conclusion

This study suggests that gender and exercise can modulate GPNMB cg17274742, with hypomethylation observed in exercise men. More research is needed to understand the underlying mechanisms and implications of these epigenetic changes in the context of risk and prevention strategies.

Morphological hallmarks of dopaminergic neurodegeneration are associated with altered neuron function in Caenorhabditis elegans

Caenorhabditis elegans (C. elegans) is an excellent model system to study neurodegenerative diseases, such as Parkinson's disease, as it enables analysis of both neuron morphology and function in live animals. Multiple structural changes in neurons, such as cephalic dendrite morphological abnormalities, have been considered hallmarks of neurodegeneration in this model, but their relevance to changes in neuron function are not entirely clear. We sought to test whether hallmark morphological changes associated with chemically induced dopaminergic neuron degeneration, such as dendrite blebbing, breakage, and loss, are indicative of neuronal malfunction and result in changes in behavior. We adapted an established dopaminergic neuronal function assay by measuring paralysis in the presence of exogenous dopamine, which revealed clear differences between cat-2 dopamine deficient mutants, wildtype worms, and dat-1 dopamine abundant mutants. Next, we integrated an automated image processing algorithm and a microfluidic device to segregate worm populations by their cephalic dendrite morphologies. We show that nematodes with dopaminergic dendrite degeneration markers, such as blebbing or breakage, paralyze at higher rates in a dopamine solution, providing evidence that dopaminergic neurodegeneration morphologies are correlated with functional neuronal outputs.

NLRP3 mediates the neuroprotective effects of SVHRSP derived from scorpion venom in rotenone-induced experimental Parkinson's disease model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, scorpion is used to treat diseases with symptoms such as trembling, convulsion and dementia. Our laboratory employs patented technology to extract and purify the active single component from scorpion venom. We then utilize mass spectrometry to determine the amino acid sequence of the polypeptide and synthesize it artificially to acquire the polypeptide with a purity of 99.3%, named SVHRSP (Scorpion Venom Heat-Resistant Peptide). SVHRSP has been demonstrated to display potent neuroprotective efficacy in Parkinson's disease.

AIM OF THE STUDY

To explore the molecular mechanisms and potential molecular targets of SVHRSP-afforded neuroprotection in PD mouse models, as well as to investigate the role of NLRP3 in SVHRSP-mediated neuroprotection.

MATERIALS AND METHODS

The PD mouse model was induced by rotenone and the neuroprotective role of SVHRSP on the PD mouse model was measured using the gait test, rotarod test, the number of dopaminergic neurons, and the activation of microglia. RNA sequencing and GSEA analysis were performed to find the differentially biological pathways regulated by SVHRSP. Primary mid-brain neuron-glial cultures and NLRP3-/- mice were applied to verify the role of NLRP3 by using qRT-PCR, western blotting, enzyme-linked immunosorbent assay (ELISA) and immunostaining.

RESULTS

SVHRSP-afforded dopaminergic neuroprotection was accompanied with inhibition of microglia-mediated neuroinflammatory pathways. Importantly, depletion of microglia markedly reduced the neuroprotective efficacy of SVHRSP against rotenone-induced dopaminergic neurotoxicity in vitro. SVHRSP inhibited microglial NOD-like receptor pathway, mRNA expression and protein level of NLRP3 in rotenone PD mice. SVHRSP also reduced rotenone-induced caspse-1 activation and IL-1β maturation, indicating that SVHRSP mitigated activation of NLRP3 inflammasome. Moreover, inactivation of NLRP3 inflammasome by MCC950 or genetic deletion of NLRP3 almost abolished SVHRSP-afforded anti-inflammatory, neuroprotective effects and improvement of motor performance in response to rotenone.

CONCLUSIONS

NLRP3 mediated the neuroprotective effects of SVHRSP in rotenone-induced experimental PD model, providing additional evidence for the mechanisms of SVHRSP-afforded anti-inflammatory and neuroprotective effects in PD.

An unbiased, automated platform for scoring dopaminergic neurodegeneration in C. elegans

Caenorhabditis elegans (C. elegans) has served as a simple model organism to study dopaminergic neurodegeneration, as it enables quantitative analysis of cellular and sub-cellular morphologies in live animals. These isogenic nematodes have a rapid life cycle and transparent body, making high-throughput imaging and evaluation of fluorescently tagged neurons possible. However, the current state-of-the-art method for quantifying dopaminergic degeneration requires researchers to manually examine images and score dendrites into groups of varying levels of neurodegeneration severity, which is time consuming, subject to bias, and limited in data sensitivity. We aim to overcome the pitfalls of manual neuron scoring by developing an automated, unbiased image processing algorithm to quantify dopaminergic neurodegeneration in C. elegans. The algorithm can be used on images acquired with different microscopy setups and only requires two inputs: a maximum projection image of the four cephalic neurons in the C. elegans head and the pixel size of the user's camera. We validate the platform by detecting and quantifying neurodegeneration in nematodes exposed to rotenone, cold shock, and 6-hydroxydopamine using 63x epifluorescence, 63x confocal, and 40x epifluorescence microscopy, respectively. Analysis of tubby mutant worms with altered fat storage showed that, contrary to our hypothesis, increased adiposity did not sensitize to stressor-induced neurodegeneration. We further verify the accuracy of the algorithm by comparing code-generated, categorical degeneration results with manually scored dendrites of the same experiments. The platform, which detects 20 different metrics of neurodegeneration, can provide comparative insight into how each exposure affects dopaminergic neurodegeneration patterns.

Protective Effect of Hirsutidin against Rotenone-Induced Parkinsonism via Inhibition of Caspase-3/Interleukins-6 and 1β

A participant of the chemical family recognized as anthocyanins, hirsutidin is an O-methylated anthocyanidin. It is a natural substance, i.e., existing in Catharanthus roseus (Madagascar periwinkle), the predominant component in petals, as well as callus cultures. The literature review indicated a lack of scientifically verified findings on hirsutidin's biological activities, particularly its anti-Parkinson's capabilities. Using the information from the previous section as a reference, a present study has been assessed to evaluate the anti-Parkinson properties of hirsutidin against rotenone-activated Parkinson's in experimental animals. For 28 days, rats received hirsutidin at a dose of 10 mg/kg and rotenone at a dose of 0.5 mg/kg s.c. to test the neuroprotective effects. The hirsutidin was given 1 h before the rotenone. Behavioral tests, including the rotarod test, catalepsy, Kondziela's inverted screen activity, and open-field analysis, were performed. The levels of neurotransmitters (5-HT, DOPAC, 5-HIAA, dopamine, and HVA), neuroinflammatory markers (TNF-α, IL-6, IL-1β, caspase-3), an endogenous antioxidant, nitrite content, and acetylcholine were measured in all the rats on the 29th day. Hirsutidin exhibited substantial behavioral improvement in the rotarod test, catalepsy, Kondziela's inverted screen activity, and open-field test. Furthermore, hirsutidin restored neuroinflammatory markers, cholinergic function, nitrite content, neurotransmitters, and endogenous antioxidant levels. According to the study, hirsutidin has anti-inflammatory and antioxidant characteristics. As a result, it implies that hirsutidin may have anti-Parkinsonian effects in rats.

Rotenone-Induced Model of Parkinson's Disease: Beyond Mitochondrial Complex I Inhibition

Parkinson's disease (PD) is usually diagnosed through motor symptoms that make the patient incapable of carrying out daily activities; however, numerous non-motor symptoms include olfactory disturbances, constipation, depression, excessive daytime sleepiness, and rapid eye movement at sleep; they begin years before motor symptoms. Therefore, several experimental models have been studied to reproduce several PD functional and neurochemical characteristics; however, no model mimics all the PD motor and non-motor symptoms to date, which becomes a limitation for PD study. It has become increasingly relevant to find ways to study the disease from its slowly progressive nature. The experimental models most frequently used to reproduce PD are based on administering toxic chemical compounds, which aim to imitate dopamine deficiency. The most used toxic compounds to model PD have been 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA), which inhibit the complex I of the electron transport chain but have some limitations. Another toxic compound that has drawn attention recently is rotenone, the classical inhibitor of mitochondrial complex I. Rotenone triggers the progressive death of dopaminergic neurons and α-synuclein inclusions formation in rats; also, rotenone induces microtubule destabilization. This review presents information about the experimental model of PD induced by rotenone, emphasizing its molecular characteristics beyond the inhibition of mitochondrial complex I.

Cilostazol novel neuroprotective mechanism against rotenone-induced Parkinson's disease in rats: Correlation between Nrf2 and HMGB1/TLR4/PI3K/Akt/mTOR signaling

Neuroinflammation induced by activation of the high mobility group box 1/ toll-like receptor 4 (HMGB1/TLR4) axis is one of the principal mechanisms involved in dopaminergic neuronal loss in Parkinson's disease (PD), and its activation exacerbates oxidative stress augmenting neurodegeneration.

AIMS

This study investigated the novel neuroprotective effect of cilostazol on rotenone-intoxicated rats focusing on the HMGB1/TLR4 axis, erythroid-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1), and phosphoinositide 3-kinase (PI3K)/Protein kinase B (Akt)/the mammalian target of rapamycin (mTOR) pathway. The aim is extended to correlate the Nrf2 expression with all assessed parameters as promising therapeutic targets for neuroprotection.

MAIN METHODS

Our experiment was designed as follows: vehicle group, cilostazol group, rotenone group (1.5 mg/kg, s.c), and the rotenone pretreated with cilostazol (50 mg/kg, p.o.) group. Eleven rotenone injections were injected day after day, while cilostazol was administered daily for 21 days.

KEY FINDINGS

Cilostazol significantly improved the neurobehavioral analysis, the histopathological examination, and dopamine levels. Moreover, the immunoreactivity of tyrosine hydroxylase (TH) in substantia nigra pars compacta (SNpc) enhanced. These effects were associated with enhancement of the antioxidant expression of Nrf2 and HO-1 by 1.01 and 1.08-fold, respectively, and repression of HMGB1/TLR4 pathway by 50.2 % and 39.3 %, respectively. Upregulation of the neuro-survival PI3K and Akt expression by 2.26 and 2.69-fold, respectively, and readjusting mTOR overexpression.

SIGNIFICANCE

Cilostazol exerts a novel neuroprotective strategy against rotenone-induced neurodegeneration via activation of Nrf2/HO-1, suppression of HMGB1/TLR4 axis, upregulation of PI3K/Akt besides mTOR inhibition that compels more investigations with different PD models to clarify its precise role.

Naphthalimide Fluorescent Skeleton for Facile and Accurate Quantification of Glutathione

Glutathione (GSH), the most prevalent nonprotein thiol in biological systems, acts as both an antioxidant to manipulate intracellular redox homeostasis and a nucleophile to detoxify xenobiotics. The fluctuation of GSH is closely related to the pathogenesis of diverse diseases. This work reports the construction of a nucleophilic aromatic substitution-type probe library based on the naphthalimide skeleton. After an initial evaluation, the compound R13 was identified as a highly efficient GSH fluorescent probe. Further studies demonstrate that R13 could readily quantify GSH in cells and tissues via a straightforward fluorometric assay with a comparable accuracy to the results from the HPLC. We then used R13 to quantify the content of GSH in mouse livers after X-ray irradiation, revealing that irradiation-induced oxidative stress leads to the increase of oxidized GSH (GSSG) and depletion of GSH. In addition, probe R13 was also applied to investigate the alteration of the GSH level in the Parkinson's mouse brains, showing a decrease of GSH and an increase of GSSG in Parkinson's mouse brains. The convenience of the probe in quantifying GSH in biological samples facilitates further understanding of the fluctuation of the GSH/GSSG ratio in diseases.

UBA52 Attunes VDAC1-Mediated Mitochondrial Dysfunction and Dopaminergic Neuronal Death

Mitochondrial homeostasis regulates energy metabolism, calcium buffering, cell function, and apoptosis. The present study has been conducted to investigate the implications of the ubiquitin-encoding gene UBA52 in mitochondrial physiology. Transient expression of Myc-UBA52 in neurons significantly inhibited the rotenone-induced increase in reactive oxygen species generation, nitrite level, and depleted glutathione level. Mass spectrometric and coimmunoprecipitation data suggested the profound interaction of UBA52 with mitochondrial outer membrane channel protein, VDAC1 in both the wild-type and Myc-α-synuclein overexpressed neuronal cells and in the Parkinson's disease (PD)-specific substantia nigra and striatal region of the rat brain. In vitro ubiquitylation assay revealed that UBA52 participates in the ubiquitylation of VDAC1 through E3 ligase CHIP. Myc-UBA52 overexpression in neurons further improved the mitochondrial functionality and cell viability by preventing the alteration in mitochondrial membrane potential, mitochondrial complex I activity, and translocation of cytochrome c and p-Nrf2 along with the effect on intracellular calcium uptake, thus collectively inhibiting the opening of mitochondrial permeability transition pore. Additionally, Myc-UBA52 expression in neuronal cells offered protection against apoptotic and autophagic cell death. Altogether, our findings delineate a functional association between UBA52 and mitochondrial homeostasis, providing new insights into the deterrence of dopaminergic cell death during acute PD pathogenesis.

Linagliptin counteracts rotenone's toxicity in non-diabetic rat model of Parkinson's disease: Insights into the neuroprotective roles of DJ-1, SIRT-1/Nrf-2 and implications of HIF1-α

While all current therapies' main focus is enhancing dopaminergic effects and remission of symptoms, delaying Parkinson's disease (PD) progression remains a challenging mission. Linagliptin, a Dipeptidyl Peptidase-4 (DPP-4) Inhibitor, exhibited neuroprotection in various neurodegenerative diseases. This study aims to evaluate the neuroprotective effects of Linagliptin in a rotenone-induced rat model of PD and investigate the possible underlying mechanisms of Linagliptin's actions. The effects of two doses of Linagliptin (5 and 10 mg/kg) on spontaneous locomotion, catalepsy, coordination and balance, and histology were assessed. Then, after Linagliptin showed promising results, it was further tested for its potential anti-inflammatory, antiapoptotic effects, and different pathways for oxidative stress. Linagliptin prevented rotenone-induced motor deficits and histological damage. Besides, it significantly inhibited the rotenone-induced increase in pro-inflammatory cytokines: Tumor Necrosis Factor-α (TNF-α) and Interleukin-6 (IL-6) and decrease in caspase 3 levels. These effects were associated with induction in the levels of Protein deglycase also known as DJ-1, Hypoxia-inducible factor 1-alpha (HIF-1α), potentiation in the Sirtuin 1 (SIRT-1)/Nuclear factor erythroid-2-related factor 2 (Nrf-2)/Heme oxygenase-1 (HO-1) pathway, and an increase in the antioxidant activity of catalase which provided neuroprotection to the neurons from rotenone-induced PD. Collectively, these results suggest that Linagliptin might be a suitable candidate for the management of PD.

Barbigerone Potentially Alleviates Rotenone-Activated Parkinson's Disease in a Rodent Model by Reducing Oxidative Stress and Neuroinflammatory Cytokines

BACKGROUND

Parkinson's disease (PD) is a common age-related and slowly progressive neurodegenerative disease that affects approximately 1% of the elderly population. In recent years, phytocomponents have aroused considerable interest in the research for PD treatment as they provide a plethora of active compounds including antioxidant and anti-inflammatory compounds. Herein, we aimed to investigate the anti-Parkinson's effect of barbigerone, a natural pyranoisoflavone possessing antioxidant activity in a rotenone-induced rat model of PD.

METHODS

To evaluate antioxidant activity, a 0.5 mg/kg dose of rotenone was injected subcutaneously into rats. Barbigerone (10 and 20 mg/kg) was administered to rats for 28 days 1 h prior to rotenone. All behavioral parameters were assessed before sacrificing the rats. On the 29th day, all of the rats were humanely killed and assessed for biochemical changes in antioxidant enzymes (superoxide dismutase, glutathione, malondialdehyde, and catalase), neurotransmitter levels (dopamine, 5-hydroxyindoleacetic acid, serotonin, dihydroxyphenylacetic acid, and homovanillic acid levels), and neuroinflammatory cytokines [interleukin (IL)-1β, tumor necrosis factor-α, nuclear factor kappa B, and IL-6].

RESULTS

The data presented in this study has shown that barbigerone attenuated rotenone-induced motor deficits including the rotarod test, catalepsy, akinesia, and open-field test. Additionally, barbigerone has shown improvements in the biochemical and neuroinflammatory parameters in the rotenone-induced rat model of PD.

CONCLUSION

The results demonstrated that barbigerone exhibits antioxidant and anti-inflammatory actions via reducing oxidative stress and inflammatory cytokines. Altogether, these findings suggest that barbigerone could potentially be utilized as a therapeutic agent against PD.

An unbiased, automated platform for scoring dopaminergic neurodegeneration in C. elegans

Caenorhabditis elegans ( C. elegans ) has served as a simple model organism to study dopaminergic neurodegeneration, as it enables quantitative analysis of cellular and sub-cellular morphologies in live animals. These isogenic nematodes have a rapid life cycle and transparent body, making high-throughput imaging and evaluation of fluorescently tagged neurons possible. However, the current state-of-the-art method for quantifying dopaminergic degeneration requires researchers to manually examine images and score dendrites into groups of varying levels of neurodegeneration severity, which is time consuming, subject to bias, and limited in data sensitivity. We aim to overcome the pitfalls of manual neuron scoring by developing an automated, unbiased image processing algorithm to quantify dopaminergic neurodegeneration in C. elegans . The algorithm can be used on images acquired with different microscopy setups and only requires two inputs: a maximum projection image of the four cephalic neurons in the C. elegans head and the pixel size of the user’s camera. We validate the platform by detecting and quantifying neurodegeneration in nematodes exposed to rotenone, cold shock, and 6-hydroxydopamine using 63x epifluorescence, 63x confocal, and 40x epifluorescence microscopy, respectively. Analysis of tubby mutant worms with altered fat storage showed that, contrary to our hypothesis, increased adiposity did not sensitize to stressor-induced neurodegeneration. We further verify the accuracy of the algorithm by comparing code-generated, categorical degeneration results with manually scored dendrites of the same experiments. The platform, which detects 19 different metrics of neurodegeneration, can provide comparative insight into how each exposure affects dopaminergic neurodegeneration patterns.

Neuroprotective effect of anethole against rotenone induced non-motor deficits and oxidative stress in rat model of Parkinson's disease

INTRODUCTION

Non-motor symptoms (NMS) have high prevalence in patients with Parkinson's disease (PD). These symptoms are mainly the result of increased oxidative stress and neuronal damage. In this study we investigated the possible neuroprotective effects of anethole as a potent antioxidant on rotenone-induced behavioral deficits, hippocampal neuronal death, and oxidative stress profile in rats.

METHODS

Male Wistar rats were administered with anethole (62.5, 125, and 250 mg/kg, i.g) concomitantly with rotenone (2 mg/kg, s.c) for 35 days. Shuttle box and novel object recognition tests were performed to determine cognitive functions, and tail flick test was used to measure pain sensitivity. The levels of BDNF, MDA, SOD, and GPx were assayed in the hippocampus. Hippocampal neuronal damage was evaluated using cresyl violet staining technique.

RESULTS

Chronic administration of rotenone induced cognitive deficit and reduced thermal pain threshold. Rotenone also decreased SOD and GPx activities, increased MDA level, and reduced the expression of BDNF in the hippocampus. In addition, hippocampal neuronal loss was increased in rotenone treated rats. Treatment with high dose of anethole (250 mg/kg) improved cognitive function and increased pain threshold in all three doses (62.5, 125, and 250 mg/kg). Despite the unchanged SOD and GPx activities, hippocampal levels of MDA was significantly decreased after high-dose anethole treatment. Moreover, High dose of anethole increased the number of surviving neurons in the hippocampus, but couldn't increase the BDNF expression.

CONCLUSION

Our findings indicated that anethole has antioxidant and neuroprotective effects against non-motor disorders induced by rotenone toxicity.

Protective effects of evening primrose oil on behavioral activities, nigral microglia and histopathological changes in a rat model of rotenone-induced parkinsonism

Parkinson's disease (PD) is a neurodegenerative illness described as damage to dopaminergic neurons. There is increasing evidence that neuroinflammatory activity mediated by microglia is extensively involved in the initiation and development of PD. This study assessed the protective effect of evening primrose oil [EPO] as an anti-inflammatory mediator in rotenone-induced Parkinsonism in rats. Forty-eight adult male albino rats were distributed into four groups. Group I: control. Group II: rotenone [1.5 mg/kg/48 h] was administered subcutaneously to the rats. Groups III and IV: the rats had rotenone plus daily oral [EPO] 5 and 10 mg/kg respectively. After 24 days, motor behaviour was assessed by the open field and rotarod tests. The brain striata were isolated and tested for tumor necrosis factor (TNF)-α, interleukin 6, NF-B [nuclear factor-kappa B], and dopamine levels. The mid-brain tissues were processed for light and electron microscopy examinations, and immunohistochemical staining for tyrosine hydroxylase [TH], and microglia cells' markers: [CD68 and IBA1]. Results revealed that rotenone-treated rats had poor motor function, a significantly increased striatal level of inflammatory markers, markedly shrunken neurons, degeneration, pyknotic neuroglia, neuropil vacuolation, markedly destructed swollen mitochondria with loss of their cristae, and dilated rough endoplasmic reticulum, as well as decreased TH and increased CD68 and IBA1-positive cells. Treatment with EPO ameliorates all the neuropathological changes of rotenone in the rat brain. In conclusion, EPO enhanced the motor performance, reduced the inflammatory marker levels, restored dopamine levels, and ameliorated the neurohistopathological lesions of rats with experimental parkinsonism, suggesting its neuroprotective and anti-inflammatory effects.

Neuroprotective Effects of Some Nutraceuticals against Manganese-Induced Parkinson's Disease in Rats: Possible Modulatory Effects on TLR4/NLRP3/NF-κB, GSK-3β, Nrf2/HO-1, and Apoptotic Pathways

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting the substantia nigra where functions controlling body movement take place. Manganese (Mn) overexposure is linked to a neurologic syndrome resembling PD. Sesamol, thymol, wheat grass (WG), and coenzyme Q10 (CoQ10) are potent antioxidants, anti-inflammatory, and anti-apoptotic nutraceuticals. We investigated the potential protective effects of these nutraceuticals alone or in combinations against MnCl₂-induced PD in rats. Seven groups of adult male Sprague Dawley rats were categorized as follows: group (I) was the control, while groups 2-7 received MnCl₂ either alone (Group II) or in conjunction with oral doses of sesamol (Group III), thymol (Group IV), CoQ10 (Group V), WG (Group VI), or their combination (Group VII). All rats were subjected to four behavioral tests (open-field, swimming, Y-maze, and catalepsy tests). Biochemical changes in brain levels of monoamines, ACHE, BDNF, GSK-3β, GABA/glutamate, as well as oxidative stress, and apoptotic and neuroinflammatory biomarkers were evaluated, together with histopathological examinations of different brain regions. Mn increased catalepsy scores, while decreasing neuromuscular co-ordination, and locomotor and exploratory activity. It also impaired vigilance, spatial memory, and decision making. Most behavioral impairments induced by Mn were improved by sesamol, thymol, WG, or CoQ10, with prominent effect by sesamol and thymol. Notably, the combination group showed more pronounced improvements, which were confirmed by biochemical, molecular, as well as histopathological findings. Sesamol or thymol showed better protection against neuronal degeneration and some behavioral impairments induced by Mn than WG or CoQ10, partly via interplay between Nrf2/HO-1, TLR4/NLRP3/NF-κB, GSK-3β and Bax/Bcl2 pathways.

Systemic Rotenone Administration Causes Extra-Nigral Alterations in C57BL/6 Mice

Systemic administration of rotenone replicates several pathogenic and behavioural features of Parkinson's disease (PD), some of which cannot be explained by deficits of the nigrostriatal pathway. In this study, we provide a comprehensive analysis of several neurochemical alterations triggered by systemic rotenone administration in the CNS of C57BL/6 mice. Mice injected with either 1, 3 or 10 mg/kg rotenone daily via intraperitoneal route for 21 days were assessed weekly for changes in locomotor and exploratory behaviour. Rotenone treatment caused significant locomotor and exploratory impairment at dosages of 3 or 10 mg/kg. Molecular analyses showed reductions of both TH and DAT expression in the midbrain, striatum and spinal cord, accompanied by altered expression of dopamine receptors and brain-derived neurotrophic factor (BDNF). Rotenone also triggered midbrain-restricted inflammatory responses with heightened expression of glial markers, which was not seen in extra-nigral regions. However, widespread alterations of mitochondrial function and increased signatures of oxidative stress were identified in both nigral and extra-nigral regions, along with disruptions of neuroprotective peptides, such as pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP) and activity-dependent neuroprotective protein (ADNP). Altogether, this study shows that systemic rotenone intoxication, similarly to PD, causes a series of neurochemical alterations that extend at multiple CNS levels, reinforcing the suitability of this pre-clinical model for the study extra-nigral defects of PD.

UBA52 Is Crucial in HSP90 Ubiquitylation and Neurodegenerative Signaling during Early Phase of Parkinson's Disease

Protein aggregation is one of the major pathological events in age-related Parkinson's disease (PD) pathology, predominantly regulated by the ubiquitin-proteasome system (UPS). UPS essentially requires core component ubiquitin; however, its role in PD pathology is obscure. This study aimed to investigate the role of ubiquitin-encoding genes in sporadic PD pathology. Both cellular and rat models of PD as well as SNCA C57BL/6J-Tg (Th-SNCA*A30P*A53T)39 Eric/J transgenic mice showed a decreased abundance of UBA52 in conjunction with significant downregulation of tyrosine hydroxylase (TH) and neuronal death. In silico predictions, mass spectrometric analysis, and co-immunoprecipitation findings suggested the protein-protein interaction of UBA52 with α-synuclein, HSP90 and E3-ubiquitin ligase CHIP, and its co-localization with α-synuclein in the mitochondrion. Next, in vitro ubiquitylation assay indicated an imperative requirement of the lysine-63 residue of UBA52 in CHIP-mediated HSP90 ubiquitylation. Myc-UBA52 expressed neurons inhibited alteration in PD-specific markers such as α-synuclein and TH protein along with increased proteasome activity in diseased conditions. Furthermore, Myc-UBA52 expression inhibited the altered protein abundance of HSP90 and its various client proteins, HSP75 (homolog of HSP90 in mitochondrion) and ER stress-related markers during early PD. Taken together, the data highlights the critical role of UBA52 in HSP90 ubiquitylation in parallel to its potential contribution to the modulation of various disease-related neurodegenerative signaling targets during the early phase of PD pathology.

PACAP and VIP Mitigate Rotenone-Induced Inflammation in BV-2 Microglial Cells

Rotenone is a commercial pesticide commonly used to model Parkinson's disease (PD) due to its ability to induce dopaminergic degeneration. Studies have confirmed that rotenone causes microglial activation, which seems to contribute to the toxic effects seen in rodent models. Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two structurally related neuropeptides that have robust neuroprotective and anti-inflammatory properties. However, their ability to regulate microglial activity in response to rotenone is not fully understood. Using rotenone as an inflammatory stimulus, we tested whether PACAP or VIP could mitigate microglial activation in BV2 microglial cells. Rotenone dose-dependently reduced cell viability and the percentage of apoptotic cells. It also increased the release of nitric oxide (NO) in culture media and the expression of microglial activation markers and pro-inflammatory markers, including CD11b, MMP-9 and IL-6, and heightened the endogenous levels of PACAP and its preferring receptor PAC1. Co-treatment with PACAP or VIP prevented rotenone-induced increase of NO, CD11b, MMP-9 and IL-6. These results indicate that both PACAP and VIP are able to prevent the pro-inflammatory effects of rotenone in BV2 cells, supporting the idea that these molecules can have therapeutic value in slowing down PD progression.

Non-Reproducibility of Oral Rotenone as a Model for Parkinson's Disease in Mice

Oral rotenone has been proposed as a model for Parkinson’s disease (PD) in mice. To establish the model in our lab and study complex behavior we followed a published treatment regimen. C57BL/6 mice received 30 mg/kg body weight of rotenone once daily via oral administration for 4 and 8 weeks. Motor functions were assessed by RotaRod running. Immunofluorescence studies were used to analyze the morphology of dopaminergic neurons, the expression of alpha-Synuclein (α-Syn), and inflammatory gliosis or infiltration in the substantia nigra. Rotenone-treated mice did not gain body weight during treatment compared with about 4 g in vehicle-treated mice, which was however the only robust manifestation of drug treatment and suggested local gut damage. Rotenone-treated mice had no deficits in motor behavior, no loss or sign of degeneration of dopaminergic neurons, no α-Syn accumulation, and only mild microgliosis, the latter likely an indirect remote effect of rotenone-evoked gut dysbiosis. Searching for explanations for the model failure, we analyzed rotenone plasma concentrations via LC-MS/MS 2 h after administration of the last dose to assess bioavailability. Rotenone was not detectable in plasma at a lower limit of quantification of 2 ng/mL (5 nM), showing that oral rotenone had insufficient bioavailability to achieve sustained systemic drug levels in mice. Hence, oral rotenone caused local gastrointestinal toxicity evident as lack of weight gain but failed to evoke behavioral or biological correlates of PD within 8 weeks.

Assessing the Neurotoxicity of a Sub-Optimal Dose of Rotenone in Zebrafish (Danio rerio) and the Possible Neuroactive Potential of Valproic Acid, Combination of Levodopa and Carbidopa, and Lactic Acid Bacteria Strains

Parkinson’s disease (PD) is an enigmatic neurodegenerative disorder that is currently the subject of extensive research approaches aiming at deepening the understanding of its etiopathophysiology. Recent data suggest that distinct compounds used either as anticonvulsants or agents usually used as dopaminergic agonists or supplements consisting of live active lactic acid bacteria strains might alleviate and improve PD-related phenotypes. This is why we aimed to elucidate how the administration of rotenone (ROT) disrupts homeostasis and the possible neuroactive potential of valproic acid (VPA), antiparkinsonian agents (levodopa and carbidopa – LEV+CARB), and a mixture of six Lactobacillus and three Bifidobacterium species (PROBIO) might re-establish the optimal internal parameters. ROT causes significant changes in the central nervous system (CNS), notably reduced neurogenesis and angiogenesis, by triggering apoptosis, reflected by the increased expression of PARKIN and PINK1 gene(s), low brain dopamine (DA) levels, and as opposed to LRRK2 and SNCA compared with healthy zebrafish. VPA, LEV/CARB, and PROBIO sustain neurogenesis and angiogenesis, manifesting a neuroprotective role in diminishing the effect of ROT in zebrafish. Interestingly, none of the tested compounds influenced oxidative stress (OS), as reflected by the level of malondialdehyde (MDA) level and superoxide dismutase (SOD) enzymatic activity revealed in non-ROT-exposed zebrafish. Overall, the selected concentrations were enough to trigger particular behavioral patterns as reflected by our parameters of interest (swimming distance (mm), velocity (mm/s), and freezing episodes (s)), but sequential testing is mandatory to decipher whether they exert an inhibitory role following ROT exposure. In this way, we further offer data into how ROT may trigger a PD-related phenotype and the possible beneficial role of VPA, LEV+CARB, and PROBIO in re-establishing homeostasis in Danio rerio.

Rosmarinic Acid Attenuates Rotenone-Induced Neurotoxicity in SH-SY5Y Parkinson’s Disease Cell Model through Abl Inhibition

Rosmarinic acid (RA) is a natural polyphenolic compound with antioxidative property. With the present study, we aimed to evaluate the neuroprotective role of RA on Parkinson’s disease using rotenone induced SH-SY5Y cell model of Parkinson’s disease, the underlying mechanism of action of RA was also investigated. Cell viability, cell morphology, apoptosis, signaling protein phosphorylation and expression, cellular reactive oxygen species (ROS) production, ATP content, and mitochondrial membrane potential were tested in SH-SY5Y cells. RA showed a neuroprotective effect in a rotenone-induced SH-SY5Y cell model of Parkinson’s disease with dose-dependent manner, it reduced cell apoptosis and restored normal cell morphology. RA not only decreased levels of α-synuclein and Tau phosphorylation but also elevated the contents of AMPK phosphorylation, Akt phosphorylation, and PGC-1α. RA restored the reduced mitochondrial membrane potential and ATP content as well as inhibited rotenone-induced ROS overproduction. Further findings demonstrated that the neuroprotective role of RA was partially due to the inhibition of Abl tyrosine kinase. RA treatment suppressed the hyperphosphorylation of Abl Y412 and CrkII Y221 induced by rotenone. Nilotinib, a specific inhibitor of Abl, elicited a similar neuroprotective effect as that of RA. The present study indicates that RA has a property of neuroprotection against rotenone, and the neuroprotective effect is partially attributed to the inhibition of Abl.

The Reassessed Impact of Nicotine against Neurotoxicity in Mesencephalic Dopaminergic Cell Cultures and Neuroblastoma N18TG2 Cells

Neuroprotective effects of nicotine are still under debate, so further studies on its effectiveness against Parkinson's disease are required. In our present study, we used primary dopaminergic cell cultures and N18TG2 neuroblastoma cells to investigate the effect of nicotine and its neuroprotective potential against rotenone toxicity. Nicotine protected dopaminergic (tyrosine hydroxylase immunoreactive) neurons against rotenone. This effect was not nAChR receptor-dependent. Moreover, the alkaloid at a concentration of 5 µM caused an increase in neurite length, and at a concentration of 500 µM, it caused an increase in neurite count in dopaminergic cells exposed to rotenone. Nicotine alone was not toxic in either cell culture model, while the highest tested concentration of nicotine (500 µM) caused growth inhibition of N18TG2 neuroblastoma cells. Nicotine alone increased the level of glutathione in both cell cultures and also in rotenone-treated neuroblastoma cells. The obtained results may be helpful to explain the potential neuroprotective action of nicotine on neural cell cultures.

Defects of Nutrient Signaling and Autophagy in Neurodegeneration

Neurons are post-mitotic cells that allocate huge amounts of energy to the synthesis of new organelles and molecules, neurotransmission and to the maintenance of redox homeostasis. In neurons, autophagy is not only crucial to ensure organelle renewal but it is also essential to balance nutritional needs through the mobilization of internal energy stores. A delicate crosstalk between the pathways that sense nutritional status of the cell and the autophagic processes to recycle organelles and macronutrients is fundamental to guarantee the proper functioning of the neuron in times of energy scarcity. This review provides a detailed overview of the pathways and processes involved in the balance of cellular energy mediated by autophagy, which when defective, precipitate the neurodegenerative cascade of Parkinson's disease, frontotemporal dementia, amyotrophic lateral sclerosis or Alzheimer's disease.

Neuroprotective effects of catechin and quercetin in experimental Parkinsonism through modulation of dopamine metabolism and expression of IL-1β, TNF-α, NF-κB, IκKB, and p53 genes in male Wistar rats

The neurobehavioral, brain redox-stabilizing and neurochemical modulatory properties of catechin and quercetin in rotenone-induced Parkinsonism, and the involvement of NF-κB-mediated inflammation, were investigated. Male Wistar rats subcutaneously administered with multiple doses of 1.5mg/kg rotenone were post-treated with 5-20mg/kg catechin or quercetin. This was followed by neurobehavioral evaluation, biochemical estimations, and assessment of neurotransmitter metabolism in the striatum. Expression of genes involved in the canonical pathway for the activation of NF-κB mediated inflammation (IL-1β, TNF-α, NF-κB, and IκKB) and the pro-apoptotic gene, p53, in the striatum was determined by RT-qPCR. Catechin and quercetin mitigated neurobehavioral deficits caused by rotenone. Both flavonoids attenuated striatal redox stress and neurochemical dysfunction, optimized disturbed dopamine metabolism, and improved depletion of neuron density caused by rotenone toxicity. While administration of catechin produced a more pronounced attenuating effect on IL-1β, TNF-α, and p53 genes, the attenuating effect of quercetin (20mg/kg) was more pronounced on NF-κB and IκKB gene expressions when compared to the group administered with rotenone only. Comparatively, quercetin demonstrated superior protection against rotenone neurotoxicity. It is concluded that catechin and quercetin have potential relevance in Parkinson's disease therapy through amelioration of redox stress, optimization of dopamine metabolism, and modulation of anti-inflammatory and anti-apoptotic pathways.

Gene therapy of yeast NDI1 on mitochondrial complex I dysfunction in rotenone-induced Parkinson’s disease models in vitro and vivo

Purpose

Parkinson's disease (PD) is the second most common neurodegenerative disease without cure or effective treatment. This study explores whether the yeast internal NADH-quinone oxidoreductase (NDI1) can functionally replace the defective mammalian mitochondrial complex I, which may provide a gene therapy strategy for treating sporadic PD caused by mitochondrial complex I dysfunction.

Method

Recombinant lentivirus expressing NDI1 was transduced into SH-SY5Y cells, or recombinant adeno-associated virus type 5 expressing NDI1 was transduced into the right substantia nigra pars compacta (SNpc) of mouse. PD cell and mouse models were established by rotenone treatment. The therapeutic effects of NDI1 on rotenone-induced PD models in vitro and vivo were assessed in neurobehavior, neuropathology, and mitochondrial functions, by using the apomorphine-induced rotation test, immunohistochemistry, immunofluorescence, western blot, complex I enzyme activity determination, oxygen consumption detection, ATP content determination and ROS measurement.

Results

NDI1 was expressed and localized in mitochondria in SH-SY5Y cells. NDI1 resisted rotenone-induced changes in cell morphology, loss of cell viability, accumulation of α-synuclein and pS129 α-synuclein, mitochondrial ROS production and mitochondria-mediated apoptosis. The basal and maximal oxygen consumption, mitochondrial coupling efficiency, basal and oligomycin-sensitive ATP and complex I activity in cell model were significantly increased in rotenone + NDI1 group compared to rotenone + vector group. NDI1 was efficiently expressed in dopaminergic neurons in the right SNpc without obvious adverse effects. The rotation number to the right side (NDI1-treated side) was significantly increased compared to that to the left side (untreated side) in mouse model. The number of viable dopaminergic neurons, the expression of tyrosine hydroxylase, total and maximal oxygen consumption, mitochondrial coupling efficiency and complex I enzyme activity in right substantia nigra, and the content of dopamine in right striatum were significantly increased in rotenone + NDI1 group compared to rotenone + vector group.

Conclusion

Yeast NDI1 can rescue the defect of oxidative phosphorylation in rotenone-induced PD cell and mouse models, and ameliorate neurobehavioral and neuropathological damages. The results may provide a basis for the yeast NDI1 gene therapy of sporadic PD caused by mitochondrial complex I dysfunction.

Modulation of histone deacetylase, the ubiquitin proteasome system, and autophagy underlies the neuroprotective effects of venlafaxine in a rotenone-induced Parkinson's disease model in rats

Parkinson's disease (PD) is a neurodegenerative disease characterized by motor and non-motor symptoms. Impairment of the ubiquitin proteasome system (UPS) and autophagy has been suggested to contribute to α-synuclein accumulation, which is identified as the pathological hallmark of PD. Recently, alteration in histone-3 acetylation has also been found to be correlated to PD. Interestingly, the histone deacetylase 6 (HDAC6) enzyme, which regulates the acetylation of histone-3, was shown to be involved in autophagy. Venlafaxine is an antidepressant that was proposed to inhibit HDAC expression in depressive rats' hippocampi. In this study, we aimed to examine the ability of venlafaxine to inhibit striatal HDAC6 and to enhance α-synuclein clearance through the activation of the UPS and autophagy, in addition to treating depression, which is the most debilitating non-motor symptom, in a rotenone model of PD. Venlafaxine administration was noted to decrease α-synuclein accumulation and preserve dopaminergic neurons along with restoration of striatal dopamine levels and motor recovery. Its administration augmented the UPS and autophagic markers (beclin-1, p62, and LC3) with consequent modulation of apoptotic indicators (Bax/Bcl-2 ratio, cytochrome c, and caspase-3). Additionally, venlafaxine inhibited HDAC6 with further enhancement of autophagy and restoration of histone-3 acetylation with subsequent increases in survival gene expressions (Bcl-2 and brain-derived neurotrophic factor). Chloroquine (autophagy inhibitor) was used to indicate the proposed pathway. Moreover, venlafaxine hampered depressive symptoms and improved hippocampal noradrenaline and serotonin levels. Collectively, venlafaxine is suggested to display neuroprotective effects with improvement of motor and non-motor PD symptoms.