Beneficial effect of antidepressants against rotenone induced Parkinsonism like symptoms in rats

Effect of Bacille-Calmette-Guerin vaccine against rotenone-induced Parkinson's disease: Role of neuroinflammation and neurotransmitters

BACKGROUND

Parkinson's disease (PD) is an extrapyramidal movement disorder associated with a hypokinetic condition generated by impairment in dopaminergic neuronal viability in the nigrostriatal region of the brain. Current medications can only provide symptomatic management; to date, no permanent cure is available. To compensate for this lacuna, researchers are gaining interest in antigen-based therapy, and Bacille-Calmette-Guerin (BCG) is one of the vaccines with a high safety margin that acts by stimulating immunoreactive T-cells in the CNS and reducing expression of pro-inflammatory cytokines including interleukin (IL)-1β and tumor necrotic factor (TNF-α) to produce neuroprotection. A previous study reported that BCG exerts a neuroprotective effect against several neurodegenerative disorders, such as Alzheimer's disease.

OBJECTIVE

The objective of this study is to explore the neuroprotective effect of the BCG vaccine against the rotenone model of PD.

METHODS

Rotenone (1.5 mg/kg, s.c) for 28 days, and BCG vaccine (2 × 107 cfu, i.p) single dose was injected to rats, and behavioral assessments were performed on the 21st and 28th day. On the 29th day, rats were sacrificed, and brains were isolated for biochemical and neurochemical estimation.

RESULTS

BCG vaccine significantly restored rotenone-induced motor deficits (open field test, narrow beam walk, and rotarod), biochemical levels (GSH, SOD, catalase, MDA, and nitrite), neurotransmitters (dopamine, 5-hydroxy tryptamine, norepinephrine, 3,4-dihydroxyphenylacetic acid, hemovanillic acid, and 5-hydroxy indoleacetic acid), and levels of inflammatory cytokines (IL-1β and TNF-α) in the striatum. It also prevents histopathological changes by reducing eosinophilic lesions in the striatum.

CONCLUSION

From the results, we conclude that BCG vaccine showed neuroprotection through antioxidant and anti-inflammatory effect. Thus, in the future, it can be used as a neuroprotective agent for other neurological disorders, including PD.

Ultrastructural Changes of Neuroendocrine Pheochromocytoma Cell Line PC-12 Exposed In Vitro to Rotenone

Rotenone is a pesticide used in research for its ability to induce changes similar, in vivo and in vitro, to those observed in Parkinson's disease (PD). This includes a selective death of dopaminergic neurons in the substantia nigra. Nonetheless, the precise mechanism through which rotenone modifies structure and function of neurons remains unclear. The PC12 cells closely resemble dopamine terminal neurons. This makes it a preferred model for studying the morphology of central dopamine neurons and predicting neurotoxicity. In this paper, we investigated the effects of 0.5 µM rotenone for 24-48 h on PC12 cell viability and ultrastructure (TEM), trying to identify primary and more evident alterations that can be related to neuronal damages similar to that seen in animal PD models. Cell viability decreased after 24 h rotenone treatment, with a further decrease after 48 h. Ultrastructural changes included vacuolar degeneration, mitochondrial mild swelling, decrease in the number of neuropeptide granules, and the loss of cell-to-cell adhesion. These findings are in agreement with previous research suggesting that rotenone, by inhibiting energy production and increasing ROS generation, is responsible for significant alterations of the ultrastructure and cell death of PC12 cells. Our data confirm the link between rotenone exposure, neuronal damage, and changes in dopamine metabolism, suggesting its role in the pathogenesis of PD.

Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction

The Ndufs4 knockout (KO) mouse is a validated and robust preclinical model of mitochondrial diseases (specifically Leigh syndrome), that displays a narrow window of relative phenotypical normality, despite its inherent mitochondrial complex I dysfunction and severe phenotype. Preclinical observations related to psychiatric comorbidities that arise in patients with mitochondrial diseases and indeed in Leigh syndrome are, however, yet to be investigated in this model. Strengthening this narrative is the fact that major depression and bipolar disorder are known to present with deficits in mitochondrial function. We therefore screened the behavioural profile of male and female Ndufs4 KO mice (relative to heterozygous; HET and wildtype; WT mice) between postnatal days 28 and 35 for locomotor, depressive- and anxiety-like alterations and linked it with selected brain biomarkers, viz. serotonin, kynurenine, and redox status in brain areas relevant to psychiatric pathologies (i.e., prefrontal cortex, hippocampus, and striatum). The Ndufs4 KO mice initially displayed depressive-like behaviour in the tail suspension test on PND31 but not on PND35 in the forced swim test. In the mirror box test, increased risk resilience was observed. Serotonin levels of KO mice, compared to HET controls, were increased on PND36, together with increased tryptophan to serotonin and kynurenine turnover. Kynurenine to kynurenic acid turnover was however decreased, while reduced versus oxidized glutathione ratio (GSH/GSSG) was increased. When considering the comorbid psychiatric traits of patients with mitochondrial disorders, this work elaborates on the neuropsychiatric profile of the Ndufs KO mouse. Secondly, despite locomotor differences, Ndufs4 KO mice present with a behavioural profile not unlike rodent models of bipolar disorder, namely variable mood states and risk-taking behaviour. The model may elucidate the bio-energetic mechanisms underlying mood disorders, especially in the presence of mitochondrial disease. Studies are however required to further validate the model's translational relevance.

Effects of fluoride on oxidative DNA damage, nitric oxide level, lipid peroxidation and cholinesterase enzyme activity in a rotenone-induced experimental Parkinson's model

OBJECTIVE

Environmental toxins are known to be one of the important factors in the development of Parkinson's disease (PD). This study was designed to investigate the possible contribution of fluoride (F) exposure to oxidative stress and neurodegeneration in rats with PD induced by rotenone (ROT).

MATERIALS AND METHODS

A total of 72 Wistar albino male rats were used in the experiment and 9 groups were formed with 8 animals in each group. ROT (2 mg/kg) was administered subcutaneously (sc) for 28 days. Different doses of sodium fluoride (NaF) (25, 50 and 100 ug/mL) were given orally (po) for 4 weeks. Malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO), oxidative DNA damage (8-OHdG) and cholinesterase (AChE/BChE) enzyme activities were evaluated in serum and brain tissue homogenates.

RESULTS

Rats treated with ROT and NaF had significant increases in serum and brain MDA, NO content, and decreases in GSH. In addition, the combination of ROT and NaF triggered oxidative DNA damage and resulted in increased AChE/BChE activity.

CONCLUSIONS

Findings suggest that NaF and ROT may interact synergistically leading to oxidative damage and neuronal cell loss. As a result, we believe that exposure to pesticides in combination with NaF is one of the environmental factors that should not be ignored in the etiology of neurological diseases such as PD in populations in areas with endemic fluorosis.

Impact of manganese accumulation on Na,K-ATPase expression and function in the cerebellum and striatum of C57Bl/6 mice

Overexposure to Mn causes a neurological disorder-manganism-with motor symptoms that overlap closely with disorders associated with haploinsufficiency in the gene encoding for α3 isoform of Na+,K+-ATPase (NKA). The present study was designed to test the hypothesis that behavioral changes in the mouse model of manganism may be associated with changes in the expression and activity of α3 NKA in the cerebellum (CB) and striatum (STR)-the key brain structures responsible for motor control in adult mice. C57Bl/6 mice were exposed to MnCl2 at 0.5 g/L (in drinking water) for up to eight weeks. After four weeks of Mn consumption, Mn levels were increased in the CB only. Behavioral tests demonstrated decreased performance of Mn-treated mice in the shuttle box test (third through sixth weeks), and the inclined grid walking test (first through sixth weeks), suggesting the development of learning impairment, decreased locomotion, and motor discoordination. The activity of NKA significantly decreased, and the expression of α1-α3 isoforms of NKA increased in the second week in the CB only. Thus, signs of learning and motor disturbances developing in this model of manganism are unlikely to be directly linked to disturbances in the expression or activity of NKA in the CB or STR. Whether these early changes may contribute to the pathogenesis of later behavioral deficits remains to be determined.

Neuroprotective Efficacy of a Nanomicellar Complex of Carnosine and Lipoic Acid in a Rat Model of Rotenone-Induced Parkinson's Disease

Oxidative stress, accompanied by mitochondrial dysfunction, is a key mechanism involved in the pathogenesis of Parkinson's disease (PD). Both carnosine and lipoic acid are potent antioxidants, the applicability of which in therapy is hindered by their limited bioavailability. This study aimed to evaluate the neuroprotective properties of a nanomicellar complex of carnosine and lipoic acid (CLA) in a rotenone-induced rat model of PD. Parkinsonism was induced via the administration of 2 mg/kg rotenone over the course of 18 days. Two doses of intraperitoneal CLA (25 mg/kg and 50 mg/kg) were administered alongside rotenone to assess its neuroprotective effect. At 25 mg/kg CLA decreased muscle rigidity and partially restored locomotor activity in animals that received rotenone. Furthermore, it caused an overall increase in brain tissue antioxidant activity, accompanied by a 19% increase in neuron density in the substantia nigra and increased dopamine levels in the striatum relative to animals that only received rotenone. Based on the acquired results, it may be concluded that CLA have neuroprotective properties and could potentially be beneficial in PD treatment when used in conjunction with the base therapy.

L-theanine attenuates LPS-induced motor deficit in experimental rat model of Parkinson's disease: emphasis on mitochondrial activity, neuroinflammation, and neurotransmitters

RATIONALE

Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons. The pathogenesis of PD includes oxidative stress, mitochondrial dysfunction, neuroinflammation, and neurotransmitter dysregulation. L-theanine is found in green tea and has antioxidant, anti-inflammatory, and neuroprotective effects with a high blood brain barrier permeability.

OBJECTIVE

The objective of this study was to investigate the possible neuroprotective effect of L-theanine in lipopolysaccharide (LPS) induced motor deficits and striatal neurotoxicity in a rat model of PD.

METHODS

LPS was infused at a dose of 5 μg/5 μl PBS stereotaxically into SNpc of rats. Treatment with L-theanine (50 and 100 mg/kg; po) and Sinemet (36 mg/kg; po) was given from day 7 to 21 in of LPS injected rat. On a weekly basis all behavioral parameters were assessed, and animals were sacrificed on day 22. The striatum tissue of brain was isolated for biochemicals (Nitrite, GSH, catalase, SOD, mitochondrial complexes I and IV), neuroinflammatory markers, and neurotransmitters (serotonin, dopamine, norepinephrine, GABA, and glutamate) estimations.

RESULTS

Results revealed that L-theanine dose-dependently and significantly reversed motor deficits, assessed through locomotor and rotarod activity. Moreover, L-theanine attenuated biochemical markers, reduced oxidative stress, and neurotransmitters dysbalance in the brain. L-theanine treatment at 100 mg/kg; po substantially reduced these pathogenic events by increasing mitochondrial activity, restoring neurotransmitter levels, and inhibiting neuroinflammation.

CONCLUSIONS

These data suggest that the positive effects of L-theanine on motor coordination may be mediated by the suppression of NF-κB induced by LPS. Therefore, L-theanine would have a new therapeutic potential for PD.

Synergistic effects of lipopolysaccharide and rotenone on dopamine neuronal damage in rats

INTRODUCTION

The etiology of Parkinson's disease (PD) is still unknown. Until now, oxidative stress and neuroinflammation play a crucial role in the pathogenesis of PD. However, the specific synergistic role of oxidative stress and neuroinflammation in the occurrence and development of PD remains unclear.

METHODS

The changes in motor behavior, dopamine (DA) neurons quantification and their mitochondrial respiratory chain, glial cells activation and secreted cytokines, Nrf2 signaling pathway, and redox balance in the brain of rats were evaluated.

RESULTS

Lipopolysaccharide (LPS)-induced neuroinflammation and rotenone (ROT)-induced oxidative stress synergistically aggravated motor dysfunction, DA neuron damage, activation of glial cells, and release of related mediators, activation of Nrf2 signaling and destruction of oxidative balance. In addition, further studies indicated that after ROT-induced oxidative stress caused direct damage to DA neurons, LPS-induced inflammatory effects had stronger promoting neurotoxic effects on the above aspects.

CONCLUSIONS

Neuroinflammation and oxidative stress synergistically aggravated DA neuronal loss. Furtherly, oxidative stress followed by neuroinflammation caused more DA neuronal loss than neuroinflammation followed by oxidative stress.

Pharmacological approach using doxycycline and tocopherol in rotenone induced oxidative stress, neuroinflammation and Parkinson's like symptoms

BACKGROUND

Parkinson's disease (PD) is a second most common neurodegenerative disorder characterized by the selective and progressive degeneration of dopaminergic neurons in substantia nigra pars compacta. Rotenone is a neurotoxin which selectively degenerate dopaminergic neurons in striatum, leading to cause PD like symptoms.

METHOD

Rotenone was administered at a dose of 1.5 mg/kg, i.p. from day 1 to day 40. Treatment with doxycycline (50 and 100 mg/kg, p.o), tocopherol (5 mg and 10 mg/kg, p.o) alone, doxycycline (50 mg/kg, p.o) in combination with tocopherol (10 mg/kg, p.o), and ropinirole (0.5 mg/kg, i.p.) was given for 40 days 1 h prior to administration of rotenone. All behavioral parameters were analyzed on weekly basis. On day 41, animals were sacrificed and the striatum region was isolated for neurotransmitters estimation (dopamine, serotonin, norepinephrine, GABA and glutamate), biochemical analysis (GSH, nitrite, LPO, mitochondrial complexes I and IV), inflammatory markers estimation (IL-6, IL-1β and TNF-α) and activity of MAO-A, MAO-B.

RESULT

Doxycycline and tocopherol in combination significantly attenuated behavioral, neurotransmitters and biochemical alterations induced by rotenone in experimental rats as compared to alone treatment with DOX and TOCO. Similarly, DOX and TOCO combination significantly reduced the level of inflammatory markers, prevented the biochemical changes, decreased MAO-A and MAO-B and improved complex-I, complex-IV, cAMP levels significantly.

CONCLUSION

The current study revealed that a combination of doxycycline with tocopherol contributed to the prevention of PD like symptoms in rats by antioxidant, anti-inflammatory, MAO inhibitory and neuromodulatory mechanisms.

Europinidin Inhibits Rotenone-Activated Parkinson's Disease in Rodents by Decreasing Lipid Peroxidation and Inflammatory Cytokines Pathways

Background: Europinidin is a derivative of delphinidin obtained from the plants Plumbago Europea and Ceratostigma plumbaginoides. This herb has wide medicinal applications in treating various diseases but there are very few studies available on this bioactive compound. Considering this background, the present study is designed for the evaluation of Europinidin against Parkinson’s disease. Aim: The investigation aims to assess the effect of Europinidin in the rotenone-activated Parkinson’s paradigm. Methods: To evaluate neuroprotective activity, rotenone (1.5 mg/kg s.c) and europinidin (10 mg/kg and 20 mg/kg) was administered in rats for 21 days. The behavioural parameters were performed before sacrificing the rats. On the 22nd day, all the rats were assessed for biochemical markers (SOD, GSH, MDA, Catalase), neurotransmitter levels (Dopamine, 5-HIAA, DOPAC, and HVA levels), and neuroinflammatory markers (IL-6, IL-1β and TNF-α). Results: It was found that rotenone produced significant (p < 0.001) oxidative damage, a cholinergic deficit, dopaminergic loss, and a rise in neuroinflammatory markers in rats. Conclusion: The study concludes that europinidin possesses anti-oxidant and anti-inflammatory properties. The results suggest the therapeutic role of europinidin against rotenone-activated behavioural, biochemical, and neuroinflammatory alterations in rats.

GJA1/CX43 High Expression Levels in the Cervical Spinal Cord of ALS Patients Correlate to Microglia-Mediated Neuroinflammatory Profile

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motoneurons (MNs) with a fatal outcome. The typical degeneration of cortico-spinal, spinal, and bulbar MNs, observed in post-mortem biopsies, is associated with the activation of neuroimmune cells. GJA1, a member of the connexins (Cxs) gene family, encodes for connexin 43 (Cx43), a core gap junctions (GJs)- and hemichannels (HCs)-forming protein, involved in cell death, proliferation, and differentiation. Recently, Cx43 expression was found to play a role in ALS pathogenesis. Here, we used microarray and RNA-seq datasets from the NCBI of the spinal cord of control (NDC) and ALS patients, which were stratified according to the GJA1 gene expression. Genes that positively or negatively correlated to GJA1 expression were used to perform a genomic deconvolution analysis (GDA) using neuroimmune signatures. Expression analysis revealed a significantly higher GJA1 expression in the MNs of ALS patients as compared to NDC. Gene deconvolution analysis revealed that positively correlated genes were associated with microglia activation, whereas negatively correlated genes were associated with neuronal activation profiles. Moreover, gene ontology analysis, performed on genes characterizing either microglia or neuronal signature, indicated immune activation or neurogenesis as main biological processes. Finally, using a synthetic analysis of drugs able to revert the GJA1 transcriptomic signatures, we found a specific drug profile for ALS patients with high GJA1 expression levels, composed of amlodipine, sertraline, and prednisolone. In conclusion, our exploratory study suggests GJA1 as a new neuro-immunological gene correlated to microglial cellular profile in the spinal cord of ALS patients. Further studies are warranted to confirm these results and to evaluate the therapeutic potential of drugs able to revert typical GJA1/CX43 signature in ALS patients

Update to the Treatment of Parkinson's Disease Based on the Gut-Brain Axis Mechanism

Gastrointestinal (GI) symptoms represented by constipation were significant non-motor symptoms of Parkinson’s disease (PD) and were considered early manifestations and aggravating factors of the disease. This paper reviewed the research progress of the mechanism of the gut-brain axis (GBA) in PD and discussed the roles of α-synuclein, gut microbiota, immune inflammation, neuroendocrine, mitochondrial autophagy, and environmental toxins in the mechanism of the GBA in PD. Treatment of PD based on the GBA theory has also been discussed, including (1) dietary therapy, such as probiotics, vitamin therapy, Mediterranean diet, and low-calorie diet, (2) exercise therapy, (3) drug therapy, including antibiotics; GI peptides; GI motility agents, and (4) fecal flora transplantation can improve the flora. (5) Vagotomy and appendectomy were associated but not recommended.

Ginkgo biloba protects striatal neurodegeneration and gut phagoinflammatory damage in rotenone-induced mice model of Parkinson's disease: Role of executioner caspase-3/Nrf2/ARE signaling

Asymptomatic and early clinical stages of Parkinson's disease (PD) have been linked with comorbid non-motor symptoms including dysfunction of the gastrointestinal (GI) tract. Notwithstanding, neuroprotective and gastroprotective effects of Ginkgo biloba supplements (GBS) have been investigated independently. Hence, whether GBS-mediated GIT-protective capacity could be helpful in PD via gut-brain anti-inflammatory signaling still remains unknown. Treatment with GBS significantly repressed the motor behavioral and neuromuscular deficits and prevented loss of striatal dopaminergic loss by improving the level of tyrosine hydroxylase enzyme and suppressing synucleinopathy development. Striatal neurons and ileal epithelial injury following intraperitoneal rotenone administration were accompanied with oxidoinflammatory/nitroinflammatory stress and marked inhibition of cholinergic transmission. Moreover, there was increased striatal executioner caspase-3 and decreased nuclear factor erythroid-2-related factor 2 (Nrf2) immunoexpression, loss of striatal pyramidal neuron with a marked decrease in length and width of the dendritic spines as well as significant hyperplasia of cryptal cells in the ileal epithelial tissues, all which were reversed by the pretreatment + concurrent (Pre-CONC) and concurrent (CONC) GBS treatment pattern. In sum, we proved the potential dual effects of GBS in preventing both dopaminergic neural-related impairments and gut wall abnormalities linked with PD.

Parkinsonism Attenuation by Antihistamines via Downregulating the Oxidative Stress, Histamine, and Inflammation

Parkinson disease (PD) is a neurodegenerative disorder of the motor activity of the brain, regulated by dopaminergic neurons of substantia nigra, resulting in an increased density of histaminergic fibers. This study was aimed to evaluate the effects of H1 antagonist's ebastine and levocetirizine in PD per se and in combination. Animals were divided into 9 groups (n = 10). Group 1 received carboxymethyl cellulose CMC (1 mL/kg). Group II was treated with haloperidol (1 mg/kg) (diseased group). Group III was treated with levodopa/carbidopa (levo 20 mg/kg). Groups IV and V were treated with ebastine at dose levels of 2 and 4 mg/kg, respectively. Groups VI and VII were treated with levocetirizine at dose levels of 0.5 and 1 mg/kg, respectively. Group VIII was treated with ebastine (4 mg/kg) + levo (20 mg/kg) in combination. Group IX was treated with levocetirizine (1 mg/kg) + levo (20 mg/kg). PD was induced with haloperidol (1 mg/kg iv, once daily for 23 days) for a duration of 30 min. Behavioral tests like rotarod, block and triple horizontal bars, actophotometer, and open field were performed. Biochemical markers of oxidative stress, i.e., SOD, CAT, GSH, MDA, dopamine, serotonin, and nor-adrenaline and nitrite, were determined. Histamine, mRNA expression of α-synuclein, and TNF-α level in the serum and brain of mice were analyzed. Endogenous biochemical markers were increased except mRNA expression of α-synuclein, which was reduced. In combination therapy with the standard drug, ebastine (4 mg/kg) significantly improved the cataleptic state and dopamine levels, but no significant difference in the renal and liver functioning tests was observed. This study concluded that ebastine (4 mg/kg) might work in the treatment of PD as it improves the cataleptic state in haloperidol-induced catalepsy.

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.

Vortioxetine ameliorates motor and cognitive impairments in the rotenone-induced Parkinson's disease via targeting TLR-2 mediated neuroinflammation

Parkinson's disease (PD) is characterized by motor and non-motor symptoms associated with dopaminergic and non-dopaminergic injury. Vortioxetine is a multimodal serotonergic antidepressant with potential procognitive effects. This study aimed to explore the effects of vortioxetine on motor functions, spatial learning and memory, and depression-like behavior in the rotenone-induced rat model of PD. Male Sprague-Dawley rats were daily administered with the rotenone (2 mg·kg^-1, s.c.) and/or vortioxetine (10 mg·kg^-1, s.c.) for 28 days. Motor functions (rotarod, catalepsy, open-field), depression-like behaviors (sucrose preference test), anxiety (elevated plus maze), and spatial learning and memory abilities (novel object recognition and Morris water maze) were evaluated in behavioral tests. Then immunohistochemical, neurochemical, and biochemical analysis on specific brain areas were performed. Vortioxetine treatment markedly reduced rotenone-induced neurodegeneration, improved motor and cognitive dysfunction, decreased depression-like behaviors without affecting anxiety-like parameters. Vortioxetine also restored the impaired inflammatory response and affected neurotransmitter levels in brain tissues. Interestingly, vortioxetine was thought to trigger a sort of dysfunction in basal ganglia as evidenced by increased Toll-like receptor-2 (TLR-2) and decreased TH immunoreactivity only in substantia nigra tissue of PD rats compared to the control group. The present study indicates that vortioxetine has beneficial effects on motor dysfunction as well as cognitive impairment associated with neurodegeneration in the rotenone-induced PD model. Possible mechanisms underlying these beneficial effects cover TLR-2 inhibition and neurochemical restoration of vortioxetine.

Testing efficacy of the nicotine protection of the substantia nigra pars compacta in a rat Parkinson disease model. Ultrastructure study

Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) with subsequent motor manifestations. This study aimed to assess the ameliorative effects of nicotine, in rotenone-induced PD rat model. Thirty adult male Albino Wistar rats were divided into three equal groups. Group I received an injection of normal saline. Group II received subcutaneous injection of rotenone at a dose of 1.5 mg/kg every other day. Group III received rotenone in the same previous dose and nicotine at a dose of 1.5 mg/kg daily. After 11 days of treatment, body weight (BW) and rat motor behavior were estimated. Specimens from the midbrain were processed for light and electron microscopy. The expression of tyrosine hydroxylase (TH), α-synuclein, and GFAP was examined. Serum levels of total antioxidant capacity (TAC) and malondialdehyde (MDA), and striatal levels of dopamine (DA) were analyzed. Group III revealed a significant improvement in BW and motor activity. Nicotine upregulated the expression of TH, downregulated the expression of α-synuclein and GFAP. The levels of MDA and TAC were improved but were still far from those of the control. Striatal DA levels increased. Nicotine activated the neurons and glial cells. The vascular endothelium, however, did not elicit improvement. Although nicotine ameliorated the loss of the dopaminergic neurons and motor deficit, it did not show improvement of vascular endothelium. It is still necessary to examine nicotin's ability to maintain the dopaminergic neurons in a good functioning state.

Mitochondria-affecting small molecules ameliorate proteostasis defects associated with neurodegenerative diseases

Macroautophagic recycling of dysfunctional mitochondria, known as mitophagy, is essential for mitochondrial homeostasis and cell viability. Accumulation of defective mitochondria and impaired mitophagy have been widely implicated in many neurodegenerative diseases, and loss-of-function mutations of PINK1 and Parkin, two key regulators of mitophagy, are amongst the most common causes of heritable parkinsonism. This has led to the hypothesis that pharmacological stimulation of mitophagy may be a feasible approach to combat neurodegeneration. Toward this end, we screened ~ 45,000 small molecules using a high-throughput, whole-organism, phenotypic screen that monitored accumulation of PINK-1 protein, a key event in mitophagic activation, in a Caenorhabditis elegans strain carrying a Ppink-1::PINK-1::GFP reporter. We obtained eight hits that increased mitochondrial fragmentation and autophagosome formation. Several of the compounds also reduced ATP production, oxygen consumption, mitochondrial mass, and/or mitochondrial membrane potential. Importantly, we found that treatment with two compounds, which we named PS83 and PS106 (more commonly known as sertraline) reduced neurodegenerative disease phenotypes, including delaying paralysis in a C. elegans β-amyloid aggregation model in a PINK-1-dependent manner. This report presents a promising step toward the identification of compounds that will stimulate mitochondrial turnover.

The Beneficial Effect of Rice Bran Extract Against Rotenone-Induced Experimental Parkinson's Disease in Rats

BACKGROUND

Neurodegenerative diseases have become an increasing cause of various disabilities worldwide, followed by aging, including Parkinson's disease (PD). Parkinson's disease is a degenerative brain disorder distinguished by growing motor & non-motor failure due to the degeneration of medium-sized spiked neurons in the striatum region. Rotenone is often employed to originate the animal model of PD. It is a powerful blocker of mitochondrial complex-I, mitochondrial electron transport chain that reliably produces Parkinsonism-like symptoms in rats. Rice bran (RB) is very rich in polyunsaturated fatty acids (PUFA) and nutritionally beneficial compounds, such as γ-oryzanol, tocopherols, and tocotrienols and sterols are believed to have favorable outcomes on oxidative stress & mitochondrial function.

OBJECTIVE

The present study has been designed to explore RB extract's effect against rotenone-induced neurotoxicity in rats.

METHODS

In the present study, Rotenone (2 mg/kg, s.c) was administered systemically for 28 days. The hexane extract of RB was prepared using Soxhlation. Hexane extract (250 & 500 mg/kg) was administered per oral for 28 days in rotenone-treated groups. Behavioral parameters (grip strength, motor coordination, locomotion, and catalepsy) were conducted on the 7th, 14th, 21st, and 28th day. Animals were sacrificed on the 29th day for biochemical estimation in the striatum and cortex.

RESULTS

This study demonstrates significant alteration in behavioral parameters, oxidative burden (increased lipid peroxidation, nitrite concentration, and decreased glutathione, catalase, SOD) in rotenone-treated animals. Administration of hexane extract of RB prevented the behavioral, biochemical alterations induced by rotenone. The current research has been sketched to inspect RB extract's effect against rotenone-developed neurotoxicity in rats.

CONCLUSION

The findings support that PD is associated with impairments in motor activity. The results also suggest that the nutraceutical rice bran that contains γ-oryzanol, Vitamin-E, ferulic acid etc., may underlie the adjuvant susceptibility towards rotenone-induced PD in experimental rats.

l-Theanine ameliorates motor deficit, mitochondrial dysfunction, and neurodegeneration against chronic tramadol induced rats model of Parkinson's disease

Parkinson's disease (PD) is the second most prevalent progressive neurodegenerative disease, characterized by loss of dopaminergic neurons in substantia nigra, with deficiency of dopamine in the striatum. Tramadol is safe analgesic but long-term use confirmed to elevate oxidative stress, neuroinflammation, mitochondrial dysfunction, in brain leads to motor deficits. l-Theanine is an active constituent of green tea which prevents neuronal loss, mitochondrial failure and improves dopamine, gamma-aminobutyric acid (GABA), serotonin levels and in the central nervous system (CNS) via antioxidant, anti-inflammatory, and neuromodulatory properties. In the present study, tramadol was injected intraperitoneally to Wister rats for 28 days at a dose of 50 mg/kg. l-Theanine (25, 50, and 100 mg/kg) was administered orally 3 h before tramadol administration from day 14 to day 28. Behavioral analyses including rotarod, narrow beam walk, open field, and grip strength were used to evaluate motor coordination on a weekly basis. On the day 29, all Wistar rats were sacrificed and striatum homogenates were used for biochemical (lipid peroxidation, nitrite, glutathione, glutathione peroxidase activity, superoxide dismutase, catalase, mitochondrial complex I, IV, and cyclic adenosine monophosphate), neuroinflammatory markers (tumor necrosis factor-α, interleukin-1β, and interleukin-17), and neurotransmitters (dopamine, norepinephrine, serotonin, GABA, and glutamate) analysis. Chronic tramadol treatment caused motor deficits reduced antioxidant enzymes level, increased striatal proinflammatory cytokines release, dysbalanced neurotransmitters, and reduced mitochondrial complex activity I, IV, and cAMP activity. However, l-theanine administration attenuated behavioral, biochemical, neuroinflammatory, neurotransmitters, and mitochondrial activity indicated it as a promising neuroprotective potential against degenerative changes in experimental model of PD.

The dynamics of nigrostriatal system damage and neurobehavioral changes in the rotenone rat model of Parkinson's disease

Subcutaneous administration of rotenone to rats is currently a widely used method of reproducing Parkinson's disease (PD) symptoms, due to its convenience and effectiveness. Despite this, its influence on the temporal dynamics of parkinsonism development has yet to be investigated. The present study characterizes behavioral and neurochemical disruptancies underlying the dynamics of parkinsonism development in rats, induced by chronic subcutaneous administration of 2 mg/kg rotenone over the course of 18 days. In this article, the presence of two stages of pathology development in the model in question - the premotor and motor disability stages - are illustrated through a complex assessment of animal behavior, the development of an original neurological symptoms scale, and the establishment of the dynamics of histological and neurochemical changes in the brain. The premotor stage was observed up to 3 days of rotenone administration, and was characterized by a decrease in the motivational component of behavior, shown both in the food-getting task and in the "sucrose preference" test. A 30 % decrease in the number of cells in the substantia nigra pars compacta by the 3rd day of rotenone administration was also shown during the premotor stage. No changes in the metabolism of dopamine and other monoamine mediators were observed at this time. At the same time, acute administration of rotenone caused an increase in the GSH / GSSG ratio by 69 %. The motor stage developed after a decrease in the number of cells in the SNpc by more than 30 %, and was characterized by changes in the dopaminergic system, leading up to a 71 % reduction in dopamine levels in the striatum. It was shown that starting from 4 to 6 days of rotenone injection, experimental group animals begin to develop motor symptoms of Parkinson's disease, including bradykinesia, rigidity and postural instability. The development of motor impairment in all rats of this group was accompanied by significantly reduced activity of the antioxidant system in brain frontal lobe tissue homogenates, as compared to intact rats. Thus, in the used model of rotenone-induced parkinsonism, the dynamics of neuropathology development are described and the premotor stage of the disease is highlighted, which allows future using of this model in developing new approaches for treatment of parkinsonism at an early stage.

Microglial Activation Mediates Noradrenergic Locus Coeruleus Neurodegeneration via Complement Receptor 3 in a Rotenone-Induced Parkinson's Disease Mouse Model

Background

Chronic exposure to the insecticide rotenone can damage dopaminergic neurons and lead to an increased risk of Parkinson’s disease (PD). Whereas it is not clear whether rotenone induces neurodegeneration of noradrenergic locus coeruleus (LC/NE) neurons. Chronic neuroinflammation mediated by microglia has been involved in the pathogenesis of PD. Evidence shows that complement receptor 3 (CR3) is a crucial regulator of microglial activation and related neurodegeneration. However, it is not clear whether CR3 mediates rotenone-elicited degeneration of LC/NE neurons through microglia-mediated neuroinflammation.

Materials and Methods

Wild type (WT) and CR3 knockout (KO) mice were treated with rotenone. PLX3397 and minocycline were used to deplete or inactivate the microglia. Leukadherin-1 (LA-1) was used to modulate CR3. LC/NE neurodegeneration, microglial phenotype, and expression of CR3 were determined by using immunohistochemistry, Western blot and real-time polymerase chain reaction (PCR) techniques. The glutathione (GSH) and malondialdehyde (MDA) contents were measured by using commercial kits.

Results

Rotenone exposure led to dose- and time-dependent LC/NE neuronal loss and microglial activation in mice. Depletion of microglia by PLX3397 or inhibition of microglial activation by minocycline significantly reduced rotenone-induced LC/NE neurodegeneration. Mechanistic studies revealed that CR3 played an essential role in the rotenone-induced activation of microglia and neurodegeneration of LC/NE neurons. Rotenone elevated the expression of CR3, and genetic ablation of CR3 markedly reduced rotenone-induced microglial activation and M1 polarization. LA-1 also suppressed rotenone-induced toxic microglial M1 activation. Furthermore, lack of CR3 or treatment with LA-1 reduced oxidative stress in the brainstem of rotenone-intoxicated mice. Finally, we found that mice deficient in CR3 or treated with LA-1 were more resistant to rotenone-induced LC/NE neurodegeneration than WT or vehicle-treated mice, respectively.

Conclusion

Our results indicate that CR3-mediated microglial activation participates in rotenone-induced LC/NE neurodegeneration, providing novel insight into environmental toxin-induced neurotoxicity and related Parkinsonism.

Pharmacological validation of TDO as a target for Parkinson's disease

Parkinson’s disease patients suffer from both motor and nonmotor impairments. There is currently no cure for Parkinson’s disease, and the most commonly used treatment, levodopa, only functions as a temporary relief of motor symptoms. Inhibition of the expression of the L‐tryptophan‐catabolizing enzyme tryptophan 2,3‐dioxygenase (TDO) has been shown to inhibit aging‐related α‐synuclein toxicity in Caenorhabditis elegans. To evaluate TDO inhibition as a potential therapeutic strategy for Parkinson’s disease, a brain‐penetrable, small molecule TDO inhibitor was developed, referred to as NTRC 3531‐0. This compound potently inhibits human and mouse TDO in biochemical and cell‐based assays and is selective over IDO1, an evolutionary unrelated enzyme that catalyzes the same reaction. In mice, NTRC 3531‐0 increased plasma and brain L‐tryptophan levels after oral administration, demonstrating inhibition of TDO activity in vivo. The effect on Parkinson’s disease symptoms was evaluated in a rotenone‐induced Parkinson’s disease mouse model. A structurally dissimilar TDO inhibitor, LM10, was evaluated in parallel. Both inhibitors had beneficial effects on rotenone‐induced motor and cognitive dysfunction as well as rotenone‐induced dopaminergic cell loss and neuroinflammation in the substantia nigra. Moreover, both inhibitors improved intestinal transit and enhanced colon length, which indicates a reduction of the rotenone‐induced intestinal dysfunction. Consistent with this, mice treated with TDO inhibitor showed decreased expression of rotenone‐induced glial fibrillary acidic protein, which is a marker of enteric glial cells, and decreased α‐synuclein accumulation in the enteric plexus. Our data support TDO inhibition as a potential therapeutic strategy to decrease motor, cognitive, and gastrointestinal symptoms in Parkinson’s disease.

Intranasal Administration of Rotenone Reduces GABAergic Inhibition in the Mouse Insular Cortex Leading to Impairment of LTD and Conditioned Taste Aversion Memory

The pesticide rotenone inhibits mitochondrial complex I and is thought to cause neurological disorders such as Parkinson’s disease and cognitive disorders. However, little is known about the effects of rotenone on conditioned taste aversion memory. In the present study, we investigated whether intranasal administration of rotenone affects conditioned taste aversion memory in mice. We also examined how the intranasal administration of rotenone modulates synaptic transmission and plasticity in layer V pyramidal neurons of the mouse insular cortex that is critical for conditioned taste aversion memory. We found that the intranasal administration of rotenone impaired conditioned taste aversion memory to bitter taste. Regarding its cellular mechanisms, long-term depression (LTD) but not long-term potentiation (LTP) was impaired in rotenone-treated mice. Furthermore, spontaneous inhibitory synaptic currents and tonic GABA currents were decreased in layer V pyramidal neurons of rotenone-treated mice compared to the control mice. The impaired LTD observed in pyramidal neurons of rotenone-treated mice was restored by a GABA_A receptor agonist muscimol. These results suggest that intranasal administration of rotenone decreases GABAergic synaptic transmission in layer V pyramidal neurons of the mouse insular cortex, the result of which leads to impairment of LTD and conditioned taste aversion memory.

Neuron-Astrocyte Interactions in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease. PD patients exhibit motor symptoms such as akinesia/bradykinesia, tremor, rigidity, and postural instability due to a loss of nigrostriatal dopaminergic neurons. Although the pathogenesis in sporadic PD remains unknown, there is a consensus on the involvement of non-neuronal cells in the progression of PD pathology. Astrocytes are the most numerous glial cells in the central nervous system. Normally, astrocytes protect neurons by releasing neurotrophic factors, producing antioxidants, and disposing of neuronal waste products. However, in pathological situations, astrocytes are known to produce inflammatory cytokines. In addition, various studies have reported that astrocyte dysfunction also leads to neurodegeneration in PD. In this article, we summarize the interaction of astrocytes and dopaminergic neurons, review the pathogenic role of astrocytes in PD, and discuss therapeutic strategies for the prevention of dopaminergic neurodegeneration. This review highlights neuron-astrocyte interaction as a target for the development of disease-modifying drugs for PD in the future.

Cerebral and cerebellar histological changes in the rat animal model of rotenone induced parkinsonism can be ameliorated by bone marrow derived stem cell conditioned media

Parkinson disease is the second most common neurodegenerative disease affecting elderly patients. It occurs due to the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). We continue our work in this model focusing on other brain areas affected with this disorder; cerebral cortex and cerebellum (areas other than substantia nigra) for better understanding the motor and behavior effect of the Parkinson disease as a forward steep for its treatment and medical control. This work aims to evaluate the therapeutic effect of stem cell-conditioned medium in the Parkinsonism model. In this study, Parkinsonism model was induced in rats by daily subcutaneous injection of 0.5 mg/Kg of rotenone for 28 days. Thirty rats were divided randomly into 3 groups; control, Parkinson, and conditioned medium (CM) treated groups. Cerebral Cortex and Cerebellum were obtained for histological, immunohistochemical and biochemical studies. In the Parkinsonism group, marked histological changes were observed. These findings were nearly ameliorated in CM treated group as confirmed by the biochemical, histological, and immunohistochemical (anti-alpha synculein, anti GFAP and anti nestin) studies. It could be concluded that CM had a good therapeutic effect on Parkinsonism induced damage in both the cerebral cortex and cerebellum.

Cordycepin Exerts Neuroprotective Effects via an Anti-Apoptotic Mechanism based on the Mitochondrial Pathway in a Rotenone-Induced Parkinsonism Rat Model

BACKGROUND

Cordycepin (Cor), one of the major bioactive components of the traditional Chinese medicine Cordyceps militaris, has been used in clinical practice for several years. However, its neuroprotective effect remains unknown.

AIMS

The purpose of the study was to evaluate the neuroprotective effects of Cor using a rotenoneinduced Parkinson's Disease (PD) rat model and to delineate the possible associated molecular mechanisms.

METHODS

In vivo, behavioural tests were performed based on the 10-point scale and grid tests. Levels of dopamine and its metabolites in the striatum and the numbers of TH-positive neurons in the Substantia Nigra pars compacta (SNpc) were investigated by high-performance liquid chromatography with electrochemical detection and immunohistochemical staining, respectively. In vitro, cell apoptosis rates and Mitochondrial Membrane Potential (MMP) were analysed by flow cytometry and the mRNA and protein levels of Bax, Bcl-2, Bcl-xL, Cytochrome c (Cyt-c), and caspase-3 were determined by quantitative real-time PCR and western blotting.

RESULTS

Showed that Cor significantly improved dyskinesia, increased the numbers of TH-positive neurons in the SNpc, and maintained levels of dopamine and its metabolites in the striatum in rotenone- induced PD rats. We also found that apoptosis was suppressed and the loss of MMP was reversed with Cor treatment. Furthermore, Cor markedly down-regulated the expression of Bax, upregulated Bcl-2 and Bcl-xL, inhibited the activation of caspase-3, and decreased the release of Cyt-c from the mitochondria to the cytoplasm, as compared to those in the rotenone-treated group.

CONCLUSION

Therefore, Cor protected dopamine neurons against rotenone-induced apoptosis by improving mitochondrial dysfunction in a PD model, demonstrating its therapeutic potential for this disease.

Comparative study between bone marrow mesenchymal stem cell and their conditioned medium in the treatment of rat model of Parkinsonism

Parkinsonism is one of the most common aging neurodegenerative disorders. This study aims to compare the therapeutic effect of stem cell versus its conditioned medium in the Parkinsonism model. Parkinsonism was induced by daily subcutaneous injection of 0.5 mg/kg of rotenone dissolved in dimethyl sulfoxide for 28 days. Fifty rats were divided randomly into five groups: control, dimethyl sulfoxide, Parkinsonism, stem cell-treated, and conditioned medium-treated groups. Midbrain specimens were obtained for histological, immunohistochemical, and biochemical studies. Lewy bodies were observed in the Parkinsonism group in the dopaminergic neuron and neuropil as well. Almost all of the pathological changes were clearly ameliorated in both stem cell- and conditioned medium-treated groups as confirmed by biochemical, histological, and immunohistochemical (anti-nestin, anti-glial fibrillary acidic protein, and anti-α synuclein) studies. However, the conditioned medium showed more superior therapeutic effect establishing nearly the normal histological architecture of substantia nigra. These results may pave the future for using stem cell-conditioned medium as a more convenient and effective adjuvant therapy in Parkinsonism and other neurodegenerative disorders.

The protective effect of inosine against rotenone-induced Parkinson's disease in mice; role of oxido-nitrosative stress, ERK phosphorylation, and A2AR expression

Parkinson's disease (PD) is a severe disabling syndrome in which neuroinflammation and various signaling pathways are believed to mediate dopaminergic neurodegeneration. Here, the possible disease-modifying effects of the purine nucleoside inosine were examined against rotenone-induced PD. Mice were allocated into six groups, namely, a normal control group receiving dimethylsulfoxide, a PD control group receiving rotenone, a standard treatment group receiving L-dopa/carbidopa together with rotenone, and three treatment groups receiving inosine in low, medium, and high doses together with rotenone. At the end of the experimental protocol, three behavioral tests were performed to assess PD motor manifestations, namely, wire-hanging test, wood-walking test, and stair test. After performing the behavioral study, mice striata were isolated for the colorimetric assay of hypoxanthine, the enzyme-linked immunosorbent assay of dopamine, tumor necrosis factor-α, interleukin-6 and nitrite, the Western blot estimation of total and phosphorylated extracellular signal-regulated kinase (tERK and pERK), the polymerase chain reaction estimation of adenosine A_2A receptor (A2AR) expression, as well as the histopathological examination of substantia nigra and striatal tissue. Inosine protected against PD progression in a dose-dependent manner, with the effect comparable to the standard treatment L-dopa/carbidopa, evidenced by behavioral, biochemical, and histologic findings. The beneficial antiparkinsonian effect of inosine could be attributed to the ability of the drug to ameliorate neuroinflammation and oxido-nitrosative stress, together with suppression of ERK phosphorylation and down-regulation of A2AR expression. Inosine could therefore be considered as a disease-modifying agent against PD, but further studies are claimed to confirm such effects clinically.

Protective Effect of (-)Epigallocatechin-3-gallate on Rotenone-Induced Parkinsonism-like Symptoms in Rats

Rotenone (ROT)-induced neurotoxicity has been used for decades as an animal model of Parkinson's disease (PD) in humans. This model exhibits pathophysiological features similar to those reported in patients with PD, namely, striatal nitrosative and oxidative stress, mitochondrial dysfunction, and neural cytoarchitecture alteration. (-)Epigallocatechin-3-gallate (EGCG), the most abundant and potent green tea catechin, has notable anti-oxidative, anti-inflammatory, and neuroprotective effects. The objective of the present study was to investigate the potential protective effects of EGCG on ROT-induced motor and neurochemical dysfunctions in rats. Furthermore, we also aimed to study the neuroprotective mechanisms underlying these effects. ROT treatment (0.5 mg/kg s.c., 21 days) reduced body weight and induced significant motor impairments as assessed using an open-field test, rotarod test, grip strength measurement, and beam-crossing task. EGCG treatment (100 or 300 mg/kg i.p., 60 min prior to ROT administration, 21 days) prevented most of the ROT-induced motor impairments. Moreover, EGCG treatment reduced ROT-induced nitric oxide (NO) level and lipid peroxidation (LPO) production; increased the activity of succinate dehydrogenase (SDH), ATPase, and ETC enzymes and the levels of catecholamines in the striatum; and reduced the levels of neuroinflammatory and apoptotic markers. These results demonstrate the possible neuroprotective effects of EGCG against ROT-induced motor impairments, including anti-oxidatory effect, prevention of mitochondrial dysfunction, prevention of neurochemical deficiency, anti-neuroinflammatory effect, and anti-apoptotic effect. This is the first report about the neuroprotective effect of EGCG against ROT-induced motor impairments, and the above evidence provides a potential clinically relevant role for EGCG in delaying or treating human PD.

Psychotropic and neurological medication effects on mitochondrial complex I and IV in rodent models

Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported to be affected by drugs used to treat psychiatric or neurodegenerative diseases, including antidepressants, antipsychotics, anxiolytics, mood stabilizers, stimulants, antidementia, and antiparkinsonian drugs. We conducted meta-analyses examining the effects of each drug category on complex I and IV. The electronic databases Pubmed, EMBASE, CENTRAL, and Google Scholar were searched for studies published between 1970 and 2018. Of 3105 screened studies, 68 articles covering 53 drugs were included in the meta-analyses. All studies assessed complex I and IV in rodent brain at the level of enzyme activity. Results revealed that selected antidepressants increase or decrease complex I and IV, antipsychotics and stimulants decrease complex I but increase complex IV, whereas anxiolytics, mood stabilizers, antidementia, and antiparkinsonian drugs preserve or even enhance both complex I and IV. Potential contributions to the drug effects were found to be related to the drugs' neurotransmitter receptor profiles with adrenergic (α1B), dopaminergic (D1/2), glutaminergic (NMDA1,3), histaminergic (H1), muscarinic (M1,3), opioid (OP1-3), serotonergic (5-HT_2A, 5-HT_2C, 5-HT_3A) and sigma (σ1) receptors having the greatest effects. The findings are discussed in relation to pharmacological mechanisms of action that might have relevance for clinical and research applications.

Neuroinflammatory Reactions in the Brain of 1,2-DCE-Intoxicated Mice during Brain Edema

We previously reported that expression of matrix metalloproteinase-9 (MMP-9) mRNA and protein was upregulated during 1,2-dichloroethane (1,2-DCE) induced brain edema in mice. We also found that the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway resulted in MMP-9 overexpression and nuclear factor-κB (NF-κB) activation in mice treated with 1,2-DCE. In this study, we further hypothesized that inflammatory reactions mediated by the p38 MAPK/ NF-κB signaling pathway might be involved in MMP-9 overexpression, blood–brain barrier (BBB) disruption and edema formation in the brain of 1,2-DCE-intoxicated mice. Our results revealed that subacute poisoning by 1,2-DCE upregulates protein levels of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), interleukin-1β (IL-1β), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), inducible nitric oxide synthase (iNOS) and p-p65 in mouse brains. Pretreatment with an inhibitor against p38 MAPK attenuates these changes. Moreover, pretreatment with an inhibitor against NF-κB attenuates alterations in brain water content, pathological indications notable in brain edema, as well as mRNA and protein expression on levels of MMP-9, VCAM-1, ICAM-1, iNOS, and IL-1β, tight junction proteins (TJs), GFAP and Iba-1 in the brain of 1,2-DCE-intoxicated mice. Furthermore, pretreatment with an inhibitor against MMP-9 obstructs the decrease of TJs in the brain of 1,2-DCE-intoxicated mice. Lastly, pretreatment with an antagonist against the IL-1β receptor also attenuates changes in protein levels of p-p38 MAPK, p-p65, p-IκB, VCAM -1, ICAM-1, IL-1β, and Iba-1 in the brain of 1,2-DCE-intoxicated-mice. Taken together, findings from the current study indicate that the p38 MAPK/ NF-κB signaling pathway might be involved in the activation of glial cells, and the overproduction of proinflammatory factors, which might induce inflammatory reactions in the brain of 1,2-DCE-intoxicated mice that leads to brain edema.

In silico drug screening by using genome-wide association study data repurposed dabrafenib, an anti-melanoma drug, for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopaminergic neuron loss. At present, there are no drugs that stop the progression of PD. As with other multifactorial genetic disorders, genome-wide association studies (GWASs) found multiple risk loci for PD, although their clinical significance remains uncertain. Here, we report the identification of candidate drugs for PD by a method using GWAS data and in silico databases. We identified 57 Food and Drug Administration-approved drug families as candidate neuroprotective drugs for PD. Among them, dabrafenib, which is known as a B-Raf kinase inhibitor and is approved for the treatment of malignant melanoma, showed remarkable cytoprotective effects in neurotoxin-treated SH-SY5Y cells and mice. Dabrafenib was found to inhibit apoptosis, and to enhance the phosphorylation of extracellular signal-regulated kinase (ERK), and inhibit the phosphorylation of c-Jun NH2-terminal kinase. Dabrafenib targets B-Raf, and we confirmed a protein-protein interaction between B-Raf and Rit2, which is coded by RIT2, a PD risk gene in Asians and Caucasians. In RIT2-knockout cells, the phosphorylation of ERK was reduced, and dabrafenib treatment improved the ERK phosphorylation. These data indicated that dabrafenib exerts protective effects against neurotoxicity associated with PD. By using animal model, we confirmed the effectiveness of this in silico screening method. Furthermore, our results suggest that this in silico drug screening system is useful in not only neurodegenerative diseases but also other common diseases such as diabetes mellitus and hypertension.

Curcumin restores rotenone induced depressive-like symptoms in animal model of neurotoxicity: assessment by social interaction test and sucrose preference test

Environmental toxin rotenone has been associated to with increased Parkinson's disease (PD) prevalence in population. Depression is one of the main non-motor symptoms of PD. Curcumin exhibits neuroprotective action in neurodegenerative diseases. In the study we investigated the effect of pre- and post-treatment of curcumin on rotenone-induced depressive-like behaviors and neurotransmitter alterations in rat model of PD. In pre-treatment phase rats were administered with curcumin (100 mg/kg/day, p.o.) for 2 weeks. After curcumin treatment rotenone (1.5 mg/kg/day, s.c.) was administered in Pre-Cur + Rot group and rotenone alone group for 8 days. Meanwhile, in Post-Cur + Rot group rotenone was injected for 8 days in order to develop PD-like symptoms. After rotenone administration curcumin (100 mg/kg/day, p.o.) was administered in Post-Cur + Rot group for 2 weeks. Depressive-like behaviors were monitored by the forced swim test (FST), open field test (OFT), sucrose preference test (SPT) and social interaction test (SIT). Animals were decapitated after behavioral analysis, striatum and hippocampus were dissected out for neurochemical estimations. Results showed that the rotenone administration significantly (p < 0.01) produced depressive-like symptoms in all depression-related behavioral test. All these behavioral deficits were accompanied by the reduction of striatal and hippocampal neurotransmitter levels following rotenone administration. Pre- and post-treatment with curcumin significantly (p < 0.01) reversed the depressive-like behavior induced by rotenone and significantly (p < 0.01) improved neurotransmitter levels as compared to rotenone injected rats. Our results strongly suggest that normalization of neurotransmitter levels particularly highlights the antidepressant effect of curcumin against rotenone-induced depressive behavior.

Insight Into the Emerging Role of Striatal Neurotransmitters in the Pathophysiology of Parkinson's Disease and Huntington's Disease: A Review

Alteration in neurotransmitters signaling in basal ganglia has been consistently shown to significantly contribute to the pathophysiological basis of Parkinson's disease and Huntington's disease. Dopamine is an important neurotransmitter which plays a critical role in coordinated body movements. Alteration in the level of brain dopamine and receptor radically contributes to irregular movements, glutamate mediated excitotoxic neuronal death and further leads to imbalance in the levels of other neurotransmitters viz. GABA, adenosine, acetylcholine and endocannabinoids. This review is based upon the data from clinical and preclinical studies to characterize the role of various striatal neurotransmitters in the pathogenesis of Parkinson's disease and Huntington's disease. Further, we have collected data of altered level of various neurotransmitters and their metabolites and receptor density in basal ganglia region. Although the exact mechanisms underlying neuropathology of movement disorders are not fully understood, but several mechanisms related to neurotransmitters alteration, excitotoxic neuronal death, oxidative stress, mitochondrial dysfunction, neuroinflammation are being put forward. Restoring neurotransmitters level and downstream signaling has been considered to be beneficial in the treatment of Parkinson's disease and Huntington's disease. Therefore, there is an urgent need to identify more specific drugs and drug targets that can restore the altered neurotransmitters level in brain and prevent/delay neurodegeneration.

Neuroprotective potential of spermidine against rotenone induced Parkinson's disease in rats

Parkinson's disease is a leading hypokinetic disorder characterized by selective loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) region of mid-brain. Degeneration of dopaminergic neurons is considered to be due to oxidative stress, neuroinflammation, disturbed calcium homeostasis and glutamate excitotoxicity etc. Spermidine is a polyamine which counteracts age associated cell death by scavenging free radical formation, activates authophagic machinery by enhancing formation of autophagosome, and antagonizes NMDA receptor. In the current study we investigated the neuroprotective potential of spermidine against rotenone induced PD in rats. Rats were treated subcutaneously with rotenone 1.5 mg/kg daily for 28 days. Spermidine 5&10 mg/kg was administered orally 1 h prior to rotenone administration from 15 to 28. Rotenone caused significant reduction in motor functioning and elevated levels of oxidative stress markers and proinflammatory cytokines levels (IL-1β, IL6 and TNF-α). The neurochemical analysis revealed a significant decrease in serotonin, norepinephrine, dopamine and their metabolites accompanied by a significant loss of dopaminergic neurons in the SNpc following ROT injection. However, treatment with spermidine rescued DAergic neurons in SNpc and nerve terminals in the striatum following ROT insult. Spermidine treatment also attenuated oxidative stress, neuroinflammation and restored striatal neurochemistry. Results of our study suggest that spermidine has promising neuroprotective effect against degenerative changes in experimental PD, and the protective effects are mediated through its antioxidant and anti-inflammatory properties.

The effects of rotenone-induced toxicity via the NF-κB-iNOS pathway in rat liver

Rotenone has been used as a pesticide for many years, it is an environmental poison reported to cause neurological diseases. However, the effects of rotenone on the rat liver are unclear, as are the mechanisms of toxicity. In the present study, Sprague-Dawley (SD) rats were divided into five groups: control, dimethyl sulfoxide (DMSO), rotenone low-dose (1 mg/kg), rotenone mid-dose (2 mg/kg) and rotenone high-dose (4 mg/kg). The treatments were orally administered daily for 28 days, we assessed health status, mRNA expression levels of inflammatory factors, protein levels, nitric oxide (NO) content and histological changes. The results showed that body weight was significantly decreased in each rotenone group in a dose-dependent manner, compared with the control group. Rotenone significantly increased the mRNA levels of cyclooxygenase-2 (COX-2), nuclear factor kappaB (NF-κB), prostaglandin E₂ (PGE₂), inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF-α) in each rotenone group compared with the control group, except iNOS and TNF-α mRNA expression in the low-dose group. The protein levels of COX-2 were significantly higher in each rotenone group compared with the control group, NF-κB protein expression were significantly higher in the rotenone mid and high-dose groups, but not in the low-dose group, compared with the control group, similar changes were observed in NO content. Additionally, histological analysis revealed that the most severe tissue damage occurred in the high-dose group. These results indicated that rotenone has toxic effect in rat liver relating to inflammatory factors. Our findings provide insight into the mechanisms of rotenone hepatotoxicity.

Using the shared genetics of dystonia and ataxia to unravel their pathogenesis

In this review we explore the similarities between spinocerebellar ataxias and dystonias, and suggest potentially shared molecular pathways using a gene co-expression network approach. The spinocerebellar ataxias are a group of neurodegenerative disorders characterized by coordination problems caused mainly by atrophy of the cerebellum. The dystonias are another group of neurological movement disorders linked to basal ganglia dysfunction, although evidence is now pointing to cerebellar involvement as well. Our gene co-expression network approach identified 99 shared genes and showed the involvement of two major pathways: synaptic transmission and neurodevelopment. These pathways overlapped in the two disorders, with a large role for GABAergic signaling in both. The overlapping pathways may provide novel targets for disease therapies. We need to prioritize variants obtained by whole exome sequencing in the genes associated with these pathways in the search for new pathogenic variants, which can than be used to help in the genetic counseling of patients and their families.

Sertraline and venlafaxine improves motor performance and neurobehavioral deficit in quinolinic acid induced Huntington's like symptoms in rats: Possible neurotransmitters modulation

BACKGROUND

Huntington Disease is autosomal, fatal and progressive neurodegenerative disorder for which clinically available drugs offer only symptomatic relief. Emerging strides have indicated that antidepressants improve motor performance, restore neurotransmitters level, ameliorates striatal atrophy, increases BDNF level and may enhance neurogenesis. Therefore, we investigated sertraline and venlafaxine, clinically available drugs for depression with numerous neuroprotective properties, for their beneficial effects, if any, in quinolinic acid induced Huntington's like symptoms in rats.

METHODS

Rats were administered quinolinic acid (QA) (200 nmol/2μl saline) intrastriatal bilaterally on 0day. Sertraline and venlafaxine (10 and 20mg/kg, po) each were administered for 21days once a day. Motor performance was assessed using rotarod test, grip strength test, narrow beam walk test on weekly basis. On day 22, animals were sacrificed and rat striatum was isolated for biochemical (LPO, GSH and Nitrite), neuroinflammation (TNF-α, IL-1β and IL-6) and neurochemical analysis (GABA, glutamate, norepinephrine, dopamine, serotonin, DOPAC, HVA and 5-HIAA).

RESULTS

QA treatment significantly altered body weight, motor performance, oxidative defense (increased LPO, nitrite and decreased GSH), pro-inflammatory cytokines levels (TNF-α, IL-6 and IL-1β), neurochemical level (GABA, glutamate, nor-epinephrine, dopamine, serotonin, HVA, DOPAC, 5-HIAA). Sertraline and venlafaxine at selected doses significantly attenuated QA induced alterations in striatum.

CONCLUSION

The present study suggests that modulation of monoamines level, normalization of GABA and glutamatergic signaling, anti-oxidant and anti-inflammatory properties could underlie the neuroprotective effect of sertraline and venlafaxine in QA induced Huntington's like symptoms.

Imipramine and amitriptyline ameliorate the rotenone model of Parkinson's disease in rats

Amitriptyline (AMI), a commonly prescribed tricyclic antidepressant (TCA) to parkinsonian patients, specifically showed a significant delay in dopaminergic therapy initiation and improvement in motor disability in parkinsonian patients. Moreover, it was recently shown that AMI has neuroprotective properties; however, the mechanisms underlying this effect in Parkinson's disease (PD) are not fully understood. The current study aimed to investigate the possible neuroprotective mechanisms afforded by AMI in the rotenone model of PD and to assess whether another TCA member, imipramine (IMI), shows a corresponding effect. Rats were allocated into seven groups. Four groups were given either saline, dimethyl sulfoxide, AMI or IMI. Three rotenone groups were either untreated or treated with AMI or IMI. Rats receiving rotenone exhibited motor impairment in open field and rotarod tests. Additionally, immunohistochemical examination revealed dopaminergic neuronal damage in substantia nigra. Besides, striatal monoamines and brain derived neurotrophic factor levels were declined. Furthermore, oxidative stress, microglial activation and inflammation were evident in the striata. Pretreatment of rotenone groups with AMI or IMI prevented rotenone-induced neuronal degeneration and increased striatal dopamine level with motor recovery. These effects were accompanied by restoring striatal monoamines and brain-derived neurotrophic factor levels, as well as reducing oxidative damage, microglial activation and expression of proinflammatory cytokines and inducible nitric oxide synthase. The present results suggest that modulation of noradrenaline and serotonin levels, up-regulation of neurotrophin, inhibition of glial activation, anti-oxidant and anti-inflammatory activities could serve as important mechanisms underlying the neuroprotective effects of the used drugs in the rotenone model of PD.

Ameliorative Effect of Quercetin on Neurochemical and Behavioral Deficits in Rotenone Rat Model of Parkinson's Disease: Modulating Autophagy (Quercetin on Experimental Parkinson's Disease)

Autophagy is necessary for neuronal homeostasis and its dysfunction has been implicated in Parkinson's disease (PD) as it can exacerbate endoplasmic reticulum (ER) stress and ER stress-induced apoptosis. Quercetin is a flavonoid known for its neuroprotective and antioxidant effects. The present study investigated the protective, autophagy-modulating effects of quercetin in the rotenone rat model of PD. Rotenone was intraperitoneally injected at dose of 2 ml/kg/day for 4 weeks. Simultaneous intraperitoneal injection of quercetin was given at a dose of 50 mg/kg/day also for 4 weeks. Neurobehavioral changes were studied. Oxidative/antioxidant status, C/EBP homologous protein (CHOP), Beclin-1, and dopamine levels were assessed. DNA fragmentation and histopathological changes were evaluated. This research work revealed that quercetin significantly attenuated rotenone-induced behavioral impairment, augmented autophagy, ameliorated ER stress- induced apoptosis with attenuated oxidative stress. From the current study, quercetin can act as an autophagy enhancer in PD rat model and modulates the microenvironment that leads to neuronal death.