Wuzi Yanzong pill attenuates MPTP-induced Parkinson's Disease via PI3K/Akt signaling pathway

Wuzi Yanzong Pill (WYP) was found to play a protective role on nerve cells and neurological diseases, however the molecular mechanism is unclear. To understand the molecular mechanisms that underly the neuroprotective effect of WYP on dopaminergic neurons in Parkinson's disease (PD). PD mouse model was induced by the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Gait and hanging tests were used to assess motor behavioral function. Immunofluorescence assay was used to determine TH-positive neurons in substantia nigra (SN). Apoptosis, dopamine and neurotrophic factors as well as expression of PI3K/Akt pathway were detected by TUNEL staining, ELISA and western blotting, respectively. First, it was observed that WYP intervention improved abnormal motor function in MPTP-induced PD model, alleviated the loss of TH⁺ neurons in SN, and increased dopamine content in brain, revealing a potential protective effect. Second, network pharmacology was used to analyze the possible targets and pathways of WYP action in the treatment of PD. A total of 126 active components related to PD were screened in WYP, and the related core targets included ALB, GAPDH, Akt1, TP53, IL6 and TNF. Particularly, the effect of WYP on PD may be medicate through PI3K/Akt signaling pathway and apoptotic regulation. The WYP treated PD mice had higher expression of p-PI3K, p-Akt and Bcl-2 but lower expression of Bax and cleaved caspase-3 than the non-WYP treated PD mice. Secretion of brain-derived neurotrophic factor (BDNF) and cerebral dopamine neurotrophic factor (CDNF) were also increased in the treated mice. WYP may inhibit apoptosis and increase the secretion of neurotrophic factor via activating PI3K/ Akt signaling pathway, thus protecting the loss of dopamine neurons in MPTP-induced PD mice.

Comparison of the effect of rotenone and 1‑methyl‑4‑phenyl‑1,2,3,6‑tetrahydropyridine on inducing chronic Parkinson's disease in mouse models

Animal models for Parkinson's disease (PD) are very useful in understanding the pathogenesis of PD and screening for new therapeutic approaches. The present study compared two commonly used neurotoxin‑induced mouse models of chronic PD to guide model selection, explore the pathogenesis and mechanisms underlying PD and develop effective treatments. The chronic PD mouse models were established via treatment with rotenone or 1‑methyl‑4‑phenyl‑1,2,3,6-tetrahydropyridine (MPTP) for 6 weeks. The effects of rotenone and MPTP in the mice were compared by assessing neurobehavior, neuropathology and mitochondrial function through the use of the pole, rotarod and open field tests, immunohistochemistry for tyrosine hydroxylase (TH), glial fibrillary acidic protein (GFAP), ionized calcium‑binding adapter molecule 1 (Iba‑1), neuronal nuclear antigen (NeuN) and (p)S129 α‑synuclein, immunofluorescence for GFAP, Iba‑1 and NeuN, western blotting for TH, oxygen consumption, complex I enzyme activity. The locomotor activity, motor coordination and exploratory behavior in both rotenone and MPTP groups were significantly lower compared with the control group. However, behavioral tests were no significant differences between the two groups. In the MPTP group, the loss of dopaminergic (DA) neurons in the substantia nigra (SN) pars compacta, the reduction of the tyrosine hydroxylase content in the SN and striatum and the astrocyte proliferation and microglial activation in the SN were more significant compared with the rotenone group. Notably, mitochondrial‑dependent oxygen consumption and complex I enzyme activity in the SN were significantly reduced in the rotenone group compared with the MPTP group. In addition, Lewy bodies were present only in SN neurons in the rotenone group. Although no significant differences in neurobehavior were observed between the two mouse models, the MPTP model reproduced the pathological features of PD more precisely in terms of the loss of DA neurons, decreased dopamine levels and neuroinflammation in the SN. On the other hand, the rotenone model was more suitable for studying the role of mitochondrial dysfunction (deficient complex I activity) and Lewy body formation in the SN, which is a characteristic pathological feature of PD. The results indicated that MPTP and rotenone PD models have advantages and disadvantages, therefore one or both should be selected based on the purpose of the study.

Mechanism for antiParkinsonian effect of resveratrol: Involvement of transporters, synaptic proteins, dendrite arborization, biochemical alterations, ER stress and apoptosis

The present study was undertaken to evaluate the mechanism for antiParkinsonian effect of resveratrol employing 6-hydroxydopamine (6-OHDA) induced experimental model of Parkinson's disease (PD). Resveratrol treatment significantly protects the PD related pathological markers like level of tyrosine hydroxylase, dopamine and apoptotic proteins (Bax and cleaved caspase-3). Disease pathology involves significantly decreased level of dopamine transporter, synaptophysin and postsynaptic density protein 95 (PSD-95) along with augmented level of vesicular monoamine transporter and considerably affected the dendrite arborization. Such affected neuronal communication was significantly restored with resveratrol treatment. Biochemical alterations include the depleted level of glutathione (GSH), mitochondrial complex-I activity with concomitant increased level of lipid peroxidation, nitrite level and calcium levels, which were also significantly inhibited with resveratrol treatment. Altered calcium level induces the endoplasmic reticulum (ER) stress related signalling and phosphorylated Nuclear factor erythroid 2-related factor 2 (Nrf2), and with resveratrol treatment the level of phosphorylated Nrf2 was further increased. The concurrent depleted level of proteasome activity was observed which was attenuated with resveratrol treatment. Proinflammatory cytokines and activated astrocytes were observed which was inhibited with resveratrol treatment. In conclusion, findings suggested that resveratrol exhibits the interference in neuronal communication, oxidative stress, mitochondrial pathophysiology, ER stress, protein degradation mechanism and inflammatory responses and could be utilize in clinics to treat the PD patients.

An extended release GLP-1 analogue increases α-synuclein accumulation in a mouse model of prodromal Parkinson's disease

The repurposing of drugs developed to treat type 2 diabetes for the treatment of Parkinson's disease (PD) was encouraged by the beneficial effect exerted by the glucagon-like peptide 1 (GLP-1) analogue exenatide in a phase 2 clinical trial. The effects of GLP-1 analogues have been investigated extensively using rodent toxin models of PD. However, many of the toxin-based models used lack robust α-synuclein (α-syn) pathology, akin to the Lewy bodies and neurites seen in PD. One prior study has reported a protective effect of a GLP-1 analogue on midbrain dopamine neurons following injection of α-syn preformed fibrils (PFF) into the striatum. Here, we used olfactory bulb injections of PFF as a model of prodromal PD and monitored the effect of a long-acting GLP-1 analogue on the propagation of α-syn pathology in the olfactory system. Thirteen weeks after PFF injection, mice treated with long-acting the GLP-1 analogue had a significant increase in pathological α-syn in brain regions connected to the olfactory bulb, accompanied by signs of microglia activation. Our results suggest that the nature of the neuronal insult and intrinsic properties of the targeted neuronal population markedly influence the effect of GLP-1 analogues.

MicroRNA-93 Blocks Signal Transducers and Activator of Transcription 3 to Reduce Neuronal Damage in Parkinson's Disease

MicroRNA-93 (miR-93) is an oncogene that promotes tumor growth and angiogenesis. However, its role in Parkinson's disease (PD) remains unknown. This study aimed at investigating the role of miR-93 in PD and the molecular mechanisms involved. 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mouse model and lipopolysaccharide (LPS)-exposed BV2 cells were constructed. Real-time quantitative PCR was used to detect the mRNA expression of miR-93, iNOS, IL-6, IL-10, TNF-α and TGF-β1. Bioinformatics analysis and luciferase reporter assay were used to predict and confirm the interaction between miR-93 and STAT3. Flow cytometry was used to detect cell apoptosis. Western blotting was used to detect the protein expression of STAT3. Immunohistochemistry was used to analyze the Iba1-positive and TH positive cells. It was found that the expression of miR-93 was down-regulated in LPS-exposed BV2 cells. Overexpression of miR-93 inhibited the expression of iNOS, IL-6 and TNF-α, while enhanced the expression of TGF-β1 and IL-10. The expression of transcriptional activator 3 (STAT3) was found to be up-regulated in LPS-exposed BV2 cells. Knockdown of STAT3 inhibited the expression of iNOS, IL-6 and TNF-α, while enhanced the expression of TGF-β1 and IL-10. Moreover, STAT3 was found to be a direct target of miR-93, and miR-93 overexpression inhibited the expression of STAT3. Furthermore, both miR-93 overexpression and STAT3 knockdown reduced LPS-induced BV2 cell apoptosis, whereas STAT3 overexpression eliminated the inhibitory effect of miR-93 on LPS-induced BV2 cell apoptosis. In addition, miR-93 overexpression inhibited MPTP-induced STAT3 expression, microglial activation and inflammatory reaction and reduced the loss of tyrosine hydroxylase in the substantia nigra of mice. In conclusion, we demonstrate that miR-93 may be involved in PD by regulating the expression of STAT3.

Neuroprotective effects of garlic extract on dopaminergic neurons of substantia nigra in a rat model of Parkinson's disease: motor and non-motor outcomes

Parkinson's disease (PD) is a common and severe neurodegenerative disorder associated with a selective loss of dopaminergic neurons in substantia nigra pars compacta. The crucial role of oxidative stress and inflammation in PD onset and progression is evident. It has been proven that garlic extract (GE) protects the cells from oxidative stress, inflammation, mitochondrial dysfunction and apoptosis. That is, we aimed to investigate if GE reveals protective features on the preclinical model of PD. The study has been designed to evaluate both preventive (GE administered before 6-OHDA injection) and therapeutic (GE administered after 6-OHDA injection) effects of GE on the animal model. Forty male Wistar rats were divided into 4 groups including control, lesion, treatment I (received GE before 6-OHDA injection) and treatment II (received GE both before and after 6-OHDA injection). At the end of treatment, hanging, rotarod, open field and passive avoidance tests as well as immunohistochemistry were performed to evaluate the neuroprotective effects of garlic against PD. Our immunohistochemistry analysis revealed that the tyrosine hydroxylase positive cells (TH⁺) in GE treated groups were significantly higher (p˂0.001) than the lesion group. The motor deficiency significantly improved in hanging, rotarod, open-field and apomorphine-induced rotational tests. We observed an attenuation in memory impairment induced by PD on GE treated group. Therefore, we found that GE protects dopaminergic neurons in 6-OHDA-induced neurotoxicity and ameliorates movement disorders and behavioral deficits.

Intragastric Administration of Casein Leads to Nigrostriatal Disease Progressed Accompanied with Persistent Nigrostriatal-Intestinal Inflammation Activited and Intestinal Microbiota-Metabolic Disorders Induced in MPTP Mouse Model of Parkinson's Disease

Gut microbial dysbiosis and alteration of gut microbiota composition in Parkinson's disease (PD) have been increasingly reported, no recognized therapies are available to halt or slow progression of PD and more evidence is still needed to illustrate its causative impact on gut microbiota and PD and mechanisms for targeted mitigation. Epidemiological evidence supported an association between milk intake and a higher incidence of Parkinson's disease (PD), questions have been raised about prospective associations between dietary factors and the incidence of PD. Here, we investigated the significance of casein in the development of PD. The mice were given casein (6.75 g/kg i.g.) for 21 days after MPTP (25 mg/kg i.p. × 5 days) treatment, the motor function, dopaminergic neurons, inflammation, gut microbiota and fecal metabolites were observed. The experimental results revealed that the mice with casein gavage after MPTP treatment showed a persisted dyskinesia, the content of dopamine in striatum and the expression of TH in midbrain and ileum were decreased, the expression of Iba-1, CD4, IL-22 in midbrain and ileum increased continuously with persisted intestinal histopathology and intestinal barrier injury. Decreased intestinal bile secretion in addition with abnormal digestion and metabolism of carbohydrate, lipids and proteins were found, whereas these pathological status for the MPTP mice without casein intake had recovered after 24 days, no significant differences were observed with regard to only treated with casein. Our study demonstrates that intestinal pathologic injury, intestinal dysbacteriosis and metabolism changes promoted by casein in MPTP mice ultimately exacerbated the lesions to dopaminergic neurons.

In Vivo Diagnosis of Synucleinopathies: A Comparative Study of Skin Biopsy and RT-QuIC

OBJECTIVE

To determine whether (1) immunofluorescence is a reproducible technique in detecting misfolded α-synuclein in skin nerves and subsequently whether (2) immunofluorescence and real-time quaking-induced conversion (RT-QuIC) (both in skin and CSF) show a comparable in vivo diagnostic accuracy in distinguishing synucleinopathies from non-synucleinopathies in a large cohort of patients.

METHODS

We prospectively recruited 90 patients fulfilling clinical and instrumental diagnostic criteria for all synucleinopathies variants and non-synucleinopathies (mainly including Alzheimer disease, tauopathies, and vascular parkinsonism or dementia). Twenty-four patients with mainly peripheral neuropathies were used as controls. Patients underwent skin biopsy for immunofluorescence and RT-QuIC; CSF was examined in patients who underwent lumbar puncture for diagnostic purposes. Immunofluorescence and RT-QuIC analysis were made blinded to the clinical diagnosis.

RESULTS

Immunofluorescence showed reproducible results between 2 pairs of neighboring skin samples. Both immunofluorescence and RT-QuIC showed high sensitivity and specificity in discriminating synucleinopathies from non-synucleinopathies and controls but immunofluorescence presented higher diagnostic accuracy. Immunofluorescence presented a good level of agreement with RT-QuIC in both skin and CSF in synucleinopathies.

CONCLUSIONS

Both immunofluorescence and RT-QuIC showed high diagnostic accuracy, although immunofluorescence displayed the better value as well as optimal reproducibility; they presented a good level of agreement in synucleinopathies, supporting the use of less invasive tests such as skin immunofluorescence or RT-QuIC instead of CSF RT-QuIC as a diagnostic tool for synucleinopathies.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that immunofluorescence or RT-QuIC accurately distinguish synucleinopathies from non-synucleinopathies.

Cascading from SARS-CoV-2 to Parkinson's Disease through Protein-Protein Interactions

Extensive extrapulmonary damages in a dozen of organs/systems, including the central nervous system (CNS), are reported in patients of the coronavirus disease 2019 (COVID-19). Three cases of Parkinson's disease (PD) have been reported as a direct consequence of COVID-19. In spite of the scarce data for establishing a definitive link between COVID-19 and PD, some hypotheses have been proposed to explain the cases reported. They, however, do not fit well with the clinical findings reported for COVID-19 patients, in general, and for the PD cases reported, in particular. Given the importance of this potential connection, we present here a molecular-level mechanistic hypothesis that explains well these findings and will serve to explore the potential CNS damage in COVID-19 patients. The model explaining the cascade effects from COVID-19 to CNS is developed by using bioinformatic tools. It includes the post-translational modification of host proteins in the lungs by viral proteins, the transport of modified host proteins via exosomes out the lungs, and the disruption of protein-protein interaction in the CNS by these modified host proteins. Our hypothesis is supported by finding 44 proteins significantly expressed in the CNS which are associated with PD and whose interactions can be perturbed by 24 host proteins significantly expressed in the lungs. These 24 perturbators are found to interact with viral proteins and to form part of the cargoes of exosomes in human tissues. The joint set of perturbators and PD-vulnerable proteins form a tightly connected network with significantly more connections than expected by selecting a random cluster of proteins of similar size from the human proteome. The molecular-level mechanistic hypothesis presented here provides several routes for the cascading of effects from the lungs of COVID-19 patients to PD. In particular, the disruption of autophagy/ubiquitination processes appears as an important mechanism that triggers the generation of large amounts of exosomes containing perturbators in their cargo, which would insult several PD-vulnerable proteins, potentially triggering Parkinsonism in COVID-19 patients.

Conveyance of cortical pacing for parkinsonian tremor-like hyperkinetic behavior by subthalamic dysrhythmia

Parkinson's disease is characterized by both hypokinetic and hyperkinetic symptoms. While increased subthalamic burst discharges have a direct causal relationship with the hypokinetic manifestations (e.g., rigidity and bradykinesia), the origin of the hyperkinetic symptoms (e.g., resting tremor and propulsive gait) has remained obscure. Neuronal burst discharges are presumed to be autonomous or less responsive to synaptic input, thereby interrupting the information flow. We, however, demonstrate that subthalamic burst discharges are dependent on cortical glutamatergic synaptic input, which is enhanced by A-type K+ channel inhibition. Excessive top-down-triggered subthalamic burst discharges then drive highly correlative activities bottom-up in the motor cortices and skeletal muscles. This leads to hyperkinetic behaviors such as tremors, which are effectively ameliorated by inhibition of cortico-subthalamic AMPAergic synaptic transmission. We conclude that subthalamic burst discharges play an imperative role in cortico-subcortical information relay, and they critically contribute to the pathogenesis of both hypokinetic and hyperkinetic parkinsonian symptoms.

Age-related vulnerability to nigral dopaminergic degeneration in rats via Zn2+-permeable GluR2-lacking AMPA receptor activation

On the basis of the evidence that extracellular Zn2+ influx induced with AMPA causes Parkinson's syndrome in rats that apomorphine-induced movement disorder emerges, here we used a low dose of AMPA, which does not increase intracellular Zn2+ level in the substantia nigra pars compacta (SNpc) of young adult rats, and tested whether intracellular Zn2+ dysregulation induced with AMPA is accelerated in the SNpc of aged rats, resulting in age-related vulnerability to Parkinson's syndrome. When AMPA (1 mM) was injected at the rate of 0.05 μl/min for 20 min into the SNpc, intracellular Zn2+ level was increased in the SNpc of aged rats followed by increase in turning behavior in response to apomorphine and nigral dopaminergic degeneration. In contrast, young adult rats do not show movement disorder and nigral dopaminergic degeneration, in addition to no increase in intracellular Zn2+. In aged rats, movement disorder and nigral dopaminergic degeneration were rescued by co-injection of either extracellular (CaEDTA) or intracellular (ZnAF-2DA) Zn2+ chelators. 1-Naphthyl acetyl spermine (NASPM), a selective blocker of Ca2+- and Zn2+-permeable GluR2-lacking AMPA receptors blocked increase in intracellular Zn2+ in the SNpc of aged rats followed by rescuing nigral dopaminergic degeneration. The present study indicates that intracellular Zn2+ dysregulation is accelerated by Ca2+- and Zn2+-permeable GluR2-lacking AMPA receptor activation in the SNpc of aged rats, resulting in age-related vulnerability to Parkinson's syndrome.

MiR-421 Aggravates Neurotoxicity and Promotes Cell Death in Parkinson's Disease Models by Directly Targeting MEF2D

Parkinson's disease (PD) is a severe neurodegenerative disease characterized by selective loss of dopaminergic neurons, which reduces quality of life of patients and poses a heavy burden to the society. The pathological mechanism of PD remains unclear, and increasing efforts are aimed to solve this problem. MiRNAs are a kind of small noncoding RNA regulating target gene expression. Previous studies have shown that dysregulation of miRNAs is involved in the development of PD. In the present study, we determined that miR-421 and MEF2D are increased and decreased, respectively, in a cellular model of PD. The data on the mechanism of action indicate that miR-421 directly binds to MEF2D mRNA and negatively regulates MEF2D expression. An increase in miR-421 disrupted the Bcl2/Bax system. Functional assays indicated that enhanced miR-421 promotes cell death by negative modulation of MEF2D expression. Inhibition of miR-421 or restoration of MEF2D protected neurons from neurotoxicity in cellular and animal models of PD. Our study is the first to demonstrate that miR-421 is decreased in PD models and to determine a novel putative mechanism of PD pathogenesis.

Hesperidin protects against behavioral alterations and loss of dopaminergic neurons in 6-OHDA-lesioned mice: the role of mitochondrial dysfunction and apoptosis

Hesperidin is a flavonoid glycoside that is frequently found in citrus fruits. Our group have demonstrated that hesperidin has neuroprotective effect in 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD), mainly by antioxidant mechanisms. Although the pathophysiology of PD remains uncertain, a large body of evidence has demonstrated that mitochondrial dysfunction and apoptosis play a critical role in dopaminergic nigrostriatal degeneration. However, the ability of hesperidin in modulating these mechanisms has not yet been investigated. In the present study, we examined the potential of a 28-day hesperidin treatment (50 mg/kg/day, p.o.) in preventing behavioral alterations induced by 6-OHDA injection via regulating mitochondrial dysfunction, apoptosis and dopaminergic neurons in the substantia nigra pars compacta (SNpc) in C57BL/6 mice. Our results demonstrated that hesperidin treatment improved motor, olfactory and spatial memory impairments elicited by 6-OHDA injection. Moreover, hesperidin treatment attenuated the loss of dopaminergic neurons (TH+ cells) in the SNpc and the depletion of dopamine (DA) and its metabolities 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum of 6-OHDA-lesioned mice. Hesperidin also protected against the inhibition of mitochondrial respiratory chain complex-I, -IV and V, the decrease of Na + -K + -ATPase activity and the increase of caspase-3 and -9 activity in the striatum. Taken together, our findings indicate that hesperidin mitigates the degeneration of dopaminergic neurons in the SNpc by preventing mitochondrial dysfunction and modulating apoptotic pathways in the striatum of 6-OHDA-treated mice, thus improving behavioral alterations. These results provide new insights on neuroprotective mechanisms of hesperidin in a relevant preclinical model of PD.

The Delta-Specific Opioid Glycopeptide BBI-11008: CNS Penetration and Behavioral Analysis in a Preclinical Model of Levodopa-Induced Dyskinesia

In previous work we evaluated an opioid glycopeptide with mixed μ/δ-opioid receptor agonism that was a congener of leu-enkephalin, MMP-2200. The glycopeptide analogue showed penetration of the blood-brain barrier (BBB) after systemic administration to rats, as well as profound central effects in models of Parkinson's disease (PD) and levodopa (L-DOPA)-induced dyskinesia (LID). In the present study, we tested the glycopeptide BBI-11008 with selective δ-opioid receptor agonism, an analogue of deltorphin, a peptide secreted from the skin of frogs (genus Phyllomedusa). We tested BBI-11008 for BBB-penetration after intraperitoneal (i.p.) injection and evaluated effects in LID rats. BBI-11008 (10 mg/kg) demonstrated good CNS-penetrance as shown by microdialysis and mass spectrometric analysis, with peak concentration levels of 150 pM in the striatum. While BBI-11008 at both 10 and 20 mg/kg produced no effect on levodopa-induced limb, axial and oral (LAO) abnormal involuntary movements (AIMs), it reduced the levodopa-induced locomotor AIMs by 50% after systemic injection. The N-methyl-D-aspartate receptor antagonist MK-801 reduced levodopa-induced LAO AIMs, but worsened PD symptoms in this model. Co-administration of MMP-2200 had been shown prior to block the MK-801-induced pro-Parkinsonian activity. Interestingly, BBI-11008 was not able to block the pro-Parkinsonian effect of MK-801 in the LID model, further indicating that a balance of mu- and delta-opioid agonism is required for this modulation. In summary, this study illustrates another example of meaningful BBB-penetration of a glycopeptide analogue of a peptide to achieve a central behavioral effect, providing additional evidence for the glycosylation technique as a method to harness therapeutic potential of peptides.

Cell Type-Specific Oxidative Stress Genomic Signatures in the Globus Pallidus of Dopamine-Depleted Mice

Neuron subtype dysfunction is a key contributor to neurologic disease circuits, but identifying associated gene regulatory pathways is complicated by the molecular complexity of the brain. For example, parvalbumin-expressing (PV+) neurons in the external globus pallidus (GPe) are critically involved in the motor deficits of dopamine-depleted mouse models of Parkinson's disease, where cell type-specific optogenetic stimulation of PV+ neurons over other neuron populations rescues locomotion. Despite the distinct roles these cell types play in the neural circuit, the molecular correlates remain unknown because of the difficulty of isolating rare neuron subtypes. To address this issue, we developed a new viral affinity purification strategy, Cre-Specific Nuclear Anchored Independent Labeling, to isolate Cre recombinase-expressing (Cre+) nuclei from the adult mouse brain. Applying this technology, we performed targeted assessments of the cell type-specific transcriptomic and epigenetic effects of dopamine depletion on PV+ and PV- cells within three brain regions of male and female mice: GPe, striatum, and cortex. We found GPe PV+ neuron-specific gene expression changes that suggested increased hypoxia-inducible factor 2α signaling. Consistent with transcriptomic data, regions of open chromatin affected by dopamine depletion within GPe PV+ neurons were enriched for hypoxia-inducible factor family binding motifs. The gene expression and epigenomic experiments performed on PV+ neurons isolated by Cre-Specific Nuclear Anchored Independent Labeling identified a transcriptional regulatory network mediated by the neuroprotective factor Hif2a as underlying neural circuit differences in response to dopamine depletion.SIGNIFICANCE STATEMENT Cre-Specific Nuclear Anchored Independent Labeling is an enhanced, virus-based approach to isolate nuclei of a specific cell type for transcriptome and epigenome interrogation that decreases dependency on transgenic animals. Applying this technology to GPe parvalbumin-expressing neurons in a mouse model of Parkinson's disease, we discovered evidence for an upregulation of the oxygen homeostasis maintaining pathway involving Hypoxia-inducible factor 2α. These results provide new insight into how neuron subtypes outside the substantia nigra pars compacta may be compensating at a molecular level for differences in the motor production neural circuit during the progression of Parkinson's disease. Furthermore, they emphasize the utility of cell type-specific technologies, such as Cre-Specific Nuclear Anchored Independent Labeling, for isolated assessment of specific neuron subtypes in complex systems.

Amelioration of motor and non-motor deficits and increased striatal APoE levels highlight the beneficial role of pistachio supplementation in rotenone-induced rat model of PD

Pistachio contains polyphenolic compounds including flavonoids and anthocyanins which have antioxidant and antiinflammatory activity. Present study was aimed to evaluate the protective effects of pistachio on neurobehavioral and neurochemical changes in rats with Parkinson's disease (PD). Animal model of PD was induced by the injection of rotenone (1.5 mg/kg/day, s.c.) for 8 days. Pistachio (800 mg/kg/day, p.o.) was given for two weeks in both pre- and post-treatment. At the end of treatment brain was dissected out and striatum was isolated for biochemical and neurochemical analysis. Memory was assessed by Morris water maze (MWM) and novel object recognition (NOR) test while open field test (OFT), Kondziela inverted screen test (KIST), pole test (PT), beam walking test (BWT), inclined plane test (IPT) and footprint (FP) test were used to observe motor behavior. Rotenone administration significantly (p < 0.01) impaired the memory but pistachio in both pre- and post-treatment groups significantly (p < 0.01) improved memory performance. Rotenone-induced motor deficits were significantly attenuated in both pre- and post-pistachio treatment. Increased oxidative stress and decreased DA and 5-HT levels induced by rotenone were also significantly attenuated by pistachio supplementation. Furthermore, raised apolipoprotein E (APoE) levels in rotenone injected rats were also normalized following treatment with pistachio. Present findings show that pistachio possesses neuroprotective effects and improves memory and motor deficits via increasing DA levels and improving oxidative status in brain.

Nigral and ventral tegmental area lesioning induces testicular and sperm morphological abnormalities in a rotenone model of Parkinson's disease

Although sexual health is affected by Parkinson's disease (PD), the effect on testicular health and/or sperm quality is not well discussed. After 21 days of rotenone lesioning, we observed dopaminergic neuronal degeneration in the substantia nigra and hypothalamus. There were minimal SPACA-1-expressing epididymal spermatozoa with morphological abnormalities, scanty luminal spermatozoa and reduced testicular spermatids and post-meiotic germ cells indicating hypospermatogenesis. Occludin-expressing sertoli cells were dispersed over a wide area indicating compromised blood-testes barrier. Activated caspase-3 expression was intense while immunoreactivity of spermatogenic-enhancing SRY and GADD45 g was weak. Although serum follicle stimulating hormone level was not affected, the lesion was associated with reduced serum testosterone level, testicular oxidative damage and inhibition of acetylcholinesterase activity, even when rotenone was not detected in the testes. Together, dopaminergic lesions may mediate testicular and sperm abnormalities via the brain-hypothalamic-testicular circuit independent of the pituitary, thereby establishing a causal link between Parkinsonism and reproductive dysfunction.

Impact of Aging on the 6-OHDA-Induced Rat Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder. The neurodegeneration leading to incapacitating motor abnormalities mainly occurs in the nigrostriatal pathway due to the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Several animal models have been developed not only to better understand the mechanisms underlying neurodegeneration but also to test the potential of emerging disease-modifying therapies. However, despite aging being the main risk factor for developing idiopathic PD, most of the studies do not use aged animals. Therefore, this study aimed at assessing the effect of aging in the unilateral 6-hydroxydopamine (6-OHDA)-induced animal model of PD. For this, female young adult and aged rats received a unilateral injection of 6-OHDA into the medial forebrain bundle. Subsequently, the impact of aging on 6-OHDA-induced effects on animal welfare, motor performance, and nigrostriatal integrity were assessed. The results showed that aging had a negative impact on animal welfare after surgery. Furthermore, 6-OHDA-induced impairments on skilled motor function were significantly higher in aged rats when compared with their younger counterparts. Nigrostriatal histological analysis further revealed an increased 6-OHDA-induced dopaminergic cell loss in the SNpc of aged animals when compared to young animals. Overall, our results demonstrate a higher susceptibility of aged animals to 6-OHDA toxic insult.

Downregulation of lncRNA BACE1-AS improves dopamine-dependent oxidative stress in rats with Parkinson's disease by upregulating microRNA-34b-5p and downregulating BACE1

Objective: Long noncoding RNAs (lncRNAs) have already been proposed to function in Parkinson's disease (PD). However, the role of lncRNA BACE1-AS in PD has never been discussed. This study aims to examine the mechanism of BACE1-AS on oxidative stress injury of dopaminergic neurons in PD rats.Methods: Rat models of PD were established through the injection of 6-hydroxydopamine. The rotation of rats was induced by intraperitoneal injection of apomorphine, and number of rotations per minute was detected. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), glutamic acid (Glu), dopamine (DA), tyrosine hydroxylase (TH), α-synuclein and inducible nitric oxide synthase (iNOS) in the substantia nigra of rats in each group were detected. Apoptosis and pathological changes in the substantia nigra were also observed. BACE1-AS, miR-34b-5p, BACE1, Bax and Bcl-2 expression in the substantia nigra were detected. The binding of BACE1-AS and miR-34b-5p and the targeting relationship of miR-34b-5p and BACE1 were further determined.Results: Downregulated BACE1-AS reduced iNOS, α-synuclein and Glu levels and elevated DA and TH levels in the substantia nigra of PD rats. Downregulated BACE1-AS repressed apoptosis and oxidative stress injury in the substantia nigra neurons of PD rats. BACE1-AS specifically bound to miR-34b-5p. BACE1 was a direct target gene of miR-34b-5p.Conclusion: Collectively, our study reveals that downregulation of lncRNA BACE1-AS inhibits iNOS activation in the substantial nigra and improve oxidative stress injury in PD rats by upregulating miR-34b-5p and downregulating BACE1.

Respiratory pattern and phrenic and hypoglossal nerve activity during normoxia and hypoxia in 6-OHDA-induced bilateral model of Parkinson's disease

Respiratory disturbances present in Parkinson's disease (PD) are not well understood. Thus, studies in animal models aimed to link brain dopamine (DA) deficits with respiratory impairment are needed. Adult Wistar rats were lesioned with injection of 6-hydroxydopamine (6-OHDA) into the third cerebral ventricle. Two weeks after hypoxic test was performed in whole-body plethysmography chamber, phrenic (PHR) and hypoglossal (HG) nerve activities were recorded in normoxic and hypoxic conditions in anesthetized, vagotomized, paralyzed and mechanically ventilated rats. The effects of activation and blockade of dopaminergic carotid body receptors were investigated during normoxia in anesthetized spontaneously breathing rats. 6-OHDA injection affected resting respiratory pattern in awake animals: an increase in tidal volume and a decrease in respiratory rate had no effect on minute ventilation. Hypoxia magnified the amplitude and minute activity of the PHR and HG nerve of 6-OHDA rats. The ratio of pre-inspiratory to inspiratory HG burst amplitude was reduced in normoxic breathing. Yet, the ratio of pre-inspiratory time to total time of the respiratory cycle was increased during normoxia. 6-OHDA lesion had no impact on DA and domperidone effects on the respiratory pattern, which indicate that peripheral DA receptors are not affected in this model. Analysis of monoamines confirmed substantial striatal depletion of dopamine, serotonin and noradrenaline (NA) and reduction of NA content in the brainstem. In bilateral 6-OHDA model changes in activity of both nerves: HG (linked with increased apnea episodes) and PHR are present. Demonstrated respiratory effects could be related to specific depletion of DA and NA.

The effects simultaneous inhibition of dipeptidyl peptidase-4 and P2X7 purinoceptors in an in vivo Parkinson's disease model

Loss of dopaminergic neurons following Parkinson's disease (PD) diminishes quality of life in patients. The present study was carried out to investigate the protective effects of simultaneous inhibition of dipeptidyl peptidase-4 (DPP-4) and P2X7 purinoceptors in a PD model and explore possible mechanisms. The 6-hydroxydopamine (6-OHDA) was used as a tool to establish PD model in male Wister rats. The expressions of SIRT1, SIRT3, mTOR, PGC-1α, PTEN, P53 and DNA fragmentation were evaluated by ELISA assay. Behavioral impairments were determined using apomorphine-induced rotational and narrow beam tests. Dopamine synthesis and TH-positive neurons were detected by tyrosine hydroxylase (TH) immunohistochemistry. Neuronal density was determined by Nissl staining. OHDA-lesioned rats exhibited behavioral impairments that reversed by BBG, lin and lin + BBG. We found significant reduced levels of SIRT1, SIRT3, PGC-1α and mTOR in both mid brain and striatum from OHDA-lesioned rats that reversed by BBG, lin and lin + BBG. Likewise, significant increased levels of PTEN and P53 were found in both mid brain and striatum from OHDA-lesioned rats that was reversed by BBG, lin and lin + BBG. TH-positive neurons and neuronal density were markedly reduced OHDA-lesioned rats that reversed by BBG, lin and lin + BBG. Collectively, our results showed protective effects of simultaneous inhibition of DPP-4 and P2X7 purinoceptors in a rat model of PD can be linked to targeting SIRT1/SIRT3, PTEN-mTOR pathways. Moreover, our findings demonstrated that simultaneous inhibition of DPP-4 and P2X7 purinoceptors might have stronger effect on mitochondrial biogenesis compared to only one.

Neuroprotective effects of Bacopa monnieri in Parkinson's disease model

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by loss of dopaminergic neurons in substantia nigra region and the presence of α-synuclein aggregates in the striatum and surrounding areas of brain. Evidences suggest that neuroinflammation plays a role in the progression of PD. We examined the neuro-protective effects of Bacopa monnieri (BM) in regulating neuroinflammation. Administration of BM suppressed the level of pro-inflammatory cytokines, decreased the levels of α-synuclein, and reduced reactive oxygen species (ROS) generation in PD animal model. Pre-treatment of BM showed more prominent results as compare to co- and post-treatment. Results suggest that Bacopa can limit inflammation in the different areas of brain, thus, offers a promising source of novel therapeutics for the treatment of many CNS disorders.

Reciprocal cross-sensitization of D1 and D3 receptors following pharmacological stimulation in the hemiparkinsonian rat

In the majority of Parkinson's disease (PD) patients, long-term dopamine (DA) replacement therapy leads to dyskinesia characterized by abnormal involuntary movements (AIMs). There are various mechanisms of dyskinesia, such as the sensitization of striatal DA D1 receptors (D₁R) and upregulation of DA D3 receptors (D₃R). These receptors interact physically and functionally in D₁R-bearing medium spiny neurons to synergistically drive dyskinesia. However, the cross-receptor-mediated effects due to D₁R-D₃R cooperativity are still poorly understood. In pursuit of this, we examined whether or not pharmacological D₁R or D₃R stimulation sensitizes the dyskinetic response to the appositional agonist, a process known as cross-sensitization. First, we established D₁R-D₃R behavioral synergy in a cohort of 6-OHDA-lesioned female adult Sprague-Dawley rats. Then, in a new cohort, we tested for cross-sensitization in a between-subject design. Five groups received a sub-chronic regimen of either saline, the D₁R agonist SKF38393 (1.0 mg/kg), or the D₃R agonist PD128907 (0.3 mg/kg). For the final injection, each group received an acute injection of the other agonist. AIMs were monitored following each injection. Sub-chronic administration of both SKF38393 and PD128907 induced the development of dyskinesia. More importantly, cross-agonism tests revealed reciprocal cross-sensitization; chronic treatment with either SKF38393 or PD128907 induced sensitization to a single administration of the other agonist. This reciprocity was not marked by changes to either D₁R or D₃R striatal mRNA expression. The current study provides key behavioral data demonstrating the role of D3R in dyskinesia and provides behavioral evidence of D1R and D3R functional interactions.

Effects of bromelain on motor responses following intra-medial forebrain bundle 6-OHDA injection in rat model of parkinsonism

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. The conventional therapeutic measures which include the widely used L-DOPA therapy, are inefficient especially when dopamine loss is severe, and the physical symptoms are full blown. Since neuroinflammation is a core feature of PD, this raised the question of whether early treatment with an anti-inflammatory agent may provide a more efficient intervention for PD. In this study, we investigated the effect of bromelain (an anti-inflammatory drug) on motor responses and dopamine levels in a parkinsonian rat model. Male Sprague-Dawley rats were lesioned stereotaxically with the neurotoxin 6-OHDA. The anti-inflammatory agent, bromelain (40 mg/kg i.p) was used to treat a subset of the rats prior to or 24 h post 6-OHDA lesion. Locomotor activity was assessed after 6-OHDA injection, using the cylinder and step tests. The cortical and striatal concentrations of dopamine were also measured. 6-OHDA injection resulted in marked motor impairment which was prevented by pretreatment with bromelain prior to the lesion. Also, the injection of 6-OHDA into the medial forebrain bundle resulted in a significant reduction in dopamine concentration in the striatum and PFC. Bromelain treatment did not alter the suppression of cortical and striatal dopamine levels. Pre-treatment with bromelain reduced the motor dysfunction in the parkinsonian rat model of PD. The efficacy of treatment with bromelain does not appear to be via preservation of the dopaminergic system. The efficacy of bromelain in 6-OHDA injected rats still remains unclear.

Immature mDA neurons ameliorate motor deficits in a 6-OHDA Parkinson's disease mouse model and are functional after cryopreservation

Parkinson's disease is associated with the loss of dopaminergic neurons in the midbrain. Clinical studies investigating replacement of these neurons with in vitro-generated neurons are currently underway. However, this approach has been limited by difficulties in scaling up on-demand production of midbrain dopaminergic (mDA) neurons from pluripotent stem cells. Cryo-preservation may offer a solution, as it allows for banking of quality controlled mDA neurons. In this study, we tested different freezing conditions and found that optimal cryopreservation of immature human mDA neurons at an early differentiation time point was achieved in STEM-CELLBANKER medium using a controlled freezing program.

Study of BDE-47 induced Parkinson's disease-like metabolic changes in C57BL/6 mice by integrated metabolomic, lipidomic and proteomic analysis

As the predominant congener of polybrominated diphenyl ethers (PBDEs) detected in human serum, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) has been reported to induce neurotoxicity. However, the possible linkage between BDE-47 and typical neurodegenerative diseases such as Parkinson's disease (PD) is still unclear. Here we carried out omics studies using liquid chromatography-orbitrap mass spectrometry (LC-orbitrap MS) to depict the BDE-47 induced metabolic changes in C57BJ/L mice to explore the possible contribution of BDE-47 exposure to PD pathology. BDE-47 dissolved in corn oil was orally administered to mice for 30 consecutive days. Results of metabolomics and lipidomics studies of PD-related brain regions revealed significant metabolite changes in pathways involved in oxidative stress and neurotransmitter production. Moreover, isobaric tags for relative and absolute quantitation (iTRAQ) proteomics study of the striatum, which is the part of brain that is most intensively studied in PD pathogenesis, revealed that BDE-47 could induce neurotransmitter system disturbance, abnormal phosphorylation, mitochondrial dysfunction and oxidative stress. Overall, this study depicts the possible contribution of BDE-47 exposure to PD pathology and highlights the powerfulness of omics platforms to deepen the mechanistic understanding of environmental pollutant-caused toxicity.

Identification of miRNA-7 as a regulator of brain-derived neurotrophic factor/α-synuclein axis in atrazine-induced Parkinson's disease by peripheral blood and brain microRNA profiling

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine; ATR) is widely used as an herbicide, and its accumulation in the environment is a health risk to humans; for instance, it has been shown to cause dopaminergic neurotoxicity. MicroRNAs (miRNAs) are endogenous small RNAs that regulate gene expression in diverse physiological contexts; however, the extent of their involvement in the development of Parkinson's disease (PD) is not known. In this study, we carried out miRNA profiling of peripheral blood and brain tissue in a rat model of PD in order to identify factors that mediate PD pathogenesis. The miRNAmiR-7 is known to cause the downregulation of α-synuclein (α-syn), which is linked to the neuropathology of PD. Here we found that miR-7 was upregulated in brain tissue but downregulated in peripheral blood of rats with ATR-induced PD. We also found that miR-7 regulates the expression of brain-derived neurotrophic factor (BDNF) through an auto regulatory mechanism. These findings indicate that miRNA-7 regulates the BDNF/α-syn axis in the early stages of PD and can serve as a biomarker or therapeutic target for disease treatment.

Prophylactic neuroprotective propensity of Crocin, a carotenoid against rotenone induced neurotoxicity in mice: behavioural and biochemical evidence

Previously we have demonstrated the potential neuroprotective propensity of saffron and Crocin (CR) employing a Drosophila model of Parkinsonism. Rotenone (ROT) has been extensively used as a model neurotoxin to induce Parkinson's disease (PD) like symptoms in mice. In the present study, as a proof of concept we evaluated the efficacy of CR prophylaxis (25 mg/ kg bw/d, 7d) to attenuate ROT(0.5 mg/Kg bw/d,7d) -induced neurotoxic effects in male mice focussing on neurobehavioural assessments and biochemical determinants in the striatum. CR prophylaxis significantly alleviated ROT-induced behavioural alterations such as increased anxiety, diminished exploratory behaviour, decreased motor co-ordination, and grip strength. Concomitantly, we evidenced diminution of oxidative stress markers, enhanced levels of antioxidant enzyme and mitochondrial enzyme function in the striatal region. Further, varying degree of restoration of cholinergic function, dopamine and α-synuclein levels were discernible suggesting the possible mechanism/s of action of CR in this model. Based on our earlier data in flies and in worm model, we propose its use as an adjuvant therapeutic agent in oxidative stress-mediated neurodegenerative conditions such as PD.

Acrolein-mediated alpha-synuclein pathology involvement in the early post-injury pathogenesis of mild blast-induced Parkinsonian neurodegeneration

Survivors of blast-induced traumatic brain injury (bTBI) have increased susceptibility to Parkinson's disease (PD), characterized by α-synuclein aggregation and the progressive degeneration of nigrostriatal dopaminergic neurons. Using an established bTBI rat model, we evaluated the changes of α-synuclein and tyrosine hydroxylase (TH), known hallmarks of PD, and acrolein, a reactive aldehyde and marker of oxidative stress, with the aim of revealing key pathways leading to PD post-bTBI. Indicated in both animal models of PD and TBI, acrolein is likely a point of pathogenic convergence. Here we show that after a single mild bTBI, acrolein is elevated up to a week, systemically in urine, and in whole brain tissue, specifically the substantia nigra and striatum. Acrolein elevation is accompanied by heightened α-synuclein oligomerization, dopaminergic dysregulation, and acrolein/α-synuclein interaction in the same brain regions. We further show that acrolein can directly modify and oligomerize α-synuclein in vitro. Taken together, our data suggests acrolein likely plays an important role in inducing PD pathology following bTBI by encouraging α-synuclein aggregation. These results are expected to advance our understanding of the long-term post-bTBI pathological changes leading to the development of PD, and suggest intervention targets to curtail such pathology.

Apelin-13 attenuates motor impairments and prevents the changes in synaptic plasticity-related molecules in the striatum of Parkinsonism rats

The striatum plays a critical role in motor control and also learning and memory of motor skills. It has been reported that striatal synaptic components are significantly decreased in dopaminergic-denervated striatum. In this study the effects of apelin-13 were investigated on motor disorders and striatal synaptosomal expression of PSD-95, neurexin1, neuroligin, metabotropic glutamate receptor (mGlu R1) and dopaminergic receptors (DR1 and DR2) in rat parkinsonism experimental model. 6-hydroxydopamine (6-OHDA) was injected into the substantia nigra. Apelin-13 (1, 2 and 3 μg/rat) was administered into the substantia nigra one week after the 6-OHDA injection. Accelerating rotarod, beam-balance, beam-walking and bar tests were performed one month after the apelin injection. Immunohistochemistry staining of dopaminergic neurons was performed. The levels of synaptic proteins were determined by immunoblotting. 6-OHDA-treated animals showed a significant impairment in motor-skill tasks and a dramatically change in the expression levels of mentioned proteins. Apelin-13 (3 μg/rat) significantly attenuates the motor impairments and prevents the changes in striatal synaptic elements in 6-OHDA-treated animals. In addition, it could rescue the dopaminergic neurons of the substantia nigra. The data will potentially extend the possible benefic aspect of apelin in neurodegenerative disorders.

Effect of phenothiazine compounds on the secondary structure and fibrillogenesis of poly-l-lysine

Phenothiazine molecules are effective and commonly used antipsychotic drugs, especially in the treatment of schizophrenia. However, they produce strong extrapyramidal side-effects manifested by drug-induced parkinsonism. Because Parkinson's disease as a neurodegenerative illness is associated with the formation of amyloid fibrils in neuronal cells, it is postulated that the development of phenothiazine-induced parkinsonism may be related to the phenothiazine-induced formation of fibrillar aggregates. The effect of phenothiazine compounds (fluphenazine (FPh), chlorpromazine (ChP) and propionylpromazine (PP)) on the fibrillogenesis of poly-l-lysine (PLL) was studied using Fourier-transform infrared (FTIR) spectroscopy supported by principal component analysis (PCA), vibrational circular dichroism (VCD), transmission electron microscopy (TEM) and Congo red binding assay. The fibrillogenesis of PLL is accompanied by fibril formation with charged or uncharged polypeptides with PPII (polyproline-like extended helix), α-helix or β-sheet conformations. All of the phenothiazine molecules investigated effectively reduced the temperature required to induce the formation of β-sheet-rich fibrils from α-helix-rich fibrils of PLL.

Chlorpyrifos activates cell pyroptosis and increases susceptibility on oxidative stress-induced toxicity by miR-181/SIRT1/PGC-1α/Nrf2 signaling pathway in human neuroblastoma SH-SY5Y cells: Implication for association between chlorpyrifos and Parkinson's disease

BACKGROUND

The insecticide exposure has been linked to Parkinson's disease (PD). In the present study, we used a most widely used cell line in study of PD, the SH-SY5Y cells, to investigate mechanisms of chlorpyrifos (CPF) induced cell toxicity and the possible roles of cell pyroptosis and oxidative stress in SH-SY5Y cells, as well as role of miR-181/SIRT1/PGC-1α/Nrf2 signaling pathway in this process.

METHODS

SH-SY5Y cells were treated with different concentrations of CPF. Cell viability was measured using CCK-8 assay. Cell pyroptosis was determined by immunofluorescence of caspase-1 and TUNEL assay. The miR-181 (has-miR-181-5p) level was determined by qRT-PCR. Expression of SIRT1, PGC-1α, Nrf2, and pyroptosis related proteins NLRP3, caspase-1, IL-1β, and IL-18 was determined by both qRT-PCR and Western blotting.

RESULTS

Cell viability was found to be decreased with the increased CPF concentrations. The pyroptosis related proteins, ROS levels, as well as level of caspase-1 and the TUNEL positive cells were all significantly up-regulated by CPF. Meanwhile, expression of miR-181 and pyroptosis proteins was also enhanced, while the SIRT1/PGC-1α/Nrf2 signaling was inhibited by CPF. Knockdown of Nrf2 significantly up-regulated the expression of pyroptosis related proteins, ROS level, caspase-1, and the TUNEL positive cells, while over-expression of Nrf2 resulted in opposite results. The expression of PGC-1α and Nrf2 was significantly down-regulated when SIRT1 was inhibited, while over-expressed SIRT1 led to increased PGC-1α and Nrf2 levels. Besides, miR-181 promoted the CPF induced activation of pyroptosis and oxidative stress, as well as down-regulated SIRT1/PGC-1α/Nrf2 signaling, while inhibition of miR-181 led to opposite results.

CONCLUSIONS

Chlorpyrifos could inhibit cell proliferation, activate cell pyroptosis and increase susceptibility on oxidative stress-induced toxicity by elevating miR-181 through down-regulation of the SIRT1/PGC-1α/Nrf2 pathway in human neuroblastoma SH-SY5Y cells. This study might give deeper insights for mechanisms of CPF induced toxicity and might give some novel research targets for PD treatment.

Chrysin protects against behavioral, cognitive and neurochemical alterations in a 6-hydroxydopamine model of Parkinson's disease

Parkinson's disease (PD) is an age-related neurodegenerative disorder that severely affects quality of life of patients and their families. The flavonoid chrysin (5,7-dihydroxylflavone) is a naturally occurring flavone with several pharmacological activities, including anti-inflammatory and anti-oxidative. We investigated the effects of a 28-day chrysin treatment (10 mg/kg/day, i.g.) on a model of PD induced by 6-OHDA in aged (20-month old) mice. We found a protective effect of chrysin on behavioral and cognitive alterations (rotational behavior, passive avoidance and Barnes maze tests), nitric oxide synthesis (NOx), lipid peroxidation (HNE), glutathione levels (GSH), reactive species levels (RS), neuroinflammation (interleukin-1 beta - IL-1β and tumor necrosis factor alpha - TNF-α), Na⁺, K⁺-ATPase and nicotinamide adenine dinucleotide phosphate oxidase activity (NADPH oxidase) activities. In addition, chrysin protected against changes in striatal dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels. In conclusion, chrysin improved several behavioral, cognitive and neurochemical parameters in a relevant preclinical model of PD in aged mice.

Pridopidine Induces Functional Neurorestoration Via the Sigma-1 Receptor in a Mouse Model of Parkinson's Disease

Pridopidine is a small molecule in clinical development for the treatment of Huntington's disease. It was recently found to have high binding affinity to the sigma-1 receptor, a chaperone protein involved in cellular defense mechanisms and neuroplasticity. Here, we have evaluated the neuroprotective and neurorestorative effects of pridopidine in a unilateral 6-hydroxydopamine (6-OHDA) lesion model of parkinsonism in mice. By 5 weeks of daily administration, a low dose of pridopidine (0.3 mg/kg) had significantly improved deficits in forelimb use (cylinder test, stepping test) and abolished the ipsilateral rotational bias typical of hemiparkinsonian animals. A higher dose of pridopidine (1 mg/kg) significantly improved only the rotational bias, with a trend towards improvement in forelimb use. The behavioral recovery induced by pridopidine 0.3 mg/kg was accompanied by a significant protection of nigral dopamine cell bodies, an increased dopaminergic fiber density in the striatum, and striatal upregulation of GDNF, BDNF, and phosphorylated ERK1/2. The beneficial effects of pridopidine 0.3 mg/kg were absent in 6-OHDA-lesioned mice lacking the sigma-1 receptor. Pharmacokinetic data confirmed that the effective dose of pridopidine reached brain concentrations sufficient to bind S1R. Our results are the first to show that pridopidine promotes functional neurorestoration in the damaged nigrostriatal system acting via the sigma-1 receptor.

Increasing the TRPM2 Channel Expression in Human Neuroblastoma SH-SY5Y Cells Augments the Susceptibility to ROS-Induced Cell Death

Human neuroblastoma SH-SY5Y cells are a widely-used human neuronal cell model in the study of neurodegeneration. A recent study shows that, 1-methyl-4-phenylpyridine ion (MPP), which selectively causes dopaminergic neuronal death leading to Parkinson’s disease-like symptoms, can reduce SH-SY5Y cell viability by inducing H₂O₂ generation and subsequent TRPM2 channel activation. MPP-induced cell death is enhanced by increasing the TRPM2 expression. By contrast, increasing the TRPM2 expression has also been reported to support SH-SY5Y cell survival after exposure to H₂O₂, leading to the suggestion of a protective role for the TRPM2 channel. To clarify the role of reactive oxygen species (ROS)-induced TRPM2 channel activation in SH-SY5Y cells, we generated a stable SH-SY5Y cell line overexpressing the human TRPM2 channel and examined cell death and cell viability after exposure to H₂O₂ in the wild-type and TRPM2-overexpressing SH-SY5Y cells. Exposure to H₂O₂ resulted in concentration-dependent cell death and reduction in cell viability in both cell types. TRPM2 overexpression remarkably augmented H₂O₂-induced cell death and reduction in cell viability. Furthermore, H₂O₂-induced cell death in both the wild-type and TRPM2-overexpressing cells was prevented by 2-APB, a TRPM2 inhibitor, and also by PJ34 and DPQ, poly(ADP-ribose) polymerase (PARP) inhibitors. Collectively, our results show that increasing the TRPM2 expression renders SH-SY5Y cells to be more susceptible to ROS-induced cell death and reinforce the notion that the TRPM2 channel plays a critical role in conferring ROS-induced cell death. It is anticipated that SH-SY5Y cells can be useful for better understanding the molecular and signaling mechanisms for ROS-induced TRPM2-mediated neurodegeneration in the pathogenesis of neurodegenerative diseases.

ATP13A2 facilitates HDAC6 recruitment to lysosome to promote autophagosome-lysosome fusion

Mutations in ATP13A2 cause Kufor-Rakeb syndrome, an autosomal recessive form of juvenile-onset atypical Parkinson's disease (PD). Recent work tied ATP13A2 to autophagy and other cellular features of neurodegeneration, but how ATP13A2 governs numerous cellular functions in PD pathogenesis is not understood. In this study, the ATP13A2-deficient mouse developed into aging-dependent phenotypes resembling those of autophagy impairment. ATP13A2 deficiency impaired autophagosome-lysosome fusion in cultured cells and in in vitro reconstitution assays. In ATP13A2-deficient cells or Drosophila melanogaster or mouse tissues, lysosomal localization and activity of HDAC6 were reduced, with increased acetylation of tubulin and cortactin. Wild-type HDAC6, but not a deacetylase-inactive mutant, restored autophagosome-lysosome fusion, antagonized cortactin hyperacetylation, and promoted lysosomal localization of cortactin in ATP13A2-deficient cells. Mechanistically, ATP13A2 facilitated recruitment of HDAC6 and cortactin to lysosomes. Cortactin overexpression in cultured cells reversed ATP13A2 deficiency-associated impairment of autophagosome-lysosome fusion. PD-causing ATP13A2 mutants failed to rescue autophagosome-lysosome fusion or to promote degradation of protein aggregates and damaged mitochondria. These results suggest that ATP13A2 recruits HDAC6 to lysosomes to deacetylate cortactin and promotes autophagosome-lysosome fusion and autophagy. This study identifies ATP13A2 as an essential molecular component for normal autophagy flux in vivo and implies potential treatments targeting HDAC6-mediated autophagy for PD.

Axin-2 knockdown promote mitochondrial biogenesis and dopaminergic neurogenesis by regulating Wnt/β-catenin signaling in rat model of Parkinson's disease

Wnts and the components of Wnt/β-catenin signaling are widely expressed in midbrain and required to control the fate specification of dopaminergic (DAergic) neurons, a neuronal population that specifically degenerate in Parkinson's disease (PD). Accumulating evidence suggest that mitochondrial dysfunction plays a key role in pathogenesis of PD. Axin-2, a negative regulator of Wnt/β-catenin signaling affects mitochondrial biogenesis and death/birth of new DAergic neurons is not fully explored. We investigated the functional role of Axin-2/Wnt/β-catenin signaling in mitochondrial biogenesis and DAergic neurogenesis in 6-hydroxydopamine (6-OHDA) induced rat model of PD-like phenotypes. We demonstrate that single unilateral injection of 6-OHDA into the medial forebrain bundle (MFB) potentially dysregulates Wnt/β-catenin signaling in substantia nigra pars compacta (SNpc). We used shRNA lentiviruses to genetically knockdown Axin-2 to up-regulate Wnt/β-catenin signaling in SNpc in parkinsonian rats. Genetic knockdown of Axin-2 up-regulates Wnt/β-catenin signaling by destabilizing the β-catenin degradation complex in SNpc in parkinsonian rats. Axin-2 shRNA mediated activation of Wnt/β-catenin signaling improved behavioural functions and protected the nigral DAergic neurons by increasing mitochondrial functionality in parkinsonian rats. Axin-2 shRNA treatment reduced apoptotic signaling, autophagy and ROS generation and improved mitochondrial membrane potential which promotes mitochondrial biogenesis in SNpc in parkinsonian rats. Interestingly, Axin-2 shRNA-mediated up-regulation of Wnt/β-catenin signaling enhanced net DAergic neurogenesis by regulating proneural genes (Nurr-1, Pitx-3, Ngn-2, and NeuroD1) and mitochondrial biogenesis in SNpc in parkinsonian rats. Therefore, our data suggest that pharmacological/genetic manipulation of Wnt signaling that enhances the endogenous regenerative capacity of DAergic neurons may have implication for regenerative approaches in PD.

Novel action of vinpocetine in the prevention of paraquat-induced parkinsonism in mice: involvement of oxidative stress and neuroinflammation

Parkinson's disease (PD) is a multifactorial chronic progressive neurodegenerative disease caused by age, genetic and environmental factors such as paraquat (PQT). PQT (a quartenary nitrogen herbicide) is implicated in some form of idiopathic PD. This study sought to investigate the protective effect of vinpocetine on paraquat-induced Parkinsonism in mice. Forty-eight male albino mice were randomly divided into 6 groups and treated orally as follows for 21 days; Group 1: vehicle normal (10 ml/kg), group 2: vehicle control (10 ml/kg); groups 3-5: vinpocetine (5, 10 or 20 mg/kg); group 6: vinpocetine (20 mg/kg). Animals in groups 2-5 were given PQT (10 mg/kg, i.p.) every 3 days for 3 weeks. The effect of treatments on spontaneous motor activity (open field test), muscle coordination (rotarod tests), cataleptic behaviour (bar test), and working memory (Y-maze test) were assayed. After the behavioural assay on day 21, the midbrain was isolated for estimation of oxidative stress and TNF-α. Intraperitoneal injection of paraquat significantly induced motor deficits, muscle incoordination, catalepsy and working memory impairment which was ameliorated by the pretreatment of mice with vinpocetine. In addition, paraquat injection caused marked increase in nitroso-oxidative stress markers with concomitant deficits in antioxidant enzymes activities (GSH and SOD) as well as induction of tumour necrotic factor-α (TNF-α) in the mid-brain which were attenuated by the pretreatment of mice with vinpocetine. Findings from this study showed that vinpocetine prevented paraquat-induced motor deficits, memory impairment, oxidative stress and neuroinflammation through enhancement of antioxidant defense system and inhibition of neuroinflammatory cytokine. Thus, could be a potential drug in the management of Parkinsonism.

DAT-SPECT imaging in cases of drug-induced parkinsonism in a specialty movement disorders practice

OBJECTIVE

Compare clinical characteristics and outcomes in cases where DAT-SPECT imaging is used to distinguish Parkinson's disease from Drug-Induced Parkinsonsim.

BACKGROUND

Clinical uncertainty in diagnosing Parkinson's disease is common when patients are on dopamine-blocking medications. DAT-SPECT imaging can improve diagnostic certainty but little data are available on clinical characteristics and outcomes associated with normal and abnormal scan results.

METHODS

Retrospective chart review of patients seen at a movement disorders center between 2011 and 2017 where DAT-SPECT was ordered to distinguish Parkinson's disease from Drug-induced Parkinsonism. Descriptive statistics were calculated for variables of interest and compared by scan result. Chi-squared analyses was carried out for categorical variables and students' t-tests for continuous values.

RESULTS

51 patients met inclusion criteria with 36 normal scans and 15 abnormal scans. Those with greater than 2 cardinal manifestations (tremor, rigidity, akinesia, postural instability) were more likely to have an abnormal scan (63.89% vs 93.33%, p = 0.04). No other clinical characteristics assessed were associated with scan results. Atypical antipsychotics (aripiprazole 39.21%, olanzapine 31.37%) and mood stabilizers (valproic acid 33.33%, lithium 17.65%) were most commonly associated with suspected Drug-induced Parkinsonism cases. A post-scan change in management occurred in 41.18% of patients. 55.56% of patients with normal scans responded to changes in the offending medication, with 16.66% taking over 3 months to show improvement.

CONCLUSIONS

Many DAT-SPECT scans at our institution are ordered to distinguish Parkinson's disease from Drug-induced Parkinsonism because clinical characteristics alone are unreliable. DAT-SPECT results lead to changes in management and the outcomes of these changes are consistent with scan results.

Taurine protects noradrenergic locus coeruleus neurons in a mouse Parkinson's disease model by inhibiting microglial M1 polarization

Beyond nigrostriatal dopaminergic system, the noradrenergic locus coeruleus (LC/NE) neurons are also degenerated in patients with Parkinson's disease (PD), the second most common neurodegenerative disorder. We previously reported that microglia-mediated neuroinflammation contributes to LC/NE neurodegeneration. The purpose of this study is aimed to test whether taurine, an endogenous amino acid, could be able to protect LC/NE neurons through inhibition of microglial activation using paraquat and maneb-induced mouse PD model. Taurine (150 mg/kg) was administrated (i.p) to mice 30 min prior to paraquat (10 mg/kg) and maneb (30 mg/kg) intoxication for consecutive 6 weeks (twice per week). The results clearly demonstrated that paraquat and maneb co-exposure resulted in loss of tyrosine hydroxylase-positive neurons in the LC in mice, which was significantly ameliorated by taurine. Mechanistically, inhibition of microglia-mediated neuroinflammation contributed to taurine-afforded neuroprotection. Taurine attenuated paraquat and maneb-induced microglial activation and M1 polarization as well as release of proinflammatory cytokines in brainstem of mice. Taurine also abrogated microglial NADPH oxidase activation and oxidative damage in paraquat and maneb-treated mice. Furthermore, inhibition of nuclear factor-κB (NF-κB) but not signal transducers and activators of transcription 1/3 (STAT1/3) signaling pathway participated in taurine-inhibited microglial activation. Collectively, taurine exerted LC/NE neuroprotection against microglia-mediated neurotoxicity. The robust neuroprotective effects of taurine suggest that taurine may be a promising candidate for potential therapy for patients suffering from PD.

Targeted deletion of the aquaglyceroporin AQP9 is protective in a mouse model of Parkinson's disease

More than 90% of the cases of Parkinson’s disease have unknown etiology. Gradual loss of dopaminergic neurons of substantia nigra is the main cause of morbidity in this disease. External factors such as environmental toxins are believed to play a role in the cell loss, although the cause of the selective vulnerability of dopaminergic neurons remains unknown. We have previously shown that aquaglyceroporin AQP9 is expressed in dopaminergic neurons and astrocytes of rodent brain. AQP9 is permeable to a broad spectrum of substrates including purines, pyrimidines, and lactate, in addition to water and glycerol. Here we test our hypothesis that AQP9 serves as an influx route for exogenous toxins and, hence, may contribute to the selective vulnerability of nigral dopaminergic (tyrosine hydroxylase-positive) neurons. Using Xenopus oocytes injected with Aqp9 cRNA, we show that AQP9 is permeable to the parkinsonogenic toxin 1-methyl-4-phenylpyridinium (MPP⁺). Stable expression of AQP9 in HEK cells increases their vulnerability to MPP+ and to arsenite—another parkinsonogenic toxin. Conversely, targeted deletion of Aqp9 in mice protects nigral dopaminergic neurons against MPP⁺ toxicity. A protective effect of Aqp9 deletion was demonstrated in organotypic slice cultures of mouse midbrain exposed to MPP⁺in vitro and in mice subjected to intrastriatal injections of MPP⁺in vivo. Seven days after intrastriatal MPP⁺ injections, the population of tyrosine hydroxylase-positive cells in substantia nigra is reduced by 48% in Aqp9 knockout mice compared with 67% in WT littermates. Our results show that AQP9 –selectively expressed in catecholaminergic neurons—is permeable to MPP⁺ and suggest that this aquaglyceroporin contributes to the selective vulnerability of nigral dopaminergic neurons by providing an entry route for parkinsonogenic toxins. To our knowledge this is the first evidence implicating a toxin permeable membrane channel in the pathophysiology of Parkinson’s disease.

Manganese exposure exacerbates progressive motor deficits and neurodegeneration in the MitoPark mouse model of Parkinson's disease: Relevance to gene and environment interactions in metal neurotoxicity

Parkinson's disease (PD) is now recognized as a neurodegenerative condition caused by a complex interplay of genetic and environmental influences. Chronic manganese (Mn) exposure has been implicated in the development of PD. Since mitochondrial dysfunction is associated with PD pathology as well as Mn neurotoxicity, we investigated whether Mn exposure augments mitochondrial dysfunction and neurodegeneration in the nigrostriatal dopaminergic system using a newly available mitochondrially defective transgenic mouse model of PD, the MitoPark mouse. This unique PD model recapitulates key features of the disease including progressive neurobehavioral changes and neuronal degeneration. We exposed MitoPark mice to a low dose of Mn (10mg/kg, p.o.) daily for 4 weeks starting at age 8 wks and then determined the behavioral, neurochemical and histological changes. Mn exposure accelerated the rate of progression of motor deficits in MitoPark mice when compared to the untreated MitoPark group. Mn also worsened olfactory function in this model. Most importantly, Mn exposure intensified the depletion of striatal dopamine and nigral TH neuronal loss in MitoPark mice. The neurodegenerative changes were accompanied by enhanced oxidative damage in the striatum and substantia nigra (SN) of MitoPark mice treated with Mn. Furthermore, Mn-treated MitoPark mice had significantly more oligomeric protein and IBA-1-immunoreactive microglia cells, suggesting Mn augments neuroinflammatory processes in the nigrostriatal pathway. To further confirm the direct effect of Mn on impaired mitochondrial function, we also generated a mitochondrially defective dopaminergic cell model by knocking out the TFAM transcription factor by using a CRISPR-Cas9 gene-editing method. Seahorse mitochondrial bioenergetic analysis revealed that Mn decreases mitochondrial basal and ATP-linked respiration in the TFAM KO cells. Collectively, our results reveal that Mn can augment mitochondrial dysfunction to exacerbate nigrostriatal neurodegeneration and PD-related behavioral symptoms. Our study also demonstrates that the MitoPark mouse is an excellent model to study the gene-environment interactions associated with mitochondrial defects in the nigral dopaminergic system as well as to evaluate the contribution of potential environmental toxicant interactions in a slowly progressive model of Parkinsonism.

Alpha-synuclein aggregation, Ubiquitin proteasome system impairment, and L-Dopa response in zinc-induced Parkinsonism: resemblance to sporadic Parkinson's disease

Alpha-synuclein (α-synuclein) aggregation and impairment of the Ubiquitin proteasome system (UPS) are implicated in Parkinson's disease (PD) pathogenesis. While zinc (Zn) induces dopaminergic neurodegeneration resulting in PD phenotype, its effect on protein aggregation and UPS has not yet been deciphered. The current study investigated the role of α-synuclein aggregation and UPS in Zn-induced Parkinsonism. Additionally, levodopa (L-Dopa) response was assessed in Zn-induced Parkinsonian model to establish its closeness with idiopathic PD. Male Wistar rats were treated with zinc sulfate (Zn; 20 mg/kg; i.p.) twice weekly for 12 weeks along with respective controls. In few subsets, animals were subsequently treated with L-Dopa for 21 consecutive days following Zn exposure. A significant increase in total and free Zn content was observed in the substantia nigra of the brain of exposed groups. Zn treatment caused neurobehavioral anomalies, striatal dopamine decline, and dopaminergic neuronal cell loss accompanied with a marked increase in α-synuclein expression/aggregation and Ubiquitin-conjugated protein levels in the exposed groups. Zn exposure substantially reduced UPS-associated trypsin-like, chymotrypsin-like, and caspase-like activities along with the expression of SUG1 and β-5 subunits of UPS in the nigrostriatal tissues of exposed groups. L-Dopa treatment rescued from Zn-induced neurobehavioral deficits and restored dopamine levels towards normalcy; however, Zn-induced dopaminergic neuronal loss, reduction in tyrosine hydroxylase expression, and increase in oxidative stress were unaffected. The results suggest that Zn caused UPS impairment, resulting in α-synuclein aggregation subsequently leading to dopaminergic neurodegeneration, and that Zn-induced Parkinsonism exhibited positive L-Dopa response similar to sporadic PD.

Brown adipose tissue activation in a rat model of Parkinson's disease

Loss of body weight and fat mass is one of the nonmotor symptoms of Parkinson's disease (PD). Weight loss is due primarily to reduced energy intake and increased energy expenditure. Whereas inadequate energy intake in PD patients is caused mainly by appetite loss and impaired gastrointestinal absorption, the underlying mechanisms for increased energy expenditure remain largely unknown. Brown adipose tissue (BAT), a key thermogenic tissue in humans and other mammals, plays an important role in thermoregulation and energy metabolism; however, it has not been tested whether BAT is involved in the negative energy balance in PD. Here, using the 6-hydroxydopamine (6-OHDA) rat model of PD, we found that the activity of sympathetic nerve (SN), the expression of Ucp1 in BAT, and thermogenesis were increased in PD rats. BAT sympathetic denervation blocked sympathetic activity and decreased UCP1 expression in BAT and attenuated the loss of body weight in PD rats. Interestingly, sympathetic denervation of BAT was associated with decreased sympathetic tone and lipolysis in retroperitoneal and epididymal white adipose tissue. Our data suggeste that BAT-mediated thermogenesis may contribute to weight loss in PD.

A Nigro-Vagal Pathway Controls Gastric Motility and Is Affected in a Rat Model of Parkinsonism

BACKGROUND & AIMS

In most patients with Parkinson's disease, gastrointestinal (GI) dysfunctions, such as gastroparesis and constipation, are prodromal to the cardinal motor symptoms of the disease. Sporadic Parkinson's disease has been proposed to develop after ingestion of neurotoxicants that affect the brain-gut axis via the vagus nerve, and then travel to higher centers, compromising the substantia nigra pars compacta (SNpc) and, later, the cerebral cortex. We aimed to identify the pathway that connects the brainstem vagal nuclei and the SNpc, and to determine whether this pathway is compromised in a rat model of Parkinsonism.

METHODS

To study this neural pathway in rats, we placed tracers in the dorsal vagal complex or SNpc; brainstem and midbrain were examined for tracer distribution and neuronal neurochemical phenotype. Rats were given injections of paraquat once weekly for 3 weeks to induce features of Parkinsonism, or vehicle (control). Gastric tone and motility were recorded after N-methyl-d-aspartate microinjection in the SNpc and/or optogenetic stimulation of nigro-vagal terminals in the dorsal vagal complex.

RESULTS

Stimulation of the SNpc increased gastric tone and motility via activation of dopamine 1 receptors in the dorsal vagal complex. In the paraquat-induced model of Parkinsonism, this nigro-vagal pathway was compromised during the early stages of motor deficit development.

CONCLUSIONS

We identified and characterized a nigro-vagal monosynaptic pathway in rats that controls gastric tone and motility. This pathway might be involved in the prodromal gastric dysmotility observed in patients with early-stage Parkinson's disease.

Effects of Electroacupuncture on Metabolic Changes in Motor Cortex and Striatum of 6-Hydroxydopamine-Induced Parkinsonian Rats

OBJECTIVE

To explore the possible underlying mechanism by investigating the effect of electroacupuncture (EA) treatment on the primary motor cortex and striatum in a unilateral 6-hydroxydopamine (6-OHDA) induced rat Parkinson's disease (PD) model.

METHODS

Male Sprague-Dawley rats were randomly divided into sham group (n=16), model group (n=14), and EA group (n=14). EA stimulation at Dazhui (GV 14) and Baihui (GV20) was applied to PD rats in the EA group for 4 weeks. Behavioral tests were conducted to evaluate the effectiveness of EA treatment. Metabolites were detected by 7.0 T proton nuclear magnetic resonance.

RESULTS

Following 4 weeks of EA treatment in PD model rats, the abnormal behavioral impairment induced by 6-OHDA was alleviated. In monitoring changes in metabolic activity, ratios of myoinositol/creatine (Cr) and N-acetyl aspartate (NAA)/Cr in the primary motor cortex were significantly lower at the injected side than the non-injected side in PD rats (P=0.024 and 0.020). The ratios of glutamate + glutamine (Glx)/Cr and NAA/Cr in the striatum were higher and lower, respectively, at the injected side than the non-injected side (P=0.046 and 0.008). EA treatment restored the balance of metabolic activity in the primary motor cortex and striatum. In addition, the taurine/Cr ratio and Glx/Cr ratio were elevated in the striatum of PD model rats compared to sham-lesioned rats (P=0.026 and 0.000). EA treatment alleviated the excessive glutamatergic transmission by down-regulating the striatal Glx/Cr ratio (P=0.001). The Glx/Cr ratio was negatively correlated with floor plane spontaneous locomotion in PD rats (P=0.027 and P=0.0007).

CONCLUSIONS

EA treatment is able to normalize the metabolic balance in the primary motor cortex and striatum of PD rats, which may contribute to its therapeutic effect on motor deficits. The striatal Glx/Cr ratio may serve as a potential indicator of PD and a therapeutic target of EA treatment.

Neuroprotective Effects of Loganin on MPTP-Induced Parkinson's Disease Mice: Neurochemistry, Glial Reaction and Autophagy Studies

Parkinson's disease (PD) is a progressive neurodegenerative disease, involving resting tremor and bradykinesia, for which no recognized therapies or drugs are available to halt or slow progression. In recent years, natural botanic products have been considered relatively safe, with limited side effects, and are expected to become an important source for clinical mediation of PD in the future. Our study focuses on the ability of loganin, a compound derived from fruits of cornus, to mediate neuroprotection in a mouse model of PD. Mice were administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) with a dosage of 30 mg/kg daily for 5 days to establish a subacute PD model and treated with loganin. Locomotor activity was assessed by a pole test, then mice were euthanized at 1 and 3 days after the last treatment, and brain tissue was prepared for subsequent assays. Loganin rescued decrease of dopamine levels and tyrosine hydroxylase (TH) expression in the striatum, and shortened total locomotor activity (TLA) time of mice. Furthermore, loganin alleviated microglia and astrocyte activation, and suppressed TNF-α and caspase-3 expression through a c-Abl-p38-NFκB pathway. Loganin also downregulated LC3-II and Drp1 expression, and decreased the level of acidic vesicular organelles (AVOs). Loganin exerts neuroprotective effects on MPTP-induced PD mice by decreasing inflammation, autophagy, and apoptosis, suggesting that loganin could serve as a therapeutic drug to ameliorate PD. J. Cell. Biochem. 118: 3495-3510, 2017. © 2017 Wiley Periodicals, Inc.

Metabolic Energy Capacity of Dopaminergic Grafts and the Implanted Striatum in Parkinsonian Nonhuman Primates as Visualized with Cytochrome Oxidase Histochemistry

Histochemistry for visualization of the mitochondrial enzyme cytochrome oxidase has been used to detect cellular and regional differences in brain energy metabolism. We have examined the pattern of cytochrome oxidase (CO) staining in grafts of embryonic ventral mesencephalic tissue, and in the implanted striatum, of MPTP-treated monkeys as one index of the functional activity of grafted tissue and its influence on the host brain. Four monkeys were selected for study based on interesting variations in dopamine (DA) neuron content of their bilateral grafts as demonstrated with tyrosine-hydroxylase (TH) immunocytochemistry. The results suggest that grafts rich in DA neurons increase the metabolic activity of the implanted striatum of DA-depleted monkeys, and that this improvement of local energy metabolism is greater in the vicinity of grafts containing greater numbers of DA neurons. In addition, the pattern of CO staining within tissue transplants indicates that DA neurons exhibit the highest rate of metabolic activity among all cell types contained in the ventral mesencephalic grafts, and that the transplants receive metabolically active innervation from outside or within the grafted tissue.

Therapeutic efficacy of AAV8-mediated intrastriatal delivery of human cerebral dopamine neurotrophic factor in 6-OHDA-induced parkinsonian rat models with different disease progression

Parkinson’s disease (PD) is a progressive and age-associated neurodegenerative disorder. Patients at different stages of the disease course have distinguished features, mainly in the number of dopaminergic neurons. Cerebral dopamine neurotrophic factor (CDNF) is a recently discovered neurotrophic factor, being deemed as a hopeful candidate for PD treatment. Here, we evaluated the efficacy of CDNF in protecting dopaminergic function using the 6-OHDA-induced PD rat model suffering from different levels of neuronal loss and the recombinant adeno-associated virus 8 (AAV8) as a carrier for the CDNF gene. The results showed that AAV8-CDNF administration significantly improved the motor function and increased the tyrosine hydroxylase (TH) levels in PD rats with mild lesions (2 weeks post lesion), but it had limited therapeutic effects in rats with severe lesions (5 weeks post lesion). To better improve the recovery of motor function in severely lesioned PD rats, we employed a strategy using the CDNF gene along with the aromatic amino acid decarboxylase (AADC) gene. This combination therapeutic strategy indeed showed an enhanced benefit in restoring the motor function of severely lesioned PD rats by providing the neuroprotective effect of CDNF and dopamine enhancing effect of AADC as expected. This study may provide a basis for future clinical application of CDNF in PD patients at different stages and offer a new alternative strategy of joint use of CDNF and AADC for advanced PD patients in clinical trials.