Changes In Dopaminergic Neurons Research Articles

Therapeutic potential of Canna edulis RS3-resistant starch in alleviating neuroinflammation and apoptosis in a Parkinson's disease rat model

This study aimed to investigate the effects of Miao medicinal Canna edulis RS3-resistant starch on behavioral performance and substantia nigra neuron apoptosis-related indicators in a rat model of Parkinson's disease (PD). Among the experimental groups, except for the control group, we induced PD rat models by subcutaneous injection of rotenone in the neck and back. After model induction, a 28-day drug intervention was conducted. Various techniques have been employed, including behavioral analysis, Real-time Polymerase Chain Reaction (RT-PCR), western blotting, enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and terminal deoxynucleotidyltransferase-mediated UTP nick-ends. labeling (TUNEL) and Nissl staining to investigate the effect of Canna edulis RS3-resistant starch on the substantia nigra and neuronal apoptosis-related markers in the brains of PD model rats. Our study revealed that Canna edulis RS3, a resistant starch, significantly reduced the climbing time of PD model rats, prolonged their hanging time, lowered the expression levels of the inflammatory factors IL-1β, IL-6, and TNF-α, increased the number of TH-positive neurons in the substantia nigra, and decreased the levels of IL-1β, IL-6, and TNF-α. Furthermore, Canna edulis RS3 elevated the protein expression levels of tyrosine hydroxylase (TH) and Bcl-2 while reducing those of Bax, TLR4, NLRP3,and p-P65, and mitigated apoptosis and morphological changes in dopaminergic neurons in the substantia nigra region. Our results suggest that Canna edulis RS3-resistant starch may offer therapeutic benefits for PD patients with PD by potentially influencing inflammation and apoptosis in the dopaminergic system.

BDNF/TrkB activators in Parkinson's disease: A new therapeutic strategy.

Parkinson's disease (PD) is a neurodegenerative disorder of the brain and is manifested by motor and non-motor symptoms because of degenerative changes in dopaminergic neurons of the substantia nigra. PD neuropathology is associated with mitochondrial dysfunction, oxidative damage and apoptosis. Thus, the modulation of mitochondrial dysfunction, oxidative damage and apoptosis by growth factors could be a novel boulevard in the management of PD. Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin receptor kinase type B (TrkB) are chiefly involved in PD neuropathology. BDNF promotes the survival of dopaminergic neurons in the substantia nigra and enhances the functional activity of striatal neurons. Deficiency of the TrkB receptor triggers degeneration of dopaminergic neurons and accumulation of α-Syn in the substantia nigra. As well, BDNF/TrkB signalling is reduced in the early phase of PD neuropathology. Targeting of BDNF/TrkB signalling by specific activators may attenuate PD neuropathology. Thus, this review aimed to discuss the potential role of BDNF/TrkB activators against PD. In conclusion, BDNF/TrkB signalling is decreased in PD and linked with disease severity and long-term complications. Activation of BDNF/TrkB by specific activators may attenuate PD neuropathology.

Vinpocetine improves dyskinesia in Parkinson's disease rats by reducing oxidative stress and activating the Wnt/β-catenin signaling pathway.

Parkinson's disease (PD) is the commonest neurodegenerative disorder. It reduces motor and cognitive function in patients. Vinpocetine (Vinp) has the effects of anti-inflammatory and antioxidant, and could improve cognitive function in patients. This study was aimed to investigating the therapeutic effects of Vinp on dyskinesia in a 6-Hydroxydopamine hydrobromide (6-OHDA)-induced PD rat model. We constructed a PD rat model by injecting 6-OHDA, and intervened with Vinp for 7 days. The motor function of the rats was evaluated by an open-field test and rotation test. Besides, H&E staining was applied to observe the changes of dopaminergic neurons in the striatum. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the rat striatum were detected. We assessed the impact of Vinp on α-synuclein (α-Syn) and Wnt/β-catenin signaling pathway-related molecules by western blot and qRT-PCR. Rats in the PD group showed reduced horizontal movement frequency and number of squares crossed, increased contact time and rotation frequency, and reduced number of dopaminergic neurons accompanied by severe morphological damage. Vinp treatment increased the horizontal movement frequency and number of squares crossed, reduced the contact time, and rotation frequency in PD rats. Also, Vinp downregulated α-Syn protein expression and MDA level, while upregulated SOD activity in the striatum of PD rats. Furthermore, Vinp treatment activated the Wnt/β-catenin signaling pathway in the striatum of PD rats. In conclusion, Vinp improved the dyskinesia in 6-OHDA-induced PD rats by alleviating oxidative stress, and these effects may be associated with activating the Wnt/β-catenin signaling pathway.

Prelimbic Cortical Stimulation Induces Antidepressant-like Responses through Dopaminergic-Dependent and -Independent Mechanisms.

High-frequency stimulation (HFS) is a promising therapy for patients with depression. However, the mechanisms underlying the HFS-induced antidepressant-like effects on susceptibility and resilience to depressive-like behaviors remain obscure. Given that dopaminergic neurotransmission has been found to be disrupted in depression, we investigated the dopamine(DA)-dependent mechanism of the antidepressant-like effects of HFS of the prelimbic cortex (HFS PrL). We performed HFS PrL in a rat model of mild chronic unpredictable stress (CUS) together with 6-hydroxydopamine lesioning in the dorsal raphe nucleus (DRN) and ventral tegmental area (VTA). Animals were assessed for anxiety, anhedonia, and behavioral despair. We also examined levels of corticosterone, hippocampal neurotransmitters, neuroplasticity-related proteins, and morphological changes in dopaminergic neurons. We found 54.3% of CUS animals exhibited decreased sucrose consumption and were designated as CUS-susceptible, while the others were designated CUS-resilient. HFS PrL in both the CUS-susceptible and CUS-resilient animals significantly increased hedonia, reduced anxiety, decreased forced swim immobility, enhanced hippocampal DA and serotonin levels, and reduced corticosterone levels when compared with the respective sham groups. The hedonic-like effects were abolished in both DRN- and VTA-lesioned groups, suggesting the effects of HFS PrL are DA-dependent. Interestingly, VTA-lesioned sham animals had increased anxiety and forced swim immobility, which was reversed by HFS PrL. The VTA-lesioned HFS PrL animals also had elevated DA levels, and reduced p-p38 MAPK and NF-κB levels when compared to VTA-lesioned sham animals. These findings suggest that HFS PrL in stressed animals leads to profound antidepressant-like responses possibly through both DA-dependent and -independent mechanisms.

The alleviative effect of Calendula officinalis L. extract against Parkinson's disease-like pathology in zebrafish via the involvement of autophagy activation.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. However, effective preventative or therapeutic agents for PD remain largely limited. Marigold Calendula officinalis L. (CoL) has been reported to possess a wide range of biological activities, but its neuroprotective activity including anti-neurodegenerative diseases is unclear. Here, we aim to investigate whether the extract of CoL (ECoL) has therapeutic activity on PD. We identified the chemical composition of flavonoid, an important active ingredient in ECoL, by a targeted HPLC-Q-TOF-MS analysis. Subsequently, we evaluated the anti-PD effect of ECoL by using zebrafish PD model induced by 1-methyl-4-phenyl-1-1,2,3,6-tetrahydropyridine (MPTP). After ECoL+MPTP co-treatments, the changes of dopaminergic neurons, neural vasculature, nervous system, and locomotor activity were examined, respectively. The expressions of genes related to neurodevelopment and autophagy were detected by RT-qPCR. Further, the interaction between autophagy regulators and ECoL flavonoids was predicted using molecular docking method. As a result, 5 kinds of flavonoid were identified in ECoL, consisting of 121 flavones and flavonols, 32 flavanones, 22 isoflavonoids, 11 chalcones and dihydrochalcones, and 17 anthocyanins. ECoL significantly ameliorated the loss of dopaminergic neurons and neural vasculature, restored the injury of nervous system, and remarkably reversed the abnormal expressions of neurodevelopment-related genes. Besides, ECoL notably inhibited the locomotor impairment in MPTP-induced PD-like zebrafish. The underlying anti-PD effect of ECoL may be implicated in activating autophagy, as ECoL significantly upregulated the expressions of genes related to autophagy, which contributes to the degradation of α-synuclein aggregation and dysfunctional mitochondria. Molecular docking simulation showed the stable interaction between autophagy regulators (Pink, Ulk2, Atg7, and Lc3b) and 10 main compounds of flavonoid in ECoL, further affirming the involvement of autophagy activation by ECoL in anti-PD action. Our results suggested that ECoL has the anti-PD effect, and ECoL might be a promising therapeutic candidate for PD treatment.

Probiotic Formulation VSL#3 Interacts with Mesenchymal Stromal Cells To Protect Dopaminergic Neurons via Centrally and Peripherally Suppressing NOD-Like Receptor Protein 3 Inflammasome-Mediated Inflammation in Parkinson's Disease Mice.

Systemic immunomodulation is increasingly recognized among the beneficial effects of mesenchymal stromal cells (MSCs) in treatment of Parkinson's disease (PD), while the underlying mechanism is not fully understood. With the growing popularity of using probiotics as an adjuvant approach in PD treatment, concerns about the added effects of probiotics have been raised. In addition to the molecular mechanism mediating the neuroprotective effects of MSCs, the combined effects of a probiotic formulation, VSL#3, and MSC infusion were also evaluated in PD mice. The animals were weekly treated with human MSCs (hMSCs) via the tail vein, VSL#3 via the gastrointestinal tract, or their combination six times. hMSCs, VSL#3 alone, and their combination markedly ameliorated the decreased striatal dopamine content, loss of dopaminergic neurons in the substantia nigra, increased levels of proinflammatory cytokines in serum, as well as tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) mRNAs in striatum and peripheral tissues induced by MPTP. Furthermore, hMSCs, VSL#3, and their combination notably downregulated mRNA expression of NOD-like receptor protein 3 (NLRP3) and caspase-1 in brain and peripheral tissues of PD mice. These results suggest that hMSCs, VSL#3, and their combination prevent neurodegenerative changes in PD mice via anti-inflammatory activities in both the central and peripheral systems, possibly through suppressing the NLRP3 inflammasome. Moreover, two-way analysis of variance (ANOVA) indicated that VSL#3 interacts with hMSCs to attenuate neurodegeneration and inhibit NLRP3 inflammasome-mediated inflammation without altering the effects of hMSCs. Major findings of our study support the usage of probiotic formulation VSL#3 as an adjuvant therapy to hMSC infusion in PD treatment. IMPORTANCE This study provides evidence for the neuroprotective activities of human umbilical cord MSCs from the aspect of anti-inflammation actions. hMSCs inhibit the NLRP3 inflammasome and MPTP-induced inflammation in both brain and periphery to relieve the degenerative changes in dopaminergic neurons in PD mice. Furthermore, as an additional therapeutic agent, probiotic formulation VSL#3 interacts with hMSCs in suppressing the NLRP3 inflammasome as well as the central and peripheral anti-inflammatory effects to exert neuroprotective actions in PD mice without altering the actions of hMSCs, suggesting the potential of VSL#3 as an adjuvant therapy in PD treatment. The findings of the present study give a further understanding of the anti-inflammatory activity and the molecular mechanism for the beneficial effects of MSCs as well as the potential application of probiotic formulation as an adjuvant approach to MSC therapy in PD treatment.

Protective effects of endotoxin tolerance on peripheral lipopolysaccharide-induced neuroinflammation and dopaminergic neuronal injury

Context Parkinson's disease is a common chronic neurodegenerative disease characterized by massive loss of dopaminergic neurons in the substantia nigra. Neuroinflammation has been shown to play an important role in the pathogenesis of neurodegenerative diseases such as Parkinson’s disease. The role of immune tolerance in neuroinflammation and neurodegenerative diseases induced by peripheral factors is unclear. Objective This study established a model of endotoxin tolerance to explore the protective effect of endotoxin tolerance on Parkinson-like changes induced by repeated peripheral injections of high-dose LPS, and to explore its inflammatory mechanism. Materials and methods In this study, mice were injected intraperitoneally with low dose (0.5 mg/kg) LPS for 4 days to induce endotoxin tolerance (ET). Then, high-dose (1 mg/kg) LPS was injected continuously intraperitoneally for 4 days to induce Parkinson-like changes. Cytokines were detected by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Activation of microglial cells was detected by protein expression of CD68 and ionized calcium binding adapter molecule 1(Iba-1) by Western blotting and immunofluorescence. Hematoxylin and eosin staining and expression of tyrosine hydroxylase (TH) and dopamine (DA) were used to assess dopaminergic neuronal injury. The open field test and muscle tension test were used to assess behavioral disorders. Results As expected, compared with non-ET animals, ET preconditioning significantly reduced the production of inflammatory cytokines in the substantia nigra, inhibited microglial activation, and alleviated the pathological changes of dopaminergic neurons. Conclusions ET may be a promising intervention method for neurodegenerative diseases. Highlights ET was successfully induced by continuous low-dose intraperitoneal LPS injection in mice. ET pretreatment inhibited neuroinflammation in the SN induced by continuous peripheral high doses of LPS. ET pretreatment inhibited continuous peripheral high-dose LPS injection-induced microglial activation in the SN. ET pretreatment decreased LPS-induced functional impairment of dopaminergic neurons. ET reversed the morphological changes of dopaminergic neurons induced by peripheral high-dose LPS. ET pretreatment improved continuous peripheral high-dose LPS injection-induced behavioral impairment.

Endoplasmic Reticulum Stress Is Associated with the Mesencephalic Dopaminergic Neuron Injury in Stressed Rats.

An increasing number of people are in a state of stress due to social and psychological pressures, which may result in mental disorders. Previous studies indicated that mesencephalic dopaminergic neurons are associated with not only reward-related behaviors but also with stress-induced mental disorders. To explore the effect of stress on dopaminergic neuron and potential mechanism, we established stressed rat models of different time durations and observed pathological changes in dopaminergic neurons of the ventral tegmental area (VTA) through HE and thionine staining. Immunohistochemistry coupled with microscopy-based multicolor tissue cytometry (MMTC) was employed to investigate the number changes of dopaminergic neurons. Double immunofluorescence labelling was used to investigate expression changes of endoplasmic reticulum stress (ERS) protein GRP78 and CHOP in dopaminergic neurons. Our results showed that prolonged stress led to pathological alteration in dopaminergic neurons of VTA, such as missing of Nissl bodies and pyknosis in dopaminergic neurons. Immunohistochemistry with MMTC indicated that chronic stress exposure resulted in a significant decrease in dopaminergic neurons. Double immunofluorescence labelling showed that the endoplasmic reticulum stress protein took part in the injury of dopaminergic neurons. Taken together, these results indicated the involvement of ERS in mesencephalic dopaminergic neuron injury induced by stress exposure.

Colonic Dopaminergic Neurons Changed Reversely With Those in the Midbrain via Gut Microbiota-Mediated Autophagy in a Chronic Parkinson's Disease Mice Model.

The role of gut-brain axis in the pathogenesis of Parkinson’s disease (PD) have become a research hotspot, appropriate animal model to study gut-brain axis in PD is yet to be confirmed. Our study employed a classical PD mice model achieved by chronic MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) injection to study concurrent changes of dopaminergic neurons in the midbrain and the colon of mice. Our results showed such a PD model exhibited apparent locomotor deficits but not gastrointestinal dysfunction. Tyrosine hydroxylase expressions and dopamine content reduced greatly in the substantia nigra pars compacta (SNpc) or striatum, but increased in the colon of PD mice. Mechanism investigation indicated autophagy activity and apoptosis were stimulated in the SNpc, but inhibited in the colon of PD mice. Interplay of gut microbiota (GM) and autophagy in response to chronic MPTP injection led to GM dysbiosis and defective autophagy in mice colon. Meanwhile, fecal short chain fatty acids (SCFAs), acetate and propionate in particular, declined greatly in PD mice, which could be attributed to the decreased bacteria abundance of phylum Bacteroidetes, but increased abundance of phylum Firmicutes. GM dysbiosis derived fecal SCFAs might be one of the mediators of downregulated autophagy in the colon of PD mice. In conclusion, colonic dopaminergic neurons changed in the opposition direction with those in the midbrain via GM dysbiosis-mediated autophagy inhibition followed by suppressed apoptosis in response to chronic MPTP injection. Such a chronic PD mice model might not be an ideal model to study role of gut-brain axis in PD progression.

Mesolimbic dopamine dysregulation as a signature of information processing deficits imposed by prenatal THC exposure

Cannabis is the illicit drug most widely used by pregnant women worldwide. Its growing acceptance and legalization have markedly increased the risks of child psychopathology, including psychotic-like experiences, which lowers the age of onset for a first psychotic episode. As the majority of patients with schizophrenia go through a premorbid condition long before this occurs, understanding neurobiological underpinnings of the prodromal stage of the disease is critical to improving illness trajectories and therapeutic outcomes. We have previously shown that male rat offspring prenatally exposed to Δ9-tetrahydrocannabinol (THC), a rat model of prenatal cannabinoid exposure (PCE), exhibit extensive molecular and synaptic changes in dopaminergic neurons of the ventral tegmental area (VTA), converging on a hyperdopaminergic state. This leads to a silent psychotic-like endophenotype that is unmasked by a single exposure to THC. Here, we further characterized the VTA dopamine neuron and sensorimotor gating functions of PCE rats exposed to acute stress or a challenge of the D2 receptor agonist apomorphine, by using in vivo single-unit extracellular recordings and Prepulse Inhibition (PPI) analyses. At pre-puberty, PCE male rat offspring display a reduced population activity of VTA dopamine neurons in vivo, the majority of which are tonically active. PCE male progeny also exhibit enhanced sensitivity to dopamine D2 (DAD2) receptor activation and a vulnerability to acute stress, which is associated with compromised sensorimotor gating functions. This data extends our knowledge of the multifaceted sequelae imposed by PCE in the mesolimbic dopamine system of male pre-adolescent rats, which renders a neural substrate highly susceptible to subsequent challenges that may trigger psychotic-like outcomes.

Association of LAG3 genetic variation with an increased risk of PD in Chinese female population

BackgroundEmerging evidence suggests that α-synuclein (α-syn) aggregation and intercellular transmission contributes to pathogenesis of Parkinson’s disease (PD) and the toxic fibrillary α-syn binds lymphocyte-activation gene 3 (LAG3) receptor that mediates α-syn transmission. The deletion of LAG3 in animal models was shown to limit α-syn spreading and alleviate the pathological changes of dopaminergic neurons and animal behavioral deficits induced by α-syn aggregation. However, little is known about the genetic association of LAG3 variation with human PD development.ObjectiveHere we investigated LAG3 single nucleotide polymorphisms (SNPs) and examined the levels of soluble LAG3 (sLAG3) of CSF and serum from Chinese PD patients.MethodsWe enrolled 646 PD patients and 536 healthy controls to conduct a case-control study. All the participants were genotyped using Sequenom iPLEX Assay and the partial cerebrospinal fluid (CSF) and serum samples were assessed by Meso Scale Discovery electrochemiluminescence (MSD-ECL) immunoassay to measure sLAG3 concentration.ResultsAs a result, distributions of rs1922452-AA (1.975, 95% confidence interval (CI) 1.311–2.888, p = 0.001) and rs951818-CC (OR = 2.03, 95% CI 1.369–3.010, p = 0.001) genotype frequencies were found higher in the female PD patients than controls, respectively, and a strong linkage disequilibrium (LD) was calculated on the variants. The level of sLAG3 in CSF of PD patients was found to significantly differ from that of controls (51.56 ± 15.05 pg/ml vs 88.49 ± 62.96 pg/ml, p < 0.0001). Meanwhile, the concentration of α-synuclein in CSF of patients was significantly lower than that of controls (939.9 ± 2900 pg/ml vs 2476 ± 4403 pg/ml, p < 0.0001) and the level of sLAG3 was detected to be positive correlation with that of α-synuclein in the control group (r = 0.597, p = 0.0042), but not in PD group (r = 0.111, p = 0.408).ConclusionIn summary, our data suggested that LAG3 SNPs increase the PD risk of Chinese female population and the sLAG3 may be a potential biomarker predicted for PD development.

Prenatal THC exposure produces a hyperdopaminergic phenotype rescued by pregnenolone.

Increased legal availability of cannabis has led to a common misconception that it is a safe natural remedy for, amongst others, pregnancy-related ailments like morning sickness. Emerging clinical evidence, however, indicates that prenatal cannabis exposure (PCE) predisposes offspring to various neuropsychiatric disorders linked to aberrant dopaminergic function. Yet, our knowledge of how cannabis exposure affects the maturation of this neuromodulatory system remains limited. Here, we show that male, but not female, offspring of Δ9-tetrahydrocannabinol (THC)-exposed dams, a rat PCE model, exhibit extensive molecular and synaptic changes in dopaminergic neurons of the ventral tegmental area, including altered excitatory-to-inhibitory balance and switched polarity of long-term synaptic plasticity. The resulting hyperdopaminergic state leads to increased behavioral sensitivity to acute THC during pre-adolescence. The FDA-approved neurosteroid pregnenolone rescues synaptic defects and normalizes dopaminergic activity and behavior in PCE offspring, suggesting a therapeutic approach for offspring exposed to cannabis during pregnancy.

Short-term mindfulness practice attenuates reward prediction errors signals in the brain

Activity changes in dopaminergic neurons encode the ongoing discrepancy between expected and actual value of a stimulus, providing a teaching signal for a reward prediction process. Previous work comparing a cohort of long-term Zen meditators to controls demonstrated an attenuation of reward prediction signals to appetitive reward in the striatum. Using a cross-commodity design encompassing primary- and secondary-reward conditioning experiments, the present study asks the question of whether reward prediction signals are causally altered by mindfulness training in naïve subjects. Volunteers were randomly assigned to 8 weeks of mindfulness training (MT), active control training (CT), or a one-time mindfulness induction group (MI). We observed a decreased response to positive prediction errors in the putamen in the MT group compared to CT using both a primary and a secondary-reward experiment. Furthermore, the posterior insula showed greater activation to primary rewards, independently of their predictability, in the MT group, relative to CT and MI group. These results support the notion that increased attention to the present moment and its interoceptive features - a core component of mindfulness practice - may reduce predictability effects in reward processing, without dampening (in fact, enhancing) the response to the actual delivery of the stimulus.

Neuroprotective effects of Danshensu in Parkinson's disease mouse model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Parkinson's disease (PD) causes major changes in dopaminergic neurons of the brain, resulting in motor symptoms in older adults. A previous study showed that Danshensu alleviates the cognitive decline by attenuating neuroinflammation. In the present study, we investigated the neuroprotective effect of Danshensu in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. C57BL/6 mice were randomly divided into the following four groups: control, MPTP, Danshensu at 15 mg/kg, and Danshensu at 60 mg/kg. The mice were administered Danshensu intragastrically for 14 days. In the behavioral tests, Danshensu treatment alleviated motor dysfunction induced by MPTP. The number of tyrosine hydroxylase-positive neurons in the substantia nigra was significantly reduced in the MPTP group, relative to the control group; Danshensu partially blocked this reduction in tyrosine hydroxylase-positive neurons. In addition, Danshensu attenuated the reductions in striatal dopamine and 5-HT levels induced by MPTP. Danshensu also diminished the increase in Iba1-positive cells in the substantia nigra and reduced the levels of interleukin-1β and tumor necrosis factor-α in the striatum. These findings suggest that Danshensu exerts neuroprotective effects and improves motor function in PD mice, at least in part, by reducing neuroinflammation.

Dysregulation of Dopaminergic Regulatory Factors TH, Nurr1, and Pitx3 in the Ventral Tegmental Area Associated with Neuronal Injury Induced by Chronic Morphine Dependence.

The ventral tegmental area (VTA), a critical portion of the mesencephalic dopamine system, is thought to be involved in the development and maintenance of addiction. It has been proposed that the dopaminergic regulatory factors TH, Nurr1, and Pitx3 are crucial for determining the survival and maintenance of dopaminergic neurons. Thus, the present study investigated whether abnormalities in these dopaminergic regulatory factors in the VTA were associated with neuronal injury induced by chronic morphine dependence. Rat models with different durations of morphine dependence were established. Thionine staining was used to observe morphological changes in the VTA neurons. Immunohistochemistry and western blot were used to observe changes in the expression of the dopaminergic regulatory proteins TH, Nurr1, and Pitx3. Thionine staining revealed that prolonged morphine dependence resulted in dopaminergic neurons with edema, a lack of Nissl bodies, and pyknosis. Immunohistochemistry showed that the number of TH+, Nurr1+, and Pitx3+ cells, and the number of TH+ cells expressing Nurr1 or Pitx3, significantly decreased in the VTA after a long period of morphine dependence. Western blot results were consistent with the immunohistochemistry findings. Chronic morphine exposure resulted in abnormalities in dopaminergic regulatory factors and pathological changes in dopaminergic neurons in the VTA. These results suggest that dysregulation of dopaminergic regulatory factors in the VTA are associated with neuronal injury induced by chronic morphine dependence.

MicroRNA alterations in iPSC-derived dopaminergic neurons from Parkinson disease patients.

MicroRNA (miRNA) misregulation in peripheral blood has been linked to Parkinson disease (PD) but its role in the disease progression remains elusive. We performed an explorative genome-wide study of miRNA expression levels in dopaminergic neurons (DAn) from PD patients generated by somatic cell reprogramming and induced pluripotent stem cells differentiation. We quantified expression levels of 377 miRNAs in DAn from 3 sporadic PD patients (sPD), 3 leucine-rich repeat kinase 2-associated PD patients (L2PD) (total 6 PD), and 4 healthy controls. We identified differential expression of 10 miRNA of which 5 were upregulated in PD (miR-9-5p, miR-135a-5p, miR-135b-5p, miR-449a, and miR-449b-5p) and 5 downregulated (miR-141-3p, miR-199a-5p, miR-299-5p, miR-518e-3p, and miR-519a-3p). Changes were similar in sPD and L2PD. Integrative analysis revealed significant correlations between miRNA/mRNA expression. Moreover, upregulation of miR-9-5p and miR-135b-5p was associated with downregulation of transcription factors related to the DNA hypermethylation of enhancer elements in PD DAn (FOXA1 and NR3C1). In summary, miRNA changes are associated with monogenic L2PD and sPD and co-occur with epigenetic changes in DAn from PD patients.

The Role of Nerve Growth Factor (NGF) and Glial Cell Line-Derived Neurotrophic Factor (GDNF) in Tic Disorders.

Objectives:Tic disorders are associated with neurodevelopmental origin, changes in dopaminergic neurons, and the formation of immunoreactivity, it is thought that neurotrophic factors may be crucial in the emergence of tic disorders. In this study, we targeted to explore role of neurotrophic factors in tic disorders. The aim of this study was to investigate serum Glial Cell Line-Derived Neurotrophic Factor (GDNF) and Nerve Growth Factor (NGF) levels in patients with tic disorder and healthy controls.Methods:Thirty-four children, constituted the case group, were diagnosed with tic disorder. The control group included 34 healthy children. Development and Well-Being Assessment (DAWBA) (structured interview) and Yale Global Tic Severity Rating Scale (YGTSRS) was applied to the patients. NGF and GDNF levels were measured with ELISA kit.Results:In case group, serum NGF and GDNF levels were found to be significantly higher in females than males (p = 0.042, p = 0.031). It was determined that serum NGF and GDNF levels were correlated with each other (r = 0.803, p <0.001) and there were no correlations between other parameters. There was no significant difference in NGF and GDNF in patients with tic disorder, compared to healthy controls.Conclusions:The absence of this relationship does not exclude the hypothesis that neurotrophic factors may play a role in the etiopathogenesis of tic disorders.

Differences in brain pathological changes between rotenone and 6-hydroxydopamine Parkinson's disease models.

Rotenone and 6-hydroxydopamine are two drugs commonly used to generate Parkinson's disease animal models. They not only achieve degenerative changes of dopaminergic neurons in the substantia nigra, but also satisfy the requirements for iron deposition. However, few studies have compared the characteristics of these two models by magnetic resonance imaging. In this study, rat models of Parkinson's disease were generated by injection of 3 μg rotenone or 10 μg 6-hydroxydopamine into the right substantia nigra. At 1, 2, 4, and 6 weeks after injection, coronal whole-brain T2-weighted imaging, transverse whole-brain T2-weighted imaging, and coronal diffusion tensor weighted imaging were conducted to measure fractional anisotropy and T2* values at the injury site. The fractional anisotropy value on the right side of the substantia nigra was remarkably lower at 6 weeks than at other time points in the rotenone group. In the 6-hydroxydopamine group, the fractional anisotropy value was decreased, but T2* values were increased on the right side of the substantia nigra at 1 week. Our findings confirm that the 6-hydroxydopamine-induced model is suitable for studying dopaminergic neurons over short periods, while the rotenone-induced model may be appropriate for studying the pathological and physiological processes of Parkinson's disease over long periods.

Transplantation of autologous neural stem cells for treatment of Parkinson's disease: study protocol for a non-randomized controlled trial

Background and objectives: As degenerative changes in dopaminergic neurons occur only in the substantia nigra and striatum of patients with Parkinson's disease (PD), cellular therapy is suitable for this condition. However, previous clinical studies using stem cells for treatment of PD have short follow-ups. Thus, studies with longer follow-ups are required to further investigate the efficacy of stem cell-based therapy. Design: A non-randomized controlled trial. Methods: Ninety eligible PD patients will be recruited from the Department of Neurology at the Affiliated Hospital of Xuzhou Medical University, China. These patients will be assigned to three groups according to each patient's or their legal guardians’ wishes (n = 30 per group). In the control group, 12-week routine drug treatment will be performed. In intrathecal administration and intravenous administration groups, intrathecal administration of autologous neural stem cells (NSCs) into the subarachnoid space or intravenous administration of autologous NSCs will be performed once a week for 4 successive weeks in addition to the 12-week routine drug treatment. Outcome measures: The primary outcome measure is symptom improvement rate at 36 months post-treatment. Secondary outcome measures are nigrostriatal dopamine content, α-synuclein content in blood and cerebrospinal fluid, Barthel index, and safety indicators. Discussion: This study will be performed to demonstrate efficacy of autologous NSC transplantation as a prospective treatment for PD and investigate differences between intrathecal and intravenous transplantation routes, thus providing objective quantitative evidence for clinical applications. Ethics and dissemination: This study was designed in July 2017. Ethics approval from Medical Ethics Committee of the Affiliated Hospital of Xuzhou Medical University of China was achieved on December 22, 2017 (approval No. XYFY2017-KL052-01). The study protocol was registered on December 25, 2017. Patient recruitment began in January 2018 and will end in January 2019. Each patient will be followed up for 36 months. Follow-ups will be completed in January 2022. Data analysis will be performed in July 2022. Results will be disseminated by publication in a peer-reviewed journal. Trial registration: This trial was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR-ONC-17014141). Protocol version (1.0).

Oleuropein and rutin protect against 6-OHDA-induced neurotoxicity in PC12 cells through modulation of mitochondrial function and unfolded protein response.

Parkinson’s disease (PD) is a highly prevalent neurodegenerative disorder, often associated with oxidative stress-induced transcriptional changes in dopaminergic neurons. Phenolic antioxidants, oleuropein (OLE) and rutin (RUT) have attracted a great interest due to their potential to counteract oxidative protein aggregation and toxicity. This study aimed at examining the effects of OLE and RUT against 6-OHDA-induced stress response in rat pheochromocytoma cells. When differentiated PC12 cells were exposed to oxidative stress composer 6-OHDA (100 μM, 8 h), a decreased mitochondrial membrane potential (ΔΨm) was observed along with a significant loss of cell viability and apoptotic nuclear changes. Exposure to 6-OHDA resulted in unfolded protein response (UPR) in differentiated PC12 cells as evidenced by an increased level of endoplasmic reticulum (ER)-localized transmembrane signal transducer IRE1α, adaptive response proteins ATF-4 and proapoptotic transcription factor CHOP. OLE or RUT pretreatment (24 h) at low doses (1–50 μM) protected the differentiated PC12 cells from 6-OHDA-induced cytotoxicity as assessed by increased viability, improved ΔΨm and inhibited apoptosis, whereas relatively high doses of OLE or RUT (>50 μM) inhibited cell growth and proliferation, indicating a typical hormetic effect. In hormetic doses, OLE and RUT up-regulated 6-OHDA-induced increase in IRE1α, ATF-4 and inhibited CHOP, PERK, BIP and PDI. 6-OHDA-activated XBP1 splicing was also inhibited by OLE or RUT. The presented results suggest that neuroprotection against 6-OHDA-induced oxidative toxicity may be attributable to neurohormetic effects of OLE or RUT at low doses through regulating mitochondrial functions, controlling persistent protein misfolding, activating and/or amplificating the adaptive response-related signaling pathways, leading to UPR prosurvival output.