Parkinsonian Rats Research Articles

Therapeutic Effects of Selenium on Alpha-Synuclein Accumulation in Substantia Nigra Pars Compacta in a Rat Model of Parkinson's Disease: Behavioral and Biochemical Outcomes.

Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder characterized by the accumulation of accumulated alpha-synuclein (α-Syn) in substantia nigra. Research has shown that selenium (Se) can protect neural cells through the actions of selenoproteins, including selenoprotein P (SelP) and selenoprotein S (SelS), which participate in endoplasmic reticulum-associated protein degradation (ERAD). In this study, we investigated the potential protective role of Se in a pre-clinical PD rat model.We aimed to evaluate the therapeutic effects of Se administration in the 6-hydroxydopamine (6-OHDA) induced unilateral rat PD model. Male Wistar rats were utilised for unilateral PD animal model which were subjected to stereotaxic surgery and injected with 20 μg 6-OHDA/5 μl 0.2% ascorbate saline. After confirming the model, the rats were intraperitoneally injected with 0.1, 0.2, and 0.3 mg/kg of sodium selenite for 7 days. We then performed behavioral tests, including apomorphine-induced rotation, hanging, and rotarod tests. Following sacrifice, we analysed the substantia nigra area of the brain and serum for protein quantification, element analysis, and gene expression analysis.Our results indicate that the administration of 0.3 mg/kg of Se improved the motor deficiency in hanging, rotarod, and apomorphine-induced rotational tests. While there was no significant improvement in the expression of α-Syn, Se increased the expression of selenoproteins. Additionally, levels of selenoproteins, Se, and α-Syn both brain and serum were re-established by the treatment, suggesting the role of Se on the α-Syn accumulation. Furthermore, Se improved PD-induced biochemical deficits by increasing the levels of SelS and SelP (p<0.005).In conclusion, our findings suggest that Se may have a protective role in PD. 0.3 mg/kg dosage of Se increased the expression of selenoproteins, reduced the accumulation of α-Syn in the brain, and improved PD-induced motor deficits. These results suggest that Se may be a potential therapeutic option for PD treatment.

MiR-210-5p promotes the differentiation of human induced pluripotent stem cells into dopaminergic neural precursors by targeting SMAD4 and SUFU and treats parkinsonian rats

The differentiation of human induced pluripotent stem cells (hiPSCs) into functional dopaminergic neural precursors is the basis of cell therapy for Parkinson's disease (PD). However, the use of small molecule inhibitors/activators in the differentiation of hiPSCs in vitro leads to cell death and low differentiation efficiency. Moreover, the mechanism of differentiation remains unclear. MiR-210-5p was increased during hiPSCs differentiation. Whether it promotes hiPSCs differentiation and transplantation needs further study. Here, we overexpressed miR-210-5p in hiPSCs to study its roles and mechanisms. We found that miR-210-5p promoted the differentiation of hiPSCs into dopaminergic neural precursors and reduced the expression of SMAD4 and SUFU meanwhile. Luciferase assays showed that miR-210-5p binded to SMAD4 and SUFU, which are key molecules in the key signals (TGF-β and SHH) of hiPSCs differentiation. Furthermore, in the effect evaluation of cell transplantation into parkinsonian rats, the degree of behavioral recovery and the growth of transplanted cells in the group overexpressed miR-210-5p were similar to those in the positive group with all small molecule inhibitors/activators. Therefore, we conclude that miR-210-5p promotes the differentiation of hiPSCs into dopaminergic neural precursors by targeting SMAD4 and SUFU. In the therapeutic evaluation of cell transplantation, miR-210-5p can replace the use of corresponding small molecule inhibitors/activators to reduce cell death. This study provides an experimental basis and a new target for the miRNA-modified differentiation of hiPSCs and cell transplantation in clinical treatment of PD in the future.

Morphological Changes in Neural Progenitors Derived from Human Induced Pluripotent Stem Cells and Transplanted into the Striatum of a Parkinson's Disease Rat Model

Introduction. Development of cell therapy for Parkinson's disease (PD) requires protocols based on transplantation of neurons derived from human induced pluripotent stem cells (hiPSCs) into the damaged area of the brain.&#x0D; Objective: to characterize neurons transplanted into a rat brain and evaluate neural transplantation efficacy using a PD animal model.&#x0D; Materials and methods. Neurons derived from hiPSCs (IPSRG4S line) were transplanted into the striatum of rats after intranigral injection of 6-hydroxydopamine (6-OHDA). Immunostaining was performed to identify expression of glial and neuronal markers in the transplanted cells within 224 weeks posttransplant.&#x0D; Results. 4 weeks posttransplant we observed increased expression of mature neuron markers, decreased expression of neural progenitor markers, and primary pro-inflammatory response of glial cells in the graft. Differentiation and maturation of neuronal cells in the graft lasted over 3 months. At 3 and 6 months we detected 2 graft zones: one mainly contained the transplanted neurons and the other human astrocytes. We detected human neurites in the corpus callosum and surrounding striatal tissue and large human tyrosine hydroxylase-expressing neurons in the graft.&#x0D; Conclusion. With graft's morphological characteristics identified at different periods we can better understand pathophysiology and temporal patterns of new dopaminergic neurons integration and striatal reinnervation in a rat PD model in the long-term postoperative period.

Repetitive transcranial magnetic stimulation alleviates glial activation through suppressing HMGB1/TLR4 pathway in a rat model of Parkinson's disease.

Repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to be effective in Parkinson's disease (PD), but whether rTMS treatment has a relieving effect on neuroinflammation remains to be investigated. In this article, we explored the effects of rTMS on forelimb use asymmetry and neuroinflammation-related mechanisms in a 6-hydroxydopamine (6-OHDA)-induced PD rat model. Rats in the 6-OHDA+rTMS group received 10Hz rTMS daily for 4 weeks. Behavioral tests (the cylinder test) were performed at the 3rd and 7th weeks after the operation. Astrocyte and microglia activation and protein levels of tyrosine hydroxylase(TH), high-mobility group box 1(HMGB1) and toll-like receptors 4(TLR4) were investigated by immunohistochemistry and Western blot analyses, respectively. After 4 weeks of treatment, forelimb use asymmetry was ameliorated in the 6-OHDA+rTMS group. Consistent with the behavioral tests, rTMS increased TH in the substantia nigra (SN) and the striatum of PD rats. High glial activation and HMGB1/TLR4 expression in the SN and the striatum were observed in the 6-OHDA group, while rTMS alleviated these changes. This study showed that rTMS might be a promising method for alleviating neuroinflammation in PD rat models, and the effects might be mediated through the downregulation of the HMGB1/TLR4 pathway.

N-Acetylcysteine Treatment May Compensate Motor Impairments through Dopaminergic Transmission Modulation in a Striatal 6-Hydroxydopamine Parkinson's Disease Rat Model.

Preventing degeneration and the loss of dopaminergic neurons (DAn) in the brain while mitigating motor symptoms remains a challenge in Parkinson's Disease (PD) treatment development. In light of this, developing or repositioning potential disease-modifying approaches is imperative to achieve meaningful translational gains in PD research. Under this concept, N-acetylcysteine (NAC) has revealed promising perspectives in preserving the dopaminergic system capability and modulating PD mechanisms. Although NAC has been shown to act as an antioxidant and (neuro)protector of the brain, it has yet to be acknowledged how this repurposed drug can improve motor symptomatology and provide disease-modifying properties in PD. Therefore, in the present work, we assessed the impact of NAC on motor and histological deficits in a striatal 6-hydroxydopamine (6-OHDA) rat model of PD. The results revealed that NAC enhanced DAn viability, as we found that it could restore dopamine transporter (DAT) levels compared to the untreated 6-OHDA group. Such findings were positively correlated with a significant amelioration in the motor outcomes of the 6-OHDA-treated animals, demonstrating that NAC may, somehow, be a modulator of PD degenerative mechanisms. Overall, we postulated a proof-of-concept milestone concerning the therapeutic application of NAC. Nevertheless, it is extremely important to understand the complexity of this drug and how its therapeutical properties interact with the cellular and molecular PD mechanisms.

Axon terminal hypertrophy of striatal projection neurons with levodopa-induced dyskinesia priming.

A rat model of levodopa-induced dyskinesia (LID) showed enlarged axon terminals of striatal direct pathway neurons in the internal segment of the globus pallidus (GPi) with excessive gamma-aminobutyric acid (GABA) storage in them. Massive GABA release to GPi upon levodopa administration determines the emergence of LID. We examined whether LID and axon terminal hypertrophy gradually develop with repeated levodopa treatment in Parkinsonian rats to examine if the hypertrophy reflects dyskinesia priming. 6-hydroxydopamine-lesioned hemiparkinsonian rats were randomly allocated to receive saline injections (placebo group, 14 days; n = 4), injections of 6 mg/kg levodopa methyl ester combined with 12.5 mg/kg benserazide (levodopa-treated groups, 3-day-treatment; n = 4, 7-day-treatment; n = 4, 14-day-treatment; n = 4), or injections of 6 mg/kg levodopa methyl ester with 12.5 mg/kg benserazide and 1 mg/kg 8-hydroxy-2-(di-n-propylamino)tetralin for 14 days (8-OH-DPAT-treated group; n = 4). We evaluated abnormal involuntary movement (AIM) scores and axon terminals in the GPi. The AIM score increased with levodopa treatment, as did the hypertrophy of axon terminals in the GPi, showing an increased number of synaptic vesicles in hypertrophied terminals. Increased GABA storage in axon terminals of the direct pathway neurons represents the priming process of LID.

The dosage of curcumin to alleviate movement symptoms in a 6-hydroxydopamine-induced Parkinson's disease rat model

BackgroundCurcumin is a natural compound with extensive pharmacological effects. This research is to verify the optimal dose and administration duration efficacy of curcumin in alleviating the movement symptoms of Parkinson's disease (PD). MethodsWistar rats were divided into six groups including control, model, levodopa treatment and low/middle/high (40/80/160 mg/kg/d) curcumin treatment groups. After stereotactic brain injection of 6-hydroxydopamine (6-OHDA), curcumin was given by intragastric administration for 2 weeks. To evaluate the drug effect, the rats received behavioral tests including apomorphine (APO)-induced rotation test, rotarod test and open field test. Then the rats were sacrificed and the brain slices including substantia nigra pars compacta (SNc) were used for immunofluorescence staining. ResultsAfter 6-OHDA injection, the model group showed typical movement symptoms including the severe APO-induced rotation to the healthy side, decreased latency in the rotarod with constant or accelerative mode, and decreased total distance and average speed in the open field test. In the results of immunofluorescence staining, the 6-OHDA induced a severe damage of dopaminergic neurons in SNc. The 160 mg/kg/d treatment of curcumin to intervene for 2 weeks alleviated most of the behavioral disorders but the 40/80 mg/kg/d treatment showed limitations. Then, we compared the effect of 1 week intervention to the 2 weeks with 160 mg/kg/d treatment of curcumin to intervene and results indicated that the treatment of 2 weeks could better alleviate the symptoms. ConclusionsCurcumin alleviated 6-OHDA-induced movement symptoms in a PD rat model. Additionally, the effect of curcumin against PD indicated dose and duration dependent and the intervention of 160 mg/kg/d for 2 weeks showed optimally therapeutic effect.

Intranasal cerium oxide nanoparticles improves locomotor activity and reduces oxidative stress and neuroinflammation in haloperidol-induced parkinsonism in rats.

Introduction: Cerium oxide nanoparticles (CONPs) have been investigated for their therapeutic potential in Parkinson's disease (PD) due to their potent and regenerative antioxidant activity. In the present study, CONPs were used to ameliorate the oxidative stress caused by free radicals in haloperidol-induced PD in rats following intranasal administration. Method: The antioxidant potential of the CONPs was evaluated in vitro using ferric reducing antioxidant power (FRAP) assay. The penetration and local toxicity of the CONPs was evaluated ex-vivo using goat nasal mucosa. The acute local toxicity of intranasal CONPs was also studied in rat. Gamma scintigraphy was used to assess the targeted brain delivery of CONPs. Acute toxicity studies were performed in rats to demonstrate safety of intranasal CONPs. Further, open field test, pole test, biochemical estimations and brain histopathology was performed to evaluate efficacy of intranasal CONPs in haloperidol-induced PD rat model. Results: The FRAP assay revealed highest antioxidant activity of prepared CONPs at a concentration of 25μg/mL. Confocal microscopy showed deep and homogenous distribution of CONPs in the goat nasal mucus layers. No signs of irritation or injury were seen in goat nasal membrane when treated with optimized CONPs. Scintigraphy studies in rats showed targeted brain delivery of intranasal CONPs and acute toxicity study demonstrated safety. The results of open field and pole test showed highly significant (p < 0.001) improvement in locomotor activity of rats treated with intranasal CONPs compared to untreated rats. Further, brain histopathology of treatment group rats showed reduced neurodegeneration with presence of more live cells. The amount of thiobarbituric acid reactive substances (TBARS) was reduced significantly, whereas the levels of catalase (CAT), superoxide dismutase (SOD), and GSH were increased significantly, while amounts of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) showed significant reduction after intranasal administration of CONPs. Also, the intranasal CONPs, significantly high (p < 0.001) dopamine concentration (13.93 ± 0.85ng/mg protein) as compared to haloperidol-induced control rats (5.76 ± 0.70ng/mg protein). Conclusion: The overall results concluded that the intranasal CONPs could be safe and effective therapeutics for the management of PD.

Membrane-stabilizing and protective effects of curcumin in a rotenone-induced rat model of Parkinson disease.

Parkinson disease (PD) is a chronic progressive neurodegenerative disease characterized by both motor and non-motor features. Numerous risk factors (oxidative stress, free radical formation, and several environmental toxins) have been associated with PD. The experimental studies were carried out under in vivo conditions. Biochemical data analysis indicated that compared with the parameters of control (C) rats, rotenone-induced PD rats showed a significant decrease in the specific content of the total fraction of isoforms of O2--producing, heat-stable, NADPH-containing associates (NLP-Nox) from membrane formations of tissues (brain, liver, lung, and small intestine). Compared with the C group indices, in the PD and PD + curcumin (PD + CU) groups there is some change in the shape of the optical absorption spectra of isoforms associated with a change in the amount of Nox in the isoform composition of the total fraction of the NLP-Nox associate. Thus, daily administration of CU (200mg/kg, i.p.) to PD rats for 63days had a regulatory effect, bringing the specific content and O2--producing activity of the total fraction of NLP-Nox isoforms closer to the norm. CU has membrane-stabilizing effects in rotenone-induced PD.

On-Off and Proportional Closed-Loop Adaptive Deep Brain Stimulation Reduces Motor Symptoms in Freely Moving Hemiparkinsonian Rats

ObjectivesClosed-loop adaptive deep brain stimulation (aDBS) continuously adjusts stimulation parameters, with the potential to improve efficacy and reduce side effects of deep brain stimulation (DBS) for Parkinson’s disease (PD). Rodent models can provide an effective platform for testing aDBS algorithms and establishing efficacy before clinical investigation. In this study, we compare two aDBS algorithms, on-off and proportional modulation of DBS amplitude, with conventional DBS in hemiparkinsonian rats. Materials and MethodsDBS of the subthalamic nucleus (STN) was delivered wirelessly in freely moving male and female hemiparkinsonian (N = 7) and sham (N = 3) Wistar rats. On-off and proportional aDBS, based on STN local field potential beta power, were compared with conventional DBS and three control stimulation algorithms. Behavior was assessed during cylinder tests (CT) and stepping tests (ST). Successful model creation was confirmed via apomorphine-induced rotation test and Tyrosine Hydroxylase–immunocytochemistry. Electrode location was histologically confirmed. Data were analyzed using linear mixed models. ResultsContralateral paw use in parkinsonian rats was reduced to 20% and 25% in CT and ST, respectively. Conventional, on-off, and proportional aDBS significantly improved motor function, restoring contralateral paw use to approximately 45% in both tests. No improvement in motor behavior was observed with either randomly applied on-off or low-amplitude continuous stimulation. Relative STN beta power was suppressed during DBS. Relative power in the alpha and gamma bands decreased and increased, respectively. Therapeutically effective adaptive DBS used approximately 40% less energy than did conventional DBS. ConclusionsAdaptive DBS, using both on-off and proportional control schemes, is as effective as conventional DBS in reducing motor symptoms of PD in parkinsonian rats. Both aDBS algorithms yield substantial reductions in stimulation power. These findings support using hemiparkinsonian rats as a viable model for testing aDBS based on beta power and provide a path to investigate more complex closed-loop algorithms in freely behaving animals.

Dysbiosis of gut microbiota inhibits NMNAT2 to promote neurobehavioral deficits and oxidative stress response in the 6-OHDA-lesioned rat model of Parkinson’s disease

BackgroundNew data are accumulating on gut microbial dysbiosis in Parkinson’s disease (PD), while the specific mechanism remains uncharacterized. This study aims to investigate the potential role and pathophysiological mechanism of dysbiosis of gut microbiota in 6-hydroxydopamine (6-OHDA)-induced PD rat models.MethodsThe shotgun metagenome sequencing data of fecal samples from PD patients and healthy individuals were obtained from the Sequence Read Archive (SRA) database. The diversity, abundance, and functional composition of gut microbiota were further analyzed in these data. After the exploration of the functional pathway-related genes, KEGG and GEO databases were used to obtain PD-related microarray datasets for differential expression analysis. Finally, in vivo experiments were performed to confirm the roles of fecal microbiota transplantation (FMT) and upregulated NMNAT2 in neurobehavioral symptoms and oxidative stress response in 6-OHDA-lesioned rats.ResultsSignificant differences were found in the diversity, abundance, and functional composition of gut microbiota between PD patients and healthy individuals. Dysbiosis of gut microbiota could regulate NAD+ anabolic pathway to affect the occurrence and development of PD. As a NAD+ anabolic pathway-related gene, NMNAT2 was poorly expressed in the brain tissues of PD patients. More importantly, FMT or overexpression of NMNAT2 alleviated neurobehavioral deficits and reduced oxidative stress in 6-OHDA-lesioned rats.ConclusionsTaken together, we demonstrated that dysbiosis of gut microbiota suppressed NMNAT2 expression, thus exacerbating neurobehavioral deficits and oxidative stress response in 6-OHDA-lesioned rats, which could be rescued by FMT or NMNAT2 restoration.

Anti-inflammatory, anti-apoptotic, and neuroprotective potentials of anethole in Parkinson's disease-like motor and non-motor symptoms induced by rotenone in rats.

Parkinson's disease (PD) is a complex neurological disorder characterized by a combination of motor and non-motor symptoms (NMS). Antioxidant and anti-inflammatory compounds are considered a potential therapeutic strategy against PD. The present study examined the neuroprotective effects of anethole as a potent antioxidant and anti-inflammatory agent against motor and non-motor deficits induced by rotenone toxicity. Rats were treated with anethole (62.5, 125, and 250mg/kg, i.g) concomitantly with rotenone (2mg/kg, s.c) for 5weeks. After the treatment, behavioral tests were performed to evaluate motor function and depression-/anxiety-like behaviors. Afterthebehavioral tests, rats were decapitated and brains were removed for histological analysis. Striatum samples were also isolated for neurochemical, and molecular analysis. Our data showed that rotenone-induced motor deficit, anxiety-and depression-like behaviors were significantly improved in rats treated with anethole.Furthermore, anethole treatment reduced inflammatory cytokines tumor necrosis factor α (TNFα) and Interleukin 6 (IL-6), and increased anti-inflammatory cytokine IL-4 in the striatum of rotenone-induced PD rats.Western blot analysis showed that treatment with anethole markedly suppressed caspase-3 activation induced by rotenone. Moreover, histological examination of striatumshowed an increase in the number of surviving neurons after treatment with anethole. Anethole also significantlyenhanced the striatal levels of dopamine in rotenone-induced PD rats. In addition, treatment with L-Dopa as a positive control group had effects similar to those of anethole on histological, neurochemical, and molecular parameters in rotenone-induced parkinsonian rats. Our results suggested the neuroprotective effects of anethole through anti-inflammatory, anti-apoptotic, and antioxidant mechanisms against rotenone-induced toxicity in rats.

Inosine attenuates rotenone-induced Parkinson's disease in rats by alleviating the imbalance between autophagy and apoptosis.

Growing evidence points to impaired autophagy as one of the major factors implicated in the pathophysiology of Parkinson's disease (PD). Autophagy is a downstream target of adenosine monophosphate-activated protein kinase (AMPK). Inosine has already demonstrated a neuroprotective effect against neuronal loss in neurodegenerative diseases, mainly due its anti-inflammatory and antioxidant properties. We, herein, aimed at investigating the neuroprotective effects of inosine against rotenone-induced PD in rats and to focus on the activation of AMPK-mediated autophagy. Inosine successfully increased p-AMPK/AMPK ratio in PD rats and improved their motor performance and muscular co-ordination (assessed by rotarod, open field, and grip strength tests, as well as by manual gait analysis). Furthermore, inosine was able to mitigate the rotenone-induced histopathological alterations and to restore the tyrosine hydroxylase immunoreactivity in PD rats' substantia nigra. Inosine-induced AMPK activation resulted in an autophagy enhancement, as demonstrated by the increased striatal Unc-S1-like kinase1 and beclin-1 expression, and also by the increment light chain 3II to light chain 3I ratio, along with the decline in striatal mammalian target of rapamycin and p62 protein expressions. The inosine-induced stimulation of AMPK also attenuated neuronal apoptosis and promoted antioxidant activity. Unsurprisingly, these neuroprotective effects were antagonized by a preadministration of dorsomorphin (an AMPK inhibitor). In conclusion, inosine exerted neuroprotective effects against the rotenone-induced neuronal loss via an AMPK activation and through the restoration of the imbalance between autophagy and apoptosis. These findings support potential application of inosine in PD treatment.

Bio-synthesized selenium nanoparticles ameliorateBrain oxidativestress in Parkinson disease rat models.

Parkinson disease (PD) is a prevalent central nervous system degenerative condition that impacts elderly people. Recent clinical and experimental study findings have established oxidative stress as one of the main pathogeneses of PD. Selenium, a trace metals with antioxidant effects, might reverse the neurobehavioral impairments and oxidative stress in rats. Thus, the goal of this study was to ascertain if Selenium Nano Particles (SeNPs) are also effective to protect brain cells from oxidative stress or not. SeNPs were synthesized utilizing Ascorbic acid and chitosan as a reducing and stabilizing agent. Next, eight groups (N: 6) of male Wistar rats were randomly assigned and injected by different dosage (0.1, 0,2, and 0.3mg/kg) of Se and SeNP. Finally, to ascertain the protective benefits of SeNP on PD rats, behavioral evaluation, clinical symptoms, antioxidant activity, and oxidant levels were examined. According to the findings, PD rats' motor functions had developed by SeNP injection. Higher MDA levels and inhibited antioxidant activities (SOD, CAT, and GPX) in lesion group are highlighting the significant role of oxidative stress in dopaminergic neuron death and neurobehavioral abnormalities. SeNP also protect against oxidative stress as compared to the lesion group. The levels of MDA had greatly reduced while the activities of enzymes, TAC, and SeNP both had significantly increased. By enhancing antioxidant activity, administration of SeNP can reduce the hazardousconsequences of oxidative stress.

Neural pathway connectivity and discharge changes between M1 and STN in Hemiparkinsonian Rats.

Alterations of electrophysiological activities, such as changed spike firing rates, reshaping the firing patterns, and aberrant frequency oscillations between the subthalamic nucleus (STN) and the primary motor cortex (M1), are thought to contribute to motor impairment in Parkinson's disease (PD). However, the alterations of electrophysiological characteristics of STN and M1 in PD are still unclear, especially under specific treadmill movement. To examine the relationship between electrophysiological activity in the STN-M1 pathway, extracellular spike trains and local field potential (LFPs) of STN and M1 were simultaneously recorded during resting and movement in unilateral 6-hydroxydopamine (6-OHDA) lesioned rats. The results showed that the identified STN neurons and M1 neurons exhibited abnormal neuronal activity after dopamine loss. The dopamine depletion altered the LFP power in STN and M1 whatever in rest or movement states. Furthermore, the enhanced synchronization of LFP oscillations after dopamine loss was found in 12-35Hz (beta frequencies) between the STN and M1 during rest and movement. In addition, STN neurons were phase-locked firing to M1 oscillations at 12-35Hz during rest epochs in 6-OHDA lesioned rats. The dopamine depletion also impaired the anatomical connectivity between the M1 and STN by injecting anterograde neuroanatomical tracing virus into M1 in control and PD rats. Collectively, impairment of' electrophysiological activity and anatomical connectivity in the M1-STN pathway may be the basis for dysfunction of the cortico-basal ganglia circuit, correlating with motor symptoms of PD.

Assessment of heart rate variability (HRV) in SN rotenone-induced lesion Parkinson's disease rat model

Parkinson’s disease (PD) is a progressive neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra (SN). While PD is clinically characterized by motor deficits, non-motor symptoms such as autonomic dysfunction that can lead to deficits in cardiovascular function are common in early PD. Autonomic dysfunction is an imbalance in sympathetic (SNS) and parasympathetic (PNS; vagal) tone, which directly impacts cardiovascular function and responsiveness, leading to alterations in heart rate variability (HRV). HRV is the fluctuation in time intervals between consecutive heartbeats, and reduced HRV has been linked to increased risk for cardiovascular morbidity and mortality in both cardiac and non-cardiac disorders, including those associated with PD. To gain further insight into the influence of PD on autonomic balance, we investigated measures of HRV quantified from a 20-min segment of basal ECG activity recorded in a rat model of PD generated by unilateral injection of the pesticide rotenone (ROT; n=8) into the SN; SN injection of vehicle (VEH) in a separate group of rats (n=7) served as a control. At 2-weeks after SN injection, ECG activity was recorded in urethane-anesthetized adult female Sprague-Dawley rats using needle electrodes inserted into each forepaw, RR interval data were obtained from the ECG records, and HRV was quantified using time-domain analysis to obtain SDRR and RMSSD, frequency-domain analysis to obtain spectral power in the low (LF) and high (HF) frequency bands and the LF/HF ratio, and non-linear Poincaré plot analysis to obtain SD1, SD2, and the SD1/SD2 ratio, with all data presented as mean±SE. Evaluation of mixed SNS/PNS tone measures showed that SDRR (2.89±1.09 vs 2.60±0.98 ms), relative LF power (49.9±18.9 vs 44.8±16.9% (nu)), and SD2 (4.25±1.60 vs 3.38±1.27 ms) were similar in ROT- and VEH-injected rats while evaluation of PNS tone measures showed that RMSSD (3.59±1.36 ms vs 2.00±0.75 ms) and SD1 (2.55±0.96 vs 1.42±0.53 ms) were slightly but not significantly higher in ROT-injected rats albeit relative HF power (50.1±18.9 vs 55.2±20.9% (nu)) was similar in both groups. Evaluation of sympatho-vagal balance measures showed that LF/HF ratio (1.05±0.40 vs 1.52±0.58) and SD1/SD2 ratio (0.56±0.21 vs 0.46±0.17) were similar in ROT- and VEH-injected rats albeit both measures appeared to favor slightly enhanced PNS tone in ROT-injected rats. Qualitative evaluation of Poincaré plot histogram data revealed that ROT-injected rats exhibited multiple modal clusters of beat-to-beat RR interval behaviors, suggesting that alterations in HRV are likely present. While our preliminary data show some slight alterations in HRV in ROT-injected rats, additional data are needed to improve statistical power of our comparisons as well as to better capture changes in sympatho-vagal balance and identify underlying mechanisms responsible for autonomic dysfunction in PD. Thomas Hartman Center for Parkinson's Disease Research at Stony Brook University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparison of basal and hypoxic respiratory behaviors in 6-OHDA and rotenone induced SN lesion Parkinson's disease rat models

Parkinson’s disease (PD) is the second most prominent neurodegenerative disease in the world and is increasing in incidence. PD symptomology includes both motor- and non-motor symptoms (NMS). Respiratory deficits are a common PD NMS, likely caused by alterations in brainstem neurotransmission; several studies have begun to address respiratory deficits utilizing nigrostriatal pathway site-targeted 6-OHDA neurotoxin induced models of PD. While these models exhibit a loss of dopaminergic (DA) neurons in the substantia nigra (SN), they do not exhibit pathological changes such as α-synuclein aggregates or tau tangles which may play crucial roles in PD pathology. To better capture these additional features and more accurately reflect the development of PD, pesticide-based models are used albeit little is known about the respiratory deficits in these models. To begin to address this issue, we examined basal breathing behaviors and the acute hypoxic ventilatory response (HVR) in the SN 6-OHDA PD rat model and a PD rat model generated by unilateral SN injection of the pesticide rotenone (ROT); SN vehicle injections served as controls for each model (VehROT; Veh6-OHDA). At 2-weeks after SN injection, diaphragm EMG activity was recorded in urethane-anesthetized adult female Sprague-Dawley rats under baseline conditions (40% O2) and during and after an acute hypoxic (HYP) challenge (12% O2, 90 s), and the timing and patterning features of the EMG bursts were analyzed. We found that rats in all groups had a similar basal breathing rate of 86-89 bpm though ROT and 6-OHDA rats had slightly shorter TI and slightly longer TE, resulting in lower inspiratory duty cycles than their respective controls. During HYP, all groups displayed increased respiratory activity; however, ROT and 6-OHDA rats reached their peak increases at a later time than their respective controls. While 6-OHDA rats showed an attenuated HVR burst amplitude increase during the early- and mid-HYP response and a slightly reduced HVR frequency increase than Veh6-OHDA rats, ROT rats exhibited a larger HVR burst amplitude and frequency increase than VehROT rats. Surprisingly, differential magnitude increases in HVR burst amplitude were noted in Veh6-OHDA and VehROT rats (17% and 30% above baseline, respectively). 6-OHDA rats also had a milder post-HYP breathing frequency decline (PHFD) than Veh6-OHDA rats, while ROT rats had a more severe PHFD but recovered to basal breathing frequency more rapidly than rats in other groups. These findings indicate that DA neuron depletion exerts an impact on respiratory behaviors during the HVR; however, differences in the mechanisms of destruction may contribute to the different respiratory behaviors noted during and following HYP in these two models, warranting further study into the differences between them. Additionally, care must be given to better understand how injected vehicle solutions affect respiratory behaviors in control rats in these types of studies. Support: Thomas Hartman Center for Parkinson's Disease Research at Stony Brook University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Establishment and characterization of bone marrow mesenchymal stem cell lines stably synthesizing high-level dopamine

A triple-transgenic (tyrosine hydroxylase/dopamine decarboxylase/GTP cyclohydrolase 1, TH/DDC/GCH1) bone marrow mesenchymal stem cell line (BMSCs) capable of stably synthesizing dopamine (DA) transmitters were established to provide experimental evidence for the clinical treatment of Parkinson's disease (PD) by using this cell line. The DA-BMSCs cell line that could stably synthesize and secrete DA transmitters was established by using the triple transgenic recombinant lentivirus. The triple transgenes (TH/DDC/GCH1) expression in DA-BMSCs was detected using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. Moreover, the secretion of DA was tested by enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). Chromosome G-banding analysis was used to detect the genetic stability of DA-BMSCs. Subsequently, the DA-BMSCs were stereotactically transplanted into the right medial forebrain bundle (MFB) of Parkinson's rat models to detect their survival and differentiation in the intracerebral microenvironment of PD rats. Apomorphine (APO)-induced rotation test was used to detect the improvement of motor dysfunction in PD rat models with cell transplantation. The TH, DDC and GCH1 were expressed stably and efficiently in the DA-BMSCs cell line, but not expressed in the normal rat BMSCs. The concentration of DA in the cell culture supernatant of the triple transgenic group (DA-BMSCs) and the LV-TH group was extremely significantly higher than that of the standard BMSCs control group (P < 0.000 1). After passage, DA-BMSCs stably produced DA. Karyotype G-banding analysis showed that the vast majority of DA-BMSCs maintained normal diploid karyotypes (94.5%). Moreover, after 4 weeks of transplantation into the brain of PD rats, DA-BMSCs significantly improved the movement disorder of PD rat models, survived in a large amount in the brain microenvironment, differentiated into TH-positive and GFAP-positive cells, and upregulated the DA level in the injured area of the brain. The triple-transgenic DA-BMSCs cell line that stably produced DA, survived in large numbers, and differentiated in the rat brain was successfully established, laying a foundation for the treatment of PD using engineered culture and transplantation of DA-BMSCs.

Quantifying changes in local basal ganglia structural connectivity in the 6-hydroxydopamine model of Parkinson's Disease using correlational tractography.

In recent years, tractography based on diffusion magnetic resonance imaging (dMRI) has become a popular tool for studying microstructural changes resulting from brain diseases like Parkinson's Disease (PD). Quantitative anisotropy (QA) is a parameter that is used in deterministic fiber tracking as a measure of connection between brain regions. It remains unclear, however, if microstructural changes caused by lesioning the median forebrain bundle (MFB) to create a Parkinsonian rat model can be resolved using tractography based on ex-vivo diffusion MRI. This study aims to fill this gap and enable future mechanistic research on structural changes of the whole brain network rodent models of PD. Specifically, it evaluated the ability of correlational tractography to detect structural changes in the MFB of 6-hydroxydopamine (6-OHDA) lesioned rats. The findings reveal that correlational tractography can detect structural changes in lesioned MFB and differentiate between the 6-OHDA and control groups. Imaging results are supported by behavioral and histological evidence demonstrating that 6-OHDA lesioned rats were indeed Parkinsonian. The results suggest that QA and correlational tractography is appropriate to examine local structural changes in rodent models of neurodegenerative disease. More broadly, we expect that similar techniques may provide insight on how disease alters structure throughout the brain, and as a tool to optimize therapeutic interventions.

Menstrual blood-derived endometrial stem cells alleviate neuroinflammation by modulating M1/M2 polarization in cell and rat Parkinson’s disease models

BackgroundNeuroinflammation is closely related to the development of Parkinson's disease (PD). Because of the extensive sources, non-invasive and periodical collection method, human menstrual blood-derived endometrial stem cells (MenSCs) have been explored as a promising tool for treatment of PD. This study aimed to investigate if MenSCs could inhibit neuroinflammation in PD rats by regulating M1/M2 polarization and to excavate the underlying mechanisms.MethodsMenSCs were co-cultured with 6-OHDA-exposed microglia cell lines. Then the morphology of microglia cells and the level of inflammatory factors were assessed by immunofluorescence and qRT-PCR. After MenSCs were transplanted into the brain of PD rats, animal motor function, the expression of tyrosine hydroxylase, and the level of inflammatory factors in the cerebrospinal fluid (CSF) and serum were detected to evaluate the therapeutic potential of MenSCs. Meanwhile, the expression of M1/M2 phenotype related genes was detected by qRT-PCR. One protein array kit containing 1000 kinds of factors was used to detect the protein components in the conditioned medium of MenSCs. Finally, bioinformatic analysis was performed to analyze the function of factors secreted by MenSCs and the signal pathways involved in.ResultsMenSCs could suppress 6-OHDA-induced microglia cell activation and significantly decrease inflammation in vitro. After transplantation into the brain of PD rats, MenSCs improved animal motor function, which was indicated by the increased movement distance, ambulatory episodes, exercise time on the rotarod, and less contralateral rotation. Additionally, MenSCs reduced the loss of dopaminergic neurons and down-regulated the level of pro-inflammatory factors in the CSF and serum. Moreover, q-PCR and WB results showed the transplantation of MenSCs significantly down-regulated the expression of M1 phenotype cell markers and meanwhile up-regulated the expression of M2 phenotype cell markers in the brain of PD rats. 176 biological processes including inflammatory response, negative regulation of apoptotic process, and microglial cell activation were enriched by GO-BP analysis. 58 signal pathways including PI3K/Akt and MAPK were enriched by KEGG analysis.ConclusionsIn conclusion, our results provide preliminary evidence for the anti-inflammation capacity of MenSCs by regulating M1/M2 polarization. We firstly demonstrated the biological process of factors secreted by MenSCs and the signal pathways involved in using protein array and bioinformatic analysis.