scholarly journals Acute Neuroinflammatory Response in the Substantia Nigra Pars Compacta of Rats after a Local Injection of Lipopolysaccharide

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Yazmin M. Flores-Martinez ◽  
Manuel A. Fernandez-Parrilla ◽  
Jose Ayala-Davila ◽  
David Reyes-Corona ◽  
Victor M. Blanco-Alvarez ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Inflammatory Response ◽  
Microglial Activation ◽  
Sickness Behavior ◽  
Substantia Nigra Pars Compacta ◽  
No Production ◽  
Body Contour ◽  
Neuroinflammatory Response ◽  
Dopaminergic Neurodegeneration ◽  
Irregular Body

Models of Parkinson’s disease with neurotoxins have shown that microglial activation does not evoke a typical inflammatory response in the substantia nigra, questioning whether neuroinflammation leads to neurodegeneration. To address this issue, the archetypal inflammatory stimulus, lipopolysaccharide (LPS), was injected into the rat substantia nigra. LPS induced fever, sickness behavior, and microglial activation (OX42 immunoreactivity), followed by astrocyte activation and leukocyte infiltration (GFAP and CD45 immunoreactivities). During the acute phase of neuroinflammation, pro- and anti-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-4, and IL-10) responded differentially at mRNA and protein level. Increased NO production and lipid peroxidation occurred at 168 h after LPS injection. At this time, evidence of neurodegeneration could be seen, entailing decreased tyrosine hydroxylase (TH) immunoreactivity, irregular body contour, and prolongation discontinuity of TH+ cells, as well as apparent phagocytosis of TH+ cells by OX42+ cells. Altogether, these results show that LPS evokes a typical inflammatory response in the substantia nigra that is followed by dopaminergic neurodegeneration.

scholarly journals Daily Subacute Paraquat Exposure Decreases Muscle Function and Substantia Nigra Dopamine Level

2013 ◽  
pp. 313-321 ◽  
Author(s):  
M. A. FAHIM ◽  
S. SHEHAB ◽  
A. NEMMAR ◽  
A. ADEM ◽  
S. DHANASEKARAN ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Substantia Nigra ◽  
High Performance ◽  
Motor Coordination ◽  
Neuronal Loss ◽  
Male Rats ◽  
Substantia Nigra Pars Compacta ◽  
Motor Deficit ◽  
Dopamine Level ◽  
Dopaminergic Neurodegeneration

The use of the herbicide paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride; PQ) which is widely used in agriculture is known to cause dopaminergic neurotoxicity. However, the mechanisms underlying this effect are not fully understood. This present study investigated the behavioral manifestations, motor coordination, and dopaminergic neurodegeneration following exposure to PQ. Male rats were injected with PQ (10 mg/kg i.p.) daily for three weeks. Rotarod systems were used for measuring locomotor activity and motor coordination. The effects of PQ on dorsiflexor, electrophysiologically-induced muscle contraction were studied. Dopamine concentrations in the ventral mesencephalon were measured by high performance liquid chromatography and the number of dopaminergic neurons in substantia nigra pars compacta was estimated by tyrosine hydroxylase immunohistochemistry. PQ induced difficulty in movement and significant reduction in motor activity and twitch tension at the dorsiflexor skeletal muscle. The number of tyrosine hydroxylase positive neurons was significantly less in the substantia nigra pars compacta and nigral dopamine level was significantly reduced in PQ treated animals (20.4±3.4 pg/mg) when compared with control animals (55.0±2.4 pg/mg wet tissue). Daily treatment of PQ for three weeks induces selective dopaminergic neuronal loss in the substantia nigra and significant behavioral and peripheral motor deficit effects.

scholarly journals The pentose phosphate pathway regulates chronic neuroinflammation and dopaminergic neurodegeneration

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Dezhen Tu ◽  
Yun Gao ◽  
Ru Yang ◽  
Tian Guan ◽  
Jau-Shyong Hong ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Pentose Phosphate Pathway ◽  
Microglial Activation ◽  
Redox Homeostasis ◽  
Pentose Phosphate ◽  
Transgenic Expression ◽  
Dopaminergic Neurodegeneration ◽  
Locomotor Impairment

Abstract Background Metabolic dysfunction and neuroinflammation are increasingly implicated in Parkinson’s disease (PD). The pentose phosphate pathway (PPP, a metabolic pathway parallel to glycolysis) converts glucose-6-phosphate into pentoses and generates ribose-5-phosphate and NADPH thereby governing anabolic biosynthesis and redox homeostasis. Brains and immune cells display high activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP. A postmortem study reveals dysregulation of G6PD enzyme in brains of PD patients. However, spatial and temporal changes in activity/expression of G6PD in PD remain undetermined. More importantly, it is unclear how dysfunction of G6PD and the PPP affects neuroinflammation and neurodegeneration in PD. Methods We examined expression/activity of G6PD and its association with microglial activation and dopaminergic neurodegeneration in multiple chronic PD models generated by an intranigral/intraperitoneal injection of LPS, daily subcutaneous injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 6 days, or transgenic expression of A53T α-synuclein. Primary microglia were transfected with G6PD siRNAs and treated with lipopolysaccharide (LPS) to examine effects of G6PD knockdown on microglial activation and death of co-cultured neurons. LPS alone or with G6PD inhibitor(s) was administrated to mouse substantia nigra or midbrain neuron-glia cultures. While histological and biochemical analyses were conducted to examine microglial activation and dopaminergic neurodegeneration in vitro and in vivo, rotarod behavior test was performed to evaluate locomotor impairment in mice. Results Expression and activity of G6PD were elevated in LPS-treated midbrain neuron-glia cultures (an in vitro PD model) and the substantia nigra of four in vivo PD models. Such elevation was positively associated with microglial activation and dopaminergic neurodegeneration. Furthermore, inhibition of G6PD by 6-aminonicotinamide and dehydroepiandrosterone and knockdown of microglial G6PD attenuated LPS-elicited chronic dopaminergic neurodegeneration. Mechanistically, microglia with elevated G6PD activity/expression produced excessive NADPH and provided abundant substrate to over-activated NADPH oxidase (NOX2) leading to production of excessive reactive oxygen species (ROS). Knockdown and inhibition of G6PD ameliorated LPS-triggered production of ROS and activation of NF-кB thereby dampening microglial activation. Conclusions Our findings indicated that G6PD-mediated PPP dysfunction and neuroinflammation exacerbated each other mediating chronic dopaminergic neurodegeneration and locomotor impairment. Insight into metabolic-inflammatory interface suggests that G6PD and NOX2 are potential therapeutic targets for PD.

scholarly journals The CD200R1 microglial inhibitory receptor as a therapeutic target in the MPTP model of Parkinson’s disease

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Neus Rabaneda-Lombarte ◽  
Joan Serratosa ◽  
Jordi Bové ◽  
Miquel Vila ◽  
Josep Saura ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Mrna Expression ◽  
Therapeutic Target ◽  
Inflammatory Markers ◽  
Microglial Activation ◽  
Microglial Cells ◽  
Substantia Nigra Pars Compacta ◽  
Mrna Levels ◽  
Dopaminergic Neurodegeneration

Abstract Background It is suggested that neuroinflammation, in which activated microglial cells play a relevant role, contributes to the development of Parkinson’s disease (PD). Consequently, the modulation of microglial activation is a potential therapeutic target to be taken into account to act against the dopaminergic neurodegeneration occurring in this neurological disorder. Several soluble and membrane-associated inhibitory mechanisms contribute to maintaining microglial cells in a quiescent/surveillant phenotype in physiological conditions. However, the presence of activated microglial cells in the brain in PD patients suggests that these mechanisms have been somehow overloaded. We focused our interest on one of the membrane-associated mechanisms, the CD200-CD200R1 ligand-receptor pair. Methods The acute MPTP experimental mouse model of PD was used to study the temporal pattern of mRNA expression of CD200 and CD200R1 in the context of MPTP-induced dopaminergic neurodegeneration and neuroinflammation. Dopaminergic damage was assessed by tyrosine hydroxylase (TH) immunoreactivity, and neuroinflammation was evaluated by the mRNA expression of inflammatory markers and IBA1 and GFAP immunohistochemistry. The effect of the modulation of the CD200-CD200R1 system on MPTP-induced damage was determined by using a CD200R1 agonist or CD200 KO mice. Results MPTP administration resulted in a progressive decrease in TH-positive fibres in the striatum and TH-positive neurons in the substantia nigra pars compacta, which were accompanied by transient astrogliosis, microgliosis and expression of pro- and anti-inflammatory markers. CD200 mRNA levels rapidly decreased in the ventral midbrain after MPTP treatment, while a transient decrease of CD200R1 mRNA expression was repeatedly observed in this brain area at earlier and later phases. By contrast, a transient increase in CD200R1 expression was observed in striatum. The administration of a CD200R1 agonist resulted in the inhibition of MPTP-induced dopaminergic neurodegeneration, while microglial cells showed signs of earlier activation in CD200-deficient mice. Conclusions Collectively, these findings provide evidence for a correlation between CD200-CD200R1 alterations, glial activation and neuronal loss. CD200R1 stimulation reduces MPTP-induced loss of dopaminergic neurons, and CD200 deficiency results in earlier microglial activation, suggesting that the potentiation of CD200R1 signalling is a possible approach to controlling neuroinflammation and neuronal death in PD.

scholarly journals The tectonigral pathway regulates appetitive locomotion in predatory hunting in mice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Meizhu Huang ◽  
Dapeng Li ◽  
Xinyu Cheng ◽  
Qing Pei ◽  
Zhiyong Xie ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Superior Colliculus ◽  
Dopamine Release ◽  
Dorsal Striatum ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Neuronal Circuitry ◽  
Locomotion Speed ◽  
Brain Circuit ◽  
Goal Directed Behavior

AbstractAppetitive locomotion is essential for animals to approach rewards, such as food and prey. The neuronal circuitry controlling appetitive locomotion is unclear. In a goal-directed behavior—predatory hunting, we show an excitatory brain circuit from the superior colliculus (SC) to the substantia nigra pars compacta (SNc) to enhance appetitive locomotion in mice. This tectonigral pathway transmits locomotion-speed signals to dopamine neurons and triggers dopamine release in the dorsal striatum. Synaptic inactivation of this pathway impairs appetitive locomotion but not defensive locomotion. Conversely, activation of this pathway increases the speed and frequency of approach during predatory hunting, an effect that depends on the activities of SNc dopamine neurons. Together, these data reveal that the SC regulates locomotion-speed signals to SNc dopamine neurons to enhance appetitive locomotion in mice.

scholarly journals Comparing the protective effects of resveratrol, curcumin and sulforaphane against LPS/IFN-γ-mediated inflammation in doxorubicin-treated macrophages

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haidy A. Saleh ◽  
Eman Ramdan ◽  
Mohey M. Elmazar ◽  
Hassan M. E. Azzazy ◽  
Anwar Abdelnaser
Keyword(s):  
Nitric Oxide ◽  
Inflammatory Response ◽  
Raw 264.7 Cells ◽  
Inos Mrna ◽  
No Production ◽  
Raw 264.7 ◽  
Mrna Levels ◽  
Protective Effects ◽  
Tnf Α ◽  
Ifn Γ

AbstractDoxorubicin (DOX) chemotherapy is associated with the release of inflammatory cytokines from macrophages. This has been suggested to be, in part, due to DOX-mediated leakage of endotoxins from gut microflora, which activate Toll-like receptor 4 (TLR4) signaling in macrophages, causing severe inflammation. However, the direct function of DOX on macrophages is still unknown. In the present study, we tested the hypothesis that DOX alone is incapable of stimulating inflammatory response in macrophages. Then, we compared the anti-inflammatory effects of curcumin (CUR), resveratrol (RES) and sulforaphane (SFN) against lipopolysaccharide/interferon-gamma (LPS/IFN-γ)-mediated inflammation in the absence or presence of DOX. For this purpose, RAW 264.7 cells were stimulated with LPS/IFN-γ (10 ng/mL/10 U/mL) in the absence or presence of DOX (0.1 µM). Our results showed that DOX alone is incapable of stimulating an inflammatory response in RAW 264.7 macrophages. Furthermore, after 24 h of incubation with LPS/IFN-γ, a significant increase in tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) mRNA levels was observed. Similarly, nitric oxide (NO) production and TNF-α and IL-6 protein levels were significantly upregulated. Moreover, in LPS/IFN-γ-treated macrophages, the microRNAs (miRNAs) miR-146a, miR-155, and miR-21 were significantly overexpressed. Interestingly, upon testing CUR, RES, and SFN against LPS/IFN-γ-mediated inflammation, only SFN was able to significantly reverse the LPS/IFN-γ-mediated induction of iNOS, TNF-α and IL-6 and attenuate miR-146a and miR-155 levels. In conclusion, SFN, at the transcriptional and posttranscriptional levels, exhibits potent immunomodulatory action against LPS/IFN-γ-stimulated macrophages, which may indicate SFN as a potential treatment for DOX-associated inflammation.

Struktur und Efferenzen der Substantia nigra pars compacta beim idiopathischen Parkinson-Syndrom

2020 ◽  
Vol 88 (09) ◽  
pp. 591-599
Author(s):  
Peter Urban ◽  
Bjorn Falkenburger ◽  
Wolfgang H. Jost ◽  
Gerhard Ransmayr ◽  
Peter Riederer ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Substantia Nigra Pars Compacta

ZusammenfassungEs besteht Konsens, dass das neuropathologische Merkmal des idiopathischen Parkinson-Syndroms (IPS) der neuronale Zellverlust der Substantia nigra pars compacta (SNc) in Verbindung mit einer Lewy-Pathologie ist. Die transsynaptische Ausbreitung der Lewy-Pathologie wird als wesentlich in der Parkinson-Pathogenese angesehen. Daher ist die Kenntnis präexistenter neuroanatomischer Verbindungen der SNc wesentlich. Wir beschreiben hier neuere tierexperimentelle Befunde zu den afferenten und efferenten Projektionen der SNc und diskutieren die Evidenz für und gegen die sequentielle transsynaptische Ausbreitung der Lewy-Pathologie in der Pathogenese des IPS.

scholarly journals Substantia nigra neuromelanin magnetic resonance imaging in patients with different subtypes of Parkinson disease

2021 ◽  
Author(s):  
Lu Wang ◽  
Yayun Yan ◽  
Liyao Zhang ◽  
Yan Liu ◽  
Ruirui Luo ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Substantia Nigra ◽  
Parkinson Disease ◽  
Clinical Symptoms ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Resonance Imaging ◽  
Mean Values

AbstractNeuromelanin (NM) is a dark pigment that mainly exists in neurons of the substantia nigra pars compacta (SNc). In Parkinson disease (PD) patients, NM concentration decreases gradually with degeneration and necrosis of dopamine neurons, suggesting potential use as a PD biomarker. We aimed to evaluate associations between NM concentration in in vivo SN and PD progression and different motor subtypes using NM magnetic resonance imaging (NM-MRI). Fifty-four patients with idiopathic PD were enrolled. Patients were divided into groups by subtypes with different clinical symptoms: tremor dominant (TD) group and postural instability and gait difficulty (PIGD) group. Fifteen healthy age-matched volunteers were enrolled as controls. All subjects underwent clinical assessment and NM-MRI examination. PD patients showed significantly decreased contrast-to-noise ratio (CNR) values in medial and lateral SN (P < 0.05) compared to controls. CNR values in lateral SN region decreased linearly with PD progression (P = 0.001). PIGD patients showed significant decreases in CNR mean values in lateral SN compared to TD patients (P = 0.004). Diagnostic accuracy of using lateral substantia nigra (SN) in TD and PIGD groups was 79% (sensitivity 76.5%, specificity 78.6%). NM concentration in PD patients decreases gradually during disease progression and differs significantly between PD subtypes. NM may be a reliable biomarker for PD severity and subtype identification.

scholarly journals Lipopolysaccharide induces neuroinflammation in microglia by activating the MTOR pathway and downregulating Vps34 to inhibit autophagosome formation

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Xiaoxia Ye ◽  
Mingming Zhu ◽  
Xiaohang Che ◽  
Huiyang Wang ◽  
Xing-Jie Liang ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Microglial Activation ◽  
Adaptor Protein ◽  
Mtor Pathway ◽  
Microglial Cells ◽  
Inflammatory Factors ◽  
Intraventricular Injection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Autophagic Flux

Abstract Background Microglial activation is a prominent feature of neuroinflammation, which is present in almost all neurodegenerative diseases. While an initial inflammatory response mediated by microglia is considered to be protective, excessive pro-inflammatory response of microglia contributes to the pathogenesis of neurodegeneration. Although autophagy is involved in the suppression of inflammation, its role and mechanism in microglia are unclear. Methods In the present study, we studied the mechanism by which lipopolysaccharide (LPS) affects microglial autophagy and the effects of autophagy on the production of pro-inflammatory factors in microglial cells by western blotting, immunocytochemistry, transfection, transmission electron microscopy (TEM), and real-time PCR. In a mouse model of neuroinflammation, generated by intraventricular injection of LPS (5 μg/animal), we induced autophagy by rapamycin injection and investigated the effects of enhanced autophagy on microglial activation by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. Results We found that autophagic flux was suppressed in LPS-stimulated N9 microglial cells, as evidenced by decreased expression of the autophagy marker LC3-II (lipidated form of MAP1LC3), as well as increased levels of the autophagy adaptor protein SQSTM1. LPS significantly decreased Vps34 expression in N9 microglial cells by activating the PI3KI/AKT/MTOR pathway without affecting the levels of lysosome-associated proteins and enzymes. More importantly, overexpression of Vps34 significantly enhanced the autophagic flux and decreased the accumulation of SQSTM1 in LPS-stimulated N9 microglial cells. Moreover, our results revealed that an LPS-induced reduction in the level of Vps34 prevented the maturation of omegasomes to phagophores. Furthermore, LPS-induced neuroinflammation was significantly ameliorated by treatment with the autophagy inducer rapamycin both in vitro and in vivo. Conclusions These data reveal that LPS-induced neuroinflammation in N9 microglial cells is associated with the inhibition of autophagic flux through the activation of the PI3KI/AKT/MTOR pathway, while enhanced microglial autophagy downregulates LPS-induced neuroinflammation. Thus, this study suggests that promoting the early stages of autophagy might be a potential therapeutic approach for neuroinflammation-associated diseases.

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