Parkinsonian Neurotoxins Impair the Pro-inflammatory Response of Glial Cells

Vortioxetine attenuates rotenone-induced enteric neuroinflammation via modulation of the TLR2/S100B/RAGE signaling pathway in a rat model of Parkinson's disease

Emerging evidence suggests that gastrointestinal dysfunction and enteric nervous system pathology play a critical role in the early stages of Parkinson's disease. Considering the bidirectional relationship between gastrointestinal symptoms and mood disorders, this study aimed to elucidate the effects and possible mechanisms of action of vortioxetine, a serotonergic antidepressant, on the pathophysiological changes induced by rotenone in the enteroglial cells. α-synuclein, phosphorylated α-synuclein, TLR2, S100B and RAGE expression were detected in duodenal tissues of rats administered rotenone (2 mg/kg/day, s.c.) and/or vortioxetine (10 mg/kg/day, s.c.) for 28 days. For the mechanism of action studies, rat-derived enteroglial cells were treated with rotenone (10 μM) and/or vortioxetine (5 μM or 1 μM) for 24 h. The effects of vortioxetine were evaluated in the presence of the TLR2 antagonist C29, RAGE antagonist FPS-ZM1 and the S100B inhibitor pentamidine. TLR2, S100B, RAGE, and NFκB mRNA levels and proinflammatory cytokines via RT-qPCR and ELISA. Our results demonstrate that rotenone treatment significantly increased α-synuclein, pS129-α-synuclein, TLR2, and S100B expression while reducing RAGE levels, indicating marked enteric pathology. Vortioxetine administration attenuated these effects, reducing α-synuclein accumulation and proinflammatory markers. In vitro, rotenone impaired glial responses, decreasing S100B, RAGE, and NFκB markers, while vortioxetine improved these responses, promoting resynthesis of inflammatory molecules. Notably, S100B, NFκB, and cytokine levels (TNF-α, IL-1β, IL-6) were affected by C29, FPS-ZM1, and pentamidine pretreatments. Thus, vortioxetine is thought to have beneficial effects on rotenone-induced pathological changes in EGCs, and some of these effects are thought to be mediated by the TLR2/S100B/RAGE pathway.

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

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

Parkinsonian neurotoxicants impair the anti-inflammatory response induced by IL4 in glial cells: involvement of the CD200-CD200R1 ligand-receptor pair

Exposure to pesticides such as rotenone is a risk factor for Parkinson's disease. Dopaminergic neurons are especially sensitive to the toxicity of compounds that inhibit the mitochondrial respiratory chain such as rotenone and 1-methyl-4-phenylpyridinium (MPP+). However, there is scarce information on their effects on glia. To evaluate whether these neurotoxicants affect the immune response of glia, primary mouse mixed glial and microglial cultures were treated with interleukin (IL) 4 in the absence and presence of MPP+ or rotenone. Using qRTPCR or western blot, we determined the expression of anti-inflammatory markers, the CD200R1 microglial receptor and its ligand CD200, and genes regulating glycolysis and oxidative metabolism. ATP and lactate levels were additionally determined as an index of cell metabolism. Microglial phagocytosis was also evaluated. MPP+ and rotenone clearly abrogated the IL4-induced expression of anti-inflammatory markers in mixed glial cultures. CD200 and CD200R1 expression and microglia phagocytosis were also affected by the neurotoxicants. Changes in the mRNA expression of the molecules regulating glycolysis and oxidative metabolism, as well as in ATP levels and lactate release suggested that metabolic reprogramming in response to MPP+ and rotenone differs between microglial and mixed glial cultures. These findings support the hypothesis that parkinsonian neurotoxicants may impair brain immune response altering glial cell metabolism.