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Browsing by Subject "dopaminergic neuron"

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  • Pykälämäki, Matias (2023)
    Parkinson’s disease (PD) is a progressive neurodegenerative disease characterized by the death of nigrostriatal dopaminergic neurons and formation of intraneuronal protein aggregates called Lewy bodies and Lewy neurites. These inclusions consist of a protein called α-synuclein (aSyn) but also of other proteins, lipids and cell organelles. Progressive cell death leads to nonmotor and motor symptoms. Current therapies for PD are symptomatic and do not modify the disease progression. Therefore, there is a need for the development of therapies attenuating the neurodegeneration. The pre-formed fibrils (PFF) model enables studying of aSyn aggregation and mechanisms behind inclusion formation. The PFF model is based on the exogenous aSyn fibrils’ tendency to result in formation of Lewy body -like inclusions when added in cell culture or in animals. Primary neuronal cultures of mice and rats have typically been used to model aSyn aggregation in vitro with the PFF model. Primary neuronal cultures provide practicality and are able to depict relevant features of dopaminergic neurons. To gain insight about the composition of E13.5 primary embryonic mouse midbrain culture and to enable adaptation of an existing protocol to study other cell types, this study identified and quantified several relevant cellular phenotypes in the micro island culture. The cells were fixed on day in vitro (DIV) 8 or DIV 22 and analysis was conducted using fluorescent immunocytochemistry combined with automated image analysis software, CellProfiler. On DIV 8, tyrosine hydroxylase -positive dopaminergic neurons represented 5 % of the total cells in the culture. Neuronal nuclear antigen -positive neurons resulted representing 30 % of the total cells. Gabaergic neurons were identified to be abundant in the culture and certain dopaminergic neurons were identified as immunoreactive for GABA. Choline acetyltransferase -positive cholinergic neurons were also identified to be present in the culture. The number of oligodendrocyte precursors (OPCs) was observed to be significantly smaller than the number of dopaminergic neurons. OPCs represented around 1 % of the culture on DIV 8. Glutaminergic neurons, parvalbumin-positive interneurons, microglia or astrocytes were not identified in the culture on DIV 8. The number of astrocytes was observed to increase as the incubation time was prolonged to DIV 22. Overall these findings provide valuable insights of the composition of cell phenotypes in E13.5 mouse midbrain culture. The results also provide additional validation for suitability of the original protocol to robustly produce midbrain dopaminergic cultures with minimal number of glial cells. Understanding more about the relevance and interplay of different cell phenotypes in PD pathophysiology can provide valuable insight for the development of potential therapeutic strategies.
  • Kulmala, Veera (2022)
    Parkinson’s disease (PD) is a progressive neurodegenerative disorder with the neuropathological hallmark of intraneuronal inclusions called Lewy bodies (LB). Accumulation of α-synuclein (α-syn) and cellular components into LBs coincides with degeneration of dopaminergic neurons in the midbrain, substantia nigra. Degeneration of dopaminergic neurons eventually leads to motor dysfunctions. Currently, the treatments for PD are symptomatic. For this reason, new disease-modifying treatments are needed to slow down or prevent the disease progression. Neurotrophic factors (NTFs) have been an interest of research for a couple of decades because of their neuroprotective properties. The main aim of this study was to investigate if brain-derived neurotrophic factor (BDNF) reduces pre-formed fibril (PFF) induced aggregation of α-syn in dopaminergic neurons. PFF-model was used to mimic the accumulation of LBs in neurons, as PFFs induce aggregation of endogenous α-syn in neurons. Additionally, the dose dependence of BDNF was tested. The secondary objective was to investigate the interaction of tropomyosin receptor kinase B (TrkB) signaling pathway and α-syn aggregation using TrkB agonists and antagonists. The cultured dopaminergic neurons isolated from the midbrain of mouse embryos were treated with PFFs on the day in vitro (DIV) 8. BDNF or control treatments were added either 1 hour after the PFF-treatment or on DIV 12. Neurons were fixed on DIV 15 and fluorescent immunohistochemistry was performed. After the detection of fluorescence with automated, high-content imaging, image analysis was done for quantifying dopaminergic neurons, and dopaminergic neurons positive for LB-like aggregates by using unbiased image analysis CellProfilerTM software. Both BDNF and positive control glial cell line-derived neurotrophic factor (GDNF) significantly reduced LB-like aggregates in dopaminergic neurons at both timepoints. GDNF was more effective at both timepoints than BDNF. Both tested doses of BDNF lowered the number of LB-like aggregates, but a more robust effect was seen with the higher dose. The highest tested dose for the TrkB agonists was toxic to the cultured dopaminergic neurons, whereas the lower doses did not affect either the survival or the number of LB-like aggregates. BDNF promoted the survival of the dopaminergic neurons despite the survival-reducing adverse effect of TrkB antagonist K252a. This study provided new information on the effects of exogenously added BDNF on PFF-model with primary neuronal culture. Research on the underlying mechanisms of α-syn aggregation and the protective effects of NTFs can forward the development of new therapies against PD.