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Background: Alzheimer´s and Parkinson´s disease are the two great neurodegenerative diseases of our time. Both diseases share an accumulation of misfolded proteins, the oligomers of which have a toxic effect and may cause neuronal cell death. Furthermore, both diseases are characterized by neuro-inflammatory processes caused by activated microglia. ER stress is one of the mechanisms in neurodegeneration. Caused inter alia by an accumulation of misfolded proteins, ER stress activates different signalling cascades needed to restore cell homeostasis. Failure of these regulatory mechanisms induces apoptosis.
Objective: This thesis explores the effects of ER stress induced by amyloid-beta 1 42 (Aβ1 42) oligomers and 6 hydroxydopamine (6 OHDA) on murine neuronal and microglial cell culture models of Alzheimer´s and Parkinson´s disease. Furthermore, the microglial activation was measured to gain deeper insight into the relationship between ER stress and neuroinflammation.
Methodology: Embryonic primary murine cortical neurons and mesencephalic microglia were treated with toxic concentrations of Aβ1 42 oligomers and 6 OHDA, the effectivity of which was identified by means of MTT assay and double staining. Furthermore, ELISA and Griess assay were used to determine the inflammatory activity of microglial cells by measuring TNF α, IL 6 and nitrite level. Subsequently, changes in the concentration of Activating Transcription Factor 6 (ATF6), Glucose Regulated Protein 78 (GRP78), C/EBP Homologous Protein (CHOP) and Caspase 3 were identified using Western blot analysis.
Results: 6 OHDA treatment leads to the induction of Caspase 3 and ATF6 in neuronal cells. There is no evidence that Aβ1 42 treatment induces a change in neuronal protein concentration. Both treatments result in a decrease in the protein concentration of GRP78, CHOP expression could not be detected in microglial cells. Furthermore, 6 OHDA and Aβ1 42 treatment fails to induce activation of microglia.
Discussion: The results show the partial induction of ER stress activating signalling cascades in neuronal cells unter 6 OHDA treatment. Aβ1 42 treatment could not induce ER stress in microglial or neuronal cells. The established cell culture models are rather not suited for further investigation of ER stress regulation in neurodegenerative diseases. The results, however, indicate that the state of development of the cell might have an influence on the regulatory mechanisms activated by ER stress.