Comparison of protective effects of A-tocopherol and A-tocotrienol forms of vitamin e against beta amyloid plaque accumulation in the brain

In this thesis study, the protective effects of α-tocopherol and α-tocotrienol forms of vitamin E, a powerful antioxidant, against beta amyloid-induced neurodegeneration were experimentally investigated and compared on a two-dimensional in vitro neurodegeneration model using cell culture methods. The focus of the study was to examine the protective effect of α-tocopherol and α-tocotrienol derivatives of vitamin E against cell death caused by beta amyloid accumulation and to compare the protective effects of these two vitamin E derivatives with each other. In this context, primary neuron isolation was performed and beta amyloid was applied on the obtained primary neurons in order to establish a two-dimensional neurodegeneration model. Afterwards, cell viability was determined by analysis of 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide, cytotoxicity was determined by neutral red analysis, beta amyloid accumulation amount was determined by Congo Red analysis and percent apoptosis, and necrosis were determined by Acridine Orange / Propidium Iodide analysis. In addition, the expression amounts of voltage-dependent l-type calcium channel and Beta-Secretase 1 genes whose expression increased in beta amyloid-induced neurodegeneration mechanism were measured by Real Time Polymerase Chain Reaction. Experimental studies were carried out using 17-18 day old rat pups obtained from mating six female and one male rats. According to the findings, α-tocopherol and α-tocotrienol derivatives of vitamin E showed a protective effect against beta amyloid-induced neurodegeneration at 48 and 72 hours of application. As a result of the Real Time Polymerase Chain Reaction analysis, it was revealed that α-tocopherol and α-tocotrienol were effective on Voltage-gated L-type calcium channel and Beta secretase 1 mechanism. These two components of vitamin E have been observed to significantly reduce the expression of the Voltage-gated L-type calcium channel gene. On the other hand, the decrease observed on Beta secretase 1 expression was not statistically significant. The protective effect of α-tocopherol and α-tocotrienol against beta amyloid-induced neurodegeneration was observed at different levels in terms of cell viability and cytotoxicity in 48 and 72 hours applications. In this context, more detailed studies are required in the future in order to better understand the difference between the protective effects of α-tocopherol and α-tocotrienol against beta amyloid-induced neurodegeneration and the effect of vitamin E on beta secretase 1 gene expression.