The first hypothesis was not supported, as the assays performed revealed that alpha-synuclein expression was highest in the control sample (see Figure 9). This was unexpected because the control cells were not exposed to MPP+, which has been shown to induce alpha-synuclein expression through apoptosis. However, comparison of the results shows that the control and MPP+ samples are almost identical, which suggests that the concentration of MPP+ used in this model was too small to provoke an increase in the amount of α-synuclein. Also, the duration of the model of exposure may need to be lengthened to see a difference in the amount of alpha-synuclein expression in SH-SY5Y cells.
The second hypothesis was partially supported, although the unexpected MPP+ results and statistical analysis prove that these results are not quite statistically significant. The cells treated with guanosine have the lowest alpha-synuclein expression (see Figure 9). The pre-treatment sample had the lowest expression overall and the post-treatment sample had the highest expression overall of the treated samples.
The mechanism by which guanosine prevents alpha-synuclein expression and subsequent apoptosis is not currently known. When guanosine was seen to be anti-apoptotic against β-amyloid induced apoptosis, the mechanism it used was activating intracellular pathways (eg. mitogen-activated protein (MAP) kinase pathway) that protect against apoptosis. It is assumed that guanosine works the same way for alpha-synuclein, although further research is needed to determine exactly which intracellular pathways are activated.