MPP+ is taken up via the dopamine transporter (DAT) into DA neurons where it triggers the formation of reactive oxygen species (ROS) [20]. Next, it accumulates inside the mitochondria and impairs the mitochondrial respiration by inhibition of complex I [21]. This leads to a combination of a reduction in cellular ATP and a further upregulation of ROS, which initiates cell death-related signalling pathways. Since rats do not have sufficient MAO-B in the brain to convert MPTP, they are not suited for MPTP induced PD. However, some investigators directly inject MPP+ into rat brains. Because the mechanisms of MPTP intoxication are quite similar to features seen in PD, the MPTP model is seen as a valid PD model [14].