The production of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF) and/or neurotrophin 3 (NT3) can be very supportive in stroke [101-103], Huntington’s disease [104], Parkinson’s disease [26,105,106], spinal cord injury [107,108], and traumatic brain injury [109,110]. Here, GDNF is linked to Parkinson disease.