In contrast to this, the GFRα1 is the core receptor for the neurotrophic peptide GDNF.92 Originally, GDNF-GFRα1 was found to support survival of mid-brain dopaminergic neurons and was thus of interest in Parkinson's disease research,93 but has since been seen to be important also for neuronal maintenance and plasticity in homeostasis.94,95 GDNF rather than GFRα1 has been investigated in experimental TBI96,97 and showed some promise. The gene discussed is GDNF; the disease is Parkinson disease.