Glial-Derived Neurotrophic Factor, also known as GDNF and ATF-1, is a neurotrophic factor belonging to the TGF-beta family. It is expressed in both central nervous system (CNS) and non-CNS tissues. GDNF signals through a receptor system composed of a RET and one of the four GFR alpha receptors. It promotes the survival and differentiation of dopaminergic neurons, and increases their high-affinity dopamine uptake. In a mouse Parkinson’s Disease model, GDNF has been shown to improve bradykinesia, rigidity, and postural instability. GDNF has also been shown to regulate kidney development, spermatogenesis and affect alcohol consumption.