Compositions and methods for administering proteins GDNF ligand family

A pharmaceutical composition comprising: (i) a protein of the family of ligands derived neurotrophic factor selected glial cell line (GDNF) the group consisting of a neublastin polypeptide, a polypeptide of GDNF, a polypeptide of Neurturin, and a polypeptide persephin; and (ii) an amount of heparin or heparan sulfate increases serum exposure of the protein family ligands GDNF administered in a subject, for use in treating a disorder of the nervous system by systemic release of the pharmaceutical composition.