Another study employing a rat model of PD with unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA) shows that ambroxol treatment initiated 4 weeks after 6-OHDA injection (when motor symptoms have fully developed and nigral cell loss has reached maximal levels) results in restoration of GCase activity, restoration of the dopaminergic system measured by tyrosine hydroxylase and DA transporter levels, reduction in α-syn pathology, and recovery of behavioral symptoms [102], suggesting disease-modifying effects in PD. This evidence concerns the gene SLC6A3 and Parkinson disease.