In the study after the induction of PD through the administration of MPTP for 5 weeks, despite the number of TH+ neurons being reduced dramatically, the levels of D-ser and SR were lower and not observed in the TH+ neurons of the substantia nigra but the levels of D-Ser and SR were higher in both astrocytes and nondopaminergic neurons in the striatum [31]. The gene discussed is TH; the disease is Parkinson disease.