Amphetamine administration elevates the endogenous GDNF expression in the nigrostriatal tract (Morrow et al., 2011; Valian et al., 2017), increases the concentration of dopamine in synapses, and elevates the schizophrenia susceptibility (Morrow et al., 2011; Li et al., 2014; Valian et al., 2017). Here, GDNF is linked to schizophrenia.