4.4. The [3H] DA Uptake Assay

The [³H] DA uptake assay was performed following previous studies [68]. Briefly, after being rinsed with warm Krebs–Ringer buffer (KRB; Sigma-Aldrich Chemical Co.), neuron cultures were incubated in 0.5 ml of uptake buffer containing 5 µM dopamine and 20 nM [³H] dopamine for 10 min at 37°C. After the assay was stopped by being washed 3 times with ice-cold KRB, the cells were collected and solubilized in 1 M NaOH. Radioactivity was determined by liquid scintillation counting. Nonspecific dopaminergic (DA) uptake determined in the presence of mazindol (10 mM) was subtracted from total uptake to obtain specific DA uptake.