Regional concentration of DA was analyzed by high-performance liquid chromatography with HPLC-ECD (Waters 2465, Meliford, MA, USA) as previously described29 . Briefly, the rats were sacrificed and the striatum tissues were dissected and immediately homogenized with 0.1 M perchloric acid, homogenates were centrifuged at 12,000 rpm for 15 min at 4°C and the resulting supernatants were stored at −80°C until analysis.
Before detection, the supernatants were collected and filtered through microcentrifuge filters. Compound separation was achieved on a C18 reverse-phase analytical column (50 mm × 2.1 mm, 1.9 µm particle size, Thermo, Rockford, IL, USA) with a mobile phase consisting of 150 mM citric acid, 150 mM trisodium citrate dihydrate, 100 mM ethylenediamine tetraacetic acid disodium salt (EDTA · 2Na), 1 mM sodium 1-heptanesulfonate and 10% methanol (v/v). Elution was carried out at a flow rate of 0.2 ml/min, and the working electrode potential of the electrochemical detector was set at 0.8 V. The column was maintained at 28°C.
Before detection, the supernatants were collected and filtered through microcentrifuge filters. Compound separation was achieved on a C18 reverse-phase analytical column (50 mm × 2.1 mm, 1.9 µm particle size, Thermo, Rockford, IL, USA) with a mobile phase consisting of 150 mM citric acid, 150 mM trisodium citrate dihydrate, 100 mM ethylenediamine tetraacetic acid disodium salt (EDTA · 2Na), 1 mM sodium 1-heptanesulfonate and 10% methanol (v/v). Elution was carried out at a flow rate of 0.2 ml/min, and the working electrode potential of the electrochemical detector was set at 0.8 V. The column was maintained at 28°C.