HPLC analysis of striatal dopamine and its metabolites

Samples were prepared and quantified as described previously (Ghosh et al., 2010). In brief, 7 days after MPTP injection, mice were sacrificed and striata were collected and stored at -80°C. On the day of analysis, neurotransmitters from striatal tissues were extracted using an antioxidant extraction solution (0.1 M perchloric acid containing 0.05% Na₂EDTA and 0.1% Na₂S₂O₅) and isoproterenol (internal standard). Dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were separated isocratically using a reversed-phase column with a flow rate of 0.6 mL/min. An HPLC system (ESA Inc., Bedford, MA) with a thermostatted automatic sampler (model 542; ESA Inc.) was used for these experiments. The electrochemical detection system consisted of a Coulochem model 5100A with a microanalysis cell (model 5014A, ESA Inc.) and a guard cell (model 5020, ESA Inc.). Data acquisition and analysis were performed using EZStart HPLC Software (ESA Inc.).