All collections were made in a Raturn (BASi, West Lafayette, IN) while the animal kept awake and acitve freely. Collections probes were acutely implanted after surgery. Using a syringe pump (BASi BEE), a 30 min flush was performed through the microdialysis probe at 1 μL/min after which collections began at 1 μL/min for 60 min for 5 hours. Samples were stored on ice, and kept frozen at -80oC until analysis.
The analysis of dopamine (DA) using HPLC-ECD method
The separation of dopamine (DA) was performed using HPLC. The Eclipse XDB-C18 column (250mm ×4.6 mm, 5μm) was used, and the mobile phase contained 85 mM citric acid, 100 mM sodium acetate, 0.2 mM Na2-EDTA, 0.9 mM octane sulfonic natrium, 300 mL methanol (pH=3.7). The elute velocity was 1 ml/min, and the column temperature was maintained at 35oC. The applied potentials (mV): conditioning cell = +10 V; analytical cell, E1 = +50 V; E2 = +340V.
Statistical analysis
The data was given as mean±S.D. Statistical differences were evaluated using the two-tailed Student’s t-test and considered significant at the *p < 0.05 level.