The guide cannulae were secured in place GABA receptor signaling using two small stainless steel screws anchored to the skull with dental acrylic cement [16]. Animals were allowed 7 d of recovery following the surgery. The D1R antagonist SCH23390 (0.6 μg/200 nL/side; Tocris Bioscience, Ellisville, MO, USA) and the D2R antagonist eticlopride (0.7 μg/200 nL/side; Tocris Bioscience) were separately dissolved in modified Ringer’s solution (MRS; 150mM NaCl, 3.0mM KCl, 1.4mM CaCl2, and 0.8mM MgCl2 in

10mM phosphate buffer with a pH of 7.1) and individually delivered over a period of 60 s using motorized syringe pumps (Sage Instruments, Boston, MA, USA) [17]. Immediately following the EPM test, the rats were decapitated and their brains were removed to verify the guide cannula placements. The CeA tissue samples were sonicated in 1 mL 0.1 M perchloric acid (HClO4) and centrifuged (26,000 × g)

at 4°C for 15 min. Then, a 20 μL aliquot of supernatant was injected directly into an HPLC machine with a coulometric detector (Coulochem II; ESA, Bedford, MA, USA). The HPLC system was composed of a C18 reverse-phase column (5 U ODS; Altex, Ann Arbor, MI, USA) and an electrochemical transducer with a glassy carbon electrode set at 350 mV. The mobile phase contained 0.16 M citric acid (pH 3.0), 0.02mM EDTA with 0.69mM sodium octanesulfonic acid as an ion-pairing reagent, ABT 737 4% (v/v) acetonitrile, and 1.7% (v/v) tetrahydrofuran. The peaks and values of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) were identified and calculated based on a comparison of their retention times and peak heights with those of standards. The protein concentrations in the brain homogenate samples were determined using a Bicinchoninic acid (BCA) protein assay with the HPLC results expressed as ng/g of protein. The frozen CeA tissues were homogenized in lysis buffer [20mM Tris, 5mM EDTA, 1% Nonidet P-40 (vol/vol), and protease Fossariinae inhibitors], incubated on ice for 20 min, and centrifuged (19,000 × g) at 4°C for 20 min. Then the supernatants were resolved

via electrophoresis on a 12% sodium dodecyl sulfate-polyacrylamide gel and the proteins were transferred onto a nitrocellulose membrane (Schleicher & Schuell GmbH, Dassel, Germany). The membrane was incubated with either an anti-mouse tyrosine hydroxylase (TH) antibody or an anti-goat β-actin antibody (Santa Cruz Biotechnology, Santa Cruz, CA, USA), washed with tris buffered saline with Tween-20 (TBST; 10mM Tris-Cl pH 7.5, 150mM NaCl, and 0.05% Tween-20), and incubated for 1 h with the appropriate peroxidase conjugated secondary antibodies. Bands corresponding to TH and β-actin were visualized using enhanced chemiluminescence Western blot detection reagents (Amersham Biosciences, Piscataway, NJ, USA).