Nalgene sterile filter units

All solutions were prepared with ultrapure water (Nanopure; Barnstead, Dubuque, IA). Artificial cerebrospinal fluid (aCSF) contained 142 mM NaCl, 1.2 mM CaCl₂, 2.7 mM KCl, 1.0 mM MgCl₂, and 2.0 mM NaH₂PO₄, adjusted to a pH 7.4. Dexamethasone sodium phosphate (APP Fresenius Kabi USA, LLC, Lake Zurich IL) was diluted in aCSF. The microdialysis perfusion fluids were filtered with Nalgene sterile filter units (Fisher, Pittsburgh, PA; PES 0.2 μm pores). Glucose oxidase (GOx, 100–200 units/mg) and horseradish peroxidase (HRP, ≥ 250 units/mg) were obtained from Sigma Aldrich. The ferrocene solution contained 1.5 mM ferrocenecarboxylic acid, 1 mM EDTA, 150 mM sodium chloride and 100 mM sodium citrate and was filtered before use with 0.1 µm and 0.02 µm pore size filters.

Chemicals (disodium EDTA, sodium acetate, sodium 1-octanesulfonate (SOS), acetonitrile, glacial acetic acid, NaCl, KCl, CaCl₂, MgCl₂, and NaH₂PO₄) were purchased from either Fisher Scientific (Fair Lawn, NJ) or Sigma (St. Louis, MO) and used as received. Dexamethasone sodium phosphate was from APP Fresenius Kabi USA, LLC, Lake Zurich IL. Ultra-pure water used was filtered using a Millipore Mili-Q Synthesis A10 system (Belford, MA).
Artificial cerebrospinal fluid (aCSF: 142 mM NaCl, 1.2 mM CaCl₂, 2.7 mM KCl, 1.0 mM MgCl₂, and 2.0 mM NaH₂PO₄, pH 7.4) was used as the perfusion fluid for the microdialysis probes. The high K⁺ aCSF solutions were kept isotonic by lowering the Na⁺ concentration (60 mM K⁺ aCSF: 84.7 mM NaCl, 1.2 mM CaCl₂, 60 mM KCl, 1.0 mM MgCl₂, and 2.0 mM NaH₂PO₄. 100 mM K⁺ aCSF: 44.7 mM NaCl, 1.2 mM CaCl₂, 100 mM KCl, 1.0 mM MgCl₂, and 2.0 mM NaH₂PO₄). Dexamethasone sodium phosphate (APP Pharmaceuticals LLC, Schaumburg, IL) and nomifensine maleate (Sigma-Aldrich, St. Louis, MO) were diluted in aCSF. The microdialysis perfusion fluids were filtered with Nalgene sterile filter units (Fisher, Pittsburgh, PA; PES 0.2 μm pores).

All solutions were prepared with ultrapure water (Nanopure; Barnstead, Dubuque, IA). Artificial cerebrospinal fluid (aCSF: 142 mM NaCl, 1.2 mM CaCl₂, 2.7 mM KCl, 1.0 mM MgCl₂, 2.0 mM NaH₂PO₄, pH 7.4) was used for voltammetric DA calibration and as the perfusion fluid of the microdialysis probe. Dexamethasone sodium phosphate (APP Pharmaceuticals LLC, Schaumburg, IL) was diluted in aCSF. The perfusion fluids for microdialysis were filtered with Nalgene sterile filter units (Fisher, Pittsburgh, PA; PES 0.2 μm pores). Nomifensine maleate and S(−)raclopride (+)-tartrate (Sigma Aldrich, St. Louis, MO) were dissolved in phosphate-buffered saline (PBS: 137 mM NaCl, 2.7 mM KCl, 1.47 mM KH₂PO₄, 10 mM Na₂HPO₄, pH 7.4) and administered at 20 mg/kg and 2 mg/kg (i.p.) respectively. DA (Sigma-Aldrich, St. Louis, MO) standards were prepared in N₂-purged aCSF for electrode calibration.