Capcell c18 mg s 5

The dorsolateral striatum from both the left and right sides (n = 10, per group) was dissected and frozen at −80°C. Brain tissue samples were weighed and then homogenized in 700 μL of ice-cold lysis buffer [19 (link)], containing o-phthalaldehyde 27 mg, anhydrous ethanol 1 mL, tetraborate buffer 9 mL, andβ-mercaptoethanol 5 μL.
The homogenate was centrifuged at 14000 rpm for 15 min at 4°C and filtered through a 0.22 μm filter (Costar, Spin-X) and then centrifuged at 7000 rpm. Standard solution or the filtrate obtained from brain homogenate (20 μL) was injected into the HPLC. Chromatographic conditions were as follows. The precolumn was Shiseido (Guard Cartridge, Capcell C18 MG S-5, 4.0 × 10 mm). The chromatographic column was Waters XTerra MS (3.0 × 50 mm, 2.5 um, Part no. 186000598). The mobile phase was composed of 100 mM disodium hydrogen phosphate, 25% methanol, and 10% acetonitrile (pH 6.70). The flow rate was 0.6 mL/min. The column oven was held constant at 40°C. Working solutions of GABA (40, 20, 8, 4, 2, 1, and 0.5 μg/mL) were used. The calibration curve of each compound was determined by plotting the ratio of peak area to internal standard versus concentration of the spiked standard solution. A linear regression equation (y = ax + b) was evaluated, where x is the concentration of the analytes and y is the peak area ratio. The correlation coefficient (R²) was calculated.

High-performance liquid chromatography (HPLC) was performed using ESA 5600A HPLC with model 5600A CoulArray Detector-8, and ESA MD-15 column (3.2 × 150 mm, 5 µm). Data were collected and analyzed with ESA Software Version. Separation of analysis was performed using a Waters XterraTM MS column (3.0 × 50 mm, 2.5 µm, Part 186000598), preceded by a pre-column filter (Shiseido, Guard Cartridge, Capcell C18 MG S-5, 4.0 × 10 mm). The mobile phase consisted of methanol (20%), acetonitrile (3.5%), disodium hydrogen phosphate (100 mM) (pH 6.7, adjusted by phosphoric acid). Woking solutions of GABA (G1251; Sigma, St. Louis, MO, USA) and GLU (5835, sigma, St. Louis, MO, USA) (40, 20, 10, 5, 2.5, and 1.25 μg/ml) were used. The column temperature was maintained at an ambient temperature of 40°C. The flow rate was set to 0.6 ml min⁻¹.