25 m KH2PO4 and 0.75 mm NaN3 (flow rate of 0.6 mL/min). They were then automatically derivatized by online mixing with 0.1% o-phthalaldehyde, 2 m NaOH and 0.2 m H3BO3 in a reaction coil incubated at 45 °C, and finally stabilized this website with 3 m H3PO4. Fluorescence was measured at λEm 450 nm (λEx 360 nm). The method was based on post-column o-phthalaldehyde/β-mercaptoethanol derivatization as described in detail in Miyamoto et al. (2004). The supernatants of precipitated samples collected as described

above were neutralized with 10 volumes of 0.4 m borate buffer. They were then subjected to solid-phase extraction with BondElut CBA 100-mg SPE cartridges (Varian, Palo Alto, CA, USA) that were equilibrated selleck chemicals with 1 mL of CH3OH, 1 mL of 0.01 m HCl, and 3 mL of H2O. The cartridges were washed with 1 mL of water, and histamine, 1-methylhistamine

and 3-methylhistamine were then eluted with 500 μL of 0.1 m HCl containing 1 mm EDTA. Then, 50 μL of the elution fraction was injected into the HPLC system for further analysis. Histamine and 1-methylhistamine were separated on a 4.6 × 150-mm, 5-μm C18 Phenomenex Gemini column equipped with a SecurityGuard C18 4 × 3-mm pre-column cartridge (Phenomenex) with the HPLC system described above. The mobile phase consisted of methanol/0.15 m KH2PO4 (4 : 96, v/v) containing 200 mg/L sodium salt of octanesulphonic acid (flow rate of 0.6 mL/min). The eluent line was connected by a T-piece to a reagent line that mixed a 0.05% o-phthalaldehyde/0.2% β-mercaptoethanol solution and 0.5 m NaOH in a short reaction coil. The analytical column and the reaction coil were kept at 42 °C with a HIS25 heating oven (Grant Institute, Olopatadine Edinburgh, UK). Fluorescence was measured at λEm 450 nm (λEx 360 nm). Male 10-week-old C57BL/6J mice were kept individually for 2 weeks before surgery. Mice were operated on under general anaesthesia

induced by intraperitoneal ketamine (75 mg/kg) in combination with intraperitoneal medetomidine (1 mg/kg). The guide cannula (CMA 7 Guide; CMA/Microdialysis, Solna, Sweden) was implanted into the posterior part of the hypothalamus 1 mm above the target site, the TMN. Stereotaxic coordinates (relative to bregma) were: anterior, −2.5; lateral, +0.5; and vertical, −4.4 (Paxinos & Franklin, 2004). Electrodes for electromyography were placed in the neck musculature. Two gold-coated screws were installed into the skull for frontoparietal epidural EEG recording. The electrodes, guide cannula and supporting screws were secured to the skull with dental cement. To enable mice to recover from anaesthesia, they were injected with subcutaneous Antisedane (0.5 mg/kg) and given the analgesic buprenorphine (0.1 mg/kg, subcutaneous). Five mice were used for microdialysis sampling and EEG/electromyographic (EMG) recording. EEG/EMG recording was started 5–6 days after surgery.