Ketamine hydrochloride

Ketamine hydrochloride was purchased from Tocris/Bio-Techne (Warsaw, Poland) and psilocybin was synthesized at the Department of Medicinal Chemistry of the Maj Institute of Pharmacology using the method described by Shirota et al. [62 (link)]; both were dissolved in sterile water. All solutions were made fresh on the day of the experiment. The dose of ketamine (10 mg/kg) was based on a report by Popik et al. [63 (link)], while doses of psilocybin (2 and 10 mg/kg) were based on work by Jefsen et al. [61 (link)]. Psilocybin was given subcutaneously (sc) while ketamine was given intraperitoneally (ip) in the volume of 2 mL/kg. The control group was treated with 0.9% NaCl solution. Ketamine, xylasine hydrochlorides and sodium pentobarbital used for anesthetizing the animals came from Biowet Puławy (Puławy, Poland). All necessary chemicals of the highest purity used for analysis by high-performance liquid chromatography (HPLC) were obtained from Merck (Warsaw, Poland). O-phthalaldehyde (OPA) from Sigma-Aldrich (Poznań, Poland) was used for the derivatization of glutamate and GABA to electroactive compounds. The reagents used in immunohistochemistry were purchased from Sigma-Aldrich (Poznań, Poland), Vector Laboratories (Burlingame, CA, USA), and Proteintech (Manchester, UK).

DL-TBOA, DL-AP-5 sodium salt, MK-801 maleate, ketamine hydrochloride, NBQX disodium salt, were purchased from Tocris Bioscience (Bristol, UK).

Ten male PLB1_WT mice were implanted at ~4 months of age to investigate the effects of ketamine and diazepam on sleep and EEG profiles. A 4-week Latin square based drug administration regime was constructed where animals were allocated to 4 groups. Once per week each group received an intraperitoneal injection of either 10 mg/kg ketamine hydrochloride (Tocris Bioscience, UK) in vehicle (saline), saline only (ketamine vehicle), diazepam (Sigma Aldrich, UK) in a vehicle composed of a 1:1:18 ratio of ethanol, Cremaphor and saline, or the diazepam vehicle only. Treatment group allocations were rotated such that each animal received each of the 4 treatments with a 1 week washout between treatments. Following administration, recording devices were attached and animals were placed in individual holding cages where EEG activity was recorded for 6 hours. Five animals were selected for data analysis where high quality recordings had been obtained from recordings conducted both after administration of a drug treatment and administration of its respective vehicle. Sleep staging of EEG was conducted as in experiment 1. Here, a 60 second artefact free strip of EEG from periods of NREM sleep was extracted for each animal and condition. Power spectra and cross-channel coherence were then assessed using AR and rPDC analyses, respectively, and results were pooled by treatment group.