Human embryonic kidney 293 (HEK293) cells were cultured in Opti-MEM I media supplemented with 5% fetal bovine serum (FBS; v/v; Thermo Fisher Scientific). Subsequent transfections were carried out in Opti-MEM I media, utilizing 0.9 μL of MATra-A Reagent (IBA) and 900 ng of DNA vectors containing the human versions of the GluN1-1a and GluN2B subunits along with green fluorescent protein (GFP, pQBI, Takara). Following transfection, the cells were put on the magnet for 30 min. Then, HEK293 cells were trypsinized, cultivated in Opti-MEM I with 1% FBS, 2 mM MgCl2, and 3 mM kynurenic acid on glass coverslips, and subjected to electrophysiological recordings within 24-48 h .