In brief, the neocortices of 17-day embryos from Sprague-Dawley rats were collected and placed in a Ca2+ and Mg2+-free Krebs buffer. Following a trypsinization step, the cortices were mechanically dissociated and the Krebs buffer was replaced with NB medium supplemented with 2 mmol/L l-glutamine, penicillin (100 U/mL), streptomycin (100 U/mL), and 10% FBS. Cell counting was performed using a Nucleocounter Inhibitors,research,lifescience,medical NC-100 (Chemometec, Allerod, Denmark), and neurons
were plated into 24-well poly-d-lysine-coated plates at a density of 0.25 × 106 cells per well. The cultures were maintained at 37°C in a humidified atmosphere with 5% CO2/95% air. After 24 h in culture, the FBS-containing medium was replaced with NB supplemented with 2% B27. Ninety-six hours following the isolation, 10 μmol/L cytosine-d-arabinofuranoside
was added to the medium. After 48 h, this medium was completely substituted with fresh Inhibitors,research,lifescience,medical NB/B27 medium and partial medium changes were performed on alternate days until the 13th day in vitro. Excitotoxicity Excitotoxicity was induced by a 3-h exposure of the neuronal cultures to 100 μmol/L of NMDA, carried out at 37°C in a 4-(2-hydroxyethyl)-1-piperazineethanesulfonic Inhibitors,research,lifescience,medical acid (HEPES)-buffered solution containing 120 mmol/L NaCl, 5.4 mmol/L KCl, 0.8 mmol/L MgCl2, 20 mmol/L HEPES, 15 mmol/L glucose, and 0.01 mmol/L glycine. Cell treatments After 14 days in vitro, neurons were exposed to appropriate concentrations (see Figs. 1–4) of NMDA alone or in coadministration with memantine, Inhibitors,research,lifescience,medical ifenprodil, MK-801, galantamine, MCC citrate, DHBE hydrobromide, and ARR hydrochloride, separately or in different combinations. The duration of the treatment was 3 h. Figure 1 Protective effects afforded by individual treatments with memantine, ifenprodil, and galantamine Inhibitors,research,lifescience,medical against NMDA neurotoxicity in cultured rat cortical neurons. Memantine (A, B), ifenprodil (C, D), and galantamine (E, F) caused a significant and dose-dependent … Figure 4 Combined administration of α7 and
α4β2 nAChR antagonists abolishes the neuroprotective effect of memantine or ifenprodil plus galantamine. The neuroprotective effect of (A) memantine/galantamine and (B) ifenprodil/galantamine combinations PD184352 (CI-1040) … Neurotoxicity assessment Neurotoxic damage was evaluated using the MTT and LDH assays according to the protocols provided by manufacturers. MTT MTT is reduced to formazan by metabolic active cells, and therefore, this conversion is directly related to the amount of viable cells. Briefly, after the cell treatments, MTT in a concentration of 5 mg/mL was added to the neuronal culture medium for 4 h at 37°C. After this incubation, a solubilization solution (10% selleck chemicals llc sodium dodecyl sulfate [SDS] in 0.01 mol/L HCl) was added to the wells and left overnight at 37°C to dissolve the formazan crystals formed. Absorbance was measured at 570 nm on a Tecan Infinite M200 (Tecan, Männedorf, Switzerland) plate reader.