Total BDNF levels were measured using rat BDNF ELISA Kit (Cat # ERBDNF, Invitrogen, Thermo Fisher Scientific), in triplicate, according to the manufacturer’s instructions as previously described.1 (link), 45 (link) Initially, 100 μl of standards and samples at RT were added to each well and incubated for 2.5 h. Assay diluent served as a zero standard (0 pg/ml) for background subtraction to construct a standard curve.
Following standard curves analysis (in triplicate), the optical density or absorbance of each well was measured using an automated ELISA plate reader (Spectra Max®-Multi Microplate Reader, Molecular Devices) at 450 nm and 550 nm, within 30 min of adding the stop solution. Absorbance values of 550 nm were subtracted from 450 nm to correct for the optical density. BDNF values (in pg/ml) in test samples were calculated using the standard curve.