Protein levels of BDNF (A) and Bcl-2 (B) in frontal cortex of control rats (n = 10) and chronic NMDA-treated rats (n = 10), measured using ELISA and immunoblot as described in the method section. Optical densities of immunoblot bands were normalized to b-actin to correct for unequal loading. Values are expressed as percent of control. Phosphorylated CREB (C) was measured in frontal cortex of control rats (n = 8) and of chronic NMDA-treated rats (n = 8) by ELISA, as described in manufacturer's instructions. mRNA levels of BDNF (C) and Bcl-2 (D) in frontal cortex of control rats (n = 6) and of chronic NMDA-treated rats (n = 6), measured using RT-PCR. Data are expressed as mRNA level in frontal cortex of chronic NMDA administered rats, normalized to the endogenous level of β-globulin mRNA, and relative to the control (calibrator), using the ΔΔCT method (means ± SEM, *p < 0.05, **p < 0.01, ***p < 0.001).