Experimental design. Male and female Wistar rat pups were sacrificed by decapitation at each of Postnatal Days (PND) 1, 2, 3, 4, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17. The prefrontal cortex (PFC), hippocampus (HC), striatum (STR), and hypothalamus (HY) were separately dissected and homogenized for the measurement of NO concentrations by using the diazotization method based on the Griess reaction.