The postnatal period represents the critical window referring to specific intervals of time during which the brain’s development exhibits increased sensitivity to specific types of learning and external influences. This period is usually associated with the development of age-related neurodevelopmental processes. Nitric oxide (NO) is an essential signaling molecules that play an important role in physiological processes including neuronal survival and differentiation, neurogenesis, synaptogenesis, pruning, and brain plasticity. In the present study, we aimed to determine the activity of NO during the early and late critical periods of structural and functional maturation of the central nervous system (CNS). In this study, we focused on the prefrontal cortex, hippocampus, striatum, and hypothalamus of male and female “Wistar” rat pups, as these areas have differential developing states. NO level was determined on postnatal days (PND) 1, 2, 3, 4, 7, 8, 9, 10, 11, 12, 14, 15, 16, and 17. The supernatant nitrite/nitrate (NOx) concentration was assessed after the reduction of nitrates to nitrites using the Griess reaction. Results revealed three distinct periods during postnatal development. In the first period, between PND1 and PND4, NO expression in both sexes increased, reaching a peak at PND8. The second period (PND8 to PND10) showed a slight decrease in NO expression. In the last period (PND11 to PND17), NO expression showed a high level. In summary, NO exhibited variations across the four examined areas, suggesting a complicated regulation of NO production during neonatal and infantile neurodevelopment.
Keywords | Nitric oxide, Postnatal development, Neuronal physiology, Signaling pathways, Neurotransmitter and free radicals, Sex-dimorphic, Rat, Age, Brain