A Study on the Postnatal Development of NADPH-Diaphorase Positive Neurons in the Cerebral Cortex and Striatum of Apodemus agrarius

Hwang, Seung Jun; Lee, Jong Hwan; Hong, Hea Nam; Lee, Heungshik S; Huh, Young Buhm; Cho, Jung Sik

Abstract

Nitric oxide (NO) is a short lived membrane permeable gas, a recently identified neuronal messenger molecule, and implicated in several activity-dependent forms of synaptic plasticity. The histochemical staining of NADPH-diaphorase (NADPH-d) provides a simple method to select populations of neurons containing nitric oxide synthase (NOS), throughout the brain. The NADPH-d positive neurons, uniquely resistant to toxic insults and neurodegenerative diseases, have been colocalized with neurons in the brain and peripheral tissue containing NOS. Apodemus agrarius has been used for experimental purpose to identify the route of infection and pathogenesis of korean hemorrhagic fever. However, despite of the increasing publication at present about the physiologic and ecologic characteristics of Apodemus, a few data are available about the morphologic findings in the brain. In this study we used NADPH-d histochemistry to evaluate the distribution of neurons, contain NOS, on the postnatal development in cerebral cortex and striatum of the Apodemus agrarius. In the cerebral cortex of Apodemus agrarius, NADPH-d positive neurons were observed in all cortical layers, but were concentrated in V-VI layer. NADPH-d positive neurons of forebrain were more dense than other cortical regions. At 1 week after birth, NADPH-d positive neurons had short processes and immature features. In contrast, at 12 weeks after birth, NADPH-d positive neurons had longer and more complex processes than that of earlier ages. In the striatum, NADPH-d positive neurons were intensely stained, predominantly medium-sized neurons. They had multipolar or bipolar dendritic branches which belong to fusiform or stellate cell types in all groups. In addition, at 4 and 12 weeks after birth, NADPH-d positive neurons had long and complex fiber network. The number of NADPH-d positive neurons in the striatum was relatively decreased during postnatal development. However, the length and complexity of their processes were relatively increased after birth. Present results showed postnatal maturation patterns such as morphological features of NADPH-d positive neurons. These findings suggest that NADPH-d positive neurons will be reach adult level after 4 weeks of postnatal age. Therefore, this report provide the morphological evidence supporting the hypothesis that NO may be play a role in regulation of neuronal development and synaptic plasticity during postnatal development of Apodemus agrarius.