Distribution, Morphology And Origins Of NNOS-expressing Neurons In The Adult Mouse Brain

Neuronal isoform of nitric oxide synthase, nNOS, plays important roles in neurogenesis and synaptic plasticity. In the present study, we examine the distribution and morphology of nNOS-expressing cells in the adult mouse brain. By BrdU birth-dating methords, we investigate when these neurons are produced. We then explore the origiins of nNOS-expressing cells in different brain regions.We found nNOS-expressing cells distributed in the olfactory bulb (OB), neocortex, hippocampus, striatum, septum/DB region, telencephalon, hypothalamus and cerebellum. nNOS-expressing cells in the adult brain could be subdivided into those groups according their morphology. These cells in the neocortex, striatum and septum/DB region are produced at different developmental stages.We then demonstrated that nNOS-expressing cells in different brain regions express different transcription factors. nNOS-positive cells express the transcription factor Sp8and Zic-1in the OB. In the neocortex and striatum, they express Sox6. Zic-1is expressed by the nNOS-expressing cells located in the septum/DB region. Zic-1, Sp8and Nkx2.1co-localized with nNOS in the neurons distributed in hypothalamus. When concerned with the origins of nNOS-expressing cells, we found that they arise from dLGE/CGE, SE,MGE/POA and Hypothalamic primordium, respectively.