Nitric oxide synthase-expressing neurons are area-specifically distributed within the cerebral cortex of the rat

Neuronal nitric oxide synthase produces nitric oxide, a radical involved in neurotransmission as well as in cytotoxicity during stroke and neurodegenerative diseases. In the adult Wistar rat neuronal nitric oxide synthase-positive neurons are inhomogenously distributed along defined cortical areas, with highest densities (18 cells/mm2) in cingular area 1, piriform cortex, frontal motor area Fr 2 and in the medial visual association area Oc 2MM. A medium packing density of neuronal nitric oxide synthase neurons (10/mm2) characterizes primary sensory areas, whereas retrosplenial cortices contain lowest cell numbers (3-5/mm2). The data suggest that functions of certain cortical areas are more dependent on intracortically produced nitric oxide than others, and that cortical injury may cause more severe nitric oxide related cytotoxicity in areas with higher numbers of neuronal nitric oxide synthase-positive neurons.