Chapter 5 - Localization of Nitric Oxide Neurons in the Central Nervous System

Abstract

The regional distribution of nitric oxide synthase (NOS) in the brain could be determined using a biochemical assay. NOS accounts for only a small fraction of the nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity in a brain homogenate and this activity has the uniquely fortuitous property of surviving formaldehyde fixation. NOS is found in cortical neurons scattered in layers II–VI and in the subcortical white matter. Populations of NADPH diaphorase-stained or NOS-immunoreactive neurons similar to those in the neocortex are also seen in allocortical areas. NADPH diaphorase has been demonstrated in magnocellular neurons in the medial septum and nucleus of the diagonal band of Broca, which project to the hippocampus. An increase in NOS mRNA can be seen in the paraventricular nucleus following immobilization stress and in lactating rats. In addition to being present in hypothalamic neurosecretory neurons, there is also evidence for NOS immunoreactivity and NOS mRNA expression in gonadotrophs and folliculostellate cells of the anterior pituitary itself. It is found that the cholinergic preganglionic autonomic neurons in the intermediolateral cell columns of the thoracic cord display high levels of NOS immunoreactivity Or NADPH diaphorase activity.