Histochemistry of nitric oxide synthase in the nervous system

Abstract

Nitric oxide synthase, which generates the physiological messenger molecule nitric oxide, and its associated NADPH diaphorase (NADPHd) activity are distributed throughout selective neuronal populations of the central and peripheral nervous system. Considerable evidence has been accumulated to indicate that NADPHd activity labels cells lacking neuronal nitric oxide synthase, i.e., the specificity of the reaction has to be considered for the reliable detection of the enzyme in neuronal but also non-neuronal tissue. In the present review, critical aspects of nitric oxide synthase visualization in neurones, using its NADPHd activity, are discussed. Furthermore, the organization of the central and peripheral nitric oxide synthase-containing neuronal systems is described. Nitric oxide synthase is present in local cortical and striatal neurones, hypothalamic magnocellular neurones, mesopontine cholinergic neurones, cerebellar interneurones, preganglionic sympathetic and parasympathetic neurones, neurones in parasympathetic autonomic and enteric ganglia and primary viscero-afferent neurones. Finally, injury-related alterations in nitric oxide synthase activity are briefly outlined. In this respect, the histochemistry of nitric oxide synthase may represent a valuable marker for neurochemical, if not structural, alterations observed in neural diseases, regeneration and transplantation.

Periaqueductal gray neuroplasticity following chronic morphine varies with age: Role of oxidative stress

“…Cholinergic neurons of LDTg/pedunculopontine tegmentum provide the only known cholinergic input to the ventral tegmental area (Oakman et al, 1995, Holmstrand and Sesack, 2011). Our preliminary data indicate that 98% of cholinergic neurons comprising the LDTg are colocalized with nNOS in the adult rat as previously reported (Blottner et al, 1995). Therefore, up-regulated nitric oxide following chronic morphine administration might also be involved in the modulation of motivated behavior and reward pathways (see reviews (Lester et al, 2010, Mark et al, 2011)).…”

Nitric oxide synthase activity and expression are decreased in the paraventricular nucleus of pregnant rats

“…NADPH-diaphorase histochemistry utilizes the properties of the enzyme NOS that catalyzes the NADPH-dependent conversion of a soluble tetrazolium salt to an insoluble and visible formazan. There are at least eight other enzymes in the central nervous system that could contribute to NADPH-diaphorase activity (Blottner et al, 1995). However, rats in the current experiments were perfused with paraformaldehyde and NOS is the only one of these enzymes which is not inactivated by formaldehyde.…”

Nitric Oxide Synthase Inhibitors as Antidepressants

“…The NOS enzymes are widely distributed within the mammalian brain [25,26]. The neuronal isoform accounts for the majority of the NOS activity in the brain [27], and NOS positive neurons are located in the hippocampal layers CA1-CA3, the medial amygdaloid nucleus, the olfactory bulb, the layers II-VI in the cerebral cortex, the granular and deep molecular layers of the cerebellum and, with special interest regarding the serotonin system, in the dorsal and medial raphe nuclei [25].…”

“…The neuronal isoform accounts for the majority of the NOS activity in the brain [27], and NOS positive neurons are located in the hippocampal layers CA1-CA3, the medial amygdaloid nucleus, the olfactory bulb, the layers II-VI in the cerebral cortex, the granular and deep molecular layers of the cerebellum and, with special interest regarding the serotonin system, in the dorsal and medial raphe nuclei [25]. Measurements of NOS activity in different brain regions have shown the highest activity in the cerebellum, the midbrain, the hypothalamus, the cortex, the striatum and the hippocampus [28,29].…”