title: Nitric oxide synthase expression in the opossum superior colliculus: a histochemical, immunohistochemical and biochemical study.
abstract: The expression of neuronal nitric oxide synthase (nNOS) in the superior colliculus (SC) of the opossum Didelphis marsupialis was studied by NADPH diaphorase (NADPH-d) histochemistry and nNOS immunohistochemistry. In addition, the activity of nNOS was quantified by measurement of [(3)H]-L-arginine conversion to [(3)H]-L-citrulline in tissue extracts from SC superficial layers in opossums and rats. Our results show that the number of NADPH-d stained cells was small and virtually identical in stratum opticum (SO) and stratum griseum superficiale (SGS) and their staining was very light, particularly in SGS. Neuropil staining was heavier in the stratum zonale (SZ) than in SGS or SO. The intermediate and deep layers contained heavily stained cells and moderate neuropil staining. Surprisingly, nNOS-immunoreactive cells were far more numerous than NADPH-d+ cells in every layer. The production of [(3)H]-L-citrulline from [(3)H]-L-arginine in tissue extracts enriched in superficial layers indicated that nNOS specific activity is as high in the opossum as in the rat. Our results suggest that the location of nNOS-expressing neurons in retino-receptive layers may be related to inter-specific differences in the processing of visual information.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Giraldi-Guimarães
authors.forename: F
authors.initials: F
authors.lastname: Tenório
authors.forename: G
authors.initials: G
authors.lastname: Brüning
authors.forename: B
authors.initials: B
authors.lastname: Mayer
authors.forename: R
authors.initials: R
authors.lastname: Mendez-Otero
authors.forename: L A
authors.initials: LA
authors.lastname: Cavalcante
mesh_terms: D000818:Animals; D002956:Citrulline / Q000378:metabolism; D007150:Immunohistochemistry; D009252:NADPH Dehydrogenase / Q000032:analysis / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052248:Nitric Oxide Synthase Type I; D009893:Opossums / Q000378:metabolism*; D051381:Rats; D013477:Superior Colliculi / Q000033:anatomy & histology / Q000201:enzymology*
chemical_list: D002956:Citrulline; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D009252:NADPH Dehydrogenase