PRECISE DISTRIBUTION OF NEURONAL NITRIC-OXIDE SYNTHASE MESSENGER-RNA IN THE RAT-BRAIN REVEALED BY NONRADIOISOTOPIC IN-SITU HYBRIDIZATION

Regional distribution of neurons expressing neuronal nitric oxide synt hase mRNA in the rat brain was examined by non-radioisotopic in situ h ybridization, using digoxigenin-labeled complementary RNA probes. Clus tering of intensely positive neurons was observed in discrete areas in cluding the main and accessory olfactory bulbs, the islands of Calleja , the amygdala, the paraventricular nucleus of the thalamus, several h ypothalamic nuclei, the lateral geniculate nucleus, the magnocellular nucleus of the posterior commissure, the superior and inferior collicu li, the laterodorsal and pedunculopontine tegmental nuclei, the nucleu s of the trapezoid body, the nucleus of the solitary tract and the cer ebellum. Strongly-stained isolated neurons were scattered mainly in th e cerebral cortex, the basal ganglia and the brain stem, especially th e medulla reticular formation. In the hippocampus, an almost uniform d istribution of moderately stained neurons was observed in the granular cell layer of the dentate gyrus and in the pyramidal cell layer of th e Ammon's horn, while more intensely stained isolated neurons were sca ttered over the entire hippocampal region. These observations can serv e as a good basis for studies on function and gene regulation of neuro nal nitric oxide synthase. (C) 1998 Elsevier Science B.V.