TRANSIENT EXPRESSION OF NADPH-DIAPHORASE IN THE LATERAL GENICULATE-NUCLEUS OF THE FERRET DURING EARLY POSTNATAL-DEVELOPMENT

Retinogeniculate projections in the ferret are refined during postnata l development so that inputs from the two eyes become segregated into eye-specific laminae, and each eye-specific lamina is further divided into sublaminae containing inputs from on-center or off-center afferen ts. Segregation into eye-specific laminae and on/off sublaminae is dep endent on neuronal activity; sublamination depends on activation of N- methyl-d-aspartate (NMDA) receptors. By analogy with the suggested rol e of nitric oxide in NMDA-mediated long-term potentiation in the hippo campus, we investigated a possible role for nitric oxide in ferret ret inogeniculate development. The expression of NADPH-diaphorase, a nitri c oxide synthase, was examined histologically in the lateral geniculat e nucleus of ferrets at several postnatal ages. At birth, neuropil is labeled in the nucleus, although no cell bodies are visible. After the first postnatal week, some labeled cells appear, predominantly in the C laminae. By three postnatal weeks, cell bodies are clearly labeled in all geniculate laminae. Staining reaches a peak in density at about four postnatal weeks, then declines such that by six postnatal weeks labeled cells are no longer visible. This transient expression of Nadp h-diaphorase activity is consistent with a role for nitric oxide in th e development of mature connections within the ferret lateral genicula te nucleus. (C) 1995 Wiley-Liss, Inc.