Plasticidade do núcleo geniculado lateral e do córtex visual primário do cebus apella adulto, após lesões do disco do nervo óptico com laser / Plascity of the lateral geniculate nucleus and primary visual cortex of the adult Cebus apella after laser lesions nerve optic disc

As expressões das proteínas GAP-43, GFAP, Calbindina-D 28kD e Parvalbumina foram estudadas no Núcleo geniculado lateral (NGL) de quatro macacos Cebus apella adultos, previamente submetidos a lesões retinianas maciças nas margens do disco de nervo óptico. As lesões foram feitas por fotocoagulação com laser de Neodimium modificado, com diferentes tempos de sobrevida para cada animal. A expressão de cada proteína foi analisada pela densitometria das imagens digitalizadas, através do programa Image-Analyzer (Image Scion, cortesia da Scion Corp.). Nos dados obtidos foi aplicada a análise de variância (ANOVA) através do tratamento estatístico do SYSTAT 8.0. Paralelamente foram realizadas montagens de imagens aplanadas da camada 4C do córtex visual primário de ambos os hemisférios com o objetivo de comparar a localização topográfica das lesões na área cortical e no NGL. Foi constatado que as expressões da GAP-43 e da GFAP aumentam depois de 1-2 dias da lesão. A este aumento segue-se uma diminuição de expressão após o terceiro dias de sobrevida do animal retornando ao normal após três semanas. As expressões da Calbindina -D 28kD e da Parvalbumina aumentam 1-2 dias depois das lesões, permanecem altas até 9 dias e retornam a níveis normais quatro semanas após a realização das lesões (25-30 dias)

Morphometric analysis of intrinsic axon terminals of Cebus monkey area 17

A morphological study of intrinsic projections in area 17 of Cebus monkey was conducted after iontophoretic injection of biocytin. Thirty axon terminals located in supragranular layers were qualitatively and quantitatively analyzed using 3-D automatic microscopy. Three types of axon terminals could be identified: Ia, Ib and II. Group I was characterized by a sparse and/or long-distance branch pattern, while type II presented compact and localized arborization. Ia axon terminals formed "clusters" and "terminaux"boutons while Ib did not. On overage, group II axon terminals tended to present straight or obtuse branching angles and a much more ramified pattern, and occupy a smaller cortical territory with shorter intermediate segments and higher density of synaptic potential sites than group I. The common characteristics of group I included innervation of larger cortical territories, longer intermediate segments, acute branching angles and lower synaptic density compared to group II. The results are compatible with the major subdivisions of neocortical neuronal morphology that classifies them as smooth and spine neurons. Smooth neurons may be related to axon terminals of group II while spine neurons may be related to group I.

Muscarinic acetylcholine receptor subtypes in rat visual cortex--a comparative study using quantitative receptor autoradiography and in situ hybridization.

The laminar pattern of M1- and M2-muscarinic acetylcholine receptors (mAChR) in rat visual cortex has been compared with the distribution of the corresponding m1, m2, m3 and m4 receptor genes using both quantitative receptor autoradiography and in situ hybridization histochemistry. The laminar distribution of 3H-pirenzepine binding to M1-mAChRs in rat visual cortex shows a bimodal pattern with higher binding levels in upper layer III and deeper layer VI. In contrast, highest binding of 3H-AF-DX384 to M2-mAChRs was observed in upper layer IV (100%) and upper layer VI (about 80% of highest binding). The m1 receptor mRNA is almost homogeneously distributed throughout the visual cortex, whereas the m2mAChr mRNA predominates in layer IV with lower levels in layers I and V. The highest amounts of m3mAChR mRNA in rat visual cortex were observed in layer II, while the distribution of m4mAChR transcripts shows a bimodal pattern with peaks in layers III and upper layer VI. The distinct laminar pattern of mRNA muscarinic receptor subtypes in rat visual cortex suggest specific roles of the muscarinic receptor in visual function.