Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were undertaken to determine whether neurons of the subplate layer represent a transient or stable population of cells in developing neocortex of rat. The first set of studies sought to determine the fraction of subplate neurons that is lost during early postnatal development. The optical dissector method was used to analyze fluorescently stained material in animals the age of postnatal day 0 (P0) to P40. These results demonstrate a reduction of slightly less than half of the total number of subplate neurons from P0 to P40. Counts of labeled cells in littermates at varied ages after [(3)H]thymidine or BRDU treatment on gestational day 14 (G14 - birthdate of occipital subplate neurons) or G18 (birthdate of layers III-IV neurons) demonstrate loss of approximately 50% of neurons in the subplate layer between P0 and P40, somewhat greater than the loss of neurons from cortical layers III-IV. The second set of studies investigated whether subplate neurons display cellular atrophy during postnatal development. Analysis of subplate neurons injected intracellularly with Lucifer yellow in fixed slice preparations indicates no reduction in soma size, number of dendrites, or extent of dendritic fields of subplate neurons taken from animals age P0 to P60. The third set of studies investigated whether functional markers of subplate neurons are reduced during postnatal development. Analysis of tissue stained histochemically for cytochrome oxidase or acetylcholinesterase, or stained immunocytochemically for GABA, somatostatin, or neuropeptide Y, demonstrate a remarkable loss of expression of staining patterns from late gestational ages to P20. These data demonstrate that, although subplate neurons seem not to be a transient population of cells in the usual sense of being eliminated by cell death or structural atrophy, the loss of histochemical and immunocytochemical markers indicates that they may be a functionally transient population of cells.
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PMID:Do subplate neurons comprise a transient population of cells in developing neocortex of rats? 1102 4

The influence of thyroid hormones on cortical development was analysed in rat somatosensory cortex. Maternal and foetal hypothyroidism was induced and maintained by methimazole treatment from embryonic day 13 onwards. 5-Bromo-2'-deoxyuridine (BrdU) labelling in hypothyroid rats showed that cell positioning during corticogenesis followed an inside-out pattern. The radial neurogenetic gradients were more diffuse at all ages with respect to normal rats due to the inappropriate location of many cells, including those of the subcortical white matter. Most (62%) of the cells in the subcortical white matter of hypothyroid rats were labelled at embryonic day 15. Nissl staining of the primary somatosensory cortex showed blurred cortical layer boundaries and an abnormal barrel cytoarchitecture. Cytochrome oxidase and peanut agglutinin staining showed that the tangential organisation of the posteromedial barrel subfield and its layer IV specificity was not lost in hypothyroid rats. However the temporal pattern of peanut agglutinin labelling was delayed 3-4 days with respect to normal rats. In hypothyroid rats, the total barrelfield tangential area was reduced by 27% with respect to normal. The total tangential barrel area, corresponding to peanut agglutinin-negative labelling, occupied 77% of the barrelfield area and only 66% in hypothyroid rats. This reduction was larger with cytochrome oxidase staining where the total barrel area occupied 69% of the barrelfield area in normal and 46% in hypothyroid rats. Our data stress the importance of maternal and foetal thyroid hormones during development, and demonstrate the irreversible effects that maternal and foetal hypothyroidism may have on the intrinsic organisation and maturation of the neocortex.
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PMID:Role of thyroid hormones in the maturation and organisation of rat barrel cortex. 1171 94