Browsing by Author "Sanhueza, M"

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    Distribution of NADPH-d positive neurons during postnatal development of the rat somatosensory cortex correlates with gradients of neurogenesis and development
    (ELSEVIER SCI IRELAND LTD, 1997) Bravo, H; Inzunza, O; Fernandez, V; Sanhueza, M
    The expression of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) was studied in the rat somatosensory cortex during postnatal development from day 6 to 120. Distribution of labeled neurons was quantified in dorso-medial and ventro-lateral aspects of the cortex, and correlated with known tridimensional gradients of histogenetic development and maturation of cortical neurons. NADPH positive neurons were non-pyramidal cells that in all developmental periods were more numerous in infragranular than in supragranular layers of the cortex. Additionally, more labeled cells were found in ventro-lateral than dorso-medial infragranular layers and in anterior than posterior aspects of the cerebral cortex. These patterns of distribution correlate well with the gradients of histogenetic development and with the pattern of maturation of cortical neurons. (C) 1997 Elsevier Science Ireland Ltd.
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    Effects of mild protein prenatal malnutrition and subsequent postnatal nutritional rehabilitation on noradrenaline release and neuronal density in the rat occipital cortex
    (1999) Soto-Moyano, R; Fernandez, V; Sanhueza, M; Belmar, J; Kusch, C; Perez, H; Ruiz, S; Hernandez, A
    There is evidence that severe malnutrition started during gestation and continued through lactation affects adversely the morphologic development of the neocortex leading to increased neuronal cell packing density and decreased dendritic branching. Nevertheless, the effect of purely mild protein prenatal malnutrition on neocortical development remains rather unexplored. This study evaluates the effects of mild protein prenatal malnutrition (8% casein diet, calorically compensated by carbohydrates) and subsequent postnatal nutritional rehabilitation (25% casein diet) on: (i) the potassium-induced release of [H-3]-noradrenaline (NA) in occipital cortex slices obtained from 1- and 22-day-old pups; and (ii) the packing density of neurons in lateral, dorso-lateral and dorsal regions of the occipital cortex of 22-day-old pups by using the optical dissector method. The experiments were performed in rats normally fed during gestation and lactation (G(+)L(+)), malnourished during gestation but rehabilitated during lactation (G(-)L(+)) and malnourished during gestation and lactation (G(-)L(-)). At day 1 of age, no significant differences in body and brain weights were observed between prenatally well-nourished and malnourished pups. Nevertheless, at this early age, pups born from mothers submitted to the 8% casein diet had significantly higher cortical net percent NA release than pups born from mothers receiving the 25% casein diet. At weaning (22 days of age) G(-)L(+) rats had, compared to the G(+)L(+) group, similar body weight, brain weight and [H-3]-NA release values, but significantly higher neuron density scores in the lateral region of the occipital cortex. In contrast, at 22 days of age, G(-)L(-) rats exhibited, compared to G(+)L(+) animals, significant deficits in body and brain weights as well as significant increases in cortical net percent NA release together with enhanced packing density of neurons in the lateral, dorso-lateral and dorsal regions of the occipital cortex. Moreover, in G(-)L(-) animals was not found the laterodorsal histogenetic gradient of neuronal cell packing density observed in G(+)L(+) rats. Results suggest that mild prenatal malnutrition per se is able to induce deleterious effects on cortical neuronal density, in spite of nutritional rehabilitation during lactation, through a mechanism involving central NA hyperactivity during gestation. Prosecution of malnutrition after birth magnifies both neurochemical and morphometric disorders. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
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    NADPH-d positive neurons in the developing somatosensory cortex of the rat: effects of early and late environmental enrichment
    (ELSEVIER SCIENCE BV, 1998) Fernandez, V; Bravo, H; Sanhueza, M; Inzunza, O
    The effects of environmental enrichment upon the topographic arrangement of NADPH diaphorase-positive neurons (NADPH-d(+) neurons) was studied in the somatosensory cortex of 56 Sprague-Dawley albino rats during early stages of development (18th, 24th, 30th and 60th postnatal days). This diaphorase is easily demonstrable, providing a convenient marker for quantitative studies. Environmental enrichment diminished the number of NADPH-d(+) neurons and exerted its maximal influence during lactation, a time of exceptional cortical susceptibility. This implies that the magnitude of such effects on the density of NADPH-d(+) neurons is age-dependent. Furthermore, it was found that the experience-dependent cortical changes persisted after a subsequent period without environmental stimulation. The effects of early environmental enrichment did not occur uniformly throughout the cerebral hemispheres but, instead, such effects were maximal in the latero-ventral sector of the cerebral cortex where a dramatic reduction in the number of NADPH-d(+) neurons was observed. Particularly striking was the existence of a latero-medial sequence of NADPH-d(+) neurons in the infragranular layer and a reversed distribution of labeled cells, in the supragranular layer. Both ontogenetic sequences of NADPH-d(+) neurons remained unchanged during postnatal development in controls and enriched subjects (18th-60th postnatal days). (C) 1998 Elsevier Science B.V.