Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
1.
Brain Behav Evol ; 98(6): 275-289, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38198769

RESUMO

INTRODUCTION: The study of non-laboratory species has been part of a broader effort to establish the basic organization of the mammalian neocortex, as these species may provide unique insights relevant to cortical organization, function, and evolution. METHODS: In the present study, the organization of three somatosensory cortical areas of the medium-sized (5-11 kg body mass) Amazonian rodent, the paca (Cuniculus paca), was determined using a combination of electrophysiological microelectrode mapping and histochemical techniques (cytochrome oxidase and NADPH diaphorase) in tangential sections. RESULTS: Electrophysiological mapping revealed a somatotopically organized primary somatosensory cortical area (S1) located in the rostral parietal cortex with a characteristic foot-medial/head-lateral contralateral body surface representation similar to that found in other species. S1 was bordered laterally by two regions housing neurons responsive to tactile stimuli, presumably the secondary somatosensory (S2) and parietal ventral (PV) cortical areas that evinced a mirror-reversal representation (relative to S1) of the contralateral body surface. The limits of the putative primary visual (V1) and primary auditory (A1) cortical areas, as well as the complete representation of the contralateral body surface in S1, were determined indirectly by the histochemical stains. Like the barrel field described in small rodents, we identified a modular arrangement located in the face representation of S1. CONCLUSIONS: The relative location, somatotopic organization, and pattern of neuropil histochemical reactivity in the three paca somatosensory cortical areas investigated are similar to those described in other mammalian species, providing additional evidence of a common plan of organization for the somatosensory cortex in the rostral parietal cortex of mammals.


Assuntos
Cuniculidae , Córtex Somatossensorial , Animais , Córtex Somatossensorial/fisiologia , Roedores , Lobo Parietal/fisiologia , Mapeamento Encefálico , América do Sul
2.
Inflammation ; 31(1): 24-35, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17899345

RESUMO

White matter damage and inflammatory response are important secondary outcomes after acute neural disorders. Nevertheless, a few studies addressed the temporal outcomes of these pathological events using non-traumatic models of acute brain injury. In the present study, we describe acute inflammatory response and white matter neuropathology between 1 and 7 days after acute excitotoxic striatal damage. Twenty micrometer sections were stained by hematoxylin and eosin technique for gross histopathological analysis and immunolabed for neutrophils (anti-mbs-1), activated macrophages/microglia (anti-ed1), astrocytes (anti-gfap), damaged axons (anti-betaapp) and myelin basic protein (MBP). Recruitment peak of neutrophils and macrophages occurred at 1 and 7 days post-nmda injection, respectively. Diffuse damaged axons (beta-app + end-bulbs) were apparent at 7 days, concomitant with progressive myelin impairment and astrocytosis. Further studies using electron microscopy and blockers of inflammatory response and glutamatergic receptors should be performed to confirm and address the mechanisms of white matter damage following an excitotoxic lesion.


Assuntos
Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Bainha de Mielina/metabolismo , N-Metilaspartato/farmacologia , Animais , Axônios/metabolismo , Agonistas de Aminoácidos Excitatórios/farmacologia , Gliose , Imuno-Histoquímica/métodos , Inflamação , Macrófagos/metabolismo , Masculino , Neutrófilos/metabolismo , Perfusão , Ratos , Ratos Wistar
3.
Front Neuroanat ; 12: 118, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30692919

RESUMO

In order to understand how the mammalian sensory cortex has been structured during evolution, it is necessary to compare data from different species across distinct mammalian lineages. Here, we investigated the organization of the secondary somatosensory area (S2) in the agouti (Dasyprocta aguti), a medium-sized Amazonian rodent, using microelectrode mapping techniques and neurotracer injections. The topographic map obtained from multiunit electrophysiological recordings were correlated with both cytochrome oxidase (CO) histochemistry and with patterns of corticocortical connections in tangential sections. The electrophysiological mapping of the lateral strip of parietal cortex adjacent to the primary somatosensory area (S1) revealed that S2 displays a mirror-reversed topographical representation of S1, but with a smaller cortical magnification factor. The caudal border of S2 is surrounded by sensory fields which also respond to auditory stimulation. BDA injections into the forelimb representation of S2 revealed a dense homotopic ipsilateral projection to S1, supplemented by a less dense projection to the caudolateral cortex located near the rhinal sulcus (parietal rhinal area) and to a frontal region probably associated with the motor cortex. Our findings were similar to those described in other mammalian species, reinforcing the existence of a common plan of organization for S2 in the mammalian parietal cortex.

4.
Neurotoxicology ; 28(1): 175-81, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16930717

RESUMO

In the present study, we investigated the effects of mercury intoxication on the structure of the posteromedial barrel subfield (PMBSF) in the primary somatosensory cortex (SI) of adult rats, as revealed by histochemical reactivity to the enzyme NADPH diaphorase (NADPH-d). Enzymatic reactivity in the neuropil inside barrels was drastically reduced in intoxicated animals, suggesting that the synthesis and/or transport of the nitric oxide synthase enzyme can be altered in acute mercury intoxication. However, the cell bodies and dendrites of barrel neurons, also strongly reactive to the enzyme, were spared from the mercury's deleterious effects.


Assuntos
Compostos de Metilmercúrio/toxicidade , NADPH Desidrogenase/metabolismo , Córtex Somatossensorial/efeitos dos fármacos , Animais , Densitometria , Histocitoquímica , Masculino , Compostos de Metilmercúrio/farmacocinética , Neurópilo/efeitos dos fármacos , Neurópilo/enzimologia , Óxido Nítrico Sintase Tipo I/biossíntese , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos Wistar
5.
Brain Res ; 1072(1): 19-25, 2006 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-16426587

RESUMO

This study investigated the effects of repeated l-arginine administration during lactation, combined with different suckling conditions, on morphometric parameters of primary visual cortex NADPH-diaphorase-positive neurons. Wistar rat pups reared in "normal-size litters" or "large litters" (N- and L-conditions; litters formed by 6 and 12 pups, respectively) received, from postnatal day 7 to 28, either arginine (300 mg/kg/day, per gavage) or distilled water (control). At 90-120 days of life, they were perfused with saline + formaldehyde, and their brains were processed for histochemical reaction to reveal NADPH-diaphorase-positive neurons (malic enzyme indirect method). Compared to the normal-size litters, L-rats had lower body weights (P < 0.05), confirming the effectiveness of the L-condition in affecting pup development. Concerning NADPH-d histochemistry, arginine treatment was associated with increased (P < 0.05) density of dendrite varicosities and of dendrite branching frequency, suggesting a plastic response of the developing brain to that treatment, even in previously malnourished rats. No difference was seen, however, in dendrite orientation, total number of neurons, soma area and perimeter, as well as dendrite bifurcation points, fractal dimension, and area and volume of dendrite field, suggesting that NADPH-d cells are resistant to arginine and nutritional changes, regarding these features. Data are considered of interest for studies of synaptic plasticity during neural development and its relationships to aggressive agents like malnutrition.


Assuntos
Arginina/farmacologia , Desnutrição/fisiopatologia , NADPH Desidrogenase/metabolismo , Neurônios/fisiologia , Córtex Visual/fisiologia , Animais , Peso Corporal , Encéfalo/crescimento & desenvolvimento , Feminino , Lactação , Neurônios/efeitos dos fármacos , Tamanho do Órgão , Ratos , Ratos Wistar , Valores de Referência , Córtex Visual/efeitos dos fármacos
6.
Brain Res ; 1106(1): 99-110, 2006 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-16854386

RESUMO

Marked phenotypic variation has been reported in pyramidal cells in the primate cerebral cortex. These extent and systematic nature of these specializations suggest that they are important for specialized aspects of cortical processing. However, it remains unknown as to whether regional variations in the pyramidal cell phenotype are unique to primates or if they are widespread amongst mammalian species. In the present study we determined the receptive fields of neurons in striate and extrastriate visual cortex, and quantified pyramidal cell structure in these cortical regions, in the diurnal, large-brained, South American rodent Dasyprocta primnolopha. We found evidence for a first, second and third visual area (V1, V2 and V3, respectively) forming a lateral progression from the occipital pole to the temporal pole. Pyramidal cell structure became increasingly more complex through these areas, suggesting that regional specialization in pyramidal cell phenotype is not restricted to primates. However, cells in V1, V2 and V3 of the agouti were considerably more spinous than their counterparts in primates, suggesting different evolutionary and developmental influences may act on cortical microcircuitry in rodents and primates.


Assuntos
Células Piramidais/citologia , Roedores/anatomia & histologia , Córtex Visual/citologia , Vias Visuais/citologia , Percepção Visual/fisiologia , Potenciais de Ação/fisiologia , Animais , Forma Celular/fisiologia , Dendritos/fisiologia , Dendritos/ultraestrutura , Espinhas Dendríticas/fisiologia , Espinhas Dendríticas/ultraestrutura , Complexo IV da Cadeia de Transporte de Elétrons , Citometria por Imagem , Isoquinolinas , Masculino , Vias Neurais/citologia , Vias Neurais/fisiologia , Estimulação Luminosa , Células Piramidais/fisiologia , Roedores/fisiologia , Especificidade da Espécie , Sinapses/fisiologia , Sinapses/ultraestrutura , Transmissão Sináptica/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia
7.
Front Neuroanat ; 10: 23, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27047345

RESUMO

It is known that microglial morphology and function are related, but few studies have explored the subtleties of microglial morphological changes in response to specific pathogens. In the present report we quantitated microglia morphological changes in a monkey model of dengue disease with virus CNS invasion. To mimic multiple infections that usually occur in endemic areas, where higher dengue infection incidence and abundant mosquito vectors carrying different serotypes coexist, subjects received once a week subcutaneous injections of DENV3 (genotype III)-infected culture supernatant followed 24 h later by an injection of anti-DENV2 antibody. Control animals received either weekly anti-DENV2 antibodies, or no injections. Brain sections were immunolabeled for DENV3 antigens and IBA-1. Random and systematic microglial samples were taken from the polymorphic layer of dentate gyrus for 3-D reconstructions, where we found intense immunostaining for TNFα and DENV3 virus antigens. We submitted all bi- or multimodal morphological parameters of microglia to hierarchical cluster analysis and found two major morphological phenotypes designated types I and II. Compared to type I (stage 1), type II microglia were more complex; displaying higher number of nodes, processes and trees and larger surface area and volumes (stage 2). Type II microglia were found only in infected monkeys, whereas type I microglia was found in both control and infected subjects. Hierarchical cluster analysis of morphological parameters of 3-D reconstructions of random and systematic selected samples in control and ADE dengue infected monkeys suggests that microglia morphological changes from stage 1 to stage 2 may not be continuous.

8.
J Chem Neuroanat ; 30(2-3): 71-81, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16002260

RESUMO

The mouse, like a few other rodent and marsupial species, displays a striking modular architecture in its primary somatosensory cortex (SI). These modules, known as barrels, are mostly defined by the peculiar arrangement of granule cells and thalamic axons in layer IV. In the present work, we studied both the distribution and morphology of neurons stained for NADPH diaphorase (NADPH-d) and neuropil reactivity in the posteromedial barrel subfield (PMBSF), which represents the mystacial whiskers. We then compared our results with previous descriptions of NADPH-d distribution in both neonatal and young mice. We found two types of neurons in the PMBSF: type I neurons, which have large cell bodies and are heavily stained by the NADPH-d reaction; and type II neurons, characterized by relatively small and poorly stained cell bodies. The distribution of type I cells in the PMBSF was not homogenous, with cells tending to concentrate in septa between barrels. Moreover, the cells found in septal region possess both a larger and more complex dendritic arborization than cells located inside barrels. Our findings are at variance with results from other groups that reported both an absence of type II cells and a homogeneous distribution of type I cells in the PMBSF of young animals. In addition, our results show a distribution of type I cells which is very similar to that previously described for the rat's barrel field.


Assuntos
NADPH Desidrogenase/metabolismo , Neurópilo/enzimologia , Neurônios Nitrérgicos/enzimologia , Córtex Somatossensorial/enzimologia , Vias Aferentes/fisiologia , Fatores Etários , Animais , Biomarcadores , Mapeamento Encefálico , Forma Celular/fisiologia , Dendritos/fisiologia , Dendritos/ultraestrutura , Histocitoquímica , Imuno-Histoquímica , Nervo Maxilar/fisiologia , Camundongos , NADPH Desidrogenase/análise , Neurópilo/citologia , Neurônios Nitrérgicos/classificação , Neurônios Nitrérgicos/citologia , Óxido Nítrico Sintase/análise , Óxido Nítrico Sintase/metabolismo , Córtex Somatossensorial/citologia , Vibrissas/fisiologia
9.
Neurosci Res ; 50(1): 55-66, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15288499

RESUMO

The distribution of NADPH diaphorase (NADPH-d)/nitric oxide synthase (NOS) neurons was evaluated during the postnatal development of the primary somatosensory cortex (SI) of the rat. Both cell counts and area measurements of barrel fields were carried out throughout cortical maturation. In addition, NADPH-d and cytochrome oxidase (CO) activities were also compared in both coronal and tangential sections of rat SI between postnatal days (P) 10 and 90. Throughout this period, the neuropil distributions of both enzymes presented a remarkable similarity and have not changed noticeably. Their distribution pattern show the PMBSF as a two-compartmented structure, displaying a highly reactive region (barrel hollows) flanked by less reactive regions (barrel septa). The number of NADPH-d neurons increased significantly in the barrel fields between P10 and P23, with peak at P23. The dendritic arborization of NADPH-d neurons became more elaborated during barrel development. In all ages evaluated, the number of NADPH-d cells was always higher in septa than in the barrel hollows. Both high neuropil reactivity and differential distribution of NADPH-d neurons during SI development suggest a role for nitric oxide throughout barrel field maturation.


Assuntos
NADPH Desidrogenase/metabolismo , Neurônios/enzimologia , Córtex Somatossensorial/enzimologia , Córtex Somatossensorial/crescimento & desenvolvimento , Fatores Etários , Animais , Animais Recém-Nascidos , Contagem de Células , Diferenciação Celular/fisiologia , Tamanho Celular/fisiologia , Dendritos/enzimologia , Dendritos/ultraestrutura , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Neurônios/citologia , Neurópilo/citologia , Neurópilo/enzimologia , Neurônios Nitrérgicos/citologia , Neurônios Nitrérgicos/enzimologia , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Wistar , Córtex Somatossensorial/citologia , Regulação para Cima/fisiologia , Vibrissas/inervação , Vibrissas/fisiologia
10.
Anat Embryol (Berl) ; 205(4): 291-300, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12136259

RESUMO

Qualitative and quantitative analyses of terminal arborizations of biocytin-labeled axon terminals were carried out in the cat primary visual cortex (V1). Extracellular iontophoretic injections of 5% biocytin were made into V1 of five adult cats. The animals were perfused 24-48 h after the injections. Labeled-axon fragments were considered to comprise two presumptive groups, according to the qualitative features, thickness, bouton features and appearance of terminal arbors. Forty axon fragments (20 for each presumptive group) were digitized using a microscope with motorized stage and a z-encoder, attached to a microcomputer. The densities of boutons, branching points and axon segments per mm of axon as well as axon segment length were used for comparison of the two groups. The two qualitative groups were confirmed to contain two axon types (I and II), according to cluster analysis of characteristics of the 40 axons in our sample. Forward stepwise discriminant analysis retained two variables as predictors of group membership: axonal length and bouton density. Parametric and non-parametric tests were employed for statistical comparisons (significance at P < 0.01). Type II axon fragments showed the greatest densities of boutons, axonal segments and branching points and the smallest values of length of segments ( P < 0.01). Both the qualitative and quantitative differences found for both types of axons suggest that they belong to different functional classes of neurons, namely spiny (type I) and smooth neurons (type II). Computer-assisted morphometric analysis of individual axon fragments seems to be a suitable approach with which different axon types can be objectively distinguished from each other.


Assuntos
Processamento de Imagem Assistida por Computador , Lisina/análogos & derivados , Terminações Pré-Sinápticas , Córtex Visual/citologia , Animais , Gatos , Análise por Conglomerados , Técnicas Imunoenzimáticas , Masculino , Coloração e Rotulagem , Córtex Visual/metabolismo
11.
Front Hum Neurosci ; 6: 249, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22969716

RESUMO

Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.

12.
Prion ; 5(3): 215-27, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21862877

RESUMO

Behavioral and neuropathological changes have been widely investigated in murine prion disease but stereological based unbiased estimates of key neuropathological features have not been carried out. After injections of ME7 infected (ME7) or normal brain homogenates (NBH) into dorsal CA1 of albino Swiss mice and C57BL6, we assessed behavioral changes on hippocampal-dependent tasks. We also estimated by optical fractionator at 15 and 18 weeks post-injections (w.p.i.) the total number of neurons, reactive astrocytes, activated microglia and perineuronal nets (PN) in the polymorphic layer of dentate gyrus (PolDG), CA1 and septum in albino Swiss mice. On average, early behavioral changes in albino Swiss mice start four weeks later than in C57BL6. Cluster and discriminant analysis of behavioral data in albino Swiss mice revealed that four of nine subjects start to change their behavior at 12 w.p.i. and reach terminal stage at 22 w.p.i and the remaining subjects start at 22 w.p.i. and reach terminal stage at 26 w.p.i. Biotinylated dextran-amine BDA-tracer experiments in mossy fiber pathway confirmed axonal degeneration, and stereological data showed that early astrocytosis, microgliosis and reduction in the perineuronal nets are independent of a change in the number of neuronal cell bodies. Statistical analysis revealed that the septal region had greater levels of neuroinflammation and extracellular matrix damage than CA1. This stereological and multivariate analysis at early stages of disease in an outbred model of prion disease provided new insights connecting behavioral changes and neuroinflammation and seems to be important to understand the mechanisms of prion disease progression.


Assuntos
Comportamento Animal , Neurônios/patologia , Doenças Priônicas/patologia , Doenças Priônicas/psicologia , Animais , Modelos Animais de Doenças , Feminino , Gliose/metabolismo , Gliose/patologia , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Microglia/patologia
13.
Brain Res ; 1329: 182-93, 2010 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-20226770

RESUMO

We investigated the protective effects of minocycline following white matter damage (WMD) in the rat striatum. Excitotoxic lesions were induced by N-Methyl-d-Aspartate (NMDA) microinjections and caused striatal damage, concomitant with microglial/macrophage activation. The excitotoxic lesion both damaged oligodendrocytes (Tau-1(+) cells) and caused a decrease in tissue reactivity for myelin basic protein (MBP) after post-lesional day 3 (PLD). Treatment with the semi-synthetic tetracycline antibiotic minocycline, however, led to oligodendrocyte preservation and decreased myelin impairment. Taken together, these results suggest that white matter damage (WMD) is an important component of the physiopathology of acute striatal damage and that microglial/macrophage activation contributes to this pathological phenomenon.


Assuntos
Antibacterianos/farmacologia , Encéfalo/efeitos dos fármacos , Corpo Estriado/efeitos dos fármacos , Minociclina/farmacologia , Oligodendroglia/efeitos dos fármacos , Animais , Antibacterianos/administração & dosagem , Anticorpos Monoclonais/metabolismo , Encéfalo/imunologia , Corpo Estriado/patologia , Modelos Animais de Doenças , Ativação de Macrófagos/efeitos dos fármacos , Ativação de Macrófagos/imunologia , Masculino , Microglia/efeitos dos fármacos , Microglia/imunologia , Microinjeções , Minociclina/administração & dosagem , Proteína Básica da Mielina/metabolismo , N-Metilaspartato , Oligodendroglia/metabolismo , Ratos , Ratos Wistar , Fatores de Tempo
14.
Brain Res ; 1318: 52-63, 2010 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-20036219

RESUMO

Previous studies have shown a noticeable phenotypic diversity for pyramidal cells among cortical areas in the cerebral cortex. Both the extent and systematic nature of this variation suggests a correlation with particular aspects of cortical processing. Nevertheless, regional variations in the morphology of inhibitory cells have not been evaluated with the same detail. In the present study we performed a 3D morphometric analysis of 120 NADPH diaphorase (NADPH-d) type I neurons in the visual cortex of a South American Hystricomorph rodent, the diurnal agouti (Dasyprocta sp.). We found significant differences in morphology of NADPH-d type I neurons among visual cortical areas: cells became progressively larger and more branched from V1 to V2 and V3. Presumably, the specialized morphology of these cells is correlated with different sampling geometry and function. The data suggest that area-specific specializations of cortical inhibitory circuitry are also present in rodents.


Assuntos
NADPH Desidrogenase/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Córtex Visual/citologia , Córtex Visual/metabolismo , Animais , Tamanho Celular , Análise por Conglomerados , Dendritos/enzimologia , Dendritos/metabolismo , Imageamento Tridimensional , Masculino , Neurônios/enzimologia , Fotomicrografia , Roedores , Córtex Visual/enzimologia
15.
Front Neuroanat ; 2: 2, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18958200

RESUMO

We evaluated the neuropil distribution of the enzymes NADPH diaphorase (NADPH-d) and cytochrome oxidase (CO) in the spinal cord of the agouti, a medium-sized diurnal rodent, together with the distribution pattern and morphometrical characteristics of NADPH-d reactive neurons across different spinal segments. Neuropil labeling pattern was remarkably similar for both enzymes in coronal sections: reactivity was higher in regions involved with pain processing. We found two distinct types of NADPH-d reactive neurons in the agouti's spinal cord: type I neurons had large, heavily stained cell bodies while type II neurons displayed relatively small and poorly stained somata. We concentrated our analysis on type I neurons. These were found mainly in the dorsal horn and around the central canal of every spinal segment, with a few scattered neurons located in the ventral horn of both cervical and lumbar regions. Overall, type I neurons were more numerous in the cervical region. Type I neurons were also found in the white matter, particularly in the ventral funiculum. Morphometrical analysis revealed that type I neurons located in the cervical region have dendritic trees that are more complex than those located in both lumbar and thoracic regions. In addition, NADPH-d cells located in the ventral horn had a larger cell body, especially in lumbar segments. The resulting pattern of cell body and neuropil distribution is in accordance with proposed schemes of segregation of function in the mammalian spinal cord.

16.
Brain Res ; 1244: 155-63, 2008 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-18835550

RESUMO

The aim of the present report is to investigate in detail morphometric changes of axon terminals of area 17 of adult cat induced by methylmercury intoxication. Six adult male cats (Felix catus), with 12 h day-light cycle and ad libitum water and food regimen, received a single dose of MeHgCl (6.4 mg/kg) dissolved in milk, whereas control subjects (n=6) received only milk. After 30 days, biocytin iontophoretic injections were done into the area 17, (Horsley-Clark coordinates between AP 3.0-6.0) on the crown of the lateral gyrus, near the border with area 18. MeHg and inorganic Hg (Hgi) concentrations were measured in the brain parenchyma of intoxicated cats and corresponded on average to 1.39+/-0.3 and 6.79+/-0.6 ppm (mean+/-s.e.m.) respectively. Twenty four hours after iontophoresis, aldehyde fixed brain sections (200 microm thick), were processed to reveal biocytin labeled terminals. Axonal microscopic 3D reconstructions using Neurolucida software (Microbright Systems Inc.) allowed estimations of boutons, branching points and segment densities for each terminal. Cluster analysis of morphometric axonal features from control and intoxicated group revealed, two distinct axon families (Type I and II) as described elsewhere. Total density values of boutons, branching points and segment densities of intoxicated group, decreased 81, 59 and 91% respectively, as compared to the control group (ANOVA two-way, Bonferroni a priori test p<0.05). Altered axonal morphology associated with MeHg, appeared early in the disease (30 days after contamination), revealing new aspects of the neuronal pathology of the methylmercury intoxication in the visual cortex.


Assuntos
Encéfalo/efeitos dos fármacos , Compostos de Metilmercúrio/toxicidade , Terminações Pré-Sinápticas/efeitos dos fármacos , Córtex Visual/efeitos dos fármacos , Administração Oral , Análise de Variância , Animais , Encéfalo/patologia , Gatos , Imageamento Tridimensional/métodos , Masculino , Compostos de Metilmercúrio/administração & dosagem , Microscopia Confocal , Terminações Pré-Sinápticas/patologia , Fatores de Tempo , Córtex Visual/patologia
17.
Psychol. neurosci. (Impr.) ; 4(1): 7-9, Jan.-June 2011. ilus
Artigo em Inglês | LILACS | ID: lil-604529

RESUMO

This paper reports the results that are part of a series of experiments designed to evaluate aspects of the spatial resolution of the visual system of the opossum, Didelphis marsupialis aurita. This nocturnal marsupial presents a well-developed eye, displaying features that reflect specialization for operation at low levels of luminosity. The species was shown to be slightly myopic, a feature that may prove to be valuable because of the increased depth of field. Opossum visual acuity has been previously evaluated by means of determining the Contrast Sensitivity Function (CSF). The results indicate rather poor visual acuity compared with other nocturnal animals. In this paper, we describe the results obtained for the optical quality of the opossum's eye using a single-pass method. The results suggest that the opossum's optical system is capable of forming images that can be resolved when separated by an angular distance on the order of 6 minutes of arc.


Assuntos
Animais , Sensibilidades de Contraste , Gambás , Acuidade Visual
18.
Psychol. neurosci. (Impr.) ; 4(1): 19-27, Jan.-June 2011. ilus
Artigo em Inglês | LILACS | ID: lil-604531

RESUMO

In the present investigation we mapped the primary visual area of the South American diurnal rodent, Dasyprocta aguti, by standardized electrophysiological mapping techniques. In particular, we performed a series of mapping experiments of the visual streak in the primary visual cortex. We found that the representation of the visual streak in V1 is greatly expanded, the nasal 10 degrees of the visual streak representation occupies ten times more cortical area than equivalent areas in the central or temporal representation. Comparison of these data with those on the density of ganglion cells in the retina at corresponding locations in the visual field reveal a significant mismatch between these two variables. The nasal representation is greatly expanded along the horizontal meridian in V1 as compared to the central and temporal regions whereas the density of ganglion cells decreases with progression along the visual streak from central region towards the nasal or temporal visual field. A review of the available data reveals that all lateral-eyed mammals exhibit a similar mismatch between the retinal and cortical representation of the visual field, and this mismatches is greater in those species with well defined visual streaks such as rabbit and agouti.


Assuntos
Animais , Coelhos , Mamíferos , Células Ganglionares da Retina , Visão Monocular , Córtex Visual , Campos Visuais
19.
Psychol. neurosci. (Impr.) ; 4(1): 49-56, Jan.-June 2011. graf, tab
Artigo em Inglês | LILACS | ID: lil-604533

RESUMO

The aim of the present study was to analyze the influence of enriched environment on the distribution of perineuronal nets (PNNs) using a stereogically based unbiased protocol and visual acuity in adult Swiss albino mice that underwent monocular deprivation during the critical period of postnatal development. Eight female Swiss albino mice were monocular deprived on postnatal day 10 and divided into two groups at weaning: standard environment (SE group, n = 4) and enriched environment (EE group, n = 4). After 3 months, all of the mice were subjected to grating visual acuity tests, sacrificed, and perfused with aldehyde fixative. The brains were removed and cut at 70 µm thickness in a vibratome and processed for lectin histochemical staining with Wisteria floribunda agglutinin (WFA). Architectonic limits of area 17 were conspicuously defined by WFA histochemical staining, and the optical fractionator stereological method was applied to estimate the total number of PNNs in the supragranular, granular, and infragranular layers. All groups were compared using Student's t-test at a 95 percent confidence level. Comparative analysis of the average PNN estimations revealed that the EE group had higher PNNs in the supragranular layer (2726.33 ± 405.416, mean ± standard deviation) compared with the SE group (1543.535 ± 260.686; Student's t-test, p = .0495). No differences were found in the other layers. Visual acuity was significantly lower in the SE group (0.55 cycles/degree) than in the EE group (1.06 cycles/degree). Our results suggest that the integrity of the specialized extracellular matrix PNNs of the supragranular layer may be essential for normal visual acuity development.


Assuntos
Animais , Camundongos , Meio Ambiente , Visão Monocular , Acuidade Visual , Córtex Visual
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA