RESUMO
PURPOSE: This study assessed whether optic radiations (OR) microstructure after temporal lobe epilepsy (TLE) surgery correlated with visual field defects (VFD). METHODS: Patients were subjected to diffusion tensor imaging (DTI) tractography of the OR and Humphrey perimetry after TLE surgery. We used Spearman's test to verify correlations between tractographic parameters and perimetry mean deviation. Tractographic variables were compared between patients with VFD or intact perimetry. Multiple logistic regression was applied between DTI and perimetry values. DTI sensitivity and specificity were assessed with a receiver operating characteristic (ROC) curve to evaluate VFD. RESULTS: Thirty-nine patients had reliable perimetry and OR tractography. There was a significant correlation between (1) fractional anisotropy (FA) and both total (rho = 0.569, p = 0.0002) and quadrant (rho = 0.453, p = 0.0037) mean deviation and (2) radial diffusivity and total mean deviation (rho = - 0.350, p = 0.0286). There was no other significant correlation. Patients with VFD showed a significantly lower FA compared with patients with normal perimetry (p = 0.0055), and a 0.01 reduction in FA was associated with a 44% increase in presenting VFD after surgery (confidence interval, CI = 1.10-1.88; p = 0.0082). Using a FA of 0.457, DTI tractography showed a specificity of 95.2% and a sensitivity of 50% to detect VFD after surgery (area under the curve = 0.7619, CI = 0.6020-0.9218). CONCLUSION: The postoperative OR microstructure correlated with visual loss after epilepsy surgery. DTI postoperative OR tractography may be helpful in evaluating VFD.
Assuntos
Imagem de Tensor de Difusão , Epilepsia do Lobo Temporal/cirurgia , Transtornos da Visão/etiologia , Campos Visuais , Vias Visuais/ultraestrutura , Adulto , Anisotropia , Feminino , Humanos , Masculino , Estudos Prospectivos , Sensibilidade e EspecificidadeRESUMO
The lobula plate is part of the lobula complex, the third optic neuropil, in the optic lobes of insects. It has been extensively studied in dipterous insects, where its role in processing flow-field motion information used for controlling optomotor responses was discovered early. Recently, a lobula plate was also found in malacostracan crustaceans. Here, we provide the first detailed description of the neuroarchitecture, the input and output connections and the retinotopic organization of the lobula plate in a crustacean, the crab Neohelice granulata using a variety of histological methods that include silver reduced staining and mass staining with dextran-conjugated dyes. The lobula plate of this crab is a small elongated neuropil. It receives separated retinotopic inputs from columnar neurons of the medulla and the lobula. In the anteroposterior plane, the neuropil possesses four layers defined by the arborizations of such columnar inputs. Medulla projecting neurons arborize mainly in two of these layers, one on each side, while input neurons arriving from the lobula branch only in one. The neuropil contains at least two classes of tangential elements, one connecting with the lateral protocerebrum and the other that exits the optic lobes toward the supraesophageal ganglion. The number of layers in the crab's lobula plate, the retinotopic connections received from the medulla and from the lobula, and the presence of large tangential neurons exiting the neuropil, reflect the general structure of the insect lobula plate and, hence, provide support to the notion of an evolutionary conserved function for this neuropil.
Assuntos
Braquiúros/anatomia & histologia , Bulbo/anatomia & histologia , Lobo Óptico de Animais não Mamíferos/anatomia & histologia , Retina/anatomia & histologia , Vias Visuais/fisiologia , Animais , Corantes Fluorescentes/metabolismo , Masculino , Bulbo/ultraestrutura , Lobo Óptico de Animais não Mamíferos/ultraestrutura , Retina/ultraestrutura , Coloração pela Prata , Vias Visuais/ultraestruturaRESUMO
BACKGROUND: Members of the proteolipid protein family, including the four-transmembrane glycoprotein M6a, are involved in neuronal plasticity in mammals. Results from our group previously demonstrated that M6, the only proteolipid protein expressed in Drosophila, localizes to the cell membrane in follicle cells. M6 loss triggers female sterility, which suggests a role for M6 in follicular cell remodeling. These results were the basis of the present study, which focused on the function and requirements of M6 in the fly nervous system. RESULTS: The present study identified two novel, tissue-regulated M6 isoforms with variable N- and C- termini, and showed that M6 is the functional fly ortholog of Gpm6a. In the adult brain, the protein was localized to several neuropils, such as the optic lobe, the central complex, and the mushroom bodies. Interestingly, although reduced M6 levels triggered a mild rough-eye phenotype, hypomorphic M6 mutants exhibited a defective response to light. CONCLUSIONS: Based on its ability to induce filopodium formation we propose that M6 is key in cell remodeling processes underlying visual system function. These results bring further insight into the role of M6/M6a in biological processes involving neuronal plasticity and behavior in flies and mammals.
Assuntos
Comportamento Animal/fisiologia , Olho/metabolismo , Regulação da Expressão Gênica/fisiologia , Glicoproteínas de Membrana/fisiologia , Vias Visuais/metabolismo , Processamento Alternativo/genética , Animais , Animais Geneticamente Modificados , Linhagem Celular Tumoral , Clonagem Molecular , Sequência Conservada/genética , Drosophila , Proteínas de Drosophila/genética , Olho/ultraestrutura , Regulação da Expressão Gênica/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Expectativa de Vida , Glicoproteínas de Membrana/genética , Microscopia Eletrônica de Varredura , Atividade Motora/genética , Mutação/genética , Neuroblastoma/patologia , Neurópilo/metabolismo , Neurópilo/ultraestrutura , Lobo Óptico de Animais não Mamíferos/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Pseudópodes/metabolismo , RNA Mensageiro/metabolismo , Transfecção , Vias Visuais/ultraestruturaRESUMO
Wallerian degeneration is a very well described phenomenon in the vertebrate nervous system. In arthropods, and especially in crustaceans, nerve fiber degeneration has not been described extensively. In addition, literature shows that the events do not follow the same patterns as in vertebrates. In this study we report, by qualitative and quantitative ultrastructural analyses, the features and time course of the protocerebral tract degeneration following extirpation of the optic stalk. No remarkable changes were observed seven days after lesion. After 28 days the protocerebral tracts presented apparently preserved small and large diameter axons and some degenerating medium axons, with irregular contours and empty-looking aspect of the axoplasm. Forty days after the ablation of the optic stalks, both small (type I) and medium (type II and III) axons revealed signs of partial or total degeneration, but large nerve fibers (type IV) were still intact. After 45 days, the tract showed signs of advanced stage of degeneration and, apart from large axons, normal-looking fibers were almost absent. At these 3 last time points, degenerating axons displayed different electron densities and aspects, probably correlating to different onset times of the process. In addition, cells with granules in their cytoplasm, possibly hemocytes, were quite distinct, especially at 40 and 45 days after axotomy. These cells might share with glial cells the function of phagocytosis of cellular debris during the protocerebral tract degeneration. Quantitative analysis showed that the number of degenerating fibers increased significantly from 28 to 40 days after lesion, whereas the number of normal fibers decreased accordingly. Measurements of cross-sectional areas of normal and degenerating axons showed that types II and III (medium) start to degenerate before type I (small). Type IV (large) axons do not degenerate, even after 40 days. Therefore, we can conclude that degeneration in these afferent fibers starts late after axotomy, but proceeds at a faster rate afterwards until the complete degeneration of small and medium axons.
Assuntos
Braquiúros/ultraestrutura , Fibras Nervosas/ultraestrutura , Sistema Nervoso/ultraestrutura , Vias Visuais/ultraestrutura , Degeneração Walleriana/patologia , Animais , Tamanho Celular , Olho/inervação , Masculino , Lobo Óptico de Animais não Mamíferos/citologia , Lobo Óptico de Animais não Mamíferos/ultraestruturaRESUMO
Neurofilaments (NFs) have not been observed in crustaceans using conventional electron microscopy, and intermediate filaments have never been described in crustaceans and other arthropods by immunocytochemistry. Since polypeptides, labeled by the NN18-clone antibody, were revealed on microtubule side-arms of crayfish, we have tested, in this study, whether proteins similar to mammalian NFs are present in the protocerebral tract (PCT) of the crab Ucides cordatus. We used immunohistochemistry for light microscopy with monoclonal antibodies against three different NF subunits, high (NF-H), medium (NF-M), and light (NF-L). Labeling was observed with the NN18-clone, which recognizes NF-M. In order to confirm the results obtained with the immunohistochemical reactions, Western blotting, using the three primary antibodies, was performed and the presence of NF-M was confirmed. The NN18-clone monoclonal antibody recognized a protein of approximately 160 kDa, similar to the mammalian NF-M protein, but NF-L and NF-H were not recognized. Conventional transmission electron microscopy was used to observe the ultrastructural components of the axons and immunoelectron microscopy was used to show the distribution of the NF-M-like polypeptides along cytoskeletal elements of the PCT. Our results agree with previous studies on crustacean NF proteins that have reported negative immunoreactions against NF-H and NF-L subunits and positive immunoreactions against the mammalian NF-M subunit. However, the protein previously referred to as P600 and recognized by the NN18-clone, has a very high molecular weight, thus, being different from mammalian NF-M subunit and from the protein revealed now in our study.
Assuntos
Axônios/metabolismo , Citoesqueleto/metabolismo , Proteínas de Neurofilamentos/isolamento & purificação , Proteínas de Neurofilamentos/metabolismo , Lobo Óptico de Animais não Mamíferos/metabolismo , Animais , Citoesqueleto/ultraestrutura , Decápodes , Eletroforese em Gel de Poliacrilamida , Immunoblotting , Imuno-Histoquímica , Masculino , Microscopia Imunoeletrônica , Lobo Óptico de Animais não Mamíferos/ultraestrutura , Vias Visuais/metabolismo , Vias Visuais/ultraestruturaRESUMO
Glial cells, in both vertebrate and invertebrate nervous systems, provide an essential environment for developmental, supportive, and physiological functions. However, information on glial cells themselves and on glial cell markers, with the exception of those of Drosophila and other insects, is not abundant in invertebrate organisms. A common ultrastructural feature of invertebrate nervous systems is that layers of glial cell cytoplasm-rich processes ensheath axons and neuronal and glial somata. In the present study, we have examined the binding of a monoclonal antibody to 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in the compound eye and optic lobe of the crab Ucides cordatus using both light and electron microscopy. CNPase is a noncompact myelin protein that is a phenotypic marker of oligodendroglial and Schwann cells, is apparently involved in the ensheathment step prior to myelin compaction, and is also expressed by the potentially myelinating olfactory ensheathing glia. CNPase has raised much interest, first by virtue of its unusual enzymatic activity and more recently by its membrane-skeletal features and possible involvement in migration or expansion of membranes. We have found CNPase-like immunoreactivity in most cells of the compound eye basement membrane and both in optic cartridges of the synaptic layer and cells of the outer sublayer of the lamina ganglionaris. The results suggest that in the crab visual system some, but not all, glial cells, including some adaxonal glia, may express the noncompact myelin protein CNPase or a related protein.
Assuntos
2',3'-Nucleotídeo Cíclico Fosfodiesterases/metabolismo , Braquiúros/metabolismo , Olho/metabolismo , Proteínas da Mielina/metabolismo , Neuroglia/metabolismo , Lobo Óptico de Animais não Mamíferos/metabolismo , Vias Visuais/metabolismo , 2',3'-Nucleotídeo Cíclico Fosfodiesterases/imunologia , Animais , Anticorpos , Membrana Basal/metabolismo , Membrana Basal/ultraestrutura , Sítios de Ligação/imunologia , Braquiúros/ultraestrutura , Olho/ultraestrutura , Feminino , Imuno-Histoquímica , Masculino , Microscopia Eletrônica , Proteínas da Mielina/imunologia , Neuroglia/ultraestrutura , Lobo Óptico de Animais não Mamíferos/ultraestrutura , Ligação Proteica/fisiologia , Membranas Sinápticas/metabolismo , Membranas Sinápticas/ultraestrutura , Vias Visuais/ultraestruturaRESUMO
The superficial layers of the rat superior colliculus (sSC) receive innervation from retina and include nitric oxide synthase (NOS)-immunoreactive neurons. We used electron microscopic immunocytochemistry to assess the subcellular localization of neuronal NOS (nNOS) in the sSC. nNOS immunoreactivity was detected on the external membrane of mitochondria, endoplasmic reticulum, in pre- and postsynaptic profiles and also diffusely distributed in the cytosol. Postsynaptic labeled regions were often associated with presumptive retinal unlabeled terminals. Microtubules also appeared intensely labeled. These results show that NOS immunoreactive neurons may be innervated by retinal terminals and suggest an association of nNOS with cytoskeletal elements.
Assuntos
Compartimento Celular/fisiologia , Neurônios/enzimologia , Óxido Nítrico Sintase/metabolismo , Células Ganglionares da Retina/enzimologia , Colículos Superiores/enzimologia , Sinapses/enzimologia , Vias Visuais/enzimologia , Animais , Imuno-Histoquímica , Membranas Intracelulares/enzimologia , Membranas Intracelulares/ultraestrutura , Microscopia Eletrônica , Microtúbulos/enzimologia , Microtúbulos/ultraestrutura , Neurônios/ultraestrutura , Óxido Nítrico/metabolismo , Organelas/enzimologia , Organelas/ultraestrutura , Ratos , Células Ganglionares da Retina/ultraestrutura , Colículos Superiores/ultraestrutura , Sinapses/ultraestrutura , Vias Visuais/ultraestruturaRESUMO
The maturation of the neuropil and synapse formation were examined in the retino-receptive layers of the superior colliculus (SCr-r) in the opossum from a period prior to the onset of arborization of retinocollicular fibers (postnatal day 22 - P22), at 44% of the coecal period (CP), to the end of the fast phase of optic fiber myelination and weaning time (P81 - 118% CP). Development of the SCr-r neuropil follows a protracted time course and can be divided into three broad stages, which are characterized by (I) Large extracellular spaces, numerous growth cones that participate rarely in synaptic junctions, vesicles-poor immature synapses (P22-P30), (II) Synapses of varied morphology with abundant synaptic vesicles, and small terminals with dark mitochondria and round synaptic vesicles (RSD terminals) synapsing mostly onto dendritic shafts, flat-vesicles (F) terminals (P40-P56), (III) Sequential appearance of retinal (R) and pleomorphic-vesicles (P) terminals and of RSD terminals synapsing onto spine or spine-like processes, appearance of glomerulus-like synaptic arrays (synaptic islets) (P61-P81). The advancement of synaptogenesis in SCr-r from stage I to II and from stage II to III correlates closely with the differentiation of astrocytes and oligodendrocytes, respectively.
Assuntos
Gambás/fisiologia , Retina/crescimento & desenvolvimento , Colículos Superiores/crescimento & desenvolvimento , Sinapses/fisiologia , Animais , Microscopia Eletrônica , Neurópilo/fisiologia , Neurópilo/ultraestrutura , Retina/fisiologia , Retina/ultraestrutura , Colículos Superiores/fisiologia , Colículos Superiores/ultraestrutura , Sinapses/ultraestrutura , Vias Visuais/crescimento & desenvolvimento , Vias Visuais/fisiologia , Vias Visuais/ultraestruturaRESUMO
The ultra-structural development of synapses in retino-receptive layers of the opossum superior colliculus was studied by the ethanolic phosphotungstic acid (E-PTA) method. There was a tendency for a slight reduction in the diameter of synaptic disks, a rise and fall of numerical densities and, except for an ephemeral period, a general increase in the proportion of "frown" among curve synapses. The lack of strict synchrony and the occurrence of different patterns of changes suggest that multiple factors contribute to synaptic maturation.