The Role Of Gap Junctions In The Brain In Health And Disease Pdf


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Cell junction

Nathan M. Kerr, Cameron S. Johnson, Clairton F. Good, Colin R. Green, Helen V. This study determines the expression pattern of gap junction protein connexin43 in the human retina and optic nerve. Postmortem human eyes were examined by immunohistochemical staining of frozen sections using antibodies to connexin Antibody binding was detected using confocal microscopy and fluorochrome-conjugated secondary antibodies.

Double-label immunohistochemistry identified the cell types expressing connexin The retinal and choroidal circulations showed strong connexin43 immunolabeling. Dense connexin43 immunoreactivity was present between adjacent cells of the retinal pigment epithelium, and there was diffuse connexin43 immunoreactivity on GFAP-positive astrocytes in the optic nerve. An understanding of the distribution of connexin43 in the normal retina and optic nerve may be used to evaluate changes associated with retinal and optic nerve disease.

Purchase this article with an account. Jump To Materials and Methods Results Discussion References. Kerr ; Cameron S. Johnson ; Clairton F. Good ; Colin R. Green ; Helen V. Alerts User Alerts. You will receive an email whenever this article is corrected, updated, or cited in the literature.

You can manage this and all other alerts in My Account. This feature is available to authenticated users only. Get Citation Citation. Get Permissions. Gap junctions are intercellular conduits that permit direct intercellular communication through the bidirectional movement of ions, metabolites, and second messengers between neighboring cells.

Connexin43 is the most abundant gap junction protein in the central nervous system and is expressed primarily on astrocyte processes surrounding blood vessels and chemical synapses. There is increasing interest in the role of gap junction communication in cell death. Connexin43 expression has been found at the mRNA and protein levels in rat, mouse, rabbit, carp, and zebrafish retina; fish and rat retinal pigment epithelium and vasculature; and rat nerve fiber layer.

In the present study, we used an immunohistochemical approach involving polyclonal antibodies to localize connexin43 immunoreactivity in the human retina and optic nerve.

Human tissue consisted of frozen sections obtained from eyes donated to the New Zealand National Eye Bank. The tissue was subsequently embedded in optimal cutting temperature compound before it was rapidly frozen by immersion in liquid nitrogen. A list of primary antibodies used in this study is shown in Table 2. All antibodies were obtained from commercial sources and were diluted in phosphate-buffered saline.

Negative controls were included by omitting the primary antibody; these did not yield any staining patterns. Immunoreactivity was visualized using either goat anti-rabbit or goat anti-mouse IgG secondary antibodies conjugated to either Alexa or Cy3, except for glial fibrillary acidic protein GFAP , which was preconjugated to Cy3. Informed consent was obtained from donors' relatives, and the tenets of the Declaration of Helsinki were upheld. Table 1. View Table. Characterization of Ocular Specimens.

MI, myocardial infarction; MVA, motor vehicle accident. Table 2. Primary Antibodies Used in This Study. Sigma: Sigma-Aldrich, St. Connexin43 immunoreactivity was detected in several locations in the human retina and optic nerve Table 3.

In the retina, strong labeling was detected in the retinal ganglion cell layer, and moderate labeling was present in the inner nuclear and plexiform layers. Beneath the neurosensory retina there was strong labeling in the retinal pigment epithelium and choroid. In the optic nerve there was abundant connexin43 immunoreactivity.

Table 3. Association of Connexin43 Immunoreactivity with Retinal Glia. To determine the relationship between the expression of connexin43 and glial cells in the human retina, cryosections were double-labeled with connexin43 and GFAP, glutamine synthetase, or oligodendrocyte specific protein Fig.

In the retinal ganglion cell layer, connexin43 immunoreactive puncta were located almost exclusively along GFAP-positive astrocyte processes Fig.

Where GFAP-positive astrocyte processes extended into the inner plexiform layer, these also colocalized with connexin43 immunoreactive puncta Fig.

These specialized radial glial cells span the entire thickness of the retina from the inner to the outer limiting membrane. No oligodendrocyte-specific, protein-labeled cells were detected in the retinas of any of the subjects examined not shown. Figure 1. View Original Download Slide. Double-labeled immunofluorescence patterns of connexin43 with glial cell markers in the human retina.

A Connexin43 immunofluorescence was detected in the ganglion cell layer on GFAP-positive astrocyte processes. B Retinal astrocyte process extending through the inner plexiform layer colocalizing with connexin43 immunoreactive puncta arrowhead. Note the perinuclear connexin43 immunoreactivity in a subpopulation of nuclei in the ganglion cell and inner nuclear layers white arrows.

Association of Connexin43 Immunoreactivity with Vascular Elements. Blood vessels were visualized by incubation with von Willebrand factor vWF , a glycoprotein synthesized exclusively by endothelial cells and megakaryocytes that is stored in intracellular granules or constitutively secreted into plasma. Connexin43 colocalized with vWF-positive cells in both the retinal and the choroidal circulations Figs.

Within the retina, punctate connexin43 immunoreactivity was present on retinal blood vessels in the inner plexiform, inner nuclear, and outer plexiform layers Fig. In the choroidal circulation, connexin43 immunoreactivity was observed in capillaries similar to those seen in Figure 2 and on endothelial cells of larger choroidal blood vessels Fig.

In addition, diffuse punctate labeling occurred, most likely in association with connective tissue fibroblasts. Figure 2. Connexin43 immunofluorescence in retinal blood vessels. A Sagittal section of the nerve fiber layer and ganglion cell layer double-labeled with connexin43 and vWF. Strong connexin43 immunoreactivity was observed in the inner vascular plexus. B Z-stack projection of a retinal capillary at the junction of the inner plexiform and inner nuclear layers white arrows.

Connexin43 immunofluorescence was detected between walls of the vessel lumen labeled with vWF arrowheads. C , D Outer vascular plexus. Figure 3. Connexin43 immunoreactivity in the retinal pigment epithelium and choroid. Strong connexin43 immunoreactivity was noted in the retinal pigment epithelium arrowheads. In the choroid, connexin43 immunoreactivity was associated with endothelial cells of larger blood vessels and formed a radial spoke-like appearance white arrow.

Diffuse punctate connexin43 immunoreactivity was also present in the choroid, most likely in association with connective tissue fibroblasts. RPE, retinal pigment epithelium; BV, blood vessel. Double labeling with cell-specific neuronal markers was performed to determine whether retinal neurons express connexin No punctate connexin43 label suggestive of gap junctions was found to be associated with any of the neuronal specific markers calretinin, calbindin, parvalbumin, or islet However, a small subpopulation of cell nuclei in the ganglion cell and inner nuclear layers was observed to have diffuse nuclear-associated connexin43 label Fig.

Occasionally, these nuclei were also calretinin positive. In the retinal pigment epithelium, immunostaining for connexin43 revealed a distinctive pattern. In this layer there was substantial punctate labeling at the margins of adjacent epithelial cells Fig. Within the optic nerve there was very strong connexin43 immunoreactivity. Connexin43 immunoreactive puncta and SMIpositive retinal ganglion cell axons were compartmentalized into distinct bundles Fig. However, the connexin43 label did not appear to be associated with the nerve axons themselves but predominantly colocalized with GFAP-positive astrocytes Figs.

Around optic nerve blood vessels and at the glial limitans, strong connexin43 immunoreactivity was observed. Figure 4. Connexin43 immunoreactivity in the human optic nerve. A Longitudinal section of the human optic nerve labeled with connexin43 and SMI Connexin43 immunoreactive puncta and SMIpositive axons were compartmentalized into distinct bundles.

Strong connexin43 immunoreactivity was present in association with the glial limitans arrowhead. GFAP, glial fibrillary acidic protein. Connexins are a class of proteins that form gap junctions between cells in various mammalian tissues. Gap junction communication may be important in the pathogenesis of neuronal degeneration and has been identified as a potential neuroprotective target.

The expression pattern in the human shows significant homology with other vertebrates.

Gap junctional communication in health and disease

Nathan M. Kerr, Cameron S. Johnson, Clairton F. Good, Colin R. Green, Helen V. This study determines the expression pattern of gap junction protein connexin43 in the human retina and optic nerve. Postmortem human eyes were examined by immunohistochemical staining of frozen sections using antibodies to connexin

The brain is responsible for every thought, feeling, and action. But how do the billions of cells that reside in the brain manage these feats? They do so through a process called neurotransmission. Simply stated, neurotransmission is the way that brain cells communicate. And the bulk of those communications occur at a site called the synapse. Neuroscientists now understand that the synapse plays a critical role in a variety of cognitive processes—especially those involved with learning and memory.

Activity-Dependent Neuronal Control of Gap-Junctional Communication in Astrocytes

Ruiz, M. Asche endowment and Research to Prevent Blindness. Both neurons and glia throughout the central nervous system are organized into networks by gap junctions. Among glia, gap junctions facilitate metabolic homeostasis and intercellular communication.

Gap junctions GJ provide intercellular communication in all multicellular animal species, being as evolutionary distant as worm and men. In the traditional view GJs are known as specialized cell junctions forming communicating channels connecting the cytoplasm of adjacent cells. In almost all tissues GJ coupled cells can rapidly exchange ions, nutrients, or small metabolites to establish electrical coupling or balancing metabolites.

A new genetically encoded system manipulates the pH inside cells to detect whether they are coupled to each other. For our bodies to work properly, cells need to communicate with each other. Cells coupled together by gap junctions often synchronize their activity Bennett and Zukin, Gap junctions have also been implicated in a variety of diseases Nielsen et al. So far, it has been difficult to identify their precise roles in health and disease, as present methods to map or monitor gap junction coupling are often invasive and damaging, or unable to measure a specific cell type in enough detail.

J Cell Biol 26 June ; 7 : —

Immunohistochemical analysis of thyroid specimens. Arch Otolaryngol Head Neck Surg. The Cx43 membrane staining pattern was evaluated.

What Happens at The Synapse?

Cell junctions or intercellular bridges [1] are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals.

Человек, к которому он направил Росио. Странно, подумал он, что сегодня вечером уже второй человек интересуется этим немцем. - Мистер Густафсон? - не удержался от смешка Ролдан.  - Ну .

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