Expression and possible functions of glutamate and GABA receptors in glial cells from the hippocampus

The mechanosensilla in spider exoskeleton are innervated by bipolar neurons with their cell bodies close to the cuticle and dendrites attached to it. Numerous efferent fibers synapse with peripheral parts of the mechanosensory neurons, with glial cells surrounding the neurons, and with each other. Most of these efferent fibers are immunoreactive to γ-aminobutyric acid (GABA), and the sensory neurons respond to agonists of ionotropic GABA receptors with a rapid and complete inhibition. In contrast, little is known about metabotropic GABAB receptors that may mediate long-term effects. We investigated the distribution of GABAB receptors on spider leg mechanosensilla using specific antibodies against 2 proteins needed to form functional receptors and an antibody that labels the synaptic vesicles on presynaptic sites. Both anti-GABAB receptor antibodies labeled the distal parts of the sensory cell bodies and dendrites but anti-GABABR1 immunoreactivity was also found in the axons and proximal parts of the cell bodies and some glial cells. The fine efferent fibers that branch on top of the sensory neurons did not show GABAB receptor immunoreactivity but were densely labeled with anti-synapsin and indicated synaptic vesicles on presynaptic locations to the GABAB receptors. Intracellular recordings from sensory neurons innervating the slit sensilla of the spider legs revealed that application of GABAB receptor agonists attenuated voltage-activated Ca2+ current and enhanced voltage-activated outward K+ current, providing 2 possible mechanisms for controlling the neurons' excitability. These findings support the hypothesis that GABAB receptors are present in the spider mechanosensilla where their activation may modulate information transmission.

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GABAA receptors are selectively expressed in NG2 glia of the cerebellar white matter

10.1101/741140 ◽

2019 ◽

Author(s):

Labrada-Moncada Emmanuel ◽

Martínez-Torres Ataulfo ◽

Reyes-Haro Daniel

Keyword(s):

White Matter ◽

Glial Cells ◽

Gaba Receptors ◽

Functional Expression ◽

Dye Coupling ◽

Cerebellar White Matter ◽

Whole Cell Patch Clamp ◽

Current Voltage ◽

Neuronal Types ◽

And Migration

AbstractThe cerebellum is involved in the coordination of movement. Its cellular composition is dominated by GABAergic neuronal types, and glial cells are known to express functional receptors. GABAergic signaling regulates cell proliferation, differentiation, and migration during neurodevelopment. However, little is known about the functional expression of GABA receptors in the cerebellar white matter (WM). Thus, the aim of this study was to test whether glial cells express functional GABA receptors during postnatal development (P7-P9) of cerebellar WM. Immunofluorescence studies showed that half of the astrocytes express GAD67, suggesting that GABA is synthetized by glial cells. Calcium imaging in cerebellar slices revealed that GABA and the GABAA agonist muscimol evoked calcium transients in sulforhodamine B (SRB) negative cells, whereas the GABAB agonist baclofen failed to evoke responses in cerebellar WM. Whole-cell patch-clamp recordings of GFAP+ cells showed dye coupling and a passive current-voltage relation typical of astrocytes. Surprisingly, these cells did not respond to muscimol. Two additional populations were identified as GFAP− cells. The first population showed dye coupling, slow decaying inward and outward currents with no voltage dependence and did not respond to GABAA agonists. The second population showed an outward-rectifying current-voltage relationship and responded to muscimol, but dye coupling was absent. These cells received synaptic input and were NG2+, but evoked calcium waves failed to modulate the frequency of sPSCs or signal directly to NG2 glia. We conclude that GABAA receptor-mediated signaling is selective for NG2 glia in the WM of the cerebellum.

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Neuron-glia relationship during the early postembryonic development of the nervous system in some oligochaetes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083874 ◽

1978 ◽

Vol 36 (2) ◽

pp. 600-601

Author(s):

Wiktor Djaczenko ◽

Carmen Calenda Cimmino

Keyword(s):

Nervous System ◽

Glial Cells ◽

Early Period ◽

Postembryonic Development ◽

Ruthenium Red ◽

The Body ◽

Tubifex Tubifex ◽

Growth Stages ◽

Cell Processes ◽

Cytoplasmic Processes

The simplicity of the developing nervous system of oligochaetes makes of it an excellent model for the study of the relationships between glia and neurons. In the present communication we describe the relationships between glia and neurons in the early periods of post-embryonic development in some species of oligochaetes.Tubifex tubifex (Mull. ) and Octolasium complanatum (Dugès) specimens starting from 0. 3 mm of body length were collected from laboratory cultures divided into three groups each group fixed separately by one of the following methods: (a) 4% glutaraldehyde and 1% acrolein fixation followed by osmium tetroxide, (b) TAPO technique, (c) ruthenium red method.Our observations concern the early period of the postembryonic development of the nervous system in oligochaetes. During this period neurons occupy fixed positions in the body the only observable change being the increase in volume of their perikaryons. Perikaryons of glial cells were located at some distance from neurons. Long cytoplasmic processes of glial cells tended to approach the neurons. The superimposed contours of glial cell processes designed from electron micrographs, taken at the same magnification, typical for five successive growth stages of the nervous system of Octolasium complanatum are shown in Fig. 1. Neuron is designed symbolically to facilitate the understanding of the kinetics of the growth process.

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High-voltage electron microscopy of subretinal scar formation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122836 ◽

1992 ◽

Vol 50 (1) ◽

pp. 486-487

Author(s):

G.E. Korte ◽

M. Marko ◽

G. Hageman

Keyword(s):

Electron Microscopy ◽

Monoclonal Antibody ◽

Retinal Pigment Epithelium ◽

Glial Cells ◽

High Voltage ◽

Pigment Epithelium ◽

Retinal Pigment ◽

Sodium Iodate ◽

High Voltage Electron Microscopy ◽

Voltage Electron

Sodium iodate iv. damages the retinal pigment epithelium (RPE) in rabbits. Where RPE does not regenerate (e.g., 1,2) Muller glial cells (MC) forma subretinal scar that replaces RPE. The MC response was studied by HVEM in 3D computer reconstructions of serial thick sections, made using the STEREC0N program (3), and the HVEM at the NYS Dept. of Health in Albany, NY. Tissue was processed for HVEM or immunofluorescence localization of a monoclonal antibody recognizing MG microvilli (4).

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Ultrasturcture of cerebellar cells and neuropil in rats subjected to partial global cerebral ischemia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014227x ◽

1986 ◽

Vol 44 ◽

pp. 126-127

Author(s):

R.V.W. Dimlich ◽

M.H. Biros

Keyword(s):

Purkinje Cells ◽

Glial Cells ◽

Granule Cells ◽

Molecular Layer ◽

Cell Types ◽

Primary Objective ◽

Global Cerebral Ischemia ◽

Forebrain Ischemia ◽

Substantial Evidence ◽

Cerebellar Cells

Although a previous study in this laboratory determined that Purkinje cells of the rat cerebellum did not appear to be damaged following 30 min of forebrain ischemia followed by 30 min of reperfusion, it was suggested that an increase in rough endoplasmic reticulum (RER) and/or polysomes had occurred in these cells. The primary objective of the present study was to morphometrically determine whether or not this increase had occurred. In addition, since there is substantial evidence that glial cells may be affected by ischemia earlier than other cell types, glial cells also were examined. To ascertain possible effects on other cerebellar components, granule cells and neuropil near Purkinje cells as well as neuropil in the molecular layer also were evaluated in this investigation.

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Extracellular filaments in the perineurium of the florida lobster, Panulirus argus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128237 ◽

1987 ◽

Vol 45 ◽

pp. 784-785

Author(s):

Roy J. Baerwald ◽

Lura C. Williamson

Keyword(s):

Blood Brain Barrier ◽

Glial Cells ◽

Tannic Acid ◽

Nerve Cord ◽

Ventral Nerve Cord ◽

Florida Keys ◽

Panulirus Argus ◽

Brain Barrier ◽

Cacodylate Buffer ◽

Nerve Cords

In arthropods the perineurium surrounds the neuropile, consists of modified glial cells, and is the morphological basis for the blood-brain barrier. The perineurium is surrounded by an acellular neural lamella, sometimes containing scattered collagen-like fibrils. This perineurial-neural lamellar complex is thought to occur ubiquitously throughout the arthropods. This report describes a SEM and TEM study of the sheath surrounding the ventral nerve cord of Panulirus argus.Juvenile P. argus were collected from the Florida Keys and maintained in marine aquaria. Nerve cords were fixed for TEM in Karnovsky's fixative and saturated tannic acid in 0.1 M Na-cacodylate buffer, pH = 7.4; post-fixed in 1.0% OsO4 in the same buffer; dehydrated through a graded series of ethanols; embedded in Epon-Araldite; and examined in a Philips 200 TEM. Nerve cords were fixed for SEM in a similar manner except that tannic acid was not used.

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