scholarly journals N-methyl-D-aspartate (NMDA) and non-NMDA (metabotropic) type glutamate receptors modulate the membrane potential of the Schwann cell of the squid giant nerve fibre.

1992 ◽  
Vol 173 (1) ◽  
pp. 229-249 ◽  
Author(s):  
P D Evans ◽  
V Reale ◽  
R M Merzon ◽  
J Villegas
Keyword(s):  
Amino Acids ◽  
Membrane Potential ◽  
Schwann Cell ◽  
Glutamate Receptors ◽  
Nerve Fibre ◽  
Excitatory Amino Acids ◽  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate ◽  
Type Receptor ◽  
Lasting Change

L-Glutamate application can produce three different responses in the membrane potential of the Schwann cell of the tropical squid, Sepioteuthis sepioidea, which appear to be mediated by three pharmacologically distinct classes of receptor. A class of non-NMDA-type receptors, with some similarities to metabotropic glutamate receptors, mediates the development of a rapid and long-lasting hyperpolarization. Two pharmacologically distinct classes of NMDA-type receptor are present. One mediates the development of a slow depolarization accompanied by a long-lasting change in responsiveness of the Schwann cell. The second produces rapid depolarizing responses during the period of this changed responsiveness. All three types of receptor can be activated by dipeptides containing excitatory amino acids.

Among the twenty classical l-amino acids, only glutamate directly activates metabotropic glutamate receptors

2006 ◽  
Vol 50 (2) ◽  
pp. 245-253 ◽  
Author(s):  
Mélanie Frauli ◽  
Pascal Neuville ◽  
Claire Vol ◽  
Jean-Philippe Pin ◽  
Laurent Prézeau
Keyword(s):  
Amino Acids ◽  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate

Intracellular Ca2+ release mediated by metabotropic glutamate receptor activation in the leech giant glial cell.

1997 ◽  
Vol 200 (19) ◽  
pp. 2565-2573
Author(s):  
C Lohr ◽  
J W Deitmer
Keyword(s):  
Membrane Potential ◽  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Glial Cells ◽  
Metabotropic Glutamate Receptors ◽  
Metabotropic Glutamate Receptor ◽  
Cyclopiazonic Acid ◽  
Receptor Activation ◽  
Atpase Inhibitor ◽  
Metabotropic Glutamate

We have investigated the effects of glutamate and glutamate receptor ligands on the intracellular free Ca2+ concentration ([Ca2+]i) and the membrane potential (Em) of single, identified neuropile glial cells in the central nervous system of the leech Hirudo medicinalis. Exposed glial cells of isolated ganglia were filled iontophoretically with the Ca2+ indicator dye Fura-2. Application of glutamate (200-500 mumoll-1) caused biphasic membrane potential shifts and increases in [Ca2+]i, which were only partly reduced by either removing extracellular Ca2+ or blocking ionotropic glutamate receptors with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 50-100 mumol l-1. Metabotropic glutamate receptor (mGluR) ligands had the following rank of potency in inducing a rise in [Ca2+]i: quisqualate (QQ, 200 mumol l-1) > glutamate (200 mumol l-1) > L(+)2-amino-3-phosphonopropionic acid (L-AP3, 200 mumol l-1 > trans-1-aminocyclopentane-1,3-dicarboxylic acid (t-ACPD, 400 mumol l-1). The mGluR-selective antagonist (RS)-alpha-methyl-4-carboxyphenylglycine [(RS)-MCPG, 1 mmol l-1] significantly reduced glutamate-evoked increases in [Ca2+]i by 20%. Incubation of the ganglia with the endoplasmic ATPase inhibitor cyclopiazonic acid (CPA, 10 mumol l-1) caused a significant (53%) reduction of glutamate-induced [Ca2+]i transients, while incubation with lithium ions (2 mmol l-1) resulted in a 46% reduction. The effects of depleting the Ca2+ stores with CPA and of CNQX were additive. We conclude that glutamate-induced [Ca2+]i transients were mediated by activation of both Ca(2+)-permeable ionotropic non-NMDA receptors and of metabotropic glutamate receptors leading to Ca2+ release from intracellular Ca2+ stores.

Selective Antagonists at Group I Metabotropic Glutamate Receptors:  Synthesis and Molecular Pharmacology of 4-Aryl-3-isoxazolol Amino Acids

2002 ◽  
Vol 45 (4) ◽  
pp. 988-991 ◽  
Author(s):  
Hasse Kromann ◽  
Frank A. Sløk ◽  
Tine B. Stensbøl ◽  
Hans Bräuner-Osborne ◽  
Ulf Madsen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Molecular Pharmacology ◽  
Metabotropic Glutamate ◽  
Selective Antagonists ◽  
Group I

scholarly journals The effect of a glutamate uptake inhibitor on axon-Schwann cell signalling in the squid giant nerve fibre.

1992 ◽  
Vol 173 (1) ◽  
pp. 251-260
Author(s):  
P D Evans ◽  
V Reale ◽  
R M Merzon ◽  
J Villegas
Keyword(s):  
Membrane Potential ◽  
Schwann Cell ◽  
Glutamate Receptors ◽  
Schwann Cells ◽  
Nerve Fibre ◽  
Glutamate Uptake ◽  
Cell Signalling ◽  
Giant Axon ◽  
Uptake System ◽  
Extracellular Level

The glutamate uptake blocker p-chloromercuriphenylsulphonic acid (PCMS) (100 mumol l-1) does not block any of the membrane potential changes induced by the application of L-glutamate to the adaxonal Schwann cells of the giant axon of the tropical squid Sepioteuthis sepioidea. This indicates that these potential changes are not due to the activation of an electrogenic glutamate uptake system and supports the idea that they are due to the activation of specific glutamate receptors. The presence of PCMS (100 mumol l-1) reduces the activity of the glutamate uptake system sufficiently for the extracellular level of axonally released glutamate to exceed the threshold for the activation of the NMDA-type glutamate receptors in this preparation.

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