Effects of excitatory amino acid antagonists on synaptic transmission in the ampullae of Lorenzini of the skate Raja clavata

1991 ◽  
Vol 168 (6) ◽  
Author(s):  
G.N. Akoev ◽  
G.N. Andrianov ◽  
B. Bromm ◽  
T. Szabo
Keyword(s):  
Amino Acid ◽  
Synaptic Transmission ◽  
Excitatory Amino Acid ◽  
Ampullae Of Lorenzini ◽  
Raja Clavata ◽  
Amino Acid Antagonists ◽  
Excitatory Amino Acid Antagonists

Physiology of excitatory synaptic transmission in cultures of dissociated rat hippocampus

1985 ◽  
Vol 54 (3) ◽  
pp. 701-713 ◽  
Author(s):  
S. M. Rothman ◽  
M. Samaie
Keyword(s):  
Amino Acid ◽  
Synaptic Transmission ◽  
Hippocampal Neurons ◽  
Excitatory Amino Acid ◽  
Excitatory Synaptic Transmission ◽  
Voltage Sensitivity ◽  
Voltage Dependent ◽  
Synaptic Receptors ◽  
Amino Acid Antagonists ◽  
Excitatory Amino Acid Antagonists

Cultures of dissociated rat hippocampal neurons were used to study the physiology and pharmacology of excitatory synaptic transmission. Rat hippocampal neurons depolarized when they were exposed to the excitatory transmitter candidates, glutamate (Glu) and aspartate (Asp), as well as to the pure excitatory amino acid agonists, N-methyl-D-aspartate (NMDA) and kainate (KA). Quisqualate (QUIS) produced responses in about two-thirds of these cells. Glu responses were much more effectively blocked by the excitatory amino acid antagonists cis-2,3-piperidine dicarboxylic acid (PDA) and gamma-D-glutamylglycine (DGG) than by D-2-amino-5-phosphonovaleric acid (APV) or D-alpha-aminoadipic acid (DAA). Asp depolarizations were depressed by all four antagonists. Monosynaptic excitatory postsynaptic potentials (EPSPs) were only decreased by PDA and DGG. Postsynaptic responses to both Glu and Asp were very voltage dependent, decreasing as the membrane potential was hyperpolarized up to 70 mV below resting levels. The EPSP, however, increased linearly in the hyperpolarized range. NMDA responses were also voltage dependent, while KA and QUIS responses behaved like EPSPs. DGG very effectively blocked KA, but not QUIS, depolarizations. APV, which only partially depressed Glu responses, markedly diminished their voltage sensitivity. These results all suggest that EPSPs in this preparation are produced by Glu acting at KA-type synaptic receptors. Exogenous Glu probably acts at both synaptic KA receptors and extrasynaptic NMDA receptors, which explains why it produces a voltage-dependent response different from the EPSP.

Sign in / Sign up

Export Citation Format

Share Document