Further characterisation of excitatory amino acid receptors coupled to phosphoinositide metabolism in astrocytes.
Excitatory amino acids stimulate phosphoinositide breakdown in astrocytes with the following rank order of effect: quisqualate greater than ibotenate = glutamate greater than kainate greater than N-methyl-D-aspartate. Quisqualate-induced responses were resistant to blockade with a range of receptor antagonists whereas those to glutamate were partially reversed by gamma-D-glutamylaminosulphonic acid and gamma-D-glutamylglycine. These antagonists were, however, more effective against kainate-stimulated phosphoinositide metabolism. These experiments together with those where combinations of agonists were used, suggest that the kainate-induced and, to some extent, the glutamate-induced responses were due to membrane depolarisation and that quisqualate activates a non-ionotropic class of receptor at which glutamate and ibotenate are partial agonists.
Pearce
B
B
Biology Department, Open University, Milton Keynes, U.K.
Morrow
C
C
Murphy
S
S
D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D007051:Ibotenic Acid / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology*; D010080:Oxazoles / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D016318:Quisqualic Acid; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*
D005971:Glutamates; D018377:Neurotransmitter Agents; D010069:Oxadiazoles; D010080:Oxazoles; D010716:Phosphatidylinositols; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D007051:Ibotenic Acid; D018698:Glutamic Acid; D016318:Quisqualic Acid