Characterization of the Quisqualate Receptor Linked to Phosphoinositide Hydrolysis in Neurocortical Cultures

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: Activation of phosphoinositide metabolism is an early event in signal transduction for a number of neurotransmitters and hormones. In primary cultures of rat neurocortical cells, various excitatory amino acids stimulate inositol phosphate production with a rank order of potency of quisqualate 〉 ibotenate 〉 glutamate 〉 kainate, N-methyl-d-aspartate 〉 α-amino-3-hydroxyl-5-methyl-4-isoxazole propionate. This response to excitatory amino acids was insensitive to a variety of excitatory amino acid antagonists including 6-cyano-7-nitroquinoxaline-2,3-dione, 3–3(2-carboxypiperazine-4-yl)propyl-l-phosphonate, and 2-amino-4-phosphonobutyrate. The individual responses of quisqualate-, ibotenate-, and kainate-stimulated inositol phosphate production were not additive. These results suggest that phosphoinositide metabolism activated by excitatory amino acids is mediated by a unique quisqualate-preferring receptor that is not antagonized by known N-methyl-d-aspartate and non-N-methyl-d-aspartate antagonists, and is relatively insensitive to α-amino-3-hydroxyl-5-methyl-4-isoxazole propionate.

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