Effects of Excitatory Amino Acids on Phosphoinositide Metabolism in Frog Retina

Effects of Excitatory Amino Acids on Phosphoinositide Metabolism in Frog Retina The effects of excitatory amino acid receptor agonists on the hydrolysis of phosphoinositides were examined using frog retinal membranes prelabeled in vitro with either 32 PO 4 or ( 3 H)inositol. Glutamate stimulated release of ( 3 H)inositol phosphates (IPs) from the retinas and altered the 32 P-labeling pattern of phosphatidylinositol (PI) cycle intermediates. This indicates that glutamate affects not only the hydrolysis of phosphoinositides but possibly other steps involved in the PI cycle. Among glutamate analogs, kainate (KA), quisqualate (QA), and, to a lesser extent, N -methyl- d -aspartate (NMDA) mimicked the glutamate effect, whereas l -2-amino-4-phosphonobutyrate ( l -AP4) was not effective in causing either the accumulation of ( 3 H)IPs or the alteration of the 32 P-labeling pattern of PI cycle intermediates. Among QA specific agonists, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), but not ibotenate (IBO) or trans -1-aminocyclopentane-1,3-dicarboxylate (ACPD) was active in stimulating IPs formation. KA effect on IPs formation may be due to indirect (polysynaptic) activation of receptor(s) other than l -AP4, IBO, or ACPD specific QA receptors. To avoid activating polysynaptic pathways, retinal synaptoneurosomes prelabeled with ( 3 H)inositol were used to examine the hydrolysis of phosphoinositides. As in whole retinas, KA, carbachol (CARB), and NMDA stimulated the release of IPs while l -AP4 had minimal effect. Glycine (GLY) had no effect. Our results show CARB and KA to be the most effective in stimulating the production of IPs. Their effects were exerted directly through separate receptors and not through polysynaptic pathways. ACPD and IBO were the least effective in eliciting the release of IPs. Our studies provide evidence that ionotropic and not metabotropic glutamate receptors are involved in PI metabolism in the retina. Copyright © 1996 Elsevier Science Ltd. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Vision Research Elsevier

Effects of Excitatory Amino Acids on Phosphoinositide Metabolism in Frog Retina

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Publisher
Elsevier
Copyright
Copyright © 1996 Elsevier Science Ltd
ISSN
0042-6989
eISSN
1878-5646
D.O.I.
10.1016/0042-6989(95)00273-1
Publisher site
See Article on Publisher Site

Abstract

The effects of excitatory amino acid receptor agonists on the hydrolysis of phosphoinositides were examined using frog retinal membranes prelabeled in vitro with either 32 PO 4 or ( 3 H)inositol. Glutamate stimulated release of ( 3 H)inositol phosphates (IPs) from the retinas and altered the 32 P-labeling pattern of phosphatidylinositol (PI) cycle intermediates. This indicates that glutamate affects not only the hydrolysis of phosphoinositides but possibly other steps involved in the PI cycle. Among glutamate analogs, kainate (KA), quisqualate (QA), and, to a lesser extent, N -methyl- d -aspartate (NMDA) mimicked the glutamate effect, whereas l -2-amino-4-phosphonobutyrate ( l -AP4) was not effective in causing either the accumulation of ( 3 H)IPs or the alteration of the 32 P-labeling pattern of PI cycle intermediates. Among QA specific agonists, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), but not ibotenate (IBO) or trans -1-aminocyclopentane-1,3-dicarboxylate (ACPD) was active in stimulating IPs formation. KA effect on IPs formation may be due to indirect (polysynaptic) activation of receptor(s) other than l -AP4, IBO, or ACPD specific QA receptors. To avoid activating polysynaptic pathways, retinal synaptoneurosomes prelabeled with ( 3 H)inositol were used to examine the hydrolysis of phosphoinositides. As in whole retinas, KA, carbachol (CARB), and NMDA stimulated the release of IPs while l -AP4 had minimal effect. Glycine (GLY) had no effect. Our results show CARB and KA to be the most effective in stimulating the production of IPs. Their effects were exerted directly through separate receptors and not through polysynaptic pathways. ACPD and IBO were the least effective in eliciting the release of IPs. Our studies provide evidence that ionotropic and not metabotropic glutamate receptors are involved in PI metabolism in the retina. Copyright © 1996 Elsevier Science Ltd.

Journal

Vision ResearchElsevier

Published: Jul 1, 1996

References

  • Inositol incorporation into phosphoinositides in retinal horizontal cells of Xenopus laevis : Enhancement by acetylcholine, inhibition by glycine
    Anderson, R.E; Hollyfield, J.G
  • Rhodopsin in the rod outer segment plasma membrane
    Basinger, S.F; Bok, D; Hall, M.O
  • Photoreceptor bipolar cell transmission in the mudpuppy retina
    Dacheux, R.F; Miller, R.F
  • Physiological and morphological identification of horizontal, bipolar, and amacrine cells in goldfish retina
    Kaneko, A
  • The excitatory amino acid receptors: Their classes, pharmacology, and distinct properties in the function of the central nervous system
    Monaghan, D.T; Bridges, R.J; Cotman, C.W
  • Coupling of inositol phospholipid metabolism with excitatory amino acid recognition sites in rat hippocampus
    Nicoletti, F; Meek, J.L; Iadarola, M.J; Chuang, D.M; Roth, B.L; Costa, E
  • Excitatory amino acid agonist-antagonist interactions at 2-amino-4-phosphonobutyric acid-sensitive quisqualate receptors coupled to phosphoinositide hydrolysis in slices of rat hippocampus
    Schoepp, D.D; Johnson, B.G
  • Comparison of excitatory amino acid-stimulated phosphoinositide hydrolysis and N -( 3 H)acetylaspartylglutamate binding in rat brain: Selective inhibition of phosphoinositide hydrolysis by 2-amino-3-phosphonopropionate
    Schoepp, D.D; Johnson, B.G
  • Inhibition of cyclic AMP formation by a selective metabotropic glutamate receptor agonist
    Schoepp, D.D; Johnson, B.G; Monn, J.A
  • Membrane currents evoked by excitatory amino acid agonists in ON bipolar cells of the mudpuppy retina
    Thoreson, W.B; Miller, R.F

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