Actions of phenylglycine derivatives at L-AP4 receptors in retinal ON bipolar cells

Actions of phenylglycine derivatives at L-AP4 receptors in retinal ON bipolar cells Phenylglycine derivatives can act as agonists or antagonists at different metabotropic glutamate receptor (mGluR) subtypes, including subtypes sensitive to l -2-amino-4-phosphonobutyric acid (L-AP4). We examined the pharmacology of four phenylglycines at L-AP4 receptors in ON bipolar cells of the amphibian retina in situ . As previously shown for S-4-carboxy-3-hydroxyphenylglycine (S-4C3H-PG) (Thoreson W. B. and Miller R. F., J. Gen. Physiol . 103 , 1019–1034, 1994), whole cell recordings indicate that S -3-carboxy-4hydroxyphenylglycine (S-3C4H-PG) and S-4-carboxyphenylglycine (S-4C-PG) are L-AP4 receptor agonists in retina. Concentration-response curves for these compounds were obtained using the b-wave of the electroretinogram (ERG) as an assay for ON bipolar cell activity. The rank-order potency and IC 50 values obtained were: S-4C-PG (204 μM) > S-4C3H-PG (399 μM) ⩾ S-3C4H-PG (558 μM). At 1 mM, RS - α -methyl4-carboxyphenylglycine (RS-M4C-PG) suppressed the b-wave by less than 20%. This weak effect is attributed to agonist actions of RS-M4C-PG. The agonist actions of phenylglycines in retina are different from their effects at L-AP4 receptors in spinal cord or the expressed L-AP4-sensitive receptor subtype, mGluR4 (Kemp et al, Eur. J. Pharmac. Molec. Pharmac. , 266 , 187–192, 1994; Thomsen et al., Eur. J. Pharmac. Molec. Pharmac. , 267 , 77–84, 1994; Hayashi et al., J. Neurosci. , 14 , 3370–3377, 1994). The results are therefore consistent with the proposal that there are multiple L-AP4-sensitive mGluR sybtypes and indicate that phenylglycine derivatives may be useful for pharmacologically discriminating among these sybtypes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Neuropharmacology Elsevier

Actions of phenylglycine derivatives at L-AP4 receptors in retinal ON bipolar cells

Neuropharmacology, Volume 34 (1) – Jan 1, 1995

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Publisher
Elsevier
Copyright
Copyright © 1995 Elsevier Ltd
ISSN
0028-3908
eISSN
1873-7064
D.O.I.
10.1016/0028-3908(94)00110-E
Publisher site
See Article on Publisher Site

Abstract

Phenylglycine derivatives can act as agonists or antagonists at different metabotropic glutamate receptor (mGluR) subtypes, including subtypes sensitive to l -2-amino-4-phosphonobutyric acid (L-AP4). We examined the pharmacology of four phenylglycines at L-AP4 receptors in ON bipolar cells of the amphibian retina in situ . As previously shown for S-4-carboxy-3-hydroxyphenylglycine (S-4C3H-PG) (Thoreson W. B. and Miller R. F., J. Gen. Physiol . 103 , 1019–1034, 1994), whole cell recordings indicate that S -3-carboxy-4hydroxyphenylglycine (S-3C4H-PG) and S-4-carboxyphenylglycine (S-4C-PG) are L-AP4 receptor agonists in retina. Concentration-response curves for these compounds were obtained using the b-wave of the electroretinogram (ERG) as an assay for ON bipolar cell activity. The rank-order potency and IC 50 values obtained were: S-4C-PG (204 μM) > S-4C3H-PG (399 μM) ⩾ S-3C4H-PG (558 μM). At 1 mM, RS - α -methyl4-carboxyphenylglycine (RS-M4C-PG) suppressed the b-wave by less than 20%. This weak effect is attributed to agonist actions of RS-M4C-PG. The agonist actions of phenylglycines in retina are different from their effects at L-AP4 receptors in spinal cord or the expressed L-AP4-sensitive receptor subtype, mGluR4 (Kemp et al, Eur. J. Pharmac. Molec. Pharmac. , 266 , 187–192, 1994; Thomsen et al., Eur. J. Pharmac. Molec. Pharmac. , 267 , 77–84, 1994; Hayashi et al., J. Neurosci. , 14 , 3370–3377, 1994). The results are therefore consistent with the proposal that there are multiple L-AP4-sensitive mGluR sybtypes and indicate that phenylglycine derivatives may be useful for pharmacologically discriminating among these sybtypes.

Journal

NeuropharmacologyElsevier

Published: Jan 1, 1995

References

  • Mediation of thalamic sensory responses in vivo by ACPD-activated excitatory amino acid receptors
    Eaton, S.A.; Birse, E.F.; Wharton, B.; Sunter, D.C.; Udvarhelyi, P.M.; Watkins, J.C.; Salt, T.E.
  • 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.
  • The ON and OFF channels of the visual system
    Schiller, P.
  • B-wave of the electroretinogram: a reflection of ON bipolar cell activity
    Stockton, R.A.; Slaughter, M.M.
  • 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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