title: Effect of the group I metabotropic glutamate agonist DHPG on the visual cortex.
abstract: Metabotropic glutamate receptors have a variety of effects in visual cortex that depend on the age of the animal, the layer of the cortex, and the group of the receptor. Here we describe these effects for group I receptors, using both in vivo and in vitro preparations. The metabotropic group I glutamate receptor agonist 3,5 dihydroxyphenylglycine (DHPG) potentiates the responses to N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) in slices of rat visual cortex. It also increases, initially, the visual response in the cat visual cortex. Both these effects are largest at 3-4 wk of age and decline to insignificance by 10 wk of age. Both are also largest in lower layers of cortex, which explains why the facilitatory effects found with the general metabotropic glutamate agonist 1S,3R aminocyclopentane-1,3-dicarboxylic acid (ACPD) are observed only in lower layers. Prolonged application of DHPG in the cat visual cortex, after the initial excitatory effect, produces depression. We also found that DHPG facilitates the NMDA response in fast-spiking cells, which are inhibitory, providing a partial explanation for this. Thus there are multiple effects of group I metabotropic glutamate receptors, which vary with layer and age in visual cortex.
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: X T
authors.initials: XT
authors.lastname: Jin
authors.forename: C J
authors.initials: CJ
authors.lastname: Beaver
authors.forename: Q
authors.initials: Q
authors.lastname: Ji
authors.forename: N W
authors.initials: NW
authors.lastname: Daw
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000367:Age Factors; D000818:Animals; D002415:Cats; D004357:Drug Synergism; D004594:Electrophysiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D016202:N-Methylaspartate / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010648:Phenylacetates / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000502:physiology; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists* / Q000502:physiology*; D012118:Resorcinols / Q000494:pharmacology*; D014793:Visual Cortex / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: C107349:2-chloro-5-hydroxyphenylglycine; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D010648:Phenylacetates; D018094:Receptors, Metabotropic Glutamate; D012118:Resorcinols; C104077:metabotropic glutamate receptor type 1; C079215:3,5-dihydroxyphenylglycine; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D005998:Glycine