Abstract
Ca2+-permeable AMPARs are inwardly rectifying due to block by intracellular polyamines. Neuronal activity regulates polyamine synthesis, yet whether this affects Ca2+-AMPAR-mediated synaptic transmission is unknown. We test whether 4 hr of increased visual stimulation regulates glutamatergic retino-tectal synapses in Xenopus tadpoles. Tectal neurons containing Ca2+-AMPARs form a gradient along the rostro-caudal developmental axis. These neurons had inwardly rectifying AMPAR-mediated EPSCs. Four hours of visual stimulation or addition of intracellular spermine increased rectification in immature neurons. Polyamine synthesis inhibitors blocked the effect of visual stimulation, suggesting that visual activity regulates AMPARs via the polyamine synthesis pathway. This modulation resulted in changes in the integrative properties of tectal neurons. Regulation of polyamine synthesis by physiological stimuli is a novel form of modulation of synaptic transmission important for understanding the short-term effects of enhanced sensory experience during development.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Biogenic Polyamines / metabolism*
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Biogenic Polyamines / pharmacology
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Calcium Signaling / drug effects
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Calcium Signaling / physiology
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Cell Differentiation / drug effects
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Cell Differentiation / physiology*
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Cell Membrane Permeability / drug effects
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Cell Membrane Permeability / physiology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Glutamic Acid / metabolism*
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Ion Channels / drug effects
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Ion Channels / metabolism
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Larva
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Photic Stimulation
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Presynaptic Terminals / metabolism*
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Presynaptic Terminals / ultrastructure
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Receptors, AMPA / drug effects
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Receptors, AMPA / metabolism
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Receptors, N-Methyl-D-Aspartate / drug effects
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Receptors, N-Methyl-D-Aspartate / metabolism
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Retina / cytology
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Retina / growth & development*
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Retina / metabolism
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Spermine / metabolism
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Spermine / pharmacology
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Superior Colliculi / cytology
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Superior Colliculi / growth & development*
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Superior Colliculi / metabolism
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Visual Pathways / cytology
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Visual Pathways / growth & development*
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Visual Pathways / metabolism
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Xenopus laevis
Substances
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Biogenic Polyamines
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Excitatory Amino Acid Antagonists
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Ion Channels
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Receptors, AMPA
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Receptors, N-Methyl-D-Aspartate
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Spermine
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Glutamic Acid