Synaptic ribbons influence the size and frequency of miniature-like evoked postsynaptic currents

Neuron. 2013 Feb 6;77(3):516-27. doi: 10.1016/j.neuron.2012.11.024.

Abstract

Nonspiking cells of several sensory systems respond to stimuli with graded changes in neurotransmitter release and possess specialized synaptic ribbons. Here, we show that manipulations to synaptic ribbons caused dramatic effects on mEPSC-like (mlEPSC) amplitude and frequency. Damage to rod-bipolar cell ribbons using fluorophore-assisted light inactivation resulted in the immediate reduction of mlEPSC amplitude and frequency, whereas the first evoked response after damage remained largely intact. The reduction in amplitude could not be recovered by increasing release frequency after ribbon damage. In parallel experiments, we looked at mlEPSCs from cones of hibernating ground squirrels, which exhibit dramatically smaller ribbons than awake animals. Fewer and smaller mlEPSCs were observed postsynaptic to cones from hibernating animals, although depolarized cones were able to generate larger mlEPSCs. Our results indicate that ribbon size may influence mlEPSC frequency and support a role for ribbons in coordinating multivesicular release.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Alcohol Oxidoreductases
  • Aminobutyrates / pharmacology
  • Animals
  • Biophysics
  • Co-Repressor Proteins
  • DNA-Binding Proteins / metabolism
  • Dose-Response Relationship, Drug
  • Electric Stimulation
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology*
  • GABA Antagonists / pharmacology
  • Glycine Agents / pharmacology
  • Hibernation / physiology
  • In Vitro Techniques
  • Mice
  • Mice, Inbred C57BL
  • Patch-Clamp Techniques
  • Phosphinic Acids / pharmacology
  • Phosphoproteins / metabolism
  • Picrotoxin / pharmacology
  • Pyridines / pharmacology
  • Receptors, AMPA / metabolism
  • Retina / cytology*
  • Retina / metabolism
  • Sciuridae
  • Strychnine / pharmacology
  • Synapses / drug effects
  • Synapses / physiology*
  • Visual Pathways / physiology
  • Wakefulness / physiology

Substances

  • (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid
  • Aminobutyrates
  • Co-Repressor Proteins
  • DNA-Binding Proteins
  • Excitatory Amino Acid Agonists
  • GABA Antagonists
  • Glycine Agents
  • Phosphinic Acids
  • Phosphoproteins
  • Pyridines
  • Receptors, AMPA
  • glutamate receptor ionotropic, AMPA 4
  • Picrotoxin
  • Alcohol Oxidoreductases
  • Ctbp2 protein, mouse
  • 2-amino-4-phosphonobutyric acid
  • Strychnine