Morphology and connectivity of the small bistratified A8 amacrine cell in the mouse retina

J Comp Neurol. 2015 Jul 1;523(10):1529-47. doi: 10.1002/cne.23752. Epub 2015 Mar 10.


Amacrine cells comprise ∼ 30 morphological types in the mammalian retina. The synaptic connectivity and function of a few γ-aminobutyric acid (GABA)ergic wide-field amacrine cells have recently been studied; however, with the exception of the rod pathway-specific AII amacrine cell, the connectivity of glycinergic small-field amacrine cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 amacrine cell. A8 cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 cells to bipolar cells and ganglion cells was studied by double and triple immunolabeling experiments by using various cell markers combined with synaptic markers. Our data suggest that A8 amacrine cells receive glutamatergic input from both OFF and ON cone bipolar cells. Furthermore, A8 cells are coupled to ON cone bipolar cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar cells and to ON A-type ganglion cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 cells express GlyRs containing the α2 subunit. The results show that the bistratified A8 cell makes very similar synaptic contacts with cone bipolar cells as the rod pathway-specific AII amacrine cell. However, unlike AII cells, A8 amacrine cells provide glycinergic input to ON A-type ganglion cells.

Keywords: AB_10013783; AB_11213019; AB_11214044; AB_2034062; AB_2086768; AB_2110230; AB_2278934; AB_2314912; AB_399431; AB_477345; AB_673015; RRIDs: AB_10058149; crossover inhibition; gap junction; glycine receptor; glycinergic; retinal circuitry; small-field amacrine cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Oxidoreductases
  • Amacrine Cells / cytology*
  • Amacrine Cells / metabolism
  • Animals
  • Co-Repressor Proteins
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Developmental / genetics
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Immediate-Early Proteins / genetics
  • Immediate-Early Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Nerve Net / cytology
  • Nerve Net / physiology*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Receptors, Glycine / genetics
  • Receptors, Glycine / metabolism
  • Retina / cytology*
  • Transcription Factors
  • Transducin / genetics
  • Transducin / metabolism
  • Vesicular Glutamate Transport Protein 1 / genetics
  • Vesicular Glutamate Transport Protein 1 / metabolism
  • Visual Pathways / physiology


  • Co-Repressor Proteins
  • DNA-Binding Proteins
  • Ier5 protein, mouse
  • Immediate-Early Proteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • Receptors, Glycine
  • Transcription Factors
  • Vesicular Glutamate Transport Protein 1
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • gustducin
  • Alcohol Oxidoreductases
  • Ctbp2 protein, mouse
  • Transducin