Immunocytochemical analysis of GABA-positive and calretinin-positive horizontal cells in the tiger salamander retina

Jian Zhang, Ai Jun Zhang, Samuel M. Wu

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

By using immunocytochemical techniques, we demonstrate that there are two distinct, nonoverlapping populations of horizontal cells (HCs) in the tiger salamander retina: GABA-positive cells account for about 72% and GABA-negative (calretinin-positive) cells account for 28% of the total HC somas. The calretinin-positive HCs have relatively sparse and thick dendrites: soma diameter of 19.72 ± 0.29 μm, and soma density of 140 ± 13 cells/mm2, morphological features very much like the A-type HCs described in the accompanying article. The GABA-positive HCs have thinner dendritic and coarse axon-terminal-like processes of higher density: soma diameter of 18 ± 0.18 μm, and soma density of 364 ± 18 cells/mm2, features that very much resemble the B-type HCs and B-type HC axon terminals in the accompanying article. By using double and triple immunostaining techniques we found that only 18% of the non-GABAergic HC dendritic clusters contact rods, whereas the remaining 82% of the dendritic clusters contact cones. This is consistent with the physiological finding in the accompanying article that the A-type HCs are cone-dominated. On the other hand, 32% of GABAergic HC dendrites contact rod pedicles and 68% contact cone pedicles, consistent with the physiological finding that B-type HCs and B-type HC axon terminals receive mixed rod/cone inputs. Detailed confocal microscope analysis shows that 4% rods, 6% principal double cones/single cones, and 100% accessory double cones contact calretinin-positive HCs, and 79% rods, 100% principal double cones, 14% accessory double cones, and 82% single cones contact GABAergic HCs. These results suggest that GABAergic and non-GABAergic HC input/output synapses differ and they may mediate different functional pathways in the outer retina.

Original languageEnglish (US)
Pages (from-to)432-441
Number of pages10
JournalJournal of Comparative Neurology
Volume499
Issue number3
DOIs
StatePublished - Nov 20 2006

Keywords

  • Amphibian retina
  • Axon terminals
  • Calretinin
  • Dendrites
  • GABA
  • Horizontal cells
  • Receptive fields
  • Rods and cones

ASJC Scopus subject areas

  • Neuroscience(all)

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