Calretinin Is Present in Serotonin- And Gamma-Aminobutyric Acid-Positive Amacrine Cell Populations in the Retina of Xenopus Laevis

Neurosci Lett. 2000 May 5;285(1):9-12. doi: 10.1016/s0304-3940(00)01005-3.


In the frog retina most bipolar cells, sparsely distributed amacrine cells and some ganglion cells contain calretinin (CaR). Double-label immunocytochemistry shows that in the Xenopus retina many calretinin positive amacrine cells are also gamma-aminobutyric acid (GABA)-immunoreactive (IR), none colocalizes glycine or dopamine but some contain serotonin (SER). The CaR-IR cells represent 8-9% of all GABA-IR amacrine cells. Only 4.6% of the CaR-positive cells contain SER. The SER-positive cells are present in two sizes in the anuran retina: the large cells never contain CaR but some of the small cells do. To further characterize the CaR+/SER+ amacrine cell population, immunolabeling for tryptophan hydroxylase (TrOH), the rate-limiting enzyme for SER synthesis, was performed. The results showed that large TrOH-containing cells are always negative for CaR. However, the small SER-synthesizing amacrine cells are invariably CaR-positive. Thus the anuran retina contains three neurochemically distinct SER-positive amacrine cell types, one of which (the small SER-synthesizing cell type) is also CaR-IR.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calbindin 2
  • Dendrites / chemistry
  • Dendrites / enzymology
  • Fluorescent Antibody Technique, Indirect
  • Immunohistochemistry
  • Neurons / chemistry*
  • Neurons / enzymology
  • Retina / chemistry*
  • Retina / cytology
  • Retina / enzymology
  • S100 Calcium Binding Protein G / analysis*
  • Serotonin / analysis
  • Serotonin / biosynthesis*
  • Tryptophan Hydroxylase / metabolism
  • Xenopus laevis
  • gamma-Aminobutyric Acid / analysis
  • gamma-Aminobutyric Acid / biosynthesis*


  • Calbindin 2
  • S100 Calcium Binding Protein G
  • Serotonin
  • gamma-Aminobutyric Acid
  • Tryptophan Hydroxylase