Calretinin is present in serotonin- and gamma-aminobutyric acid-positive amacrine cell populations in the retina of Xenopus laevis.
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.
Gábriel
R
R
Department of General Zoology & Neurobiology and MTA-PTE Adaptational Biology Research Group, University of Pécs, Ifjúság, Hungary. gabriel@ttk.jpte.hu
D000818:Animals; D064032:Calbindin 2; D003712:Dendrites / Q000737:chemistry / Q000201:enzymology; D019084:Fluorescent Antibody Technique, Indirect; D007150:Immunohistochemistry; D009474:Neurons / Q000737:chemistry* / Q000201:enzymology; D012160:Retina / Q000737:chemistry* / Q000166:cytology / Q000201:enzymology; D064030:S100 Calcium Binding Protein G / Q000032:analysis*; D012701:Serotonin / Q000032:analysis / Q000096:biosynthesis*; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000096:biosynthesis*
D064032:Calbindin 2; D064030:S100 Calcium Binding Protein G; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D014365:Tryptophan Hydroxylase