title: Co-localization of serotonin and GABA in neurons of the Xenopus laevis retina.
abstract: Serotonin-synthesizing neurons in the retina of Xenopus laevis have been identified using anti-phenylalanine hydroxylase (PH) antibody which recognizes tryptophan 5-hydroxylase, the rate-limiting enzyme for serotonin synthesis. Double-labelling experiments, using anti-PH antibody and anti-serotonin antibody/5,7-dihydroxytryptamine (5,7-DHT) uptake, have shown that some serotonin-like immunoreactive/5,7-DHT-labelled neurons exhibit PH-like immunoreactivity (PH-LI) (serotonin-synthesizing neurons), but the others do not (serotonin-accumulating neurons). In the present study, triple-labelling experiments were performed using 5,7-DHT uptake and antibodies raised against GABA and PH, to determine the possible co-localization of y-aminobutyric acid (GABA) in serotonin-synthesizing and/or -accumulating neurons in the Xenopus retina. All 5,7-DHT-labelled bipolar cells lacked PH-LI; all of them were immunoreactive to GABA. In contrast, all 5,7-DHT-labelled large amacrine cells exhibited PH-LI, but none of them expressed GABA-LI. Small amacrine cells labelled with 5,7-DHT but not PH-LI exhibited GABA-LI, whilst the small amacrine cells with PH-LI lacked GABA-LI. These observations indicate that GABA is co-localized in serotonin-accumulating amacrine and bipolar cells, whereas serotonin-synthesizing large and small amacrine cells do not contain GABA-LI.
authors.affiliation: Department of Anatomy and Histology, School of Medicine, Flinders University of South Australia, Adelaide.
authors.forename: B S
authors.initials: BS
authors.lastname: Zhu
authors.forename: C
authors.initials: C
authors.lastname: Straznicky
mesh_terms: D015116:5,7-Dihydroxytryptamine; D000818:Animals; D000906:Antibodies / Q000276:immunology; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000378:metabolism*; D010651:Phenylalanine Hydroxylase / Q000276:immunology; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D014018:Tissue Distribution; D014982:Xenopus laevis / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D010651:Phenylalanine Hydroxylase