title: The emergence, localization, and maturation of neurotransmitter systems during development of the retina in Xenopus laevis. III. Dopamine.
abstract: The uptake, synthesis, and release of dopamine was studied in retinas of Xenopus laevis. In the tadpole and adult retina, 3H-dopamine is accumulated by cells located in the inner nuclear layer. Retinas preloaded with 3H-dopamine release this compound in response to high K+ concentrations in the medium. This release is probably Ca++-dependent as it is inhibited by Co++ in the medium. Adult retinas are also capable of synthesizing 3H-dopamine from 3H-tyrosine. The appearance and maturation of these dopaminergic properties were followed during retinal development. Our data indicate that synthesis of dopamine can first be detected as early as stage 35/36 whereas uptake of dopamine first occurs at stage 43. K+-stimulated release of preloaded 3H-dopamine from putative dopaminergic neurons is, however, not evident until stage 46. These results show that similar to the development of GABA-ergic and glycinergic properties, the uptake, synthesis, and release mechanisms for dopamine emerge at different stages during retinal differentiation in Xenopus Laevis.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D002118:Calcium / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism; D007814:Larva; D011188:Potassium / Q000494:pharmacology; D012160:Retina / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D009435:Synaptic Transmission; D014982:Xenopus laevis / Q000254:growth & development*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium; D005998:Glycine; D004298:Dopamine