title: L-DOPA supply to the neuro retina activates dopaminergic communication at the early stages of embryonic development.
abstract: DOPA decarboxylase (DDC; aromatic-l-amino acid decarboxylase; EC 4.1.1.28) is absent in retinas from 6-day-old chicken embryos (E6) but is expressed in retina of E8 embryos, in the presumptive outer plexiform layer. Thereafter, DDC appears in cell bodies of presumptive amacrine cells. The dopamine (DA) content of E9/10 and E15/16 retinas, pre-incubated with l-DOPA for 1 h, increased 250- and 600-fold, respectively, showing that DDC is active since early in development. Intercellular communication, measured by endogenous cyclic AMP accumulation, was observed when retinas from E9/10 to E15/16 were pre-incubated for 1 h with 1 mm l-DOPA, washed and followed by incubation in the presence of 0.5 mm 3-isobutyl-1-methylxanthine, a phosphodiesterase inhibitor. Cyclic AMP accumulation was prevented when pre-incubation with l-DOPA was carried out in the presence of carbidopa. Moreover, the accumulation of cyclic AMP was inhibited by SCH 23390 (2 micro m). The incubation of retinas in medium previously conditioned by retina-pigmented epithelium (RPE) also increased its cyclic AMP content with the characteristics described for l-DOPA. Our results show that dopaminergic communication takes place in the embryonic retina, before tyrosine hydroxylase expression, provided l-DOPA is supplied to the tissue. It also shows that RPE is a potential source of l-DOPA early in development.
authors.affiliation: Departamento de Fisiologia e Farmacologia, UFF, CCM, Niterói, Brazil.
authors.forename: Regina C C
authors.initials: RC
authors.lastname: Kubrusly
authors.forename: Marília Zaluar P
authors.initials: MZ
authors.lastname: Guimarães
authors.forename: Ana Paula B
authors.initials: AP
authors.lastname: Vieira
authors.forename: Jan N
authors.initials: JN
authors.lastname: Hokoç
authors.forename: Dulce E
authors.initials: DE
authors.lastname: Casarini
authors.forename: Maria C F
authors.initials: MC
authors.lastname: de Mello
authors.forename: Fernando G
authors.initials: FG
authors.lastname: de Mello
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D002642:Chick Embryo; D004296:Dopa Decarboxylase / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000378:metabolism / Q000494:pharmacology; D007150:Immunohistochemistry; D007980:Levodopa / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis
chemical_list: D015259:Dopamine Agents; D007980:Levodopa; D014446:Tyrosine 3-Monooxygenase; D004296:Dopa Decarboxylase; D004298:Dopamine