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Dopaminergic retinal cell differentiation in culture: modulation by forskolin and dopamine

Authors

  • Marília Zaluar P. Guimarães,

    1. Programa de Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, CCS Bl-G Universidade Federal do Rio de Janeiro, 21949–900, Brazil
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  • Jan Nora Hokoç,

    1. Programa de Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, CCS Bl-G Universidade Federal do Rio de Janeiro, 21949–900, Brazil
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  • Robert Duvoisin,

    1. The Margaret M. Dyson Vision Institute, Cornell Medical School, 1300 York Avenue, New York, 10021, USA
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  • Ricardo A. M. Reis,

    1. Programa de Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, CCS Bl-G Universidade Federal do Rio de Janeiro, 21949–900, Brazil
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  • Fernando Garcia De Mello

    1. Programa de Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, CCS Bl-G Universidade Federal do Rio de Janeiro, 21949–900, Brazil
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: Dr Jan Nora Hokoç, as above.
E-mail: jnora@biof.ufrj.br

Abstract

We examined the effects of dopamine and cAMP on the differentiation of dopaminergic retinal cells in the chick retina, using an in vitro system and tyrosine hydroxylase immunocytochemistry. Tyrosine hydroxylase-positive cells were detected in cultures prepared from embryonic day 10 retinas. These increased in number as a function of time in vitro and by treatment for 4 days with forskolin. Besides causing a 3.4-fold increase in the tyrosine hydroxylase-positive population, forskolin also caused these cells to developed morphogenetic features of more mature cells. As opposed to forskolin, cultures treated with dopamine exhibited a 55% reduction of the tyrosine hydroxylase-positive cell population, as compared to untreated cultures. Quinpirole was able to mimic the dopamine effect. This dopamine effect could only be blocked by clozapine, whereas raclopride and eticlopride were ineffective. Our results suggest the existence of a narrow window during development when undifferentiated dopaminergic cells are capable of being influenced by specific signals, possibly via cAMP production. The data also indicate that dopamine may act as a regulatory factor limiting the tyrosine hydroxylase-positive population in the retina.

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