Triiodothyronine enhances the morphological maturation of dopaminergic neurons from fetal mouse hypothalamus cultured in serum-free medium.
In dissociated hypothalamic cell cultures of 16-day mouse embryos, growing in chemically defined medium, the catecholaminergic neurons were identified by autoradiography after labelling with [3H]dopamine and by immunocytochemistry with an anti-tyrosine hydroxylase antibody. Using selective inhibitors of amine transport and radioenzymatic determination of amine levels in these cultures, we show that these neurons were mostly dopaminergic. The number of dopaminergic neurons identified by the two techniques increased between days 5 and 8 and decreased after 15 days in vitro. The same number of neurons were identified by autoradiography and by immunocytochemistry and consisted of fusiform and multipolar neurons. The proportion of both types remained steady until 15 days in vitro. Under these conditions, the addition of triiodothyronine (10(-9) M) at the initiation of the culture increased the size but not the number of dopaminergic neurons after 8 days in vitro. Furthermore, triiodothyronine significantly increased the dopaminergic neurite length and arborization. This morphological effect of triiodothyronine was associated with an increase of 35% in [3H]dopamine uptake. Our study shows that hypothalamic dopaminergic neurons are responsive to triiodothyronine which acts as a maintenance or trophic factor having an effect on neurite extension and arborization.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D004298:Dopamine / Q000502:physiology*; D007031:Hypothalamus / Q000166:cytology / Q000196:embryology*; D051379:Mice / Q000196:embryology; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D014284:Triiodothyronine / Q000494:pharmacology*
D003470:Culture Media; D014284:Triiodothyronine; D004298:Dopamine