Journal of Neuroscience, Vol 12, 1409-1415, Copyright © 1992 by Society for Neuroscience
Mesencephalic dopaminergic neurons in primary cultures express functional neurotensin receptors
A Brouard, D Pelaprat, C Dana, M Vial, AM Lhiaubet and W Rostene
Institut National de la Sante et de la Recherche Medicale, Unite 339, Hopital Saint Antoine, Paris, France.
The cellular distribution and functional aspects of neurotensin (NT)
binding sites in rat mesencephalic cells in primary culture were
investigated by an original approach combining anatomical and biochemical
studies. Using a double-labeling protocol combining 125I-NT receptor
radioautography and tyrosine hydroxylase (TH) immunocytochemistry, we
obtained the first direct visualization of NT binding sites on
TH-immunoreactive neurons. Eighty percent of the TH neurons were endowed
with NT binding sites, which can be observed on both cell bodies and
processes. TH-immunoreactive neurons were characterized as dopaminergic
neurons by their ability to take up dopamine in a benztropine- and
nomifensine-sensitive manner. In the mesencephalic cultures, NT increased
potassium-evoked release of tritiated dopamine, and the relative potencies
of various NT-related peptides to increase dopamine release were in good
agreement with their abilities to bind to NT sites. These results show for
the first time that cultured rat mesencephalic dopaminergic cells express
functional NT receptors. Finally, the specificity and distribution of NT
receptors on dopaminergic neurons in primary culture are quite similar to
what was observed in the adult rat brain using pharmacological and
radioautographic approaches. These data indicate that NT can influence the
activity of dopaminergic neurons at very early stages of the rat brain
development.