In vitro expression of tyrosine hydroxylase by a subpopulation of rat melanotrophs is down-regulated by dopamine

  • Niquet J
  • Charli J
  • 4


    Mendeley users who have this article in their library.
  • 1


    Citations of this article.


Some rat melanotrophs express in vivo tyrosine hydroxylase mRNA. In this report we show, by Western-blotting, that cultures of adult rat melanotrophs, but not adenohypophyseal cells, express tyrosine hydroxylase. Immunocytochemical analyses confirmed the existence of a subpopulation of melanotrophs expressing tyrosine hydroxylase. Bromocryptine (2.5 x 10-7M), a D2 dopamine agonist, down-regulated melanotroph tyrosine hydroxylase expression in a time-dependent manner; initial effect was detected at 15 h and maximum at 3 days treatment (reduction to about 40% of control values). Down-regulation at 3 days was dose-dependent (ED50around 2 x 10-9M). This decrease was reversed by sulpiride, a D2 dopamine antagonist. The cell number was slightly increased by bromocryptine treatment. These data suggest tyrosine hydroxylase expression in melanotrophs being under tonic inhibitory control by dopamine innervation in vivo. Copyright (C) 2000 Elsevier Science Inc.

Author-supplied keywords

  • Bromocryptine
  • Dopamine
  • Hypophysis
  • Intermediate lobe
  • Melanotroph
  • Tyrosine hydroxylase

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free