Abstract
(1) This study investigates further the locus of action of dopamine (DA) and DA antagonists in affecting growth hormone (GH) and prolactin (PRL) secretion in normal subjects. (2) Each of three normal men was tested twice with a continuous DA infusion (0.3 mg/min) over 90 min. (3) Mean plasma GH concentration was significantly ( p < 0.05) elevated above baseline at 30 min after onset of DA infusion. (4) The same subjects were also tested twice with the identical dose of a DA infusion after a single neuroleptic drug had been given i.v. 30 min earlier. This pretreatment with an antidopaminergic drug resulted in a significant delay and attenuation of the GH response to DA. (5) The elevated plasma PRL concentration induced by the neuroleptic was suppressed to baseline within 60 min after onset of the DA infusion. (6) Since DA does not cross the blood brain barrier (BBB) these findings indicate that GH secretion can be affected in normal men by dopaminergic mechanisms operating outside the BBB.
Published Version
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