Dopamine receptor blockade induced by metoclopramide and thyroid-stimulating hormone secretion in man.

20 mg metoclopramide, intramuscularly administered to 10 healthy males and 10 healthy females, induced a significant increase in serum thyroid-stimulating hormone values in female subjects only. This finding suggests that dopamine does not play a major role in the regulation of thyroid-stimulating hormone secretion and that estrogens can act in the modulation of dopamine effects at the hypothalamic and/or pituitary level.