Dopamine infusion acutely inhibits the TSH and prolactin response to TRH.

Ten normal males were given 100 mug TRH, and blood samples obtained for serum TSH and serum prolactin. After a period of at least one week, the TRH test was repeated while the patients were receiving a dopamine infusion. Both the TSH and prolactin response to TRH were inhibited by dopamine. Dopaminergic neurons may act through the pituitary-portal system to play a role in the regulation of TSH and prolactin secretion.