Effect of dexamethasone on prolactin and TSH responses to TRH and metoclopramide in man.
We studied the effects of administration of dexamethasone, 2 mg orally every 6 h, for 5 days on the thyrotropin-releasing hormone (TRH)-induced release of prolactin (PRL), thyrotropin (TSH), triiodothyronine (T3) and thyroxine (T4) in 9 normal men and on the metoclopramide-induced release of PRL in 7 normal men. Dexamethasone suppressed the baseline serum levels of PRL, TSH and T3. The administration of dexamethasone blunted the PRL and TSH response to TRH; the blunted TSH response resulted in a decreased T3 and T4 response to TRH after dexamethasone. Following dexamethasone administration, the PRL response to metoclopramide, a dopamine antagonist which acts at the hypothalamicpituitary level to stimulate PRL secretion, was blunted in 7 normal men. The data suggest that short-term administration of pharmacological doses of glucocorticoids suppress the secretion of PRL and TSH by a direct effect on the anterior pituitary gland.
D000328:Adult; D003907:Dexamethasone; D006801:Humans; D007700:Kinetics; D008297:Male; D008787:Metoclopramide; D008875:Middle Aged; D011388:Prolactin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D003907:Dexamethasone; D011388:Prolactin; D013972:Thyrotropin; D008787:Metoclopramide; D013974:Thyroxine