title: Carbidopa plus L-dopa pretreatment inhibits the prolactin (PRL) response to thyrotropin-releasing hormone and thus cannot distinguish central from pituitary sites of prolactin stimulation.
abstract: Contrary to a previous report, pretreatment of normal men with carbidopa plus L-dopa (Sinemet 25/250) markedly inhibited the PRL response to TRH, a stimulus that acts directly on the pituitary. Thus, the results of carbidopa/L-dopa testing cannot be used to determine whether agents that stimulate PRL secretion act on the pituitary or at a higher central nervous system level.
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002230:Carbidopa / Q000494:pharmacology*; D004338:Drug Combinations / Q000494:pharmacology; D006801:Humans; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone
chemical_list: D004338:Drug Combinations; C009265:carbidopa, levodopa drug combination; D007980:Levodopa; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D002230:Carbidopa