Effects of acute hyperprolactinemia on LH pulsatile secretion in hypogonadal and early follicular phase women.
To investigate the effects of acute hyperprolactinemia on the 24 h LH pulsatile pattern, 11 women in the early follicular phase (EF, days 3 and 4) and 8 postmenopausal women (PMW) were studied before and during administration of metoclopramide, a dopamine receptor antagonist. Sequential 24 h infusions of either metoclopramide (MCP, 30 micrograms/kg/h) or normal saline were conducted and pulsatile LH activity assessed for 48 hrs. In both EF women and PMW, a prompt (within 90 min, p less than 0.001) and sustained (greater than 45 micrograms/L, p less than 0.001) release of PRL was induced by MCP infusions. MCP-induced hyperprolactinemia failed to modify the LH pulsatile activity in both EF women and PMW. These observations suggest that acute hyperprolactinemia due to dopaminergic blockade has no discernible effect on LH pulsatility and that the reduced LH pulse frequency observed in association with endogenous hyperprolactinemia may result from different neuroendocrine mechanism(s) and/or is time dependent.
Rossmanith
W G
WG
Department of Reproductive Medicine, School of Medicine, University of California, San Diego, La Jolla 92093.
Mortola
J F
JF
Yen
S S
SS
D000328:Adult; D000465:Algorithms; D005260:Female; D005498:Follicular Phase; D006801:Humans; D006966:Hyperprolactinemia / Q000097:blood* / Q000139:chemically induced; D007986:Luteinizing Hormone / Q000378:metabolism*; D008593:Menopause / Q000097:blood*; D008787:Metoclopramide / Q000494:pharmacology*; D008875:Middle Aged; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology; D012890:Sleep / Q000502:physiology
D011954:Receptors, Dopamine; D007986:Luteinizing Hormone; D008787:Metoclopramide