Thyrotropin and Gonadotropin Releasing Hormones (Trh and Gnrh) do not Alter Levels of Oxytocin and Oxytocin Does not Change the Response of Luteinizing or Follicle Stimulating Hormones to Gnrh in Humans

Four hundred üg of synthetic thyrotropin releasing hormone (TRH) were given intravenously to 4 normal men and 4 normal women, and four weeks later, 1000 üg of TRH were administered intravenously to 4 of the 8 individuals and oxytocin (OT) was measured in plasma on both occasions. Following injection of either dose of TRH, OT did not change significantly from baseline. Likewise, synthetic gonadotropin releasing hormone (GnRH), 100 üg, administered intravenously to 6 normal men did not alter the levels of OT from baseline. Synthetic OT, 300 mU/minute, administered 30 minutes before and for 90 minutes after injection of GnRH, was without effect on the GnRH-induced rise of luteinizing hormone (LH) or follicle stimulating hormone (FSH) in normal men. We conclude that continuous infusion of OT in pharmacologic concentrations does not alter the pituitary release of LH or FSH in response to GnRH in humans. TRH and GnRH given intravenously do not alter basal levels of OT in the plasma of humans, thus a physiologic role for GnRH or TRH in the neuroendocrine control of OT secretion in humans is unlikely.