Inability to demonstrate an ultrashort loop feedback mechanism for luteinizing hormone in humans

The Journal of Clinical Endocrinology and Metabolism
C V KyleW D Odell

Abstract

hCG has biological properties similar to those of LH, but can be measured separately from LH by current radioimmunometric assays. To investigate the possible existence of an autoregulatory mechanism for LH in humans, we compared the basal LH concentrations and the LH response to a GnRH stimulus with and without prior administration of hCG. On two separate occasions, at least 1 week apart, six normal (eugonadal) males and six normal postmenopausal females were given, in random order, either 10,000 IU hCG or saline followed by iv injection of a 200-micrograms bolus of GnRH. Blood samples were then taken 30, 60, 90, 120, 180, 240, and 300 min after GnRH. Serum concentrations of LH and hCG were measured at each time by two monoclonal antibody sandwich assays developed in our laboratory. After exogenous hCG, serum hCG concentrations rose rapidly to 200-500 IU/L (15,000-35,000 pg/mL) in both the men and women, remaining at this high level throughout the study. In the men, sex steroid concentrations did not change in response to the hCG during the 9 study hours. Compared to saline-treated controls, hCG had no significant effect in either men or postmenopausal women on the basal LH concentration or the response to a GnRH bolus, as dete...Continue Reading

Citations

Sep 13, 2003·Fertility and Sterility·Asimina Tavaniotou, Paul Devroey
Oct 6, 2005·Reproductive Biology and Endocrinology : RB&E·Mohamed F M MitwallyMichael P Diamond
Feb 27, 2013·Nature Reviews. Endocrinology·Johannes D Veldhuis
Mar 12, 2010·European Journal of Obstetrics, Gynecology, and Reproductive Biology·Dimitra KyrouPaul Devroey

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