Contour of the GnRH pulse independently modulates gonadotropin secretion in the human male


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Contour of the GnRH pulse independently modulates gonadotropin secretion in the human male
Pralong  F. P., Boepple  P. A., Conn  P. M., Whitcomb  R. W., Butler  J. P., Schoenfeld  D., Crowley, W. F., Jr. 
0028-3835 (Print)
Statut éditorial
Date de publication
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S. --- Old month value: Sep
GnRH pulse frequency, amplitude, and interpulse interval have all been demonstrated to regulate gonadotropin secretion individually. We tested the hypothesis that the contour of the GnRH pulse also modulates gonadotropin output in 10 men with isolated GnRH deficiency in whom a fixed GnRH dose was administered at a constant physiologic frequency by either instantaneous bolus or by 1-, 5-, or 30-min infusions. LH, FSH and free alpha subunit (FAS) responses were also compared to spontaneous gonadotropin secretion in normal adult men. While the LH and FAS pulses following the instantaneous bolus and 1-min infusion of GnRH were indistinguishable, further increases in the duration of gonadotrope stimulation by GnRH were associated with progressive decreases in all parameters of gonadotropin secretion (mean levels, amplitude, peak levels, AUC). FSH secretion was also decreased following variations in the contour of the GnRH pulse, although overall changes were less dramatic than for LH and FAS. The LH pulses following the bolus GnRH stimulation were indistinguishable from spontaneous LH pulses occurring in normal men whereas those stimulated by the 1-, 5-, and 30-min infusions of GnRH became progressively blunted with the lowest levels of secretion occurring after the longest infusion. In sharp contrast, FAS pulse parameters in the GnRH-deficient subjects greatly exceeded those of normal men regardless of the contour of the GnRH stimulus, whereas mean FSH levels were all modestly (although significantly) higher than those of normal adult men. These results demonstrate that the pituitary is sensitive to subtle changes in the contour of the GnRH stimulus, with a more prolonged duration of GnRH stimulation resulting in a diminished pituitary response. Alterations of the contour of endogenous GnRH secretion may represent an additional mechanism for altering gonadotrope function and provide additional evidence for the differential regulation of LH, FAS, and FSH by GnRH. However, the previously reported elevated levels of FAS secretion in GnRH-deficient men undergoing long-term GnRH replacement are not explained by abnormalities of GnRH contour.
Adult Case-Control Studies Drug Administration Schedule Follicle Stimulating Hormone/*secretion Gonadotropin-Releasing Hormone/deficiency/*pharmacology Humans Infusions, Intravenous Luteinizing Hormone/*secretion Male Secretory Rate/drug effects Statistics Stimulation, Chemical
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Création de la notice
25/01/2008 16:26
Dernière modification de la notice
20/08/2019 12:24
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