The Metabolic Serum Clearance of GnRH. Relationship to Age, Sex and Male Puberty

Summary

The MCR of constantly infused synthetic GnRH (1.53 μg/min) was studied in relation to age, sex, and male sexual maturation. GnRH was determined by a radioimmunoassay using a specific GnRH antiserum and ¹²⁵GnRH, prepared by the chloramine T technique and purified on Sephadex G 25. Serum LH and FSH were measured by RIA. The results (mean values ± SEM) of MCR expressed here as ml/min/1.86 m² showed a statistically significant difference: infants (6-13 yrs) 1170 ± 79, sexually mature males (22-29 yrs) 639 ± 28, elderly men (64-79 yrs) 520 ± 38, sexually mature females (20-24 yrs) follicular phases: 1354 ± 90, luteal phases: 1736 ± 242, postmenopausal women (53-74 yrs) 598 ± 45. We found a linear negative correlation between serum LH and MCR of GnRH in both sexes. During male puberty the MCR_LH-RH decreased simultaneously to the stages of pubic hair development. In conclusion: 1) The MCR of GnRH is a function of age, sex, and sexual maturation, 2) its negative linear correlation with LH in both sexes indicates that the MCR presumably reflects endogenous GnRH levels, 3) the MCR_GnRH seems to be subject to endocrine regulation.

Key-Words:

Metabolic Clearance Rate (MCR) - GnRH - Linear Correlation