Sexual dimorphism in the maturation of the pituitary-gonadal axis, assessed by GnRH agonist challenge

Hormonal Laboratory, University of Barcelona, Barcelona, Spain.

OBJECTIVE: To assess whether the maturational changes of the pituitary--gonadal axis in a healthy population show gender-specific changes and to establish normative data for the different Tanner stages. DESIGN: Prospective, cross-sectional study. METHODS: The GnRH agonist leuprolide acetate (500 microgram) was administered s.c. to 60 boys and 81 girls (age range, 5--17 years). Serum steroids and gonadotropins were determined at 0 and 24 h and at 0, 3 and 24 h after GnRH agonist challenge respectively, whereas IGF-I, IGF-binding protein-1 (IGFBP-1), IGFBP-3 and sex hormone-binding globulin were measured at baseline. RESULTS: Baseline and peak LH responses to the agonist in late puberty, and basal and peak FSH levels at all Tanner stages, were higher in girls than in boys. Girls showed higher IGF-I levels than boys throughout puberty, sharper decreases in IGFBP-1 and earlier and greater increases in 17-hydroxypregnenolone, dehydroepiandrosterone (DHEA) and DHEA-sulfate. Testosterone responses to the agonist increased during puberty in males, and showed no changes in females. Conversely, estradiol responses rose throughout puberty in females and remained unchanged until late puberty in males. CONCLUSION: Leuprolide acetate stimulates gonadotropin and gonadal steroid secretion during puberty in both sexes and increases FSH levels in prepubertal girls. Pubertal maturation of gonadotrope function is gender specific, as it appears to involve increases in both the releasable and reserve pools of LH in males, and of LH and FSH in females. The earlier increase in Delta(5)-steroids in girls may suggest a sharper rise in ovarian cytochrome P450c17 activity along the Delta(5)-steroid pathway, while the failure of estradiol to increase in response to leuprolide acetate in early pubertal males suggests a late maturation of aromatase activity.

This article has been cited by other articles:

				J. F. Dorgan, R. P. McMahon, L. A. Friedman, L. Van Horn, L. G. Snetselaar, P. O. Kwiterovich Jr., R. M. Lauer, N. L. Lasser, V. J. Stevens, A. Robson, et al. Diet and Sex Hormones in Boys: Findings from the Dietary Intervention Study in Children J. Clin. Endocrinol. Metab., October 1, 2006; 91(10): 3992 - 3996. [Abstract] [Full Text] [PDF]

				A. A. Rooney, R. A. Matulka, and R. W. Luebke Developmental Atrazine Exposure Suppresses Immune Function in Male, but not Female Sprague-Dawley Rats Toxicol. Sci., December 1, 2003; 76(2): 366 - 375. [Abstract] [Full Text] [PDF]

				L. Ibanez and F. de Zegher Flutamide-Metformin Therapy to Reduce Fat Mass in Hyperinsulinemic Ovarian Hyperandrogenism: Effects in Adolescents and in Women on Third-Generation Oral Contraception J. Clin. Endocrinol. Metab., October 1, 2003; 88(10): 4720 - 4724. [Abstract] [Full Text] [PDF]

				L. Ibanez, K. Ong, A. Ferrer, R. Amin, D. Dunger, and F. de Zegher Low-Dose Flutamide-Metformin Therapy Reverses Insulin Resistance and Reduces Fat Mass in Nonobese Adolescents with Ovarian Hyperandrogenism J. Clin. Endocrinol. Metab., June 1, 2003; 88(6): 2600 - 2606. [Abstract] [Full Text] [PDF]

				L. Ibanez, K. Ong, N. Potau, M. V. Marcos, F. de Zegher, and D. Dunger Insulin Gene Variable Number of Tandem Repeat Genotype and the Low Birth Weight, Precocious Pubarche, and Hyperinsulinism Sequence J. Clin. Endocrinol. Metab., December 1, 2001; 86(12): 5788 - 5793. [Abstract] [Full Text] [PDF]

				L. Ibáñez, C. Valls, N. Potau, M. V. Marcos, and F. de Zegher Sensitization to Insulin in Adolescent Girls to Normalize Hirsutism, Hyperandrogenism, Oligomenorrhea, Dyslipidemia, and Hyperinsulinism after Precocious Pubarche J. Clin. Endocrinol. Metab., October 1, 2000; 85(10): 3526 - 3530. [Abstract] [Full Text]

				L. Ibáñez, N. Potau, M. V. Marcos, and F. de Zegher Treatment of Hirsutism, Hyperandrogenism, Oligomenorrhea, Dyslipidemia, and Hyperinsulinism in Nonobese, Adolescent Girls: Effect of Flutamide J. Clin. Endocrinol. Metab., September 1, 2000; 85(9): 3251 - 3255. [Abstract] [Full Text]