Pubertal Maturation Of The Gonadotropin Alpha-Subunit (Gn-Alpha) Response To Lh-Rh In Normal And Pathological Conditions

Gnα is secreted in synchronism with LH pulses and is responsive to LH-RH administration. The changes of the Gnα response to LH-RH test were investigated throughout puberty in boys and girls. Gnα was measured by RIA, the assay specificity being assessed by chromatography on Sephadex G100. Basal and peak responses to LH-RH (x̄±sem, ng/ml) were respectively, in prepubertal boys (n=4) = 0.54 ± 0.22 and 3.4± 0.19, in pubertal boys (stage 2-3, n=4) : 0.88 ± 0.21 and 5.68 ±0.71, in prepubertal girls (n=4) : 0.30±0.15 and 4.30 ± 1.67, in pubertal girls (stage 2-3, n-4) = 0.44 ± 0.29 and 6.50 ± 1.96, in follicular phase (n=4) 1.40 ±0.39 and 7.40 ± 1.18. Peak values were significantly higher in pubertal than in prepubertal subjects. In 13 girls with precocious puberty basal and peak values were respectively 0.77 ± 0.21 and 12.1 ± 1.5 before treatment, 2.6 ± 0.85 and 7.86 ± 1.19 after 6 months of therapy with D-TRP-6-LH-RH (Deca-peptyl microcapsules). In adolescents with hypopituitarism (n=4), Gnα peak after LH-RH was only 0.28 + 0.18, in contrast with the high response in Klinefelter syndrome (n=4, 10,18 ± 2,71) and in Turner syndrome (n=4, 32.7 ± 6.33). This study confirm the parallelism of Gnα and LH secretions in various situations except in subject treated with a LH-RH agonist.