Sexual Maturation in Girls and the Development of Estrogen-Induced Gonadotropic Hormone Release

Abstract

SUMMARYDuring all developmental stages of female puberty (P i -P j ) plasma LH and FSH concentration determined by radioimmunoassay decreased after a single i.m. injection of 50 ygfkg estradiol-dipropionate in oil. This decrease coincidenced with the peaking level of circulating estradiol (measured by radioimmunoassay).Only in the group of girls in an advanced stage of puberty (premenarche P 4 ) this initial nadir was followed by a secondary increase in plasma LH concentration but not in that of FSH. This secondary increase occurred during the period of decreasing level of circulating estradiol. However, only in two of the five girls at this advanced stage of puberty (P 4 ) the maximum of plasma LH approached the value of the preovulatory plasma LH peak in adult women. These results suggest that the potential for a stimulatory (positive) estrogen feedback response appears after midpuberty at the stage P 4 .It has been demonstrated in rats that the mechanism of the stimulatory (positive) feedback action of estrogen on gonadotropin release becomes operative at a low level of sensitivity long before estrarche. The concentration of circulating endogenous estrogen up to that time seems insufhcient to trigger the release (PnESi, ! al., 1968, i97z ; CALIGARIS et al., 1 972 ). In contrast, in female rhesus monkeys estrogen induced gonadotropin surges were not demonstrable until some months after menarche (DIERSCHKE et al., 1974 ). In the present study, serial determinations of plasma LH and FSH levels have been made in healthy prepubertal and pubertal girls to discover the stage of female sexual development at which the stimulatory estrogen feedback mechanism attains a level of sensitivity at which an acute increase in circulating estrogen concentration induced by a single administration of steroid is able to cause the characteristic gonadotropin release.

Ovarian oestrogen-dependent maturation of the LH/FSH surge mechanism during prepubertal development in the gilt

“…However, although the interval to the surge response is characteristic of the mature ewe, the amplitude of the LH response is reduced and shows a progressive increase during development. In contrast, in man and rhesus monkeys the surge mechanism will only respond to oestrogen stimulation in the postmenarchial period (see Dierschke, Karsch, Weick et al 1974 ;Dierschke, Weiss & Knobil, 19746;Grumbach, Roth, Kaplan & Kelch, 1974;Presi, Horejsi, Stroufova & Herzmann, 1976).…”

Landmarks in the development of the female reproductive system

“…Gonadotropes acquire the capacity to respond to the stimulatory action of estradiol on LH and FSH secretion after menarche (Dierschke et al, 1974;Reiter et al, 1974;Presl et al, 1976;Terasawa, 1983).…”

“…As in the rat, there is an early postnatal rise in gonadotropin secretion in the human and monkey, followed by a reduction lasting from late infancy to the end of the prepubertal period (Dierschke et al, 1974;Reiter et al, 1974;Presl et al, 1976;Terasawa and Fernandez, 2001). Until about 12 to 24 months in girls, the ovaries respond to the increased follicle-stimulating hormone (FSH) by secreting estradiol reaching levels that are not again achieved before the onset of puberty (Brook, 1999;Grumbach, 2002).…”

“…Estradiol concentrations increase at initial stages of puberty at 2.5 to 3 years in the non-human primate (Terasawa et al, 1983;Wilson et al, 1986) and at 8 to 10 years in the human (Jenner et al, 1972;Bidlingmaier et al, 1973;Winter and Faiman, 1973;. Gonadotrophs acquire the capacity to respond to the stimulatory action of estradiol on LH secretion after menarche (Dierschke et al, 1974;Reiter et al, 1974;Presl et al, 1976). The onset of puberty in the human is marked by an increase in the amplitude of LH pulses, which is taken to indicate an increase in the amplitude of GnRH pulses.…”

When Puberty is Precocious

“…Although the suppressive effect is probably operative from late fetal life on, the positive action of endogenous (or exogenous) E 2 on gonadotropin release has not been demonstrated in normal prepubertal and early pubertal children (15,180,253). Hence, acquisition of positive feedback, a requisite for ovulation, is a late maturational event in puberty and, from the present evidence, probably does not occur before midpuberty in normal girls (15,180,253,254). Among the requirements for a positive feedback action of E 2 on gonadotropin release at puberty (180) are ovarian follicles primed by FSH to secrete sufficient E 2 to reach and maintain a critical level in the circulation, a pituitary gland that is sensitized to GnRH and contains a large enough pool of releasable LH to support an LH surge, and (controversial in the human, but not in lower animals) sufficient GnRH stores for the GnRH neurosecretory neurons to respond with an acute sustained increase in GnRH release in addition to the usual adult pattern of pulsatile GnRH secretion.…”