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Mechanism of puberty
1London Centre for Paediatric Endocrinology, Great Ormond Street Hospital for Children and The Middlesex Hospital, London, UK. c.brook@ucl.ac.uk
Insights
The hypothalamo-pituitary-gonadal axis is functional at birth, declines in childhood, and reactivates for puberty. Understanding these changes in gonadotropin pulsatility is key to explaining pubertal development.
Area of Science:
- Pediatric Endocrinology
- Reproductive Biology
- Neuroendocrinology
Background:
- The hypothalamo-pituitary-gonadal (HPG) axis is functional in fetal life and infancy.
- HPG axis activity declines during childhood, reaching a nadir in gonadotropin pulsatility around age 6.
- The reasons for this decline and subsequent reactivation are not fully understood.
Purpose of the Study:
- To explore the developmental trajectory of the hypothalamo-pituitary-gonadal axis in children.
- To elucidate the mechanisms underlying the decline and reappearance of gonadotropin pulsatility.
- To explain the hormonal basis of pubertal development and sex differences in growth spurts.
Main Methods:
- This study is a review of existing literature on pediatric HPG axis function.
- Analysis of developmental patterns of gonadotropin-releasing hormone (GnRH) and gonadotropin secretion.
- Examination of the role of sex steroids (estradiol and testosterone) in pubertal development and growth.
Main Results:
- Pubertal events are driven by pulsatile GnRH stimulation, leading to gonadotropin release and sex steroid production.
- Sex steroids mediate the development of secondary sexual characteristics.
- Differential effects of estradiol and testosterone on growth hormone secretion explain earlier pubertal growth spurts in girls.
Conclusions:
- The pulsatile nature of GnRH and gonadotropin secretion is fundamental to initiating and maintaining puberty.
- Sex steroids play a crucial role in pubertal maturation and contribute to observed sex differences in growth patterns.
- Further research is needed to fully understand the regulatory mechanisms governing HPG axis activity during childhood.
Abstract:
The hypothalamo-pituitary-gonadal axis in children is fully functional in fetal life and immediately after birth. The reason why it declines with advancing years of childhood is not clear but gonadotropin pulsatility is at a nadir at 6 years of age. From that time pulsatile gonadotropin starts to reappear but, again, the reason why this happens is completely unknown. All of the events of puberty can be ascribed to pulsatile gonadotropin-releasing hormone stimulation causing pulsatile gonadotropin stimulation of sex steroids. The sex steroids explain the development of the pubertal characteristics; the fact that girls have an earlier growth spurt than boys is explained by the differential effect of oestradiol and testosterone on hypothalamic control of pituitary growth hormone secretion.