Canvis hormonals al llarg de la pubertat femenina

Abstract

Puberty lasts between 5 and 6 years, during which a series of physical, psychological, and

neurological changes occur, culminating in the acquisition of reproductive capacity. Puberty

is regulated by the hypothalamic-pituitary-gonadal axis (HPG), in which the gonadotropinreleasing hormone (GnRH), secreted by the hypothalamus, stimulates the secretion of folliclestimulating hormona (FSH) and luteinizing hormone (LH) by the anterior pituitary: the

biological target of both hormones is the ovaries. The HPG axis is active during three diferent

periods: fetal life, shortly after birth, a period known as minipuberty and finally, during puberty,

a stage after which it remains active throughout life. During fetal life and minipuberty,

gonadotropin levels differ between sexes, favoring specific processes and marking the

observable differences during childhood. The HPG axis remains inactive throughout

childhood, and its activation occurs at the onset of puberty. Puberty is assessed using the

Tanner stages, which classify pubertal development according to three different criteria as a

pubic hair growth and female breast development. In parallel with this external development,

various endocrine processes take place, called gonadarche, thelarche, pubarche, menarche,

and growth spurt in girls. Additionally, during the prepuberal period, adrenarche or the

activation of the adrenal gland occurs, responsible for the first secondary sexual

characteristics. The main trigger for the reactivation of pulsatile GnRH secretion at the onset

of puberty is the System of kisspeptin, neurokini B (NKB) and dynorphin A (KNDy) neurons,

although the Kisspeptin-nNOs-GnRH (KING) System is also involved. Conversely, the

MKRN3 gene inhibits the activity of the axis during childhood. The onset of puberty is

determined by genetic, epigenetic, environmental and social factors. Genetic factors explain

much of the variability in the onset and progression of puberty, such that the presence of

mutations in specific genes is associated with precocious puberty or delayed puberty.

However, various epigenetiic mechanisms that regulate the expression of key genes involved

in pubertal activation have recently been studied. Finally, with regard to environmental and

social factors, it has been observed that they can alter the functionality of the HPG axis

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