60 YEARS OF NEUROENDOCRINOLOGY: The hypothalamo-pituitary–gonadal axis

Abstract

This review provides an outline of how our understanding of the neuroendocrine control of the hypothalamo-pituitary–gonadal axis has evolved since the publication of Geoffrey Harris' renowned monograph in 1955. Particular attention is directed to the neurobiology underlying pulsatile GnRH release from the hypothalamus, the neuroendocrine control of ovarian cycles, puberty and seasonality of gonadal function, and to ideas that have emerged as a result of examining the relationship between growth and the reproductive axis. The review closes with i) a brief discussion of how knowledge gained as a result of pursing the early hypotheses of Harris has led to major clinical and therapeutic applications, and ii) a personal glimpse into the future of research in this fascinating area of biology.

The Impact of Gonadal Hormones on the Expression of Human Neurological Disorders

“…In rhesus monkeys, exposure to prenatal androgens can both masculinize and defeminize various reproductive and nonreproductive juvenile and adult behaviors [13]. Finally, unlike the situation in rodents, fetal androgen exposure does not abrogate the positive feedback effect of estradiol on hypothalamic release of GnRH in adult primates [15]. …”

Advantages of pulsatile hormone treatment for assessing hormone-induced gene expression by cultured rat Sertoli cells

“…In vivo, Sc are exposed to FSH and T in a pulsatile manner rather than a constant fashion (Sharpe 1994;Plant 2015). These hormone-pulses are generated by the unique secretary nature of FSH and luteinizing hormone (LH) in the circulation from the pituitary, which is further governed by gonadotrophin-releasing hormone (GnRH) pulses generated by hypothalamus (Plant 2015).…”

“…These hormone-pulses are generated by the unique secretary nature of FSH and luteinizing hormone (LH) in the circulation from the pituitary, which is further governed by gonadotrophin-releasing hormone (GnRH) pulses generated by hypothalamus (Plant 2015). This typical pulsatile pattern of hormonal secretion is an important regulator to gain optimal hormonal action (Plant 2015).…”

A presença do hormônio concentrador de melanina no ovário no ciclo reprodutivo de ratas<i> Sprague-Dawley</i>.

“…[FSH] onde a cada 4 ou 5 dias, em ratos, apresenta um aumento de liberação dessas gonadotropinas, promovendo a ovulação (Plant, 2015). O estradiol secretado pelos folículos em desenvolvimento exerce um efeito de feedback negativo em nível hipofisário e hipotalâmico durante essa fase folicular, sendo que esse efeito de feedback no hipotálamo se dá via receptores do tipo alfa de estrógeno em neurônios que apresentam kisspeptinas, neurocinina B e dinorfina, peptídeos moduladores da secreção de gonadotropina no ARC (Levine, 1997;Lehman, Coolen, Goodman, 2010;Yeo, Herbison, 2014;Plant, 2015).…”

“…O estradiol secretado pelos folículos em desenvolvimento exerce um efeito de feedback negativo em nível hipofisário e hipotalâmico durante essa fase folicular, sendo que esse efeito de feedback no hipotálamo se dá via receptores do tipo alfa de estrógeno em neurônios que apresentam kisspeptinas, neurocinina B e dinorfina, peptídeos moduladores da secreção de gonadotropina no ARC (Levine, 1997;Lehman, Coolen, Goodman, 2010;Yeo, Herbison, 2014;Plant, 2015). Dessa forma, esse efeito de feedback negativo parece ser modulador da amplitude dos pulsos de liberação de GnRH (Plant, 2015). Esse feedback negativo é tempo e dose-dependente (Couzinet, Schaison, 1993).…”