Impact of psychosocial stress on gonadotrophins and sexual behaviour in females: role for cortisol?

Abstract

This review focuses on the importance of cortisol in mediating the inhibitory effects of psychosocial stress on reproduction in females. In particular, we have summarized our research in sheep where we have systematically established whether cortisol is both sufficient and necessary to suppress reproductive hormone secretion and inhibit sexual behaviour. Our findings are put into context with previous work and are used to develop important concepts as well as to identify productive further lines of investigation. It is clear that cortisol is necessary to inhibit some, but not all, aspects of reproduction in female sheep. These actions vary with reproductive state, and there are important interactions with gonadal steroids. The impact of cortisol on the tonic secretion of gonadotrophin-releasing hormone and luteinizing hormone has been investigated extensively, but less is known about the surge secretion of these hormones and their effects on sexual behaviour. Furthermore, there are separate effects of cortisol in the brain (hypothalamus) and at the anterior pituitary, illustrating that there are different mechanisms of action. Thus, although cortisol is important in mediating some of the effects of stress on reproduction, we need to look beyond cortisol and investigate some of the other mechanisms and mediators that relay the effects of stress on reproduction. In this regard, we propose that a group of neurons in the hypothalamus that co-synthesize kisspeptin, neurokinin B and dynorphin, termed KNDy cells, play important roles in mediating the effects of cortisol on reproduction. This hypothesis needs to be rigorously tested.Reproduction (2016) 152 R1-R14

Impacto del estrés por calor en la producción de ovinos de pelo. Revisión

“…El eje del estrés promueve la síntesis y liberación de cortisol en las glándulas adrenales, y esta hormona inhibe a nivel de hipotálamo la producción de la hormona liberadora de gonadotropinas (GnRH) (17) . La GnRH es necesaria para estimular la síntesis y liberación de la hormona folículo estimulante (FSH) y la hormona luteinizante (LH) en la hipófisis, y ambas hormonas hipofisiarias son necesarias para producir y liberar óvulos fértiles (19) . Dado que cortisol también se incrementa en ovinos de pelo en respuesta al EC (7) , se podrían plantear dos posibles hipótesis que explican la ausencia del efecto del EC sobre la fertilidad de ovejas de pelo: 1) una menor sensibilidad del eje reproductivo en reflejo al aumento del cortisol, y 2) el aumento en los niveles de cortisol debido a EC no son suficientes para afectar negativamente la funcionalidad del eje reproductivo.…”

Kisspeptin and the regulation of the reproductive axis in domestic animals

“…There is strong evidence that some stressors, such as heat, transport isolation/restraint, barking dog, hypoglycaemia and lipopolysaccharide injection can inhibit reproduction, at least in part via an inhibition of GnRH secretion (Tilbrook et al 2002, Einarsson et al 2008. Part of this is through cortisol, acting via the type II glucocorticoid receptor (Ralph et al 2016). GnRH neurons themselves do not express this receptor (Dufourny & Skinner 2002), but KNDy neurons do (unpublished data cited by Ralph et al 2016).…”

Influences of the stress endocrine system on the reproductive endocrine axis in sheep (Ovis aries)

“…There are cells within the hypothalamus that synthesise the neuropeptide kisspeptin, called KNDy cells, that are named after the three neuropeptides that they express, kisspeptin, neurokinin B and dynorphin (Dobson et al 2012), and are implicated in the control of GnRH secretion in the ewe (Ralph et al 2016). Kisspeptin from KNDy cells stimulates the release of GnRH from hypothalamic GnRH neurons, and oestrogen regulates GnRH synthesis by acting on kisspeptin neurons (Kageyama 2013).…”

“…As previously mentioned, kisspeptin from KNDy cells is believed to modulate the synthesis of GnRH, where the action of kisspeptin is regulated by oestradiol. It is postulated that stress suppresses GnRH in a similar manner, whereby glucocorticoids act on type II glucocorticoid receptors on KNDy cells, suppressing the expression of kisspeptin and, therefore, the synthesis of GnRH (Nestor 2012;Ralph et al 2016).…”

“…The blocking or blunting of the preovulatory LH surge results in the delay or cessation of ovulation, which can impair fertilisation. Stress during the late follicular phase of the oestrous cycle is most likely to impact the LH surge and thus affect ovulation, compared with stress during the early follicular phase or luteal phase (Ralph et al 2016). One study found that the administration of stress-like concentrations of cortisol during the luteal and follicular phase suppressed the preovulatory LH surge in ewes (Breen & Karsch 2004).…”