Central Circadian Control of Female Reproductive Function

Abstract

Over the past two decades, it has become clear just how much of our physiology is under the control of the suprachiasmatic nucleus (SCN) and the cell-intrinsic molecular clock that ticks with a periodicity of approximately 24 h. The SCN prepares our digestive system for meals, our adrenal axis for the stress of waking up in the morning, and the genes expressed in our muscles when we prepare to exercise. Long before molecular studies of genes such as Clock, Bmal1, and the Per homologs were possible, it was obvious that female reproductive function was under strict circadian control at every level of the hypothalamic-pituitary-gonadal axis, and in the establishment and successful maintenance of pregnancy. This review highlights our current understanding of the role that the SCN plays in regulating female reproductive physiology, with a special emphasis on the advances made possible through the use of circadian mutant mice.

Expression of a novel serine/threonine kinase gene, Ulk4, in neural progenitors during Xenopus laevis forebrain development

“…In addition there is high xUlk4 expression detected in the Xenopus hypothalamic territory, which presents a homologous regionalization pattern to the one described in mammals, as has been recently reported by an exhaustive study based on morphogenetic, neurochemical and hodological patterns (AH: supraoptoparaventricular and SCs; BH: tuberal and mammillary regions; Domı´nguez et al, 2013Domı´nguez et al, , 2014. We have observed xUlk4 expressing cells in the supraoptoparaventricular and SCs, which are closely related to the neuroendocrine system, containing neuroendocrine cells involved in the control and regulation of different physiological functions such as social and reproductive behavior, stress response and sleep among others (for a review see Markakis, 2002;Miller and Takahashi, 2013). The BH is also part of the neuroendocrine system and plays an essential role in the integration of the neuroendocrine and homeostatic functions.…”

Neuronal oscillations on an ultra‐slow timescale: daily rhythms in electrical activity and gene expression in the mammalian master circadian clockwork

“…The slow daily TTFL and electrical oscillations in SCN neurons are fundamental for providing appropriate circadian timing in physiology and behaviour, such as the sleep/wake cycle, feeding, hormone synthesis and secretion, and cardiovascular output (Kalsbeek et al, 2006;Bechtold & Loudon, 2013;Miller & Takahashi, 2013;Belle, 2015). Having such a daily timer arms organisms with the capacity to predict recurring changes in the environment, an ability that is critical for survival; maximising feeding and reproduction while avoiding predation, for example (Pittendrigh & Minis, 1972;Saunders, 1972;Ouyang et al, 1998;DeCoursey et al, 2000;Spoelstra et al, 2016).…”

Neuroendocrine underpinnings of sex differences in circadian timing systems

“…The SCN plays a critical role in female reproduction by regulating the LH surge and subsequent ovulation during the estrous cycle (reviewed in [34, 35]). Although normally the LH surge only occurs once in each estrous cycle, in ovariectomized, estrogen-treated rats, daily LH surges occur at the precisely the same time of day, every day [36, 37].…”