Neuroendocrine interactions of the stress and reproductive axes

Abstract

Reproduction is controlled by a sequential regulation of the hypothalamo-pituitary-gonadal (HPG) axis. The HPG axis integrates multiple inputs to maintain proper reproductive functions. It has long been demonstrated that stress alters fertility. Nonetheless, the central mechanisms of how stress interacts with the reproductive system are not fully understood. One of the major pathways that is activated during the stress response is the hypothalamo-pituitary-adrenal (HPA) axis. In this review, we discuss several aspects of the interactions between these two neuroendocrine systems to offer insights to mechanisms of how the HPA and HPG axes interact. We have also included discussions of other systems, for example GABA-producing neurons, where they are informative to the overall picture of stress effects on reproduction.

Keywords: CRH; Reproduction; Sex steroids; Stress.

Figure 1.

Schematic diagram of how components of HPA axis act on central components of HPG axis. A) In the presence of estradiol, activation of CRHR1 increases GABAergic inputs to GnRH neurons and increases firing activity of GnRH neurons. Corticosterone appears to suppress activity of kisspeptin neurons both in the AVPV and ARC populations. B) In the absence of estradiol, effects of CRH and corticosterone on the HPG axis are markedly diminished.