Neuropeptide and steroid hormone mediators of neuroendocrine regulation

Abstract

To maintain the health and well-being of all mammals, numerous aspects of physiology are controlled by neuroendocrine mechanisms. These mechanisms ultimately enable communication between neurones and glands throughout the body and are centrally mediated by neuropeptides and/or steroid hormones. A recent session at the International Workshop in Neuroendocrinology highlighted the essential roles of some of these neuropeptide and steroid hormone mediators in the neuroendocrine regulation of stress-, reproduction- and behaviour-related processes. Accordingly, the present review highlights topics presented in this session, including the role of the neuropeptides corticotrophin-releasing factor and gonadotrophin-releasing hormone in stress and reproductive physiology, respectively. Additionally, it details an important role for gonadal sex steroids in the development of behavioural sex preference.

Keywords: corticotrophin-releasing factor; gonadotrophin-releasing hormone; neuroactive steroids; neuropetides; reproduction; stress.

Figure 1.

The ovarian follicle contains two main cellular compartments: the granulosa cell layer and the theca cell layer. These compartments are separated by the basal lamina such that blood vessels only contact the theca cells and release FSH there. Upon diffusion, FSH can influence the function of granulosa cells by binding their FSH receptors. FSH acts on granulosa cells to increase the activity of the non-neuronal cholinergic system of the ovarian follicle. Within this system, ACh acts through its muscarinic receptors to elevate intracellular calcium which leads to transcription factor changes, breakdown of gap junction communication, and activation of ion channels. Together, these actions promote growth in granulosa cells. AChE inactivates ACh and thereby limits its actions.