Sexual dimorphism, plasticity and genomic diversity of the paraventricular nucleus

Abstract

The hypothalamic paraventricular nucleus (PVN) is the nodal point for the integration of multiple homeostatic responses. Neurons in this area display both unique and overlapping phenotypic identities and functions. They control diverse, yet related, functions, such as fluid and electrolyte homeostasis, metabolism and cardiovascular integrity, via the release of vasopressin (antidiuretic hormone) and oxytocin from the neurohypophysis and adrenocorticotrophic hormone from the adenohypophysis. Pre-autonomic fibres projecting from the PVN exert potent effects on sympathetic and parasympathic outflow from the brainstem, medulla and spinal cord, and recently, a role for those neurons in the sexual dimorphism of cardiovascular health and disease has been identified. Certainly, neurons in the PVN play important roles in the control of gonadotrophin release and thus reproductive function. Not to be overlooked is the importance of PVN neurons in behavioural functions only secondarily related to reproduction or cardiovascular status, such as thirst, sodium appetite and food intake. Over the years, the phenotypic identities of multiple cell types in the PVN have been described, and connectivity studies have elucidated their targets. New ligand–receptor pairs have been discovered based upon the interactions of peptides and their receptors in the PVN. As a result of the availability of modern molecular tools and advanced behavioural screening approaches, studies examining PVN neurons continue to reveal new insights into the integrative nature of this crucially important region of the hypothalamus. The Physiology Society-sponsored symposium entitled ‘Sexual dimorphism, plasticity and genomic diversity of the paraventricular nucleus’ held on Wednesday 26 April 2017 at Experimental Biology 2017 in Chicago, IL, USA, brought together investigators whose work addresses several of these advances. Unique insight into the genomic regulation of cells in the PVN was presented by Dr Alastair Ferguson (Loewen, 2017), and a surprising view of their ability to switch phenotypes during physiological challenges highlighted the examination of cellular function introduced by Dr Jaideep Baines. Attention then was turned to the behavioural aspects of PVN function, with the focus on sex differences described by Dr Jessica Santollo (Santolo, 2017) and the importance of chromosomal sex on cardiovascular health as illustrated by Dr Jill Barnes (Barnes, 2017). Symposium reports from those speakers are included in this issue of Experimental Physiology. The organizers acknowledge the important contributions of the speakers and the support provided by The Physiological Society.