How a Key Interface Between the Brain’s Neuro-Hormonal and Vascular Systems is Assembled

The hypothalamo-neurohypophyseal system (HNS) is a major neuroendocrine interface through which the brain regulates body homeostasis by means of releasing the hypothalamic neurohormones oxytocin and arginine-vasopressin to the general circulation. The basic components of the HNS are the hypothalamic axonal projections, endothelial blood vessels and astroglial-like cells, termed pituicytes. These three tissue types converge and interact at the ventral forebrain to establish an efficient neuro-vascular interface, which allows the release of neurohormones from the brain to the periphery. However, the mechanism underlying this process and in particular the role of the pituicytes is unknown. In the adult animal, pituicytes facilitate hormone secretion from neurohypophyseal axons to the perivascular space but their exact role is still not clear. Using zebrafish as model organism, we have been studying the role of pituicytes in HNS development and function. I will present new data concerning the molecular identity and role of pituicytes in establishing a major neuroendocrine system which regulates body homeostasis in vertebrates.