Affiliation: | 1. Department of Physiology and Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand Correspondence to: C. H. Brown, Department of Physiology, University of Otago, PO Box 913, Dunedin 9054, New Zealand (e-mail: colin.brown@otago.ac.nz).;2. Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Canada;3. Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK;4. Department of Physiology, Georgia Regents University, Augusta, GA, USA |
Abstract: | The hypothalamic supraoptic and paraventricular nuclei contain magnocellular neurosecretory cells (MNCs) that project to the posterior pituitary gland where they secrete either oxytocin or vasopressin (the antidiuretic hormone) into the circulation. Oxytocin is important for delivery at birth and is essential for milk ejection during suckling. Vasopressin primarily promotes water reabsorption in the kidney to maintain body fluid balance, but also increases vasoconstriction. The profile of oxytocin and vasopressin secretion is principally determined by the pattern of action potentials initiated at the cell bodies. Although it has long been known that the activity of MNCs depends upon afferent inputs that relay information on reproductive, osmotic and cardiovascular status, it has recently become clear that activity depends critically on local regulation by glial cells, as well as intrinsic regulation by the MNCs themselves. Here, we provide an overview of recent advances in our understanding of how intrinsic and local extrinsic mechanisms integrate with afferent inputs to generate appropriate physiological regulation of oxytocin and vasopressin MNC activity. |