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Charles W Bourque"Central mechanisms of osmosensation and systemic osmoregulation."

Abstract :


Systemic osmoregulation is a vital process whereby changes in plasma osmolality, detected by central osmoreceptors, modulate ingestive behaviors, sympathetic outflow and renal function to stabilize the tonicity and volume of the extracellular fluid. Recent work has shown osmosensory neurons transduce osmotic perturbations via the volume-dependent control of ion channels encoded by the transient receptor potential vanilloid 1 (trpv1) gene, and that encoded osmosensory information is transmitted to homeostatic effector neurons via glutamatergic synapses. Changes in the sensitivity (gain) of osmoregulatory reflexes play an important role in preserving homeostasis under specific conditions. During sleep for example, the osmotic control of vasopressin (antidiuretic hormone) release is sensitized to optimize water conservation at a time when water intake is curtailed. Osmotically-induced vasopressin release is also facilitated during hyperthermia (e.g. caused by exercise or exposure to ambient heat) and hypovolemia (e.g. after hemorrhage or during dehydration) to facilitate fluid volume recovery. Dr Bourque will present recent work from his laboratory that has explored how centrally-induced changes in cellular osmosensory transduction and synaptic efficacy may modulate osmoregulatory gain. Specifically, Dr. Bourque will describe how clock neurons in the suprachiasmatic nucleus facilitate osmosensory signaling during the late stage of sleep, and how central release of angiotensin II may sensitize both osmosensory detection and synaptic signaling to enhance homeostatic reflex gain during hypovolemia.

Selected publications

Bourque CW (2008). Central mechanisms of osmosensation and systemic osmoregulation. Nature Reviews Neuroscience 9: 519-531.