title: Effects of Salt Loading on the Regulation of Rat Hypothalamic Magnocellular Neurosecretory Cells by Ionotropic GABA and Glycine Receptors.
abstract: Synaptic and extrasynaptic transmission mediated by ionotropic GABA and glycine receptors plays a critical role in shaping the action potential firing (spiking) activity of hypothalamic magnocellular neurosecretory cells and therefore determines the rate at which vasopressin and oxytocin are released from the neurohypophysis. The inhibitory effect of these transmitters relies on the maintenance of a low concentration of intracellular chloride ions such that, when activated by GABA or glycine, a hyperpolarisation of the neuronal membrane potential results. In this review, we highlight the various ways by which the two types of inhibitory receptors contribute to homeostasis by fine-tuning the spiking rate of vasopressin-releasing magnocellular neurosecretory cells in a manner dependent on the hydration state of the animal. In addition, we review the currently available evidence on how the strength of these inhibitory pathways can be regulated during chronic hypernatraemia via a form of activity-dependent depolarisation of the chloride reversal potential, leading to an abolition of these inhibitory pathways potentially causing sodium-dependent elevations in blood pressure.
authors.affiliation: Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, Canada.
authors.forename: K Y
authors.initials: KY
authors.lastname: Choe
authors.affiliation: Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Trudel
authors.affiliation: Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, Canada.
authors.forename: C W
authors.initials: CW
authors.lastname: Bourque
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D007031:Hypothalamus / Q000166:cytology* / Q000187:drug effects*; D010121:Oxytocin / Q000502:physiology; D018079:Receptors, GABA / Q000502:physiology*; D018009:Receptors, Glycine / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology*; D014667:Vasopressins / Q000378:metabolism
chemical_list: D018079:Receptors, GABA; D018009:Receptors, Glycine; D014667:Vasopressins; D012965:Sodium Chloride; D010121:Oxytocin
keywords: GABA; KCC2; TrkB receptor; arterial pressure; baroreceptor; brain-derived neurotrophic factor; chloride; glycine; inhibition; osmolality; oxytocin; salt loading; supraoptic nucleus; vasopressin