title: Paraventricular nucleus neurons projecting to the dorsomedial medulla are influenced by systemic angiotensin.
abstract: Activation of subfornical organ (SFO) efferents has been reported to increase the excitability of paraventricular nucleus (PVN) neurons projecting to cardiovascular centres in the medulla. Such findings suggest a role for these neural projections in the cardiovascular effects of systemic angiotensin II (AII) acting at the SFO. The present studies examine the effects of peripheral AII (50-500 ng) on the activity of PVN neurons antidromically identified as projecting to the dorsomedial medulla (DM). A total of 68 neurons were tested, of which 25% were found to be specifically activated by AII, and 25% inhibited as a consequence the increased blood pressure accompanying administration of this peptide. The activity of the remaining neurons tested was unaffected by AII. These studies demonstrate that only a small proportion of PVN neurons projecting to the DM, which have been shown to be influenced by SFO efferents, are also activated by systemic AII. Such data do however, support a significant role for these neurons in the cardiovascular functions of SFO.
authors.affiliation: Department of Physiology, Queen's University, Kingston, Ontario, Canada.
authors.forename: A V
authors.initials: AV
authors.lastname: Ferguson
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D004594:Electrophysiology; D007275:Injections, Intravenous; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission
chemical_list: D000804:Angiotensin II