title: Neuronal actions of oxytocin on the subfornical organ of male rats.
abstract: The aim of this study was to investigate effects of oxytocin (OT) on electrical neuronal activities in rat subfornical organ (SFO) and compare its action with the well-described excitatory effects of blood-borne angiotensin II (ANG II) on the same SFO neurons. With the use of extracellular recordings from spontaneously active neurons in slice preparations of the SFO of male rats, 11.7% of tested neurons (n = 206) were excited and 9.7% were inhibited by superfusion with 10(-6) M OT. Both excitatory and inhibitory effects of OT were dose dependent with similar threshold concentrations and were blocked by a specific OT-receptor antagonist but not by a vasopressin receptor antagonist. Blocking synaptic transmission with low calcium medium suppressed only inhibitory effects of OT. All but one of the OT-sensitive neurons were also excited by superfusion with ANG II at a concentration much lower than required for OT, suggesting that synaptically released OT rather than blood-borne OT alters the activity of SFO neurons in vivo. The results support the hypothesis that neurally released OT may modulate SFO-mediated functions by acting on OT-sensitive neurons.
authors.affiliation: Department of Physiology, School of Allied Health Sciences, Osaka University Faculty of Medicine, Suita, Osaka 565-0871, Japan. hosono@sahs.med.osaka-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Hosono
authors.forename: H A
authors.initials: HA
authors.lastname: Schmid
authors.forename: K
authors.initials: K
authors.lastname: Kanosue
authors.forename: E
authors.initials: E
authors.lastname: Simon
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000008:administration & dosage; D003470:Culture Media / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D066298:In Vitro Techniques; D008297:Male; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors; D013356:Subfornical Organ / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D003470:Culture Media; D018045:Receptors, Oxytocin; D000804:Angiotensin II; D010121:Oxytocin; D002118:Calcium