title: Activation of Supraoptic Oxytocin Neurons by Secretin Facilitates Social Recognition.
abstract: Social recognition underlies social behavior in animals, and patients with psychiatric disorders associated with social deficits show abnormalities in social recognition. Oxytocin is implicated in social behavior and has received attention as an effective treatment for sociobehavioral deficits. Secretin receptor-deficient mice show deficits in social behavior. The relationship between oxytocin and secretin concerning social behavior remains to be determined.
  
  
  
  Expression of c-Fos in oxytocin neurons and release of oxytocin from their dendrites after secretin application were investigated. Social recognition was examined after intracerebroventricular or local injection of secretin, oxytocin, or an oxytocin receptor antagonist in rats, oxytocin receptor-deficient mice, and secretin receptor-deficient mice. Electron and light microscopic immunohistochemical analysis was also performed to determine whether oxytocin neurons extend their dendrites into the medial amygdala.
  
  
  
  Supraoptic oxytocin neurons expressed the secretin receptor. Secretin activated supraoptic oxytocin neurons and facilitated oxytocin release from dendrites. Secretin increased acquisition of social recognition in an oxytocin receptor-dependent manner. Local application of secretin into the supraoptic nucleus facilitated social recognition, and this facilitation was blocked by an oxytocin receptor antagonist injected into, but not outside of, the medial amygdala. In the medial amygdala, dendrite-like thick oxytocin processes were found to extend from the supraoptic nucleus. Furthermore, oxytocin treatment restored deficits of social recognition in secretin receptor-deficient mice.
  
  
  
  The results of our study demonstrate that secretin-induced dendritic oxytocin release from supraoptic neurons enhances social recognition. The newly defined secretin-oxytocin system may lead to a possible treatment for social deficits.
authors.affiliation: Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takayanagi
authors.affiliation: Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi.
authors.forename: Masahide
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi.
authors.forename: Akihide
authors.initials: A
authors.lastname: Takashima
authors.affiliation: Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama.
authors.forename: Keiko
authors.initials: K
authors.lastname: Takanami
authors.affiliation: Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi.
authors.forename: Shoma
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Laboratory of Molecular Biology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Miyagi, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Nishimori
authors.affiliation: Department of Biobank Lifescience, Tohoku Medical Megabank Organization, Tohoku University, Miyagi, Japan.
authors.forename: Ichiko
authors.initials: I
authors.lastname: Nishijima
authors.affiliation: Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sakamoto
authors.affiliation: Department of Pediatrics, Jichi Medical University, Tochigi.
authors.forename: Takanori
authors.initials: T
authors.lastname: Yamagata
authors.affiliation: Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi. Electronic address: tonaka@jichi.ac.jp.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Onaka
mesh_terms: D000679:Amygdala / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D000818:Animals; D003712:Dendrites / Q000502:physiology; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D010121:Oxytocin / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000502:physiology; D011964:Receptors, Gastrointestinal Hormone / Q000235:genetics / Q000502:physiology; D018045:Receptors, Oxytocin / Q000235:genetics / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*; D012633:Secretin / Q000008:administration & dosage / Q000502:physiology*; D012919:Social Behavior; D013495:Supraoptic Nucleus / Q000378:metabolism / Q000502:physiology*
chemical_list: C576074:OXTR protein, mouse; D016760:Proto-Oncogene Proteins c-fos; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D018045:Receptors, Oxytocin; C029937:secretin receptor; D012633:Secretin; D010121:Oxytocin
keywords: Dendritic release; Medial amygdala; Oxytocin; Secretin; Social recognition; Supraoptic nucleus