title: Behavioral and cardiorespiratory responses to bilateral microinjections of oxytocin into the central nucleus of amygdala of Wistar rats, an experimental model of compulsion.
abstract: BACKGROUND
  The central nucleus of amygdala plays an important role mediating fear and anxiety responses. It is known that oxytocin microinjections into the central nucleus of amygdala induce hypergrooming, an experimental model of compulsive behavior. We evaluated the behavioral and cardiorespiratory responses of conscious rats microinjected with oxytocin into the central nucleus of amygdala.
  
  
  METHODS
  Male Wistar rats were implanted with guide cannulae into the central nucleus of amygdala and microinjected with oxytocin (0.5 µg, 1 µg) or saline. After 24 h, rats had a catheter implanted into the femoral artery for pulsatile arterial pressure measurement. The pulsatile arterial pressure was recorded at baseline conditions and data used for cardiovascular variability and baroreflex sensitivity analysis. Respiratory and behavioral parameters were assessed during this data collection session.
  
  
  RESULTS
  Microinjections of oxytocin (0.5 µg) into the central nucleus of amygdala produced hypergrooming behavior but did not change cardiorespiratory parameters. However, hypergrooming evoked by microinjections of oxytocin (1 µg) into the central nucleus of amygdala was accompanied by increase in arterial pressure, heart rate and ventilation and augmented the power of low and high (respiratory-related) frequency bands of the systolic arterial pressure spectrum. No changes were observed in power of the low and high frequency bands of the pulse interval spectrum. Baroreflex sensitivity was found lower after oxytocin microinjections, demonstrating that the oxytocin-induced pressor response may involve an inhibition of baroreflex pathways and a consequent facilitation of sympathetic outflow to the cardiovascular system.
  
  
  CONCLUSIONS
  The microinjection of oxytocin (1 µg) into the central nucleus of amygdala not only induces hypergrooming but also changes cardiorespiratory parameters. Moreover, specific oxytocin receptor antagonism attenuated hypergrooming but did not affect pressor, tachycardic and ventilatory responses to oxytocin, suggesting the involvement of distinct neural pathways.
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Érica  Maria
authors.initials: É
authors.lastname: Granjeiro
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil; Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Simone Saldanha
authors.initials: SS
authors.lastname: Marroni
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Daniel Penteado
authors.initials: DP
authors.lastname: Martins Dias
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Leni Gomes
authors.initials: LG
authors.lastname: Heck Bonagamba
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Kauê Machado
authors.initials: KM
authors.lastname: Costa
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Jéssica Cristina
authors.initials: JC
authors.lastname: dos Santos
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: José Antônio Cortes
authors.initials: JA
authors.lastname: Oliveira
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Benedito H
authors.initials: BH
authors.lastname: Machado
authors.affiliation: Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil; Department of Neuroscience and Behavioral Sciences, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Norberto
authors.initials: N
authors.lastname: Garcia-Cairasco
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D066274:Central Amygdaloid Nucleus / Q000187:drug effects* / Q000502:physiology; D003192:Compulsive Behavior / Q000503:physiopathology*; D006120:Grooming / Q000187:drug effects* / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008845:Microinjections; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018045:Receptors, Oxytocin / Q000819:agonists / Q000502:physiology; D012119:Respiration / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000502:physiology
chemical_list: D018045:Receptors, Oxytocin; D010121:Oxytocin