Oxytocin modulates unconditioned fear response in lactating dams: an fMRI study

Brain Res. 2009 Dec 11:1302:183-93. doi: 10.1016/j.brainres.2009.09.043. Epub 2009 Sep 18.

Abstract

Oxytocinergic neurotransmission during lactation contributes to reduction of anxiety levels and fear. However, our knowledge of where oxytocin acts in the brain to achieve this effect, particularly to an unconditioned fear stimulus, is incomplete. We used blood oxygenation level dependent (BOLD) fMRI to test whether central administration of oxytocin 45-60 min before fMRI scanning alters maternal brain activation in response to a predator scent (TMT, trimethylthiazoline). Comparison behavioral experiments that examined maternal responses to this unconditioned fear-inducing odor were carried out in a separate cohort of lactating rats given similar treatments. Behavioral experiments confirmed the effectiveness of oxytocin at reducing freezing behavior as compared to vehicle controls. Our fMRI findings indicate that oxytocin modulated both positive and negative BOLD responses across several olfactory and forebrain nuclei. Significantly greater percent increases in BOLD signal in response to TMT were observed in the anterior cingulate, bed nucleus of stria terminalis and perirhinal area of oxytocin pretreated rats. These animals also showed significantly larger percent decreases in BOLD in mammillary bodies, secondary motor cortex, gustatory cortex, prelimbic prefrontal cortex, orbital cortex, and the anterior olfactory nucleus. The observed pattern of brain activity suggests that oxytocin enhances neural processing in emotion and cognition driven brain areas such as the cingulate cortex, while dramatically reducing activity in areas also controlling autonomic, visceromotor and skeletomotor responses. The present data contribute to the growing literature suggesting the oxytocin modulate the integration of emotional and cognitive information through myriad brain regions to facilitate decreases in anxiety (even to an unconditioned stimulus) while potentially promoting pair-bonding, social memory and parental care.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Anxiety / drug therapy
  • Anxiety / metabolism*
  • Anxiety / physiopathology
  • Autonomic Nervous System / anatomy & histology
  • Autonomic Nervous System / drug effects
  • Autonomic Nervous System / physiology
  • Behavior, Animal / drug effects
  • Behavior, Animal / physiology*
  • Brain / anatomy & histology
  • Brain / drug effects
  • Brain / physiology*
  • Brain Mapping
  • Cerebrovascular Circulation / drug effects
  • Cerebrovascular Circulation / physiology
  • Cognition / drug effects
  • Cognition / physiology
  • Emotions / drug effects
  • Emotions / physiology
  • Fear / drug effects*
  • Fear / physiology
  • Lactation / physiology*
  • Lactation / psychology
  • Limbic System / anatomy & histology
  • Limbic System / drug effects
  • Limbic System / physiology
  • Magnetic Resonance Imaging
  • Odorants
  • Olfactory Pathways / anatomy & histology
  • Olfactory Pathways / drug effects
  • Olfactory Pathways / physiology
  • Oxytocin / metabolism*
  • Oxytocin / pharmacology
  • Predatory Behavior / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Sexual Behavior, Animal / drug effects
  • Sexual Behavior, Animal / physiology
  • Smell / drug effects
  • Smell / physiology
  • Social Behavior

Substances

  • Oxytocin