Neonatal maternal separation alters stress-induced responses to viscerosomatic nociceptive stimuli in rat

Am J Physiol Gastrointest Liver Physiol. 2002 Feb;282(2):G307-16. doi: 10.1152/ajpgi.00240.2001.


This study investigated the combined effect of neonatal maternal separation and acute psychological stress on pain responses in adult rats. Long-Evans dams and their male pups were reared under two conditions: 1) 180 min daily maternal separation (MS180) on postnatal days 2-14 or 2) no handling or separation (NH). At 2 mo of age, visceromotor responses to graded intensities of phasic colorectal distension (10-80 mmHg) at baseline as well as following acute 60 min water avoidance stress (WA) were significantly higher in MS180 rats. Both groups showed similar stress-induced visceral hyperalgesia in the presence of naloxone (20 mg/kg ip). MS180 rats had smaller stress-induced cutaneous analgesia in the tail-flick test compared with NH rats, with a residual naloxone-resistant component. MS180 rats showed an enhanced fecal pellet output following WA or exposure to a novel environment. These data suggest that early life events predispose adult Long-Evans rats to develop visceral hyperalgesia, reduced somatic analgesia, and increased colonic motility in response to an acute psychological stressor, mimicking the cardinal features of irritable bowel syndrome.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Behavior, Animal
  • Colonic Diseases, Functional / physiopathology*
  • Defecation
  • Disease Models, Animal
  • Eating
  • Female
  • Gastrointestinal Motility / physiology
  • Hyperalgesia / physiopathology
  • Male
  • Maternal Deprivation*
  • Naloxone / pharmacology
  • Narcotic Antagonists / pharmacology
  • Nociceptors / drug effects
  • Nociceptors / physiology*
  • Pain Threshold / physiology
  • Pregnancy
  • Rats
  • Rats, Long-Evans
  • Stress, Psychological / physiopathology*
  • Weight Gain


  • Narcotic Antagonists
  • Naloxone