Neonatal maternal separation alters stress-induced responses to viscerosomatic nociceptive stimuli in rat.
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.
Coutinho
S V
SV
UCLA/CURE Neuroenteric Disease Program and Brain Research Institute, Department of Medicine, University of California at Los Angeles School of Medicine, 11301 Wilshire Blvd., Los Angeles, CA 90095, USA.
Plotsky
P M
PM
Sablad
M
M
Miller
J C
JC
Zhou
H
H
Bayati
A I
AI
McRoberts
J A
JA
Mayer
E A
EA
D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D003109:Colonic Diseases, Functional / Q000503:physiopathology*; D003672:Defecation; D004195:Disease Models, Animal; D004435:Eating; D005260:Female; D005769:Gastrointestinal Motility / Q000502:physiology; D006930:Hyperalgesia / Q000503:physiopathology; D008297:Male; D008426:Maternal Deprivation; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D020318:Rats, Long-Evans; D013315:Stress, Psychological / Q000503:physiopathology*; D015430:Weight Gain
D009292:Narcotic Antagonists; D009270:Naloxone