title: Mild Social Stress in Mice Produces Opioid-Mediated Analgesia in Visceral but Not Somatic Pain States.
abstract: Visceral pain has a greater emotional component than somatic pain. To determine if the stress-induced analgesic response is differentially expressed in visceral versus somatic pain states, we studied the effects of a mild social stressor in either acute visceral or somatic pain states in mice. We show that the presence of an unfamiliar conspecific mouse (stranger) in an adjacent cubicle of a standard transparent observation box produced elevated plasma corticosterone levels compared with mice tested alone, suggesting that the mere presence of a stranger is stressful. We then observed noxious visceral or somatic stimulation-induced nociceptive behavior in mice tested alone or in mildly stressful conditions (ie, beside an unfamiliar stranger). Compared with mice tested alone, the presence of a stranger produced a dramatic opioid-dependent reduction in pain behavior associated with visceral but not somatic pain. This social stress-induced reduction of visceral pain behavior relied on visual but not auditory/olfactory cues. These findings suggest that visceral pain states may provoke heightened responsiveness to mild stressors, an effect that could interfere with testing outcomes during simultaneous behavioral testing of multiple rodents.
  
  
  
  In mice, mild social stress due to the presence of an unfamiliar conspecific mouse reduces pain behavior associated with noxious visceral but not somatic stimulation, suggesting that stress responsiveness may be enhanced in visceral pain versus somatic pain states.
authors.affiliation: National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, Maryland. Electronic address: mark.pitcher@nih.gov.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Pitcher
authors.affiliation: Department of Pharmacology, University of Granada, Granada, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Gonzalez-Cano
authors.affiliation: Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, Canada.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Vincent
authors.affiliation: National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland.
authors.forename: Michael
authors.initials: M
authors.lastname: Lehmann
authors.affiliation: Department of Pharmacology, University of Granada, Granada, Spain.
authors.forename: Enrique J
authors.initials: EJ
authors.lastname: Cobos
authors.affiliation: Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, Canada.
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Coderre
authors.affiliation: Department of Pharmacology, University of Granada, Granada, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Baeyens
authors.affiliation: Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec, Canada.
authors.forename: Fernando
authors.initials: F
authors.lastname: Cervero
mesh_terms: D019342:Acetic Acid; D000818:Animals; D002211:Capsaicin; D003345:Corticosterone / Q000097:blood; D003463:Cues; D004195:Disease Models, Animal; D005557:Formaldehyde; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D059225:Nociception / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000378:metabolism* / Q000523:psychology*; D011957:Receptors, Opioid / Q000378:metabolism*; D021641:Recognition, Psychology; D012919:Social Behavior; D013315:Stress, Psychological / Q000378:metabolism*; D014796:Visual Perception
chemical_list: D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D005557:Formaldehyde; D009270:Naloxone; D019342:Acetic Acid; D002211:Capsaicin; D003345:Corticosterone
keywords: Visceral pain; mice; somatic pain; stress; stress-induced analgesia