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Visceral analgesia induced by acute and repeated water avoidance stress in rats: sex difference in opioid involvement

Authors

  • M. Larauche,

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    • Equal contribution.

  • A. Mulak,

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    • Equal contribution.

    • Present address: Department of Gastroenterology and Hepatology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland.

  • Y. S. Kim,

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    • Present address: Gastroenterology and Digestive Disease Research Institute School of Medicine, Wonkwang University, Sanbob-dong 1142, Gunpo-si, Gyeonggi-do, South Korea.

  • J. Labus,

    1. Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Healthcare System CA, USA
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  • M. Million,

    1. Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Healthcare System CA, USA
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  • Y. Taché

    1. Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Healthcare System CA, USA
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Address for Correspondence
Muriel Larauche, Center for Neurobiology of Stress, CURE: Digestive Diseases Research Center – Animal Core, VA Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, CURE Building 115, Room 111, Los Angeles, CA 90073 USA.
Tel: +001 310 478 3711 x 41827; fax: +001 310 268-4963; e-mail:mlarauche@mednet.ucla.edu

Abstract

Background  Chronic psychological stress-induced alterations in visceral sensitivity have been predominantly assessed in male rodents. We investigated the effect of acute and repeated water avoidance stress (WAS) on the visceromotor response (VMR) to colorectal distension (CRD) and the role of opioids in male and cycling female Wistar rats using a novel non-invasive manometric technique.

Methods  After a baseline VMR (1st CRD, day 0), rats were exposed to WAS (1 h day−1) either once or for four consecutive days, without injection or with naloxone (1 mg kg−1) or saline injected subcutaneously before each WAS session.

Key Results  The VMR to CRD recorded on day 1 or 4 immediately after the last WAS was reduced in both females and males. The visceral analgesia was mainly naloxone-dependent in females, but naloxone-independent in males. In non-injected animals, on days 2 and 5, VMR was not significantly different from baseline in males whereas females exhibited a significant VMR increase at 60 mmHg on day 5. Basal CRD and CRD on days 1, 2, and 5 in both sexes without WAS induced similar VMR.

Conclusions & Inferences  When monitored non-invasively, psychological stress induces an immediate poststress visceral analgesia mediated by an opiate signaling system in females while naloxone-independent in males, and hyperalgesia at 24 h after repeated stress only in females. These data highlight the importance of sex-specific interventions to modulate visceral pain response to stress.

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