Visceral analgesia induced by acute and repeated water avoidance stress in rats: sex difference in opioid involvement
Article first published online: 9 JUL 2012
© 2012 Blackwell Publishing Ltd
Neurogastroenterology & Motility
Volume 24, Issue 11, pages 1031–e547, November 2012
How to Cite
Larauche, M., Mulak, A., Kim, Y. S., Labus, J., Million, M. and Taché, Y. (2012), Visceral analgesia induced by acute and repeated water avoidance stress in rats: sex difference in opioid involvement. Neurogastroenterology & Motility, 24: 1031–e547. doi: 10.1111/j.1365-2982.2012.01980.x
- Issue published online: 11 OCT 2012
- Article first published online: 9 JUL 2012
- Received: 2 February 2012 Accepted for publication: 6 June 2012
- colorectal distension;
- estrous cycle;
- sex difference;
- stress-related visceral analgesia;
- water avoidance stress
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.