Assessment of visceral pain-related pseudo-affective responses to colorectal distension in mice by intracolonic manometric recordings.

Abstract Recently, a new manometric method has been proposed to quantify visceromotor responses (VMR) to colorectal distension (CRD) in rats. This method is based on monitoring pressure changes within the distending balloon during CRD. This study assesses the applicability of such a technique to the quantification of VMRs to CRD in mice. Electrical activity of the abdominal muscles and pressure changes within the distending balloon (mechanical response) were simultaneously recorded in conscious mice during CRD (phasic ascending, 10-80 mm Hg, or repetitive, 55 mm Hg). There was a clear stimulus-response relationship with a strong correlation between electrical and mechanical responses during the ascending (r 2 = 0.899, n = 7) or repetitive phasic CRD (r 2 = 0.926, n = 8). Repetitive phasic distensions (55 mm Hg) increased the mechanical and electrical responses by 71 ± 20% and 42 ± 16%, respectively (pulses 10-12 vs. 1-3; n = 8, both P Perspective The model presented to assess visceral pain in mice allows a broad use of this species in pharmacological studies and will be of use in the characterization of potential targets and new drugs for the treatment of human pathologies with visceral pain arising from the gut as a significant component.