Pezzone MA et al. (2005) A model of neural cross-talk and irritation in the pelvis: implications for the overlap of chronic pelvic pain disorders. Gastroenterology 128: 1953–1964

Chronic pelvic pain disorders such as irritable bowel syndrome and interstitial cystitis often overlap in terms of symptoms and prevalence, and frequently occur concurrently. Pezzone and colleagues investigated the involvement of neural cross-talk in this overlap in a newly developed rodent model, and hypothesized that acute afferent irritation of one pelvic organ could sensitize another by means of shared or convergent afferent pathways.

The effects of urinary bladder irritation (performed by means of intravesical infusions) on sensory thresholds to colorectal distension, and of acute colonic irritation (with trinitrobenzene sulfonic acid) on bladder contraction frequency, were tested in urethrane-anesthetized female rats.

Electromyography measurements were taken. These demonstrated that irritation of the bladder triggered afferent colonic sensitization by means of an afferent reflex, as measured by sensitivity thresholds to graded colorectal distension. Following colonic irritation, the frequency of bladder contractions increased, suggesting that this organ had become irritated or sensitized.

The authors conclude that this is a viable model for use in further studies of pelvic inflammatory disorders and that their results provide strong evidence for bidirectional cross-sensitization of the colon and lower urinary tract. They suggest that the overlap observed between different chronic pelvic pain disorders might be a result of this cross-sensitization, and highlight the need for further research into these pathways.