A new model of chronic visceral hypersensitivity in adult rats induced by colon irritation during postnatal development

Visceral and Somatic Hypersensitivity in TNBS-Induced Colitis in Rats

“…Collectively, these somatic symptoms are consistent with the possibility that patients with chronic visceral pain disorders may also suffer from central hyperalgesic dysfunction [44]. In fact recent investigations suggest that in both animal models and patients with chronic visceral pain there is evidence of referred somatic hypersensitivity [19,[45][46][47][48]. These findings are different from earlier studies which have revealed somatic hyposensitivity in patients with chronic visceral pain disorders such as inflammatory bowel disease and IBS [3,4,[49][50][51][52].…”

“…All rats treated with TNBS had colitis (+2-+3) characterized by diffuse infiltration of neutrophils in the lamina propia with severe interstitial edema as previously described (Al Chaer et al, 2000). The colitis was present at all of the time points: 2, 7, 14, 21, and 28 days following TNBS administration each group of rats were euthanized.…”

“…The tissue was fixed in formalin and processed using standard techniques for H & E staining. The severity of the lesions in the colon and mucosa were graded using a system previously described [19]. The grades of colitis included: mild (+1) infiltration of a limited number of neutrophils in the lamina propria with minimal interstitial edema; moderate (+2) infiltration of a moderate number of neutrophils in the lamina propria with moderate interstitial edema; severe (+3) diffuse infiltration of neutrophils in the lamina propria with severe interstitial edema.…”

Interference of age and repetition of the same noxious stimulus on hyperalgesia

“…Recently, several authors have purposed detailed theories of how nociceptive stimuli modify central nervous system (Zelter et al 1997, Al-Chaer et al 2000, Ruda et al 2000, Bhutta et al 2001, Melzak et al 2001. Although it's known that precocious stimuli modulates sensitive pathways and response to pain later, the amount of injured tissue necessary to modulate such alterations is to discuss (Walker et al 2009).…”

“…Children of different ages may experience the same painful stimulus, however, due to differences on development of the ability to graduate and report stimuli or other pain components, responses may vary largely (Goodenough et al 1999, Al-Chaer et al 2000. Some authors postulate that children and adults may see pain as a stress and functional disability generator.…”