Sensory and inflammatory colonic changes induced by vincristine in distinct rat models of colitis

Preclinical and clinical studies show that gastrointestinal (GI) inflammation can evoke sensory changes occasionally far from the original inflammatory site. Animal models of colitis with either trinitrobenzenesulphonic acid (TNBS) or mustard oil (MO) produce distinct patterns of somatic and visceral sensory changes. We evaluated the effects of four doses of i.v. vincristine 150 μg kg⁻¹ (total of 600 μg kg⁻¹) treatment on the somatic (thermal nociceptive threshold) and colonic (morphological) changes induced by TNBS or MO in rats. TNBS and MO groups were further submitted to vincristine or saline pretreatments. TNBS induced somatic hypersensitivity, while MO induced somatic hyposensitivity (P < 0.05) when compared to the saline and ethanol control groups. Vincristine per se induced somatic hypersensitivity (P < 0.05). This effect was enhanced by TNBS and reversed by MO treatments. Although vincristine increased the colitis area (colonic weight length⁻¹ ratio) and the Morris' score in TNBS-treated rats, it did not alter the colitis area and even lowered the Morris' score in MO-treated rats. Compared to the saline (control) group, vincristine did not alter the colonic microscopic pattern. However, such lesions scores are higher (P < 0.05) in colitis groups induced by TNBS and MO, pretreated or not with vincristine. In conclusion, the somatic changes induced by different models of experimental colitis are diverse and modulated differently by vincristine.