Effects of Bifidobacterium infantis 35624 on post-inflammatory visceral hypersensitivity in the rat.

Background: Irritable bowel syndrome patients have abnormal visceral perception. Probiotic organisms may produce beneficial effects in these patients by reducing visceral hypersensitivity.

Aim: To investigate the effects of the probiotic organism, Bifidobacterium infantis 35624, on post-inflammatory visceral hypersensitivity in rats.

Methods: Colitis was induced using intracolonic administration of trinitrobenzenesulfonic acid; control rats received saline (day 0). Myeloperoxidase (MPO) levels and colonic damage scores were determined. From days 15-29, rats (n = 10/group) rats were orally dosed with 2 ml of B. infantis ≥ 10(8) colony-forming units/ml or vehicle (MRS broth). A second series of rats (n = 10/group) was dosed in the same manner from days 15-59. The level of colonic stimulation during colorectal distension (CRD) was determined by recording a visceromotor response (VMR) to CRD at 30 mmHg pre- and post-treatment. Post-treatment samples of colonic tissue were weighed, graded for morphologic damage, and assayed for MPO levels.

Results: All rats were hypersensitive at day 15. On day 30, hypersensitivity to colorectal distension remained in the vehicle group, but was significantly reduced in the B. infantis group (mean VMR/10 min: vehicle = 15.4 ± 1.0 vs. B. infantis = 7.6 ± 1.0, p < 0.001). A similar, significant effect was observed at day 60. On both day 30 and day 60, tissue weight, colonic damage scores, and MPO levels resembled those of control animals.

Conclusions: Oral administration of Bifidobacterium infantis 35624 normalized sensitivity to colorectal distension in a rat model of post-inflammatory colonic hypersensitivity.