Short-chain fatty acid enemas fail to decrease colonic hypersensitivity and inflammation in TNBS-induced colonic inflammation in rats.

BACKGROUND AND AIMS

Short-chain fatty acid (SCFA) (especially butyrate) enemas are widely used to reduce symptoms associated with human inflammatory bowel disease. The purpose of this study was to evaluate their real effect on colonic sensitivity in rats.

METHODS

The effects of saline and SCFA enemas (acetate, propionate and particularly butyrate) were studied on visceral pain thresholds following colonic distension in control rats and in rats with colitis (instilled with trinitrobenzene sulfonic acid (TNBS)).

RESULTS

Butyrate enemas (40 mM twice daily for 14 days) decreased colonic pain thresholds in control rats; they did not reduce the TNBS-induced hypersensitivity, but on the contrary increased its duration (without modifying the inflammation score). This pronociceptive effect was confirmed in control rats receiving twice daily enemas of 80 mM for 3 days and two enemas of 240 mM of a butyrate solution. The other SCFA enemas did not modify the hypersensitivity of rats with colitis and induced proinflammatory effects.

CONCLUSIONS

The beneficial effect of SCFA (especially butyrate) enemas on hypersensitivity and inflammation in inflammatory bowel disease is questionable and needs to be thoroughly investigated in humans.