Sweet food improves chronic stress-induced irritable bowel syndrome-like symptoms in rats

AIM:To investigate whether palatable sweet foods have a beneficial effect on chronic stress-induced colonic motility and inflammatory cytokines.METHODS:Adult male rats were divided into 3groups:control(CON,n=5),chronic variable stress with chow(CVS-A,n=6),and chronic variable stress with chow and sweet food(CVS-B,n=6).The rats were fed standard rodent chow as the chow food and/or AIN-76A as the sweet food.A food preference test for AIN-76A was performed in another group of normal rats(n=10)for twelve days.Fecal pellet output(FPO)was measured for 6 wk during water bedding stress in the CVS groups.The weight of the adrenal glands,adrenocorticotropic hormone(ACTH)and corticosterone levels in plasma were measured.The expression levels of transforming growth factor-β,interleukin(IL)-2,and interferon-gamma(IFN-γ)were measured in the distal part of colonic tissues and plasma using Western blot analysis.RESULTS:In sweet preference test,all rats initially preferred sweet food to chow food.However,the consumption rate of sweet food gradually decreased and reduced to below 50%of total intake eight days after sweet food feeding.Accumulated FPO was higher in the CVS-A group compared with the CVS-B group over time.All stress groups showed significant increases in the adrenal to body weight ratio(CVS-A,0.14±0.01;CVS-B,0.14±0.01)compared with the control group(0.12±0.01,P<0.05).The plasma corticosterone and ACTH levels were significantly higher in the CVS-A(537.42±32.95,44.44±6.54 pg/mL)and CVS-B(655.07±30.82,65.46±4.44 pg/mL)groups than in the control group(46.96±13.29,8.51±1.35 pg/mL,P<0.05).Notably,the ratio of corticosterone to ACTH was significantly increased in the CVS-A group only.Rats exposed to CVS displayed significantly increased expression of IL-2 and IFN-γin the plasma and distal colon compared to the control group,whereas this effect was significantly attenuated in the CVS-B group.CONCLUSION:These results suggest that concurrent sweet food ingestion during CVS might have an effect on the reduction of stress-induced colonic hyper-motility and pro-inflammatory cytokine production in rats.