Original Article
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World J Gastroenterol. Mar 7, 2014; 20(9): 2365-2373
Published online Mar 7, 2014. doi: 10.3748/wjg.v20.i9.2365
Sweet food improves chronic stress-induced irritable bowel syndrome-like symptoms in rats
Sang-Gyun Rho, Yong Sung Kim, Suck Chei Choi, Moon Young Lee
Sang-Gyun Rho, Department of Emergency Medical Services, Sunmoon University, Chungnam Asan 336-708, South Korea
Yong Sung Kim, Department of Gastroenterology and Wonkwang Digestive Disease Research Institute, Wonkwang University Sanbon Hospital, Gyeonggi Gunpo 435-040, South Korea
Suck Chei Choi, Department of Gastroenterology and Wonkwang Digestive Disease Research Institute, School of Medicine, Wonkwang University, Jeonbuk Iksan 570-974, South Korea
Moon Young Lee, Department of Physiology and Institute of Wonkwang Medical Science and Wonkwang Digestive Disease Research Institute, School of Medicine, Wonkwang University, Jeonbuk Iksan 570-749, South Korea
Author contributions: Rho SG and Lee MY performed the majority of experiments; Rho SG contributed to the acquisition and analysis of data, making the draft of the manuscript and to provide funding; Kim YS contributed to make the conception and design of the study, interpretation of data and revision of the manuscript; Choi SC participated in making the conception and design of the study and contributed to the interpretation of data; Lee MY contributed to the making of conception and design of the study, analysis and interpretation of data, revision of the manuscript, approval of the final version of the manuscript.
Supported by 2011 Sunmoon University in South Korea
Correspondence to: Moon Young Lee, MD, PhD, Department of Physiology and Institute of Wonkwang Medical Science and Wonkwang Digestive Disease Research Institute, School of Medicine, Wonkwang University, Shinyong-Dong 344-2, Iksan, Jeonbuk Iksan 570-749, South Korea. lmy6774@wku.ac.kr
Telephone: +82-63-8506774 Fax: +82-63-8526108
Received: October 30, 2013
Revised: December 6, 2013
Accepted: January 3, 2014
Published online: March 7, 2014
Processing time: 127 Days and 0.3 Hours
Abstract

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 3 groups: 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-γ in 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.

Keywords: Irritable bowel syndrome; Colon; Stress; Adrenal hormones; Cytokines; Rat

Core tip: Stress has an important role in the pathogenesis of irritable bowel syndrome (IBS), and palatable foods have been used as an ameliorator for psychological stress. Several reports have supported the hypothesis that palatable foods are used for consolation from psychological stress. Thus we hypothesized that hypothalamic-pituitary-adrenal axis function and immune status in the plasma and colon could be altered by chronic stress, and these changes could be attenuated by concurrent ingestion of sweet food. These results imply that reducing the effect of stress appropriately by any means is important for preventing induces gastrointestinal symptoms in a patient with IBS.