Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 21, 2015; 21(23): 7181-7190
Published online Jun 21, 2015. doi: 10.3748/wjg.v21.i23.7181
Effects of electroacupuncture on corticotropin-releasing hormone in rats with chronic visceral hypersensitivity
Hui-Rong Liu, Xiao-Yi Fang, Huan-Gan Wu, Lu-Yi Wu, Jing Li, Zhi-Jun Weng, Xin-Xin Guo, Yu-Guang Li
Hui-Rong Liu, Xiao-Yi Fang, Yu-Guang Li, First Affiliated Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
Hui-Rong Liu, Huan-Gan Wu, Zhi-Jun Weng, Xin-Xin Guo, Shanghai Research Institute of Acupuncture and Meridian, Shanghai 200030, China
Lu-Yi Wu, Jing Li, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
Author contributions: Liu HR, Fang XY and Wu HG contributed equally to this work; Liu HR, Fang XY and Wu LY analyzed the data and wrote the paper; Liu HR, Li J, Weng ZJ and Guo XX established the animal experimental model and participated equally in animal treatment; Liu HR, Weng ZJ and Wu LY performed the molecular investigations; Li YG and Wu HG designed and coordinated the research.
Supported by China Postdoctoral Science Foundation funded project, No.200801260, No.20080430117; the National Basic Research Program of China 973 program, No.2009CB522900; and the Specialized Research Fund for the Doctoral Program of Higher Education No. 20123107110008.
Ethics approval: The study was reviewed and approved by the Shanghai University of Traditional Chinese Medicine Institutional Review Board.
Institutional animal care and use committee: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of Shanghai University of Traditional Chinese Medicine.
Conflict-of-interest: The authors declare that there is no conflict of interest regarding the publication of this paper.
Data sharing: Technical appendix, statistical code, and dataset available from the corresponding author at lhr_tcm@139.com. Participants gave informed consent for data sharing.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Yu-Guang Li, PhD, Professor, First Affiliated Hospital of Shantou University Medical College, 57 Changping Road, Shantou 515041, Guangdong Province, China. yglee317@126.com
Telephone: +86-754-88854536
Received: January 6, 2015
Peer-review started: January 6, 2015
First decision: February 10, 2015
Revised: February 26, 2015
Accepted: April 17, 2015
Article in press: April 17, 2015
Published online: June 21, 2015
Processing time: 165 Days and 7.9 Hours
Abstract

AIM: To investigate the effect of electroacupuncture on corticotropin-releasing hormone (CRH) in the colon, spinal cord, and hypothalamus of rats with chronic visceral hypersensitivity.

METHODS: A rat model of chronic visceral hypersensitivity was generated according to the internationally accepted method of colorectal balloon dilatation. In the 7th week after the procedure, rats were randomly divided into a model group (MG), electroacupuncture group (EA), and sham electroacupuncture group (S-EA). After treatment, the abdominal withdrawal reflex (AWR) score was used to assess the behavioral response of visceral hyperalgesia. Immunohistochemistry (EnVision method), ELISA, and fluorescence quantitative PCR methods were applied to detect the expression of CRH protein and mRNA in the colon, spinal cord, and hypothalamus.

RESULTS: The sensitivity of the rats to the colorectal distension stimulus applied at different strengths (20-80 mmHg) increased with increasing stimulus strength, resulting in increasing AWR scores in each group. Compared with NG, the AWR score of MG was significantly increased (P < 0.01). After conducting EA, the AWR scores of the rats were decreased compared with MG rats. The relative expression of CRH mRNA in the colon, spinal cord, and hypothalamus of MG rats was significantly increased compared with NG rats (P < 0.01). CRH mRNA in the colon and spinal cord of EA and S-EA rats was decreased to varying degrees (P > 0.05) compared with normal rats (NG). However, the decrease in EA compared with MG rats was statistically significant (P < 0.01). The average optical density of CRH expression in the colon of the MG rats was significantly enhanced compared with NG (P < 0.05), while the average optical density of CRH expression in the EA and S-EA rats was significantly decreased compared with MG rats (P < 0.01, P < 0.05, respectively). Compared with MG rats, the CRH concentration in the spinal cord of EA rats was significantly reduced (P < 0.01), but there was no significant change in S-EA rats (P > 0.05).

CONCLUSION: Electroacupuncture at the Shangjuxu acupoint was able to significantly reduce the visceral hypersensitivity in rats, and regulated the expression of CRH protein and mRNA in the colon, spinal cord and hypothalamus at different levels, playing a therapeutic role in this model of irritable bowel syndrome.

Keywords: Corticotropin-releasing hormone; Electroacupuncture; Irritable bowel syndrome; Visceral pain; Shangjuxu

Core tip: Visceral hypersensitivity is enhanced in irritable bowel syndrome (IBS) rats. Electroacupuncture at the Shangjuxu acupoint can significantly reduce the visceral hypersensitivity to colorectal distension in IBS rats, with a reduced pain threshold being observed. The expression of corticotropin-releasing hormone (CRH) protein and mRNA in the target organ and central nervous system of these rats is abnormal to varying degrees, and electroacupuncture at can regulate the expression of CRH protein and mRNA in the target organ (colon) and central nervous system (spinal cord and hypothalamus), exerting a therapeutic effect on visceral hypersensitivity in IBS rats.