J Neurogastroenterol Motil 2018; 24(4): 656-668  https://doi.org/10.5056/jnm18037
MicroRNA-200a Targets Cannabinoid Receptor 1 and Serotonin Transporter to Increase Visceral Hyperalgesia in Diarrhea-predominant Irritable Bowel Syndrome Rats
Qiuke Hou,1 Yongquan Huang,2 Changrong Zhang,1 Shuilian Zhu,1 Peiwu Li,1 Xinlin Chen,3 Zhengkun Hou,1 and Fengbin Liu1*
1Department of Gastroenterology, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; 2Department of Orthopedics, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China; and 3Department of Preventive Medicine and Health Statistics, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
Correspondence to: Fengbin Liu, MD
Department of Gastroenterology, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Qiuke Hou, No.12, Jichang Road, Guangzhou, Guangdong 510405, China
Tel: +86-136-94239909, Fax: +86-020-36591109, E-mail: liufb163@126.com
Qiuke Hou and Yongquan Huang contributed equally to this work.
Received: March 3, 2018; Revised: July 1, 2018; Accepted: July 12, 2018; Published online: October 1, 2018.
© The Korean Society of Neurogastroenterology and Motility. All rights reserved.

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Abstract
Background/Aims
MicroRNAs (miRNAs) were reported to be responsible for intestinal permeability in diarrhea-predominant irritable bowel syndrome (IBS-D) rats in our previous study. However, whether and how miRNAs regulate visceral hypersensitivity in IBS-D remains largely unknown.
Methods
We established the IBS-D rat model and evaluated it using the nociceptive visceral hypersensitivity test, myeloperoxidase activity assay, restraint stress-induced defecation, and electromyographic (EMG) activity. The distal colon was subjected to miRNA microarray analysis followed by isolation and culture of colonic epithelial cells (CECs). Bioinformatic analysis and further experiments, including dual luciferase assays, quantitative real-time polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay, were used to detect the expression of miRNAs and how it regulates visceral hypersensitivity in IBS-D rats.
Results
The IBS-D rat model was successfully established. A total of 24 miRNAs were differentially expressed in the distal colon of IBS-D rats; 9 were upregulated and 15 were downregulated. Among them, the most significant upregulation was miR-200a, accompanied by downregulation of cannabinoid receptor 1 (CNR1) and serotonin transporter (SERT). MiR-200a mimic markedly inhibited the expression of CNR1/SERT. Bioinformatic analysis and luciferase assay confirmed that CNR1/SERT are direct targets of miR-200a. Rescue experiments that overexpressed CNR1/SERT significantly abolished the inhibitory effect of miR-200a on the IBS-D rats CECs.
Conclusions
This study suggests that miR-200a could induce visceral hyperalgesia by targeting the downregulation of CNR1 and SERT, aggravating or leading to the development and progression of IBS-D. MiR-200a may be a regulator of visceral hypersensitivity, which provides potential targets for the treatment of IBS-D.
Keywords: CNR1; Diarrhea; Hypersensitivity; Irritable bowel syndrome; MiR-200a; SERT


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