Electroacupuncture alleviates zymosan-induced colorectal hypersensitivity.

Abstract

Objective: this study to investigate the mechanism underlying the electroacupuncture (EA) alleviates colorectal hypersensitivity, a feature of irritable bowel syndrome (IBS).

Methods: The colorectal hypersensitivity model was established by treating mice with zymosan. Electrophysiological techniques, Western blotting and immunofluorescence staining were used to detect the changes of the sensitive state of the colorectum and the response in spinal ganglion and spinal cord after acupuncture intervention.

Results: colorectal distension studies revealed that repetitive applied electroacupuncture treatment on mice could significant alleviates colorectal intensity. Western blotting studies with nerve growth factor (NGF) in the colorectum, substance P (SP) in the spinal ganglion, protein kinase C gamma (PKCγ) in the spinal cord, and transient receptor potential vanilloid 1 (TRPV1) showed that electroacupuncture suppressed zymosan-induced expression of TRPV1, NGF and SP in multiple tissues. Immunofluorescence labeling results showed that EA attenuated the expression of NGF in the colorectum, SP in the spinal ganglion, PKCγ in the spinal cord, and TRPV1 in all three tissues in zymosan-treated mice. Moreover, the number of neurons double-positive for TRPV1/Isolectin B4 (IB4) and TRPV1/Neurofilament (NF) 200 was increased in the spinal ganglion.

Conclusion: these results provide molecular-level evidence that EA alleviates zymosan-induced colorectal hypersensitivity by altering the expression of pain-associated proteins in the colorectum and spinal cord. EA has a potential to be therapeutic intervention option for IBS treatment.