Acupoint Specificity on Colorectal Hypersensitivity Alleviated by Acupuncture and the Correlation with the Brain–Gut Axis

This project was focused on the study of the effect of the different acupoints on visceral hypersensitivity and the correlation with the brain–gut axis. By using a mouse model of zymosan-induced colorectal hypersensitivity, and observing the response of hypersensitivity model to colorectal distension stimulation in acupuncture at different acupoints, we selected the specific acupoints. With immunohistochemical staining method, we observed c-fos expression, distribution and changes after acupuncture on sensory pathway, including colorectum, spinal dorsal horn and different regions of brain center in the model with colorectal distension stimulation, and evaluated the acupuncture effect on brain–gut axis. The results revealed that the effectiveness of acupuncture for alleviating visceral hypersensitivity was different at individual acupoint, meaning Tianshu (ST25), Zusanli (ST36) and Shangjuxu (ST37) > Quchi (LI11) and Dachangshu (BL25) > Ciliao (BL32). C-fos expression was concentrated in anterior cingulate cortex, hypothalamus, spinal dorsal horn and colorectum in model of zymosan-induced colorectal hypersensitivity and it was down-regulated after acupuncture. The results demonstrates that the acupoint specificity presents in acupuncture for relieving visceral hypersensitivity and the effects are more predominated at the acupoints on stomach meridian innervated by the same or adjacent spinal ganglion segments. The model of zymosan-induced colorectal hypersensitivity can be the animal model simulating brain–gut interaction.